Capacitors FAQ
What's a capacitor? What they do and when to use one

C
apacitors store up power from your battery, then release it to your amp during peak demand for more consistent bass. They are often used as a buffer zone between your amp and your car's electrical system to prevent the car's lights from dimming during loud playback. But how does a capacitor work? Do you really need one?
» What's a capacitor used for?
» What size capacitor should I get?
Q: What's a capacitor?
A: A capacitor, or cap, is an electronic component that can take up, store, and discharge electrical energy. Because they can do all that quickly, capacitors are used to filter or buffer any sudden changes in a circuit's voltage, smoothing the ensuing signal.
Q: What's a capacitor used for?
A: In car audio, large outboard capacitors, sometimes called stiffening caps, are used to prevent lights from dimming when loud bass notes play. They accomplish this by supplying the amplifier with a quick jolt of power.
Q: Even if my lights don't dim, won't a capacitor still improve my system's low end response and overall sound?
A: Not really. A cap prevents the sound from deteriorating due to under-voltage, but doesn't actually improve the sound. It supports the amplifier by feeding it the power it needs for short bursts. So, while not improving sound quality directly, a cap does make it easier for the amp to perform its best.
Q: What size capacitor should I get?
A: The rule of thumb is to put in 1 Farad of capacitance for every 1,000 watts RMS of total system power. But there is no electronic penalty for using larger value caps, and in fact, many see benefits with 2 or 3 Farads per 1,000 watts RMS. The larger the cap, the more charge is available for the amp when it needs it.
Get everything you need
Give your subwoofer amp the boost it needs with a capacitor. We also have all the installation hardware you need to get your capacitor and amplifier up and running.
Q: How do I hook up a capacitor?
A: If you don't have the instructions that came with your capacitor, you should know first off that a cap can be dangerous. It can charge and discharge so much power so very quickly that it can weld metal objects, like tools and jewelry, and melt its own insides out.
A new cap comes completely discharged, so it's safe. A resistor or wired light bulb usually is included in the package. Wiring the bulb or resister across the cap's terminals allows the capacitor to discharge slowly and safely. The same bulb or resistor, wired differently, also gets used to charge up the cap safely.
As in all car electronic installations, start by disconnecting the ground cable from the car battery. In this installation, also take out the in-line fuse on the amp's power wire next to the battery.
A capacitor should be mounted as close to the sub amp as possible using the shortest wires possible. This is so the extra charge doesn't have far to go to get to the amp quickly. Make sure the cap gets mounted securely and won't become a dangerous flying object in the event of an accident.
A capacitor has two poles: a positive and a negative. They should be clearly marked on the capacitor. The positive connects to the same positive power lead that goes to your sub amp's positive, 12 volt, connection. Use the same gauge wire as the amp uses for its power. This can be accomplished with a distribution block. Or, sometimes, the cap comes with multiple connection terminals that make it easier to wire it into your system. The multiple terminals act just like a distribution block so, for instance, the power wire coming from your battery can connect directly to the cap's positive terminal while a short cable connects from there to the amp's positive power connection. The negative pole of the capacitor connects to your chassis ground, just like the amp. The best practice is to use the same bolt the amp uses for ground. Make sure all the paint is scraped off around where you put the chassis ground and the connections are clean and tight.
Next, you need to charge up your capacitor. If done too quickly — it could "pop," destroying the cap.
If you don't have the original charging/discharging resistor or light, you'll need to get one. An automotive 12-volt test light, the kind with a bulb, not a small LED, will do nicely. Otherwise, you can use a high-wattage, low resistance resistor, available at most electronics parts stores. The exact value doesn't matter, but get one with a value of 10-1,000 ohms along with a rating of 1-20 watts. The lower the resistance, the higher the wattage should be.
Take the test light or resistor and connect it to the two terminals of the amp's in-line fuse holder (where you took the fuse out earlier). Re-connect the car battery's ground cable. The resistor will get hot, or the bulb will light up, while the cap charges. After 10 to 30 minutes, the bulb will fade out, or the resistor will start to cool. Remove the light or resistor carefully — they can get very hot. As you replace the fuse, you may experience a small spark — that's okay, but should remind you of how powerful the electric forces involved are. Your capacitor is now installed.
Q: My capacitor has a third terminal. What's that for?
A: Some caps come with a built-in meter that displays the voltage. If a meter were to stay on constantly, it could drain the car's battery. So caps with meters often have a remote turn-on lead connection, just like car amplifiers, so the meter turns off with the system. A thin, 18-ga. or so, wire should run from the cap's turn-on connection to the amplifier's remote turn-on terminal, or any other switched 12 volt power source.

T-Spec 3.0-farad capacitor
Reader comments (215 responses)
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Devin Wayne from bellevue
Posted on 7/26/2020
Hello buck. I know you may have answered this properly but I seem to be getting multiple answers all over. I have an enclosed sub/amp going into distribution block and amp for door speakers going in as well. The instructions on my CAP say to wire CAP into distribution block? But I keep seeing diagrams to wire DIRECTLY before the sub. Would I get the same quality of use if I connect it to distribution block? Thank you!
on 7/29/2020
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Rob Mendez from Central Islip
Posted on 6/27/2020
Hello beautiful people! My question is simple yet important. I have a capacitor, Main power going to cap, power from cap to distribution block, to amps. I'm swapping out one of my amps, my question is in regards of safety. I know it's obvious to unplug battery before anything, but do I unplug my power going from cap to distribution block as well before replacing amp? The amp is in the distribution block separated, so I was thinking unplugging the battery wouldn't be enough as the cap still supplies power to the distribution block, which will cause a huge spark when I connect the new amp. Please help I'm so confused!!
on 6/29/2020
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Jaime Tomas Cascante from Orange Park
Posted on 6/4/2020
Should I use an in line fuse for a capacitor. If so how do I determine what size fuse?
on 6/5/2020
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Baylee Vannorsdall from Valley Springs
Posted on 5/22/2020
I bought a 3 Ferry cap from you guys and it didn't come with a resistor and my truck lights still dim and it acts like I'm brake checking someone when I turn my bass up I thought it would help but it didn't
on 5/25/2020
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Jason Fewer from Mentone
Posted on 5/20/2020
I have tried charging 2 different raptor capacitor 2.5 farad. My question is on both separate caps it would only charge to 5.7 volt reading on my multimeter. I returned the 1st one and explained what happened got a new one and same thing 5.7 volts no more. Any ideas why this is happening?
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Matt W from San Francisco
Posted on 5/16/2020
I have a 17 year old car (only about 75,000 miles) that I want to keep running for years to come. If I install a capacitor, will it reduce wear and tear on the alternator? Or will the effect be minimal
on 5/18/2020
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Chris from Long Beach
Posted on 5/16/2020
I installed my capacitor and the display hasn't come on since I initially installed it. Does this mean it has gone bad?
on 5/19/2020
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Jose from Brentwood
Posted on 5/12/2020
I hooked it up not noticing i put +wire in the - post and vice versa. Now my cap is hot? Only left on few seconds. Cap was beeping.. Whats my next move?
on 5/13/2020
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Danny Grayson from EL RENO
Posted on 5/11/2020
I have a little over 1500 watts rms coming from three amps to three 12" subs. I've also accumulated three .5 farad Scosche caps over time. My question is, aside from, "as close to the sub amps as possible," is there a certain way that would be more effective to wire my caps in? Any help would be appreciated
on 5/12/2020
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Caiphus from Midrand
Posted on 5/5/2020
Is there any cap that can be connected right next before the loudspeaker
on 5/6/2020
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Lee Volk from Seymour
Posted on 4/16/2020
I have a 4 or 6 farad lighting cap and my question is can I run 0 gauge wire to my cap and then run 4 gauge to my amp
on 4/18/2020
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Jason from Denver
Posted on 4/9/2020
I have a scosche bass .5 farad capacitor, a new 750 CCA battery, all. Power wire is 4 guage. The Cap is less than 1 foot away from my Orion mono Dblock 5000 Watt amp. It's powering a Soundstream 1500 watt 1 ohm pro competition sub in a sealed box. The alternator is 130 amp. My capacitor will intermintantly not work sometimes. Causing the amp to cut out. What could be causing this? And is there a way to test my cap or is it not big enough for my system?
on 4/10/2020
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c from Abilene
Posted on 3/25/2020
I was going to use a 1 farad cap for a Rockford 500 watt prime monoblock, but its class D. Now I'm thinking I should use the cap on my 4x100 rms class a/b amp feeding 4 6.5s. Any thoughts?
on 3/26/2020
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Christopher.Abby from 7311 NW Lybyer Dr
Posted on 3/3/2020
A person's success does not depend on his wisdom, but perseverance
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dakota ash from scranton
Posted on 1/29/2020
can you run the positive and negitive to fuse boxes? i have a two 4/8 gauge fuse block spliters one has power and the other is a ground i palned on hooking one cable from the block to the cap and another from the block to the amp, but not directly connected cap to amp. dose this still work?
on 1/30/2020
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Milikona from Hawaii
Posted on 1/9/2020
I have a compasitor with remote wire but I did not hook up the remote only the positive and negative will it still work with out the numbers on
on 1/9/2020
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Joe
Posted on 1/8/2020
So if my cap only has 1 positive and 1 negative terminal can I run my single four channel amp's positive to the cap's positive and the amp's negative to the cap's negative? Thank you
on 1/9/2020
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Remy Charles from Castries
Posted on 1/1/2020
I have a total of 11,800 rms from my 3 amps what size power capacity should i get
on 1/2/2020
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Allen S from Pinole, CA
Posted on 11/21/2019
I have the T-Spec 1.5 Farad Capacitor and was just recently dealing with some rumbling noise going through the subwoofer. It wasn't engine related and sounded rather rough, like the wind blowing past your ears on a fast moving boat. It wasn't there initially until i drove on a bumpy back road and things shifted slightly in the trunk (I'll work on that later.) Today, I noticed the mounting board with the capacitor had slid about 2 inches back from the rear seats (that are covered by thin carpet.) Suddenly the noise was gone again. I noticed that I also had the sub RCA cables running close to where the capacitor head was located. What I'm wondering is, could this be possible interference through the RCA cables due to proximity, and if so, are there any rubber caps that I can put over the +/- terminals on the capacitor? Even if it's not the issue, I'd like to have those things covered in case someone's hand slips up and somehow hits both terminals at the same time... Or could this possibly be a near ground loop issue given the proximity of the cap terminals to the back seat? (i.e. being too far forward and almost making contact with the seat metal)
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Allen S from Pinole, CA
Posted on 11/14/2019
I'm putting a system I previously built back into my car, but noticed instructions for the capacitor were different from my original design. Originally, I had the battery lead going to the capacitor, and then back out to the distribution block. Then from the block, out to two separate amps. The instructions that came with my new capacitor have the cap wired up *after* the distribution block. Does it matter if it's wired before the block or after? One amp is for a 12" subwoofer, the other is just for my door speakers and doesn't require much power at all. Everything seemed to work fine in the past, I just want to make sure the ideology hasn't changed since.
on 11/15/2019
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elias
Posted on 11/3/2019
Can I use this for a 1800 Watt Amp
on 11/4/2019
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Johnathan McClendon from West Point
Posted on 10/9/2019
I have a dark audio dki 10 wired to 1 ohm and a audiopipe APMI 1500. My interior lights and license plate tags are dimming, I have led headlights so I can't tell if they are dimming or not. What size capacitor would you recommend? Or should I upgrade battery under the hood? My car is a 2018 Toyota Camry SE.
on 10/10/2019
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Jason from Aurora
Posted on 10/5/2019
Would it not be wise to install an adequately sized diode on the 12v+ line before it connects to a capacitor; so other accessories dont, sap the power from the cap, basically isolating it to the subs ?
on 10/5/2019
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Tiaan van Niekerk from Johannesburg
Posted on 9/30/2019
Would a capacitor remove alternator whine from my old amp?
on 10/1/2019
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Imran patel from GUJARAT, INDIA
Posted on 8/24/2019
Hi I have 2.4 farad capasitor. Manufacture date on the Package is of 2014 but it is never used and is in fully packed condition. is it safe to use this capasitor after this long period ? Or should i skip it?? Thanks in advance
on 8/26/2019
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John Brannon from Valdosta
Posted on 7/30/2019
I have a 2018 kia optima I have 2 12s with a 900 watt amp an a cap here recently my system has been going in and out an i watch my cap i can see the digits go up and down and then they go blank what causes that ive checked my wires an connections??
on 8/1/2019
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Daniel from Wixom
Posted on 7/3/2019
Hi Buck, in my 2014 Ford Taurus SHO with the factory Sony surround system, I am experiencing my sub not hitting nearly as hard when I have the volume turned up. I am going to purchase a single farad cap for my 250 watt Kicker DX. I am concerned that my factory Ford Sync system will fool the cap to not trigger the "auto turn-off" feature, thus draining my battery. Have you experienced this on any of the new infotainment systems?
on 7/3/2019
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Ivan from Chicago
Posted on 7/2/2019
I have a 2011 Cadillac CTS Wagon and installed 2 JL Audio 12TW3-D4 with JL Audio JX1000/1D at 1 OHM. I hooked it up to the factory Bose subwoofer connection and eliminated the Bose subwoofer. The interior lights dim when the bass hits. Would you recommend a specific cap for this?
on 7/3/2019
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karzi from kask
Posted on 6/28/2019
hey, i have a question about my capacitor , had my system installed on my old car it was working so fine , before i sold it , i removed the amps , capacitor and forget to discharge the cap , when i bought a new car i installed it again , but i found that its draining my battery, should i get a new capacitor ?
on 7/1/2019
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Jordan Bae from Middletown
Posted on 4/13/2019
1 capacitor for for 2 mv500s and a old Sony Xmas-3060 or one for each?
on 4/15/2019
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Lady J from Atlanta,GA
Posted on 4/1/2019
I have 2 audio pipe amps with 1500 watts one for the mids and one for the subs. I just recently bought a 1200 watt capacitor and when I play the sound my bass does not hit at all and when I turn the volume up to 15 my sound goes in and out on the left side. Could it be that the capacitor watts are too low and I need to put another 1200 watts with it? I need help please
on 4/1/2019
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DustinC from Fairfax,VT
Posted on 3/31/2019
I recently purchased a Alpine mv-500 wired to a 2ohm dvc kivker03cvr154 15in, when I changed boxes I noticed the sub was only wired to 1 voice coil, and it use to dim my lights VERY NOTICIBLY, I re wired the sub to 4ohm for the new box and have allot less dimming now, was wiring it to 1 voice coil actually a 2ohm final and drawing more power? I've read many articles saying it's fine to wire to 1 voice coil of a dvc speaker. But can't find ANYTHING about what that makes my impedance. I'm trying to get closer to the factory speaker specs as possible and it's not a 1ohm stable amplifier.
on 4/1/2019
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Neil Lizotte from Edmonton
Posted on 3/11/2019
What would a good price be for a 18 volts 1000 farrads capacitor made with graphene and no heat or battery management issues?
on 3/13/2019
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Rob Duchene from Cape Coral
Posted on 2/17/2019
I own a 2016 Dodge Challenger Scat Pack. I've read the stock alternator is rated at 220A. I'm unsure how much is needed for vehicle operation. My plan is to power 2 Kicker S12L7 with a Precision Power Black ICE 7000.1D ran at 1 ohm final. How do I correctly calculate expected current draw to figure out if I can add a capacitor or if I will require upgrading the alternator? (I'm hoping to avoid the latter) Thank you
on 2/18/2019
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Fuzzybarrel4563 from San Leandro
Posted on 1/22/2019
Are capacitors used only in subwoofer applications or can they be applied to a full range amplifier running the door speakers?
on 1/24/2019
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David Peterman from Chesapeake
Posted on 11/19/2018
Ive got a 04 hyundai elantra stock battery stock alternator. I was using a 500w rockford and memphis set up in my jeep with barely any noticeable problems( lights dimming) but im afraid with the smaller battery in the Elantra and the fact im also wanting to install a set of 4 Rockford speakers with 400w amp im going to be using to much power. I was thinking about getting a bigger battery and installing a 1farad cap. I figured 1farad would be fine considering i have 900 total rms watts. My question is there should be no problems with a speaker and sub system sharing a cap is there? Is there a problem with putting my cap under the hood if im going to put the amps under both front seats? Caps are suppose to be as close to amps as possible so is that to far? Thank you guys
on 11/20/2018
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Brandon
Posted on 10/16/2018
I have a 2001 F250 and the engine pulls so much of the batteries to turn over that the head unit starts and resets whenever I start the truck. The whole system goes in and out of protect mode while driving. I assume the issue is the current draw for the system from the batteries, but should 4 65W infinity speakers run off a 704a amp cause an issue like this? If it's just the electrical draw, a capacitor should help right?
on 10/16/2018
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Daniel Larson from Hurricane
Posted on 10/9/2018
Can I use a trickle charger to charge the cap?
on 10/10/2018
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Jack Bhakta from San Antonio
Posted on 9/28/2018
I am going to be using a small 200 watt 2 channel MTX sub amp to a 300w rms 10" sub in a sealed box. Currently, my lights dim EVEN with the factory audio system, when I hold up my power window switch after the window is shut. The stock alternator is only 1 year old, and puts out only 80 amps, but an upgraded one with 130 amps can be installed. Can I save money and parts by just using an existing functional old 0.5 farad capacitor, to help buffer the load and premature wear on my car's electrical charging system?
on 9/28/2018
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Normy from Carson
Posted on 9/5/2018
Good afternoon. Question I am running cxa 1200.1 amp to kicker 10L7 in custom tune box. Will I need a capacitor
on 9/7/2018
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Melissa Taylor from Canistota
Posted on 9/4/2018
Do I have to run to remote wires one to the amp and another to the capacitor? Or can I one and splice it
on 9/7/2018
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William from Highspire
Posted on 7/21/2018
I got a 12" kicker it's 1500 watts Max is 2500 was thinking about getting a 2000 watt amp what would be a good capacitor to get for it
on 7/21/2018
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Satan's Helper from Waterboro
Posted on 7/21/2018
I currently have a Sub box with two 12" Kicker subs and a Skar Audio 1000w amp. I haven't hooked anything up yet. I'm also planning on purchasing 4 Kicker door speakers and another Skar Audio 1000w amp. One will be a mono block (which I have), one a A/B (which I want). My question is with this setup, can I run two amps off one huge capacitor or do I need two capacitors to two amps? I'm thinking an 8 or 10 Farad would be more than sufficient. Thank you.
on 7/21/2018
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Joshua Essig from Glenwood
Posted on 7/18/2018
Your instructions say to ground the amp and the capacitor to the same point. I have always been told to ground the capacitor at a different point. I plan on two 1000 watt amps and two 1.5 F caps. Should I be... A) grounding all 4 wires to 1 point. B) grounding amps to caps like parallel speakers then 2 cap grounds to 1 point, or C) amps to 1 ground point and caps to a separate ground point not inline with audio equipment grounds?
on 7/19/2018
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Kevin nieto from Los Angeles
Posted on 6/5/2018
I have a small set up which is: Rockford Fosgate 801S Rockford Fosgate Punch Power 250.2 2x kicker comp VR 12" The 250 is powering all of my mid and tweeters 801s subwoofers. The lights do dim slightly with this set up will I need a capacitor?
on 6/6/2018
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Buck Pomerantz from Crutchfield
Posted on 6/1/2018
Mike, I don't know that a capacitor would do any good in your situation. I'd more likely look into getting a higher-output alternator.
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Mike from Freehold
Posted on 5/19/2018
I was looking at using a capacitor in my racecar that uses a small lithium battery. I have a good amount of electronics in the car. Problem is I have a 30amp electronic shift solenoid that controls and shifts my sequential dog box (manual transmission) and currently the lights dim and voltage drops during every shift which also effects my fuel/ timing tuning. Would I be able to use an audio capacitor and wire it in as if the shift solenoid was an amp or is there a better solution. A larger battery is not an option due to space constraints.. Would a capacitor help?
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Buck Pomerantz from Crutchfield
Posted on 4/18/2018
Shawn, Usually, capacitors are used in high-power systems to ensure constant power supply voltage. I doubt a 5.7-watt system would ever need a capacitor. But maybe I'm misunderstanding. Not knowing what your system consists of makes it impossible to give advice about it.
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Shawn Kahn from San Jose
Posted on 4/18/2018
Great article Buck. I have a slightly different setup that is been discussed here. I have a ClassD amplifier driving max power of 30W speaker with an average power close to 7.5W. I have 1uF capacitance to support the 24V rail. Does 1F per 1000W rule of thumb applies here. Is there a way to calculate exact needed capacitance based of system parameters? Thanks
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Buck Pomerantz from Crutchfield
Posted on 3/26/2018
Rick, For the short wire runs on a motorcycle, I doubt you'd notice any difference.
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Rick Bice from Zanesville
Posted on 3/24/2018
I am hooking up a sound system on a Yamaha motorcycle with the watt amp in the fairing. The battery is under the seat. There is no room for a capacitor anywhere else but in a saddlebags. My questions is can I just run a + and - 4 age wire to the battery and get the same benefit as having the capacitor right next to the amp?
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Buck Pomerantz from Crutchfield
Posted on 2/21/2018
Tomas, You are correct - the wire terminals for the T-Spec 3.0 Farad capacitor fit 8- to 4-gauge wire. The good news is that a few feet of 4-gauge wire is not expensive.
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Tomas from Lamar
Posted on 2/20/2018
My amp's 1/0 power and grounding cables look too large to fit in Crutchfield's 3.0 farad capacitor. I'm not sure if my eyes are fooling me, but if they aren't, how can I make this capacitor fit into my system without getting different power cables?
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steve carey from Richfield
Posted on 1/19/2018
how do i hook my capacitor and amp when the amp has [ +cap ] [12vpower] [grd] [ -cap] [remote]
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Buck Pomerantz from Crutchfield
Posted on 1/2/2018
Alex, A capacitor can potentially charge up instantaneously, and then explode. A capacitor should be charged up using a resistor or light bulb, so that it charges up slowly and safely. That procedure doesn't take more than 5 to 30 seconds to accomplish.
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Alex Bainter from Puyallup
Posted on 1/2/2018
How fast can a 2000 watt 2 farad capacitor charge?
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Buck Pomerantz from Crutchfield
Posted on 12/15/2017
Bradley, Every capacitor has an ESR (equivalent series resistance) factor that will act like a small drain on a battery over time. A great solution for you is to get a battery maintainer, like a RetroSound Exile EX-1 Battery Keeper.
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Buck Pomerantz from Crutchfield
Posted on 12/15/2017
Brad, That amplifier shouldn't go into protect mode at those voltages. It sounds like something's wrong with the amp and it needs repair or replacement.
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Bradley
Posted on 12/15/2017
Hi, I know you've had a thousand variations of the same question. I've read a bit and thanks for the responses. As I understand when it comes to the capacitor charge when the car is off it is like a part of the battery. So excluding any bad wiring or parasitic draws it can maintain the charge so long as the battery is fine. For instance, my car battery can go 2 months when I'm away for work when my family neglects to crank it over like I ask. So in essence the cap isn't drawing and will stay charged with the battery as long as they're attached properly? I get double checking the cap would be wise after that long to be safe. I have a bluetooth OBDII that has a tiny drain but has never killed my battery. Is the capacitor causing a drain, but one that is so nominal like the bluetooth dongle it's almost certainly another issue if the capacitor and battery is dead when I get back? I will run from the rear deepcycle battery a fuse rated below the the proper gauge wire but above what is necessary for the amps to a 3 farad cap to a two fuse block each fuse sized for each amp. The cap and 2 way will be right beside both 1500 watt amps.
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Brad Keys from St Thomas, USVI
Posted on 11/11/2017
I have a Rockford fosgate amp that keeps going into protection mode only when I increase engine rpm. I've red it could be due to my vehicle voltage regulator going bad. The voltage at the amp is around 13.5- 14 depending on rpm. Could a capacitor give my amp a more appropriateand co start voltage so it doesn't keep going into protection? Thanks
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Buck Pomerantz from Crutchfield
Posted on 10/16/2017
N, The size wire to use is totally dependent on the size of the amplifier, not whether a distribution block or capacitor is in the circuit. If your amp requires 1/0-gauge wire, then use that throughout the installation.
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N. McClaughry from Greeneville
Posted on 10/15/2017
I have a T spec cap. In this article you state it's like a distribution block so would it be okay to run 0 gauge to the cap then 4 gauge to the amp?
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Buck Pomerantz from Crutchfield
Posted on 9/30/2017
Tomas, First off, two DVC 2-ohm subs can only get wired together to form a 0.5-ohm load, a 2-ohm load, or an 8-ohm load. The good news is that that amplifier puts out 2400 watts RMS at 2-ohms as well as 1-ohm. A capacitor smooths out power fluctuations due to a bass amplifier drawing more current than the vehicle's system can provide. If your lights dim when the bass hits hard, a capacitor may solve the issue. It should be connected at the bass amplifier's power connections to be effective. The "rules of thumb" about a cap's size is just a general pointer for getting the right product. In your case this 3-Farad cap should be fine.
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Tomas
Posted on 9/29/2017
Are capacitors as necessary for lower power speakers and amps as they are for high power subs and mono amps? The gameplan for my bass is to run two Alpine SWR-12D2 (1000W RMS) subwoofers in parallel at 1 ohm impedance stability, supplied by a Kicker 44KXA2400x1 mono amp (2400W RMS at 1 ohm stability). Using the aforementioned standard you listed, I got a 3 farad capacitor to start out with for my subs. (So I'm wondering how many more farads I should wire to my subs' amp for a highly efficient draw in my car's electrical.) I also plan on getting a pair of Pioneer TS-A6996R A-Series 6x9s (100W RMS, 4 ohms) on a Alpine PDX-F4 amp (100W RMS, 4 ohms) to cover my mids and highs as well as some woofer supplementation. Do I need to account for and include capacitors for the power of this segment of my system; and is it because of the power my subs' amp will draw that I must? What kind of total farad count am I looking at? With this power should I follow the 2-3 farads per 1000W more than the 1 farad to 1000W?
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Buck Pomerantz from Crutchfield
Posted on 9/28/2017
Junior, When a discharged capacitor is directly connected to a 12-volt source, it will charge up so quickly it could explode. Use the resister or bulb that came with your cap to safely, and slowly, recharge it during installation.
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Junior from Chicago
Posted on 9/27/2017
I disconnected my subs amp and cap this summer and wanted to reconnect do I need to charge my capacitor again?
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Buck Pomerantz from Crutchfield
Posted on 9/25/2017
Kev, Did you use a resister or lightbulb when you started charging your capacitor? If not, the cap may have suffered damage while charging too quickly. If you bought your capacitor from Crutchfield, you could call Tech Support for free help troubleshooting your system. Their toll-free number is on your invoice. If you purchased your cap elsewhere, you can still get expert Crutchfield Tech Support - 90 days-worth for only $30. Click on this link for details.
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Kev
Posted on 9/25/2017
I hooked up my cap just as described in the article which is the way I've always installed caps but for some reason the cap won't charge it just blinks and says "LO" and it's been charging for while.... can you explain what's going on ad what I. Have to do??...
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Buck Pomerantz from Crutchfield
Posted on 9/12/2017
Adam, I don't know exactly what's in your system, but in car audio, ignition noise is often caused by a loose or inadequate ground or power wire connection. If something in your vehicle's system is radiating RF interference that your transceiver is picking up, I doubt a capacitor will alleviate the issue. I think there're RF filters made to clear up these kinds of problems, but you'll have to check with a ham radio dealership for more information. I think calling an amplifier linear merely means that the signal out is the same as the signal in, only larger. In ham radio circles they call a clean, non-distorting RF amplifier a linear amplifier. In the car and home audio worlds, they call a clean, non-distorting audio frequency amplifier an amplifier with a linear response. I don't think there's any difference in meanings.
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Adam from Seattle, WA
Posted on 9/12/2017
I scanned the Q&A here and don't think this question has been asked. I'm a ham radio enthusiast as well as an audio enthusiast. I have installed an 11 meter transceiver radio in my car - operates in the 27MHz frequency range. It picks up some noise from somewhere when my 2013 Malibu is running. When the car is off, the noise goes away. I was wondering, would a capacitor help with this? Currently I transmit a max of 20-watts using battery voltage but would need it to be able to handle up to 500 watts radiated power. Finally, can you explain the difference between a linear amplifier (used in radio transmitting) and an audio amplifier?
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Buck Pomerantz from Crutchfield
Posted on 8/16/2017
Kristian, Coming onto an American web site and disparaging the standard measuring system won't get you much useful advice. Nor will not providing the make and model of the amplifier you're ultimately asking about. Just like me, you can use Google to translate American Wire Gauge sizes to metric dimensions. Check out our Amplifier wire gauge chart for help finding the right size power and ground wires for your amplifier.
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Kristian N
Posted on 8/16/2017
Great article and wonderful comments section! I have a 3.0 F capacitor which I want to connect to my new stereo and I'd like to get everything done at the same time, so I'm looking for a wiring kit online. It seems nearly impossible, however, to find out how thick a power supply wire I need to hook it up. The sub and amp don't actually need a cap, because it's a slim-fit 150W (50 W nom.) model, but just for the sake of argument: Is 10 mm² enough? Or do I need 20, 25, or even 50 mm²? (Please spare me the AWG scale, what's up with that?) Regards, Kristian
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Buck Pomerantz from Crutchfield
Posted on 7/15/2017
Mario, The size of a inline fuse in a car audio power supply is dependent on the size of the power wire and how much current (amplifier power) it's expected to safely carry. A capacitor's size has nothing to do with that.
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Mario from Sacramento
Posted on 7/14/2017
I have a 4 farad cap, how many amps should the in line fuse be?
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Buck Pomerantz from Crutchfield
Posted on 7/10/2017
Rudi, A capacitor should get wired to a constantly-on 12 volt circuit, so once it's installed it's always "on" and charged. The only time you'd need to discharge a capacitor is when you uninstall it.
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Rudi Oosthuizen from Johannesburg,ZAR
Posted on 7/8/2017
hi i wanted to know if i need to charge my cap with the given resistor every time i go out to use my sound, and same discharge it completely ever time I come Home or not in use? Is there a automatic way of connecting it to discharge or do i have to do it manually every time?
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Buck Pomerantz from Crutchfield
Posted on 6/27/2017
Jay, What you're proposing is extremely dangerous. Let's say your system can draw up to 250 amperes and requires 1/0-gauge wiring. If the capacitor in such a system were to discharge, boosting the amp's power input, a 4-gauge ground wire might melt or burn because of the high current.
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Jay from Yuma, AZ
Posted on 6/27/2017
Regarding the gauge of the ground wire, you mention the power wire specifically should be the same gauge as the original power wire needed for the amp. this is fine. But does the ground really need to be 1/0 if the rest of the system is? I cannot see any use for such a heavy duty cable for a cap ground. Most of the electron flow is output to the amp, not to ground. Could you get away with using something like 4awg or even 8awg for a cap ground even if the rest of your system used a larger gauge?
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Buck Pomerantz from Crutchfield
Posted on 6/25/2017
Eric, You've raised an interesting question about wiring multiple capacitors together. The resulting capacitance of two caps wired together behave exactly opposite of how resistors and coils work. When two capacitors are wired in parallel, you simply add their capacitance values (farads) together to get the total. When you wire two equal-size capacitors in series, the total capacitance is one-half the value of a single cap. To improve the performance of a capacitor used for car audio, wire the second cap in parallel with the first, increasing the capacitance. Parallel means wiring components together positive-to-positive, and negative-to-negative, if you're not sure.
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Eric from Bartlett NH
Posted on 6/24/2017
Is iit possible to run caps in series or is there any benefit to that?
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Buck Pomerantz from Crutchfield
Posted on 6/9/2017
Mike, Once a capacitor is installed, it becomes part of the car's charging system and doesn't need to get disconnected for vehicle maintenance. When jump starting a dead electrical system, after the starting motor gets things going, the alternator should slowly recharge the battery and cap safely.
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Mike M from Wilmington NC
Posted on 6/9/2017
Does a cap need to be disconnected before doing routine service on the vehicle and if the vehicle battery dies (lights on etc.) will the cap blow upon jumpstarting?
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Buck Pomerantz from Crutchfield
Posted on 6/6/2017
Steve, I believe car battery voltage can sometimes surge to as much as 14.8 volts. If your capacitor was designed to be used in an automotive electrical system, it'll be alright.
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Steve from Black Creek
Posted on 6/5/2017
Will a capacitor with both a working voltage and surge voltage rating of 12-14 volts be ok? Doeasnt a car's voltage sometimes go over 14 volts with the engine running above idle and/or chargeing the battery?
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Buck Pomerantz from Crutchfield
Posted on 4/14/2017
Mike, Yes, you can wire your capacitor without a distribution block as you describe.
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Mike from Dickinson
Posted on 4/13/2017
I'm installing a capacitor do I need a distribution block or can I wire battery to the capacitor and then off the capacitor to the amp on the 12v + side of it
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Buck Pomerantz from Crutchfield
Posted on 4/12/2017
Shay, For playing music, I think that your high-output alternator ought to support your system using a single battery and no cap. If you're competing by playing loud bass burps, however, you may need the second battery and capacitor.
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Shay from Telford PA
Posted on 4/12/2017
Hello. Great article. I have 2 JL 1000/1 amps powering 2 JL 12W7s, 2 JL 300/4 amps powering 8 6.5 JL 5 Series door speakers. Total system power is currently 2600 watts, but the 2 JL 300/4s are gonna be upgraded to JL 600/4 because the door speakers can handle more than the current 75 watts they are getting. So, system power will eventually be at 3200 watts. I just ordered an overpowered XS power D6500 battery and I currently have an Ohio Generator Alt cranking 320 amps installed. My question is this, should I use the XS Power battery as a secondary battery and not install my Stinger 505 Cap, or use that XS Power battery as the main battery for the entire vehicle and use the Cap? Any other advice would be great as well! Thanks a lot!
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Buck Pomerantz from Crutchfield
Posted on 3/13/2017
Novice, A capacitor could hold its charge and possibly be dangerous. To make sure it's not, discharge it. Touch the two conductors of a wired light bulb or resistor (20 ohms, 10 watts for example) across the cap's terminals to discharge it slowly and safely.
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Novice
Posted on 3/12/2017
I used a rockford 1.0 farad cap in my car audio setup for years. I disconnected and uninstalled everything a few years ago and recently stumled upon the capacitor. May be a silly question--but better safe than sorry... is this thing dangerous? Does it still hold a charge? Does it need to be discharged? A friend of mine wanted it but I am afraid to give it away for risk of injury.
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Buck Pomerantz from Crutchfield
Posted on 3/3/2017
Aldrin, If you are trying to run a Skar Audio LP-1000.1D from a 10-amp battery charger, you will find it won't work. That amp will try to draw up to 90 amperes of current which that system can't provide. All adding a battery would do would be to drain the battery along with the charger. If you want to use that amp at home you'll need a 12-14 volt DC power supply (not a charger) capable of supporting a 90-amp draw.
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Aldrin Ibarra from Cheonan, South Korea
Posted on 3/3/2017
Hi...! I have a lp1000.1d hooked in a 10amp (15amp max) battery charger as an audio set up in my workplace... Problem is that the battery charger can't provide enough power for the amplifier when it hits bass notes... Can a 2f capacitor directly connected (in parallel) between the battery charger and the amplifier solve the problem...? I don't consider using a battery because it's very heavy... I can't either buy a high current DC supply because it's very expensive... I hope you can help me with this... Thank you...
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Buck Pomerantz from Crutchfield
Posted on 3/3/2017
Ben, Most people use a distribution block to wire the positive power leads of multiple devices in a system. But if your capacitor has room in its terminal system for a low-current device like an LOC, then it's probably alright to use it.
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Ben Kramper from overland park ks
Posted on 3/2/2017
Do i put the power cord from my LOC onto the positive terminal of the capacitor also?
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Buck Pomerantz from Crutchfield
Posted on 2/20/2017
Jim, Rebooting when first powering up is a normal function of a lot of receivers - it's a way for the internal computer to operate properly. I've never heard of using capacitors in the manner you describe for the reasons you state. If you want your receiver powered continuously, you'll have to use a separate battery.
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Jim from Mount Airy, MD
Posted on 2/18/2017
My touchscreen head unit reboots when I start the car. Installing two 2200uF capacitors (in parallel) to the red ACC wire (in series with a 1A diode) keeps the head unit on for about 10 seconds after switching the ignition off, but it still reboots when cranking, presumably because the starter causes a voltage drop. How much capacitance is appropriate for the yellow continuous power wire?
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Buck Pomerantz from Crutchfield
Posted on 2/10/2017
Herb, A capacitor helps when a vehicle's lights dim along with loud music, so unless you're in that situation, there's no benefit in adding one.
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Herb from Vienna
Posted on 2/9/2017
Should I use a cap even if I'm running 0awg power wire on 1000 watts
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Buck Pomerantz from Crutchfield
Posted on 2/8/2017
Dee, I'm only familiar with using an automotive capacitor to smooth out voltage fluctuations of an amplifier's power supplied by the vehicle's electrical system. I really can't tell you if a capacitor will be of any use for a fuel pump - or three. And the use of 60A relays along with 20A fuses is confusing - as is the need for filtering the power supply of a pump.
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Deejaydque from NSW Australia
Posted on 2/8/2017
Hi, I have a retro fitting situation for a 8 farad cap. Car audios will benefit from a cap in some instances. My question is, could i use the cap to assist with high current draws from high flowing fuel pumps in my vehicle that draws alot of current/voltage? I have 3x high flowing fuel pumps currently hired wired with 3x 60A relays to 3x 20A fuses to a power distribution box then direct wired to the battery. I want to install the 8F Cap in-between the power distribution box --> to the + battery terminal. Will the cap work in this situation and are there any dangers/factors in this retro fit?
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Buck Pomerantz from Crutchfield
Posted on 1/23/2017
Dan, I don't know what speed is normal for your particular capacitor, but the load provided by the multimeter itself will drain the voltage from the capacitor. And charging and discharging a capacitor repeatedly while out of circuit will eventually wear it out.
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Dan from Canada from Brandon
Posted on 1/21/2017
Hi Buck I was charging my 1 farad capacitor with a resistor. The led display and my multimeter were showimg different voltages while charging. Then at 12V charge and nothing hooked up but the test leads, meter was showing voltage drop 4-5 volts in one minute. Is that a sign of a bad cap? Thanks
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David from England
Posted on 1/19/2017
Thanks a lot Buck, much appreciated. I've removed the cap from the system now!
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Buck Pomerantz from Crutchfield
Posted on 1/19/2017
David, Capacitors are usually used in 12-volt applications to provide a quick jolt of energy to a subwoofer amplifier so a vehicle's charging system, the alternator, can catch up with a voltage drain due to the amp's current demand. Think of one like a spring that provides a lift, but then needs to get squeezed back together again for re-charging. If a capacitor has its power removed and is still connected to an amp (in circuit), it will slowly discharge. Whether that would be enough to actually turn the amp on for a little while - I don't know. Charging and discharging caps quickly is what kills them. I really don't see any benefit in using a capacitor in the manner you describe.
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David from England
Posted on 1/18/2017
Hi, I'm using a 1 Farad cap in a portable 12v sound system, which can run on a 12v battery or a computer power supply unit. So when not in use the psu or battery is disconnected from the system. On the two amps I'm using a jumper between remote and pos to turn them on when I hook up the power source. I have two questions, firstly will the cap act as battery and provide power to turn on the amps (and drain the cap) when the power source is totally removed? And secondly, when I remove the power source will the cap drain and is this bad? I appreciate any help, thanks
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Buck Pomerantz from Crutchfield
Posted on 12/30/2016
Slu, Not really. A cap prevents the sound from deteriorating due to under-voltage, but doesn't actually improve the sound or energize the battery. It supports the amplifier by feeding it the power it needs for short bursts.
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Slu from lusikisiki
Posted on 12/30/2016
The capacitor can help to automatically stop the music when the battery becomes low ?
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Buck Pomerantz from Crutchfield
Posted on 12/16/2016
Rixon, Like the article states, the rule of thumb is to put in 1 Farad of capacitance for every 1,000 watts RMS of total system power, but there is no electronic penalty for using larger value caps. In your case, with a less-than 1,000 watts RMS of amplifier power, a 1- or 1.5-Farad capacitor will do.
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Rixon from Abudhabi
Posted on 12/15/2016
I have JBL ms15sd2,1800watts 450watts RMS.2 ohms .and Alpine MRV M 500 amp so which will be suitable capacitor for my system...?
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Buck Pomerantz from Crutchfield
Posted on 11/22/2016
Matt, An intermittent power connection, one that turns on and off a lot, can definitely contribute to a capacitor's destruction.
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Matt from Burrillville
Posted on 11/22/2016
I've got a capacitor hooked up between my battery w/ fuse and a chassis ground, it's supplying power to my amp. It has worked for years with this setup, but recently my car's battery connector came loose and a few days prior to being able to tighten it with a wrench I was just jiggling it by hand to make the connection and get the car started. Still getting around 14.5V measured at the battery terminals, but my cap no longer charges to the battery's voltage. It peaks around 9V and shuts off. The toyota battery connectors are old and need to be replaced anyway, but could an inconsistent battery connection have ruined the cap?
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Buck Pomerantz from Crutchfield
Posted on 11/3/2016
Neil, The total RMS wattage of a system is simply the sum of the RMS wattages of all the channels. For example, the total power of a system consisting of a 50 watts RMS per channel 4-channel amp for speakers plus a 500 watts RMS sub amp is 700 watts RMS. (50 x 4) + 500 = 700.
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Neil from South
Posted on 11/3/2016
Hey, Please can you tell me the formula for calculating the RMS of total system power? Thanks
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Buck Pomerantz from Crutchfield
Posted on 10/18/2016
Justin, In the event of light-dimming when the music hits in a system, even one without a sub amp, a capacitor can often help maintain smooth power flow for an amp's power supply.
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Justin
Posted on 10/18/2016
Can or should one be used with an amp that's only going to drive speakers and not subs?
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Buck Pomerantz from Crutchfield
Posted on 9/27/2016
D, Capacitors can work in many different applications to smooth power supply fluctuations or to filter out certain frequencies in a signal's flow. In car audio, a cap usually is called for in systems of over 750 watts RMS output power. If you think your CB radio amplifier is drawing too much power from your vehicle's electrical system, you can connect a cap between its positive power wire and ground just like it was an audio amp to ensure smooth 12-volt power flow.
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D from nevada
Posted on 9/26/2016
can a cap be used other than car stereo equipment ? such as cb radio amps ?
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Buck Pomerantz from Crutchfield
Posted on 9/19/2016
Now, A capacitor needs to be always connected between constant 12 volt positive and ground, not a switched source of power. As soon as the battery gets disconnected, the cap will start to drain. Instead of wishing that a cap manufacturer will accommodate your misuse of their product, you should find out the source of your parasitic drain and fix that, or use a battery charger to maintain the system's charge when in storage. Otherwise you're stuck using that resister to slowly recharge your cap every time you switch the batteries on, or risk damaging it.
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Now hear this
Posted on 9/19/2016
Buck, if I may follow up to my first question, the cap is not losing its charge while the batteries are connected. It's losing its charge because as you know there are parasitic things that steal current all the time. My head unit is one of them. Even when it is off it is stealing a tiny bit of current (probably to maintain some settings). This is what discharges the capacitor eventually when we don't drive the thing for a while. And I know this happens to other guys who have some toys they don't drive that often. What the capacitor manufacturers should do is put in an input current limiter for when the voltage is real low then allow full current flow once the voltage goes beyond 8-9 volts. That would protect the capacitor no matter what anybody did with it.
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Buck Pomerantz from Crutchfield
Posted on 9/19/2016
Now, A capacitor should stay charged to the same voltage as the battery it's connected to. If your cap loses its charge while the batteries maintain theirs, the cap is defective. Or, it isn't connected correctly: between constant 12 volt positive and ground.
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Now hear this
Posted on 9/17/2016
I have a 800 RMS subwoofer amp installed in a recreational vehicle. I have a dual battery setup where there is the standard starting battery and then I put in a big marine deep cycle battery to run the amplifiers. The battery cable runs to the amps are quite long in comparison to a car. I have 2 gauge cables though that seem to be doing fine. I noticed that the sub bass was not quite as clear and crisp as I thought it should be so I bought a 18 farad capacitor and installed it right at the subwoofer amp. Immediately noticed that the punch of the sub bass was much tighter and cleaner. My only problem now is that we only occasionally use this vehicle and I've blown out the capacitor a couple times which I think is occurring because it is discharging completely over time and when I turn the battery switches on it is probably causing too much current flow. I had to put in the battery switches because otherwise both batteries would always be dead when we went to use it. The battery switches stopped that problem. Is there a way other than disconnecting the capacitor each time and using that little resistor to charge it that the capacitor can be protected from these initial current spikes that seem to be killing it? A relay? A choke?
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Buck Pomerantz from Crutchfield
Posted on 9/7/2016
Edward, Check out this how-to article for help tuning your subs.
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edward coolz from daphne
Posted on 9/7/2016
hey buck i have 3 1ohm powerbass 12s running a 1000 watt audiopipe to them they sound very good and im more than impressed with the bass im getting.. my question is what are some pointers on how should my amp settings should be i have the hardest time getting my amp tuned just write what are some simple steps or do u kno the readings i can set them amp..
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Buck Pomerantz from Crutchfield
Posted on 9/6/2016
Brian, You're right, a capacitor electrically connects to all parts of the positive power wiring. It's restorative effects, however, are best felt by the amplifier that's closest to it.
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Brian from Idaho
Posted on 9/6/2016
I've studied Crutchfield's amplifier (and cap) installation diagram, available at Crutchfiled.com. I see the cap + is connected to a + distribution block which provides + to two amps. By using a distribution block this way doesn't the cap actually provide support for both amplifiers, equally? I have three amps all tied into a single + dist block. If I were to add a cap via that + dist block, would all three amps get cap support (and I should size my cap accordingly, correct?).
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Buck Pomerantz from Crutchfield
Posted on 8/22/2016
Christian, Even when your car is "off," the battery will keep the capacitor charged. The cap is, I guess, technically "on," it has a charge, but it isn't doing any work (passing current while discharging and recharging). In effect, the capacitor is an extension of the battery itself, charged and ready for work when the switch is thrown.
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christian quiroz from riyadh
Posted on 8/21/2016
i have a question? when i put a capacitor wired direct to battery (+ to +) then ground, my question is, how about when you the car is off, the capacitor is still on? or also automatically off when you off the car? thanks
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Buck Pomerantz from Crutchfield
Posted on 8/8/2016
S, You got me on a misspelling. Thanks for the catch.
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S
Posted on 8/7/2016
dialectic??? (7/25/2015) Might want to look up the definition of "dialectic" then look up "dielectric."
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Buck Pomerantz from Crutchfield
Posted on 7/12/2016
Anthony, I'm not at all sure that a capacitor suitable for smoothing out voltage fluctuations due to an audio amplifier's power usage will work the same way for the autopilot motors in your boat. I guess in theory it could work, but without any idea of the duty cycle or current draw of the system make figuring out the proper cap size virtually impossible. I suggest you contact the manufacturer of your boat or autopilot and ask their tech department if a capacitor would work in your situation, and if so how big should it be.
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Buck Pomerantz from Crutchfield
Posted on 7/12/2016
Thomas, A capacitor is supposed to be "on" and fully charged up at all times, whether the amp or car is on or not. After all, if it's installed correctly, it connects to a constantly-powered 12-volt power line and ground. The remote lead on some caps is to turn the volt-meter or some other feature on and off, not the cap itself.
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Anthony Dragani from Swampscott
Posted on 7/12/2016
Hey I could use some guidance. I have a sailboat with an autopilot that is effectively an inductive load (DC motor pulses on and motor turns clockwise or counterclockwise to steer boat on course). The problem is I can see the voltage drop when the motor pulses on. My instruments don't like the resulting voltage drop. I think a cap would compensate for the inductive load and provide the current spike without drawing the voltage down. I would like to have the cap discharge when I leave my boat for safety reasons. So I would to charge it when I turn instruments on. I am trying to find out the motor spec. s to find out how much instant current it needs for each pulse. I think I may be looking at an amp at 12 volts but that is WAG. What would work for me size cap with charging and discharging included? Or what do I need to look for in picking one?
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Thomas Murphy from Lonoke
Posted on 7/12/2016
What if your cap does not have a remote terminal, but still comes on when fuse is hooked up as apposed to when ignition is turned on and powered up like the amp does? The amp comes on when the key is turned on, but the cap is acting like it has a constant power and turns on as soon as I install the inline fuse...
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Buck Pomerantz from Crutchfield
Posted on 7/11/2016
Dan, Alternator whine or engine noise is indicative of a bad ground, or a defective head unit or amplifier, or a radiating electrical system, and usually has nothing to do with a capacitor. If you bought your gear from Crutchfield, you could call Tech Support for free help troubleshooting your system. Their toll-free number would be on your invoice. If you purchased your equipment elsewhere, you can still get expert Crutchfield Tech Support - 90 days-worth for only $30. Click on this link for details.
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Dan from Austin
Posted on 7/8/2016
Hi, I have an RF 1 F capacitor off the battery that splits the power line to an Infiniti Basslink powered sub and an RF 4 channel amp that feeds 4 speakers. I get a lot of alternator whine and noise in the audio. I've checked all the grounds and they all look good (short runs, solid contact to chassis, paint sanded off). I had the polyfuse in the Pioneer HU replaced because I had hot-swapped the RCA cables in the past, and the RCA cables are all new. Could the cap be a cause of the signal noise?
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Buck Pomerantz from Crutchfield
Posted on 7/3/2016
Scott, Like the article says, the rule of thumb is to put in 1 Farad of capacitance for every 1,000 watts RMS of total system power. But there is no electronic penalty for using larger value caps, and in fact, many see benefits with 2 or 3 Farads per 1,000 watts RMS. The larger the cap, the faster it gets ready for the amp's next big hit. For you, if your amp truly is 2400 watts RMS and that wasn't a peak number you quoted, a 3.0 Farad T-Spec capacitor will work well.
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scott
Posted on 7/1/2016
i got 2 12" subs and a 2400w mono amp and was wondering how big of a cap would be recommended for it to perform properly and not drain my battery dead also was wondering what a cap brand makes a really high quality cap thats gonna be reliable and has a good capacity
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Buck Pomerantz from Crutchfield
Posted on 6/6/2016
Joey, I suspect those astronomical power ratings you mention are peak amplifier ratings, which should not be used when planning systems. The rule of thumb for capacitors is to have 1 Farad of capacitance for every 1000 watts RMS of amp power. Your 3.5 Farad cap can handle a 3,500 watts RMS system. If yours is indeed larger, then get a new larger cap, if you need one at all.
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Joey
Posted on 6/5/2016
Hey I got a 3.5 farad cap and it was for my one 15" sub atm I'm only using a 1,400 watt amp, I want to upgrade my system with 2, 4k watt 15" subs/amp and 2 8" subs with a 600-800 watt amp. Can I get another cap at like 4 or 6 farads and put them in a series or should I just outright buy a bigger one?
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Buck Pomerantz from Crutchfield
Posted on 6/3/2016
Norman, A tech with T-Spec told me that the volt meter on their capacitors can sense current flow and turn on when the engine is on, and slowly turns off when the engine's off. Maybe your capacitor works differently. I wouldn't think any reputable capacitor manufacturer would put out a product that would drain and possibly damage a car battery.
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Norman DeRemer from allentown
Posted on 6/3/2016
I just installed my new capacitor and the voltage meter stayed on all night. It was reading 12.4 volts the next morning. My amp and cap are grounded at the same spot, is that ok? And the voltage meter, will that being on all night eventually kill my battery? I use my truck almost every day.
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Buck Pomerantz from Crutchfield
Posted on 5/23/2016
Jason, If your battery drains when your capacitor is in the circuit, but does not when the cap is not in the circuit, then I'd leave the cap out. It sounds like it's developed an internal short. Usually, an electrical system won't need a capacitor to handle an amplifier capable of pulling 50A.
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Jason from Fort Worth
Posted on 5/23/2016
Buck question for yea. How do you know if a cap has gone bad in your system? Had the cap for 3 years with no probs. No leak in the cap. Has electronic display, display does Not stay on after charged. Uses a resistor to charge cap up however drains the battery after charged? 500k microfarad Scosche capacitor running on a 700 watt 4 channel amp with 50 amp fuse. Replaced the battery, charged the cap back up, drained the battery quick again. Removed the cap, hooked the amp up direct, car started right up. My thought is the current is back feeding causing a short in the battery?
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Buck Pomerantz from Crutchfield
Posted on 3/17/2016
Randy, A capacitor is supposed to stay charged when hooked up. Like the battery it's connected to, it's supposed to just sit energized without draining the charge when no current is flowing. Try disconnecting the capacitor and see if that was the reason your battery drained. Maybe something besides a defective cap is the culprit. And do not put a switch in-line with your capacitor. Turning on and turning off the current flow suddenly to a capacitor will most likely damage it.
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randy brillon from spokane
Posted on 3/16/2016
im having an issue with my Capacitor i got for my stereo it seems to want to stay charged up even when im not bassing out and the last couple days its ran my bat dead by i assume its trying to stay charged up all night draining my bat what i want to know is it ok to put a power cut off to cut the power from the m,ain bat to the capacitor? like an inline toggle switch between the power distribution block and the capacitor? will it hurt the capacitor to have power cut off from it all the time ?
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Buck Pomerantz from Crutchfield
Posted on 3/16/2016
Juan, It is best to mount and connect a capacitor by the subwoofer amplifier because that's where it does the most good, but I don't think it'll hurt anything installing it elsewhere on the power line. The rule of thumb for audio installations is to have all the gear grounded at the same point, but if you aren't getting any noise or interference with the way you have your grounds, go ahead and leave them as they are.
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Juan from Minneapolis
Posted on 3/15/2016
I have mine wired the 12v output of the cap(10 farad) to a DST then from there to feed my two amps one is a 4 channel and the other one is a monoblock Im a wasting power by doing this? is it better to just run the monoblock from the cap? also I also read that all the grounds should be at the same point if possible, I have my mono block ground attached to my Cap because it has two Ground terminals. Is this wrong?
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Buck Pomerantz from Crutchfield
Posted on 3/10/2016
Jeremy, I don't think that amplifier will be too much for your car's electrical system to support, so you probably won't need a capacitor at all. Even if you installed one anyway, it would not harm your alternator or battery.
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Jeremy from Grande prairie
Posted on 3/8/2016
I'm installing a 300w rms amp/300w rms subwoofer in my Toyota Echo. I have a 90amp alternator and a 30-40 ah battery. The vehicle isn't fully loaded so it has manual roll up windows no a/c etc... (Also I bought an Aftermarket pioneer stereo) anyways the question is do i need this 2 farad capacitor or will it just harm my battery or alternator and provide no real benefit. I don't know if my lights will dim I haven't installed the sub/ amp yet
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Buck Pomerantz from Crutchfield
Posted on 3/4/2016
Brett, You can definitely leave your battery hooked up in your Mustang while you keep the battery charged with a battery tender.
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Brett from Newtown, PA
Posted on 3/3/2016
Hi I'm finishing up the install of my car audio system this weekend and have a question. My car is a 1965 Mustang and I'm using a 1.5f capacitor with a 1500 watt 5 channel amp. Before big audio system, I regularly take the battery terminals off and put the battery on a tender to keep it "fresh" since I don't drive the car very often. I assume then since I remove the battery supply, the cap will discharge as from what I'm reading about now with capacitors (sorry I'm all new to car audio world). Is there anything you'd recommend in my case then? Do you know could I leave the terminals bolted/quick clipped on the battery and pop the Tender's clips right on there to keep the battery charged up, through the down times? Thank you much!
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Buck Pomerantz from Crutchfield
Posted on 3/2/2016
Travis, Not knowing exactly what amplifiers, tweeters, subs, or capacitor you have makes it impossible to give advice on how it all could get wired together. 400 watts seems like a huge amount of power for a set of tweeters, but that may be a peak spec and you'll be okay. And using a cap for a distribution block is a bad idea - how do you know that the main power wire from the cap's positive terminal to the battery can accommodate both amps? Capacitors are really only effective providing jolts of power for a subwoofer amplifier anyway.
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Travis from Hope mills, NC
Posted on 3/2/2016
Have 2 questions I have two 12" subs at 1200w with a 1200w amp 1.5f capacitor I plan on adding a 400w amp to power two tweeters 1) will this be too much power for my cap and have negative effects? Or is the power draw from the tweeters manageable without increasing the cap size 2) might sound lazy but is it possible to wire that second amp through the capacitor, using it as a distribution block, and if so does the same gauge wire need to be used as the 1200w amp
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Buck Pomerantz from Crutchfield
Posted on 2/12/2016
Dallas, It probably won't hurt anything installing your capacitor's positive terminal to the main power cable and a couple amplifier positive leads, if the main power cable can handle both amps. But it will do the most good connected to the subwoofer amp's positive lead only and as close to that amp as possible.
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Dallas
Posted on 2/10/2016
Hi, i have a BOSS CAP8 capacitor and i was wondering if it was okay to just use the capacitor as a positive distribution block?
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Buck Pomerantz from Crutchfield
Posted on 2/9/2016
Edgar, Capacitors, in car audio applications, are passive electronic devices connected to constant 12-volt power and ground, so they are always on. If you are referring to a voltmeter display, the remote lead is supposed to connect to switched 12-volt power that turns off when the car is off. You may have to find a different spot to connect your remote lead. Some capacitors have displays that sense when power flow stops and turn themselves off after a few minutes.
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Edgar from Fontana
Posted on 2/8/2016
Hi I'm having a problem with my battery drained and my compacitor staying on my compacirtor has a meter on it and I already plugged in the remote but the capacitor still stays on what's the problem?
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Buck Pomerantz from Crutchfield
Posted on 2/4/2016
Chris, Like the article says, the rule of thumb is to put in 1 Farad of capacitance for every 1,000 watts RMS of total system power, but there is no electronic penalty for using a larger value cap. A 3 Farad cap will be fine for your system to help prevent light-dimming when your music hits hard.
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Chris
Posted on 2/3/2016
If i am running 2100 rms amp with 2 1000 rms subs , what kind of capacitor do i need? I am guessing 3 farads?? And also a 600 rms amp inside for highs ... Also planning to put a battery in trunk as well
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Buck Pomerantz from Crutchfield
Posted on 1/8/2016
Ryan, Maybe the wrapper serves as an electrical insulator, maybe not. The only way to find out for sure is to check with the manufacturer.
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Ryan from Fort Wayne
Posted on 1/7/2016
I recently purchased a new capacitor. While unwrapping it I cut through the clear plastic wrap or heat shrink around the cap. It had the brand name on it. Is the wrap needed or can I peel it off and just have the bare aluminum. I wasn't sure if the wrap was an insulator or just for appearance. Thanks!
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Buck Pomerantz from Crutchfield
Posted on 12/29/2015
Yannick, Sorry, I just now figured out that you don't live in the U.S. and so can't buy Crutchfield Tech Support. Your problem, 1 to 2 second cut-out every once in a while, sounds more like a loose connection or defective amplifier than anything else. I suggest you take your vehicle back to the installers and have them diagnose and fix the issue.
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Buck Pomerantz from Crutchfield
Posted on 12/28/2015
Yannick, Here are some things to check for: Are you using 4-gauge power and ground cables for your amp? Are there any loose connections? Is the ground wire absolutely secure - bare metal-to-bare metal contact? If you bought your amp from Crutchfield, you could call Tech Support for free help troubleshooting your system. Their toll-free number is on your invoice. If you purchased your equipment elsewhere, you can still get expert Crutchfield Tech Support - 90 days-worth for only $30. Click on this link for details.
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yannick from mauritius
Posted on 12/28/2015
hi, note that i have a pioneer champion series amplifier powering a JBL subwoofer of 300 watt and 4 speakers of 80 to 100 watt for the high. when i play music for some time at higher volume and the bass are kicking hard, after a certain period of time, the music stops for 1 to 2 seconds and continue to play again. i therefore need to play the music below level 10 (30 to be the highest) so that the periodic "1 second cuts" stop. do you think that it's the power consumption and that i will need a capacitor to resolve this issue or it is being caused by another issue? Thanks
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Buck Pomerantz from Crutchfield
Posted on 12/23/2015
Chris, No, it won't hurt anything - that's how you hook it up. It sounds like you don't have the instructions that originally came with your capacitor. You should know that a capacitor can be dangerous; it can charge and discharge so much power so very quickly that it can weld metal objects, like tools and jewelry, and melt its own insides out. Please follow the steps in this article, or from another reputable source, telling how to hook up a capacitor safely.
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Chris from Brunswick
Posted on 12/22/2015
Thanks for your response. So if i jump a seperate wire from the remote terminal from the amp to the third terminal on the capacitor it wont hurt anything will it?
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Buck Pomerantz from Crutchfield
Posted on 12/22/2015
Chris, If your capacitor uses a remote turn-on, for an onboard meter for instance, it doesn't matter if it gets the connection directly from the receiver and then daisy-chain it on to the amp, or the other way around. Most people just run a jumper from the amp's remote connection to the cap's.
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Chris from Brunswick
Posted on 12/21/2015
I noticed on my capacitor there is a third spot for a remote wire. So with the remote turn on coming from the radio to the amp like i normally have it, should i run the remote wire from the radio to the capacitor, then jump it from the capacitor to the amp? I dont understand how to hook up the remote turn on. Ive been trying to find out how and i can't find any answers!!
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Buck Pomerantz from Crutchfield
Posted on 12/10/2015
Todd, The size power and ground wires to use in a system is dependent solely on the total power requirements (current draw) of the amplifiers. If you're using one amplifier and it requires 8-gauge power and ground wiring (see the owner's manual for that specification), then 8-gauge will do for the capacitor, although using a larger wire won't hurt anything.
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Todd from Lexington
Posted on 12/9/2015
I noticed the mention of using same size wire for amp and capacitor. I used 8 gauge from battery to cap and 4 gauge for the small cap to amp wire. Should I make it all 4 gauge?
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Buck Pomerantz from Crutchfield
Posted on 11/30/2015
Bret, Here's a diagram that shows how a capacitor hooks up in a typical 2-amp system.
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Bret Weaver from Clinton
Posted on 11/28/2015
How do I wire up 2 amp' s to a capacitor?
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Buck Pomerantz from Crutchfield
Posted on 11/24/2015
Matt, I think the current draw of your capacitor's meter is as small as your vehicle's clock and won't drain a healthy battery when left unused for a while. If the battery is weak or needs replacing, however, that small draw may be enough to leave you powerless.
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Matt from Indianapolis
Posted on 11/23/2015
I have a cap with a meter and it does not have a remote turn-on connection. Do I need to be worried about this draining my battery?
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Buck Pomerantz from Crutchfield
Posted on 11/16/2015
Joe, I would think that a 300 watts RMS amp added to a car's stock electrical system would not need a capacitor, but wouldn't be harmed by one either. The only way to know for sure is to remove the capacitor and see if your lights dim on heavy bass hits. If they do, re-install the cap. If they don't dim, then you never needed it to begin with.
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joe from Cincinnati
Posted on 11/16/2015
Hi. I have a 300W powered 10" sub Rockford Fosgate. My lights do not dim, etc. I bought 1.5 farat capacitor, but do I even need it, or will it provide any benefit? It's installed in a 2015 car that has a bunch of electronics, etc, and i didn't want my amp to kill my alternator faster, or worse, cause an electrical problem by pulling directly from the battery, instead of using a capacitor. Am I being paranoid? Is the capacitor beneficial in my case?
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Buck Pomerantz from Crutchfield
Posted on 11/15/2015
Jason, Like this article states, there is no electronic penalty for using large value caps - the larger the cap, the faster it gets ready for the amp's next big hit
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Jason Flanigan from LEXINGTON
Posted on 11/15/2015
Is a 20 Farad Capacitor on a 1500watt amp to big
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Buck Pomerantz from Crutchfield
Posted on 11/5/2015
Trey, The ground point used by your amplifier is a great place to also ground your capacitor.
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Trey from Uvalde
Posted on 11/5/2015
It may sound stupid but, can you connect your capacitor to the same ground area as your amplifier?
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Buck Pomerantz from Crutchfield
Posted on 10/8/2015
Kiran, It sounds like your capacitor has failed - it's probably leaking its charge internally.
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Kiran
Posted on 10/7/2015
My battery capacitor isn't charging fast it take at least 8 hours and is only half charged,, is there a reason for this?
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Buck Pomerantz from Crutchfield
Posted on 9/17/2015
Kel, It is not absolutely necessary to replace your capacitor, but it may help if your car's headlights dim a little when your music plays loud.
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Kel from Nashville
Posted on 9/17/2015
I am about to change vehicles, and was wondering if I should replace my capacitor. I have used the capacitor for a little over 3 years and didn't know if replacing it was necessary?
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Buck Pomerantz from Crutchfield
Posted on 8/6/2015
Justin, I'm afraid not. Capacitors are replaceable, but not repairable.
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Justin Stefko from Newton
Posted on 8/6/2015
Can power capacitor be rebuilt or repaired? I have a 30 figured that doesn't work
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Buck Pomerantz from Crutchfield
Posted on 8/6/2015
Mike, The capacitors made for car audio application are all made to handle the high current that flows when the cap charges and discharges. You'll have to find out the current-carrying capacity of your super caps from the manufacturer.
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Mike from Santa Rosa Beach, FL
Posted on 8/5/2015
How do you determine the MAX AMP INPUT/CHARGING AMPS a Capacitor can handle??? I would LIKE to connect a capacitor directly to the ALT. Output(My Stock one is 130AMP), to isolate the sub-woofer and any other amplifier circuit I add in the future. I have found that the MAXWELL Super-caps (2.7VOLT 350-500F), with 6 of them bundled together, 16.2VOLTS and 3000F, would make a great substitute for the car battery, as long as they don't drop below 10-11VOLTS or go without being charged for more than 2 days... What worries me, will the 130AMPS coming from my ALT destroy the caps??? THANK YOU SO MUCH in Advance!!!
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Buck Pomerantz from Crutchfield
Posted on 8/4/2015
Pelonomi, The number one cause of engine noise in a car audio system is a loose or intermittent ground connection. That could also explain the blowing fuses. Carefully check your amplifier's power and ground wiring and correct any faults you may find. Make sure the ground wire makes a clean, tight, and paint-free contact with your vehicle's chassis.
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pelonomi from gaborine
Posted on 8/4/2015
hi, amplifier(1200W), subwoofer(1000W), 6x9 speaker (350W), twitter(300W) and capacitor connected between amp and power source, my question is there is disturbing noise when car rev or on drive what could be the cause of that, and most of the time fuse (connecting amp with power source) are blown
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Buck Pomerantz from Crutchfield
Posted on 7/30/2015
SR, Check out this 5-page article How Capacitors Work. It ought to answer a lot of your questions about capacitors.
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sr5573 from bhubaneswar
Posted on 7/30/2015
what is the working principle of a capacitor?
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Buck Pomerantz from Crutchfield
Posted on 7/25/2015
Amanda, There are no fumes or gas inside capacitors. Capacitors are made of two foil sheets wrapped together with a chemical called a dialectic in between them. Like in a car battery, this substance may contain some acid, but you'd have to rub it in your eyes, roll in it, or eat a bunch before it would do you any harm. That being said, I think it is possible that when a capacitor fails catastrophically the electric charge could vaporize some of the dialectric and release a small puff of gas that if breathed in probably won't be good for you. If you or a friend think you've been exposed to such a thing, I recommend flushing the area out with water, and contacting your doctor for advice.
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Amanda
Posted on 7/25/2015
Hi! I just want to ask if an audio capacitor has fumes? And if it has fumes in it, can it be dangerous to our health? Is there any chance that the fumes will leak? Hope you could reply to my email asap. Thank you!
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Buck Pomerantz from Crutchfield
Posted on 7/20/2015
Nick, I have never personally heard of such a thing, but it probably is not good. I have seen capacitors fail by springing a leak, developing a hole where internal gases have pushed through the casing. Maybe that's what's happening to your cap.
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Nick Duval from Canada
Posted on 7/18/2015
My capacitor has recently starting making a high pitched screeching noise what could cause this? It doesn't happen all the time, it happens randomly.
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Buck Pomerantz from Crutchfield
Posted on 7/13/2015
Lee, A capacitor's function is unaffected by the technological Class of an amplifier's internal circuitry.
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Lee
Posted on 7/12/2015
I have had great success with stiffening caps in-line with A/B amps. Will a cap help with a class G amp?
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Buck Pomerantz from Crutchfield
Posted on 5/14/2015
Cory, As long as the vehicle's battery maintains a charge, it will keep the cap charged. If the battery loses its charge or gets disconnected, then the capacitor will lose its charge and need to be re-charged slowly, like it was newly installed.
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Cory Dzbinski from Oceanside, CA
Posted on 5/14/2015
Hey there, good article. I have a question that seems obvious to me but I haven't see it asked or explained anywhere. Won't the cap slowly discharge when it's off? What if you don't drive your car for a couple weeks. Won't the cap be empty and be at risk to "pop" and destroy the cap if it then recharges quickly?
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Buck Pomerantz from Crutchfield
Posted on 4/28/2015
John, A capacitor gets wired with one wire running from its negative terminal to ground and one wire from its positive terminal to the positive 12-volt power line of an amplified system. It does the most good to connect a cap closest to the subwoofer amplifier in a system, but it won't hurt to connect it elsewhere, like at a distribution block.
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John from New york
Posted on 4/27/2015
Can you put one cap on two amplifiers ?
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Buck Pomerantz from Crutchfield
Posted on 4/27/2015
K, A capacitor can certainly be used with a powered subwoofer. A capacitor should always get mounted as close to the subwoofer's amplifier as possible, never under the hood in the engine compartment.
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K. Hardy from Calgary, Alberta
Posted on 4/25/2015
Does a powered subwoofer also need a capacitor connection?
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K. Hardy from Calgary, Alberta
Posted on 4/25/2015
Can capacitors be mounted on the firewall under the hood?
Thomas A Rivera from Barstow
Posted on 1/5/2021
I have a question about how to fuse the cap. The caps I seen from Crutchfield show a Tspec cap and the wire diagram shows how to hook it on a distribution block. My question is my distro block has 3 outputs. 1 output to my JL 4 ch 300/4v2 amp and 1 output to a JL 500/1v2 amp. I have 1 connection on my distro block for 12v what size of fuse can I use for a cap?
Buck Pomerantz from Crutchfield
on 1/12/2021
Aaron Bradley from Newport News
Posted on 12/26/2020
I purchased the TSpec 3.0 farad capacitor a few months ago but I noticed recently that the display is not lit when the system comes on. When I charged it, the display was lit and when I did the final power connect it was lit. Should I discharge and charge again? Also I notice my lights dim when the bass hits sometimes.
Herbert from Houston
Posted on 12/16/2020
Is a capacitor needed for a system only a small 60*4 watt (240 watt) amp?
Buck Pomerantz from Crutchfield
on 12/21/2020
Duke from Senoia
Posted on 11/20/2020
How do I charge and install a second capacitor? Thanks
Buck Pomerantz from Crutchfield
on 11/20/2020
Tommy Keel from Tarboro
Posted on 11/3/2020
Does a capacitor need to be charged if it already has done so? Saying the cap is on low volts can I put it in line now?
Buck Pomerantz from Crutchfield
on 11/4/2020
Ken from Peoria
Posted on 9/9/2020
My. Thought s on capacitors is you should always add a capacitor when you add a amplifier to your car . Because a car 's charging system is designed. For that car electrical system only. Let's say you have a true 2000 watt amp rated 14 volts .how do you feed that amp .I would add a second battery with a resting voltage of 14.5 battery isolator a true 3 fared capacitor using stock alternator .storage. storage storage ,the second battery and the capacitors
Buck Pomerantz from Crutchfield
on 9/11/2020
J. P. from Los Angeles
Posted on 9/2/2020
I have a tsunami hcap-40 Cap. It has the two connections, pos. & neg. How do I charge it and the display lights stay on. The Cap I had before had a separate display wire. Can you help?
Buck Pomerantz from Crutchfield
on 9/3/2020
Mark C
Posted on 8/14/2020
I just left a comment but just found out my amp is pushing 170-200rms. My sub is 400rms. Would a cap help or do I need a new amp?
Buck Pomerantz from Crutchfield
on 8/15/2020
Mark C
Posted on 8/14/2020
My amp is 1100watts peak power, so my guess is the rms is about half that. Im also only pushing one 12" 800peak 400rms Kicker. Would a cap be beneficial for a small setup like mine? Would I even be pushing enough power to even fill the cap? Thanks
Jerry from Corinth New Uork
Posted on 7/26/2020
Trenton, Two DVC 2-ohm subs rated for 600 watts RMS each will work safely with an amp that will put out no more than 1200 watts at 2 ohms, like a Kicker CXA1200.1T. When you add more subs you can add another amp.
Buck Pomerantz from Crutchfield
on 8/3/2020