Boasting impressive power ratings and controls for fine-tuning your sound, Infinity Reference amplifiers are an ideal way to send your music to new sonic heights.

The Reference 611a mono subwoofer amplifier boasts a high-efficiency design that ensures steady power delivery. Delivering 456 watts of power to a 4-ohm sub, or 657 watts to a pair of subs, the 611a is powerful enough to satisfy your inner bass head. And every Infinity Reference amplifier is certified to deliver power as advertised.

Variable frequency filters let you contour the output to suit the needs of your speakers. Infinity's Dynamic Bass Optimization (DBO) circuit provides variable "Q" slopes, adjustable bass controls that allow you to tune your sub to its enclosure for more efficient output and cleaner low-end kick.

If you have multiple amps in your system you'll appreciate how the preamp outputs simplify hooking up additional amps.

Product Highlights:

  • mono subwoofer car amplifier
  • 456 watts RMS x 1 at 4 ohms (657 watts RMS x 1 at 2 ohms)
  • variable low-pass filter (32-320 Hz @ 12 dB/octave)
  • Dynamic Bass Optimization (DBO) circuit (0-12 dB at 20-80 Hz)
  • Class D design
  • CEA-2006 compliant
  • preamp inputs and outputs
  • fuse rating: 30A x 2
  • 4-gauge power and ground leads recommended — wiring and hardware not included with amplifier
  • 15-7/8"W x 2-11/16"H x 12-1/8"D
  • warranty: 1 year
  • Our 60-day money-back guarantee

My system has plenty of power. Who needs an amp?

You might think you don't need an amp because you have a 400-watt system in your car, or because your new stereo puts out 50 watts a channel. But those are peak wattage ratings, which may boil down to 15 or 20 watts per channel, using the more realistic RMS rating. An amp sends your speakers the power they need to deliver your music with clarity and impact, whether you're using factory speakers or high-performance components. And low-frequency reproduction requires lots of power, so an amp is an absolute must if you're adding a sub to your system.

Infinity Reference 611a Reviews

Average Customer Review:

38 reviews
Review this product
Great Gear Giveaway

Submit a review and then enter to win a $350 rewards card


Review this product:

Thanks for taking the time to share your experiences about this product. Please be sure to focus your comments on the product itself. Read our Review Guidelines for more information.

Your email won't be visible. Please use the email address that is associated with your order.
(e.g., JohnD) Your review will be signed using the display name and location
(e.g., Charlottesville, VA)

Click on a star to rate the overall product on a scale of 1-5
1500 characters left
  Attach a YouTube Review
Crutchfield Video Review Guidelines
  • Only submit videos that you made or are authorized to use.
  • Do not submit videos that contain music, video or visuals that are copyrighted and belong to someone else.
  • Please see our Review Guidelines for more information.
500 characters left
500 characters left

Incredibly powerful

Written By Mrburns05, Moreno Valley, CA on Tuesday, October 29, 2013

The amount of power this thing produces shocked me when I first turned it on, I have the level set less than 1/4 turn and it's just loud! Can't wait to upgrade the subs and see what this amp can really do.

Pros: Powerful!

Cons: Plastic mounting tabs...?

Fantastic amp

Written By Matt, 01440 on Sunday, June 24, 2012

AWESOME POWER. I have it pushing an Audiobahn AW1200 high excursion 12' sub in a sealed box with polyfill, and it SLAMS. Great quality sound, very power efficient, and rediculously loud. Before getting it I was using a 1200watt class AB amp, and this thing sounds way better and draws far less power.

Pros: Sound Quality Efficiency Power Price

Cons: Plastic mounting tabs. They seem strong enough, but just seem out of place on an amp that is such great quality in every other area.

Infinity preference 611a an MTX audio thunder 7500

Written By Kylew141, Lebec ca 93243 501 south drive on Thursday, May 31, 2012

I want to know how a MTX audio 7500 sub would hit with a infinity preference 611a amp

Pros: 12 inch MTX audio thunder 7500 sub and infinity preference 611a amp 2 channel

Cons: 12" inch MTX audio thunder 7500 sub and a infinity preference 611a 2 channel amp

Knockin pictures off the walls!!!!

Written By Teddy-P, Burlington, wi on Monday, April 18, 2011

I've had nothing but infinity systems and i will never switch it up. Right now im running 4 12'' infinity reference subs to this reference series 611a amp n i can't even believe how much power its pushin to these subs. Me n my buddies bet to see how maNY CAR ALARMS i can set off. i recently jus bought another 12 in reference sub wit the infinity reference series 7520a and i can't imajine what thats going to sound like now.. i'll let u know n 2 weeks when my box is built. Thanks for making my moms pictures rattle off her walls!!!!! Lol

Great amp

Written By BEAR, Texas on Thursday, July 22, 2010

This amp is so powerful it is way under rated for what the specs say. There has to be more then 657 watts i have it hooked to 4 kicker comp 12's at a 1 ohm load and let me tell you it hits so hard i put my friends 1500 watt mono block amp and 3 alpine type r subs to shame. He cant believe its a 600 watt amp. The only bad thing i have to say is the price i payed for it three years ago but i'm very happy with the way things turned out. I will never sell this amp it's mine for life i'll take it with me to my grave LOL. The amp still to this day is still just as powerful as the day i got it (three years ago). GREAT JOB Infinity keep up the good work.

Infinity Reference 611a

Written By fernski, Dallas, TX on Wednesday, June 24, 2009

I have had it for a ccouple years now. I have blown a couple speakers with it. Some jbl gt5-12 in fact. People dont think it hits untill they hear it. I feel sorry for people in the back four door sedan. broken my rear view mirror a couple times cracked a couple of windows as well


Written By Matt R, Tacoma, DC on Wednesday, May 02, 2007

Just got it and hooked it up to my 10.1 perfects in a dual.75cuft mtx SEALed(Very Well) basslammer box with no polyfill.Used EIGHT guage Monster Cable Amp kit.It said use 4 guage but the kit said it was good to 650 watts and i trust Monster cable.Best bass Ive heard.Clean,Loud,And as low as it goes(that u can hear).Shakes My 4 banger Grand Am pretty good.I feel sorry for the people that sit in the back,ouch.haha.Headlights dim of course, AND the amps only halfway up.Stays cool!!!!!2(Need A capacitor n i be good)

Infinity Reference 611a

Written By Dave, Sacramento, CA on Tuesday, May 01, 2007

Crutchfield Customer Review (What's this?)

This thing really kicks! I installed it in my new ford ranger. I Paired it with the Polk MM2124 into a custom box i built to my design specs. My box is .88cf and less than a 1/2 lb of poly-fill.

Im extremely pleased with the results. The only downside is that the mounting bracket is indeed plastic. (who thought that up?) Other than that this thing can really pack some power.

Massive bang for the buck!

Written By brennen, Las Vegas on Wednesday, April 25, 2007

Crutchfield Customer Review (What's this?)

I had this thing hooked up to a 4ohm solo L5 wired parallel to give it a 2ohm load in a slot ported box and it pounded. Infact I pushed it so hard I blew the sub, and the amp was barely warm to the touch. Great amp, especially for the price!!!

awesome amp

Written By jeff, conover,nc on Wednesday, April 18, 2007

just put this amp in yesterday to replace a 7 yr old rockford power 360 amp pushing 360 watts.
and this amp blew the rockford out of the water!!!!
it is bridged to a rockford power stage 1 10' sub and it pounds and i set no gains on the amp just installed it.
i had to lower the the sub setting on my pioneer deck to zero and the 80 hz setting to a minus 7 and it still sounds great!!
i play with some of the setting on it in a few days but like everybody else has stated it gets the job done.

Infinity Reference 611a

Written By brian, rolla , missouri on Saturday, April 14, 2007

Crutchfield Customer Review (What's this?)

i bought this amp back in marh of this yr ....i hooked it up to a 12" kicker solo baric l5 and let me tell you this thing gives out clear sound with TONS of bass ,i would recomend this amp to anyone who is looking for an awesome amp

Great amp

Written By Dave, Indiana on Wednesday, March 28, 2007

We are using this amp in two 35-ft limo coaches. The system is set up the same in both. The Infinity Reference 611a drives two Infinity Kappa Perfect 12vq component subs. The subwoofer frequencies are passed to the 611a by a Panasonic CQ-C8803U head unit. The higher frequencies are passed to an Infinity Reference 7541a four-channel amp, which is driving four pairs of Infinity Kappa 652.7i two-way speakers. Each channel drives two of the 652.7i speakers in series giving us a 4-ohm load on each channel. Two Tsunami 1.2-farad caps are installed to support the amps. As long as the levels and filters are all set properly, this system sounds great. We have had it up to around 75% with no audible clipping. We would have to wear hearing protection to get it any higher as it becomes very uncomfortable to listen to at these levels. This is certainly not a competition grade system, but we have more than enough power for our application. The sound is clear and crisp throughout the volume range that we have tested.


Written By B_DUB, Somewhere, KS on Wednesday, March 28, 2007

Ive owned one of these bad boys for nearly three months now and to sum it up in one word, "WOW!". Ive got this amp matched up to a couple 10" Infinity Kappa Perfect 10.1s in a sealed MTX BASS Slammer box lined with 1" poly fill. When I first hooked this system up, to replace my old dual 10" 10w0s paired with an Infinity Ref. 7520a, they sounded just about as loud, but much cleaner. Ive always been a fan of Alpine, and gave infinity a chance when my old amp died. After the experiance I decided to try out their subs when I upgraded. I chose the 611a and 10.1s due to thier excellent reviews. Now that the subs are broken in,not only do they SLAM they sound sooo clean! I love the way the wires connect directly to the amp, its much cleaner looking than the 7520a was.

This amp will feed all but the most power hungry subs, pushing out over 650rms at 2Ohms. Be sure your subs(in a dual setup) can handle atleast 300rms (not peak) each or you will burn them up! If your in the market for an amp pushing 650-700 at 2Ohms give this one a try, you wont regret it. At the price w/ free shipping along with Crutchfields EXCELLENT service you cant go wrong!

As for the negative side to this amp, the plastic feet are a bit flimsy. When I was mounting it my drill nearly suck the first screw through the plastic. After that I put the screws in by hand and had no problems.

My setup:
CDA-9833 one of Alpines last good HUs IMO, Alpine SPS-46C2s and SPS-69C2s, MTX Thunder4122 rated at 56rmsx2 to the rears, Inf. Kappa Perfect 10.1s and this Ref. 611a, all Streetwires wiring and RCAs, speaker Baffles, and a 1.2-fared cap to power both amps.


Written By Justin, Oconomowoc,WI on Saturday, March 24, 2007

This is a great amp. I have mine powering 2 Infinity Kappa Perfect 12" subs and they sound great. This is the first amp that I owned and the first subs that I own, and they sound awesome. My friends spent tons more on their systems and mine is hands down better. A coworker swears on Boston, while it is a good company, his system can't touch my infinity setup.

OH BOY!!!!!

Written By tipking, Atlanta, GA on Friday, March 09, 2007

Larry from IA; I have the same set up but Kappa 10.1 in a sealed 1cu. enclosure. When I first installed them they sounded like crap. I used the Alpine Mrd M301 to break them in. "YOU MUST BREAK THESE IN" They still sounded bad; after 3 years of 2 JL Audio 10W3V2 on 2 Alpine 301 I was looking for perfection. Stopped by Best Buy and p/u the 611a and OH BOY; I thoght Jl Audio was the sh** until I hooked up these perfects. Make sure your sealed box is free a leaks, don't be cheap on rca and patch cables; big difference, and allow ample break in and no other set up for the price can touch you. For you JL fans, I love em too, but Infinity has made a believer out me.

Power House

Written By Larry, Iowa on Monday, March 05, 2007

Crutchfield Customer Review (What's this?)

bought 2 Infinity Kappa Perfects 12.1's in Decemeber and just let them set around untill i can buy this amp. Recived the amp a few days agao. and Installed everything the amp blew the 2 Kappa Perfects, that or it just rattels the box to much, not sure all i get is a loud ratteling noise. But if it blew the subs this amp runs way over its RMS says.

Nice !!!!!!!

Written By Leo, Denver, Co on Wednesday, February 28, 2007

I had this amp hook up to 2 12's P3 OOOOOOOHHHHHHHH man let me tell you they would it hard i even had a epicenter hook up to it and uuuuuuuuu man i had to get a upgrade on my subs i recommend this amp!!!!!!!!!!!!!!!!!!!!!!

Love This Amp

Written By Clay, Florence,AL on Sunday, February 18, 2007

I bought this amp at a discount because it had been used. I am so glad I did.

I have the Pioneer DEH-P4900iB H.U. with Two Infinity Perfect 10.1's hooked up to the 611a and I make some racket. Clean, Raw Power. I absolutely love the way it sounds and I'll tell you why, It's not so much as that it's just noise. It's not pushing so much that it makes your head hurt. It has a job and it does it very well. Great Amp that is very clean and easy on the eyes.

Now for a downside(as with all things). This model amp has a problem with the mounting brackets breaking off and it's no wonder why: The brackets are plastic, not metal like I thought they were. Anyway, two of my brackets were broken off when I got it out of its shipping box. I plastic welded them back together, no big deal, and mounted the monster to the side of the sub-box and it looks really nice, maybe even professional looking, heheh. Be careful to mount this thing and not let it slide and hit on anything because they will break.

All-in-all, great amp with some awesome power.


Written By JT, Watsonville, CA on Tuesday, January 30, 2007

Crutchfield Customer Review (What's this?)

This amp is sick, i got it hooked up to 2 12-inch Infinity Kappa Perfects (sealed), and this amp POUNDS. This amp is great for adding some good quality bass. It isnt so loud outside the car (Unless you have it at full volume), but you can feel it by touching someones house 50 yards away. A cop told me to turn down my music when i turned it down like 100 yards away before approching him. Be sure to get a capacitor though, my lights dim alot when i have it at high volumes, im thinking about porting it to get a little more sound out of it. Anyway great sub for the money, thanks Crutchfield!

Infinity Reference 611a

Written By Anonymous, hawaii on Sunday, January 14, 2007

dis amp is da best ting i had sofar. i get 2 12" 800 rms each and 2 ref 611a amps each powering one sub and i gotta say dis thing pounds. I have my bass level to the lowest and my fade to 10 towards the front and it still pounds like crazy..... i reccomend dis amp to anybody, dis amp is solid.

Great Subwoofer Amp

Written By Walt, Indiana on Friday, January 12, 2007

I have this amp hooked up with a kenwood 5band with subwoofer controlls and a infinity 7541a amp for my main speakers, and i love how well everything works together. i have this amp pounding my 2-12inch mtx subs 4500 series with a road thunder box. People keep telling me that it sounds like there is a live preformance in my car.


Written By chaps, LO Oregon on Monday, January 08, 2007

Crutchfield Customer Review (What's this?)

I just got this amp a little over a week ago when it was in the outlet for 180. I must say that set me over the edge and I went for it. I have been looking around a lot for the past 6 months or so for a new amp. I just havent needed a new amp so I didnt jump on it til I saw the price drop. I put it in my jeep with my 2 10's and then I took it right back out. Those subs would be blown apart by this amp. I need to get bigger subs and a better amp kit before it gets a permanent spot in my jeep. I had it in there for a day for a "test drive" and it will really do the job. I had to keep it almost all the way down on the levels to avoid over using my little 10's that I have. I just wish that I had better and bigger subs to be able to give it a good test. My 300 watt amp is still running those old subs until I go for the 2 12 inch Infinity Kappas that I have been eying for the past few months. I have no doubt in my mind that this amp will more than power those 2 and then some.

Great Buy

Written By Tremain, Louisa, VA on Wednesday, December 27, 2006

This amp is very good....excellent features and especailly the subsonic filter. It is perfect for the Kappa Perfect 12.1.

Awsome amp

Written By Mike, Jax, FL on Tuesday, December 26, 2006

I've got this amp powering 2 12" Infinity ref1252 subs and it sounds awsome.

at first i was skeptical because the installer said the amp would blow my speakers but then he said that he was mistaken and they should run fine together.

this is an awsome amp so buy it!

Clean, Low, and Hard

Written By Jonny, Michigan on Tuesday, October 10, 2006

I have this running to 10.1 Perfects and they hit! It is the cleanest tightest bass i have ever heard in a car audio system. It is not muddy blurry bass like some other component setups. Nothing but solid hard thump from this amp. Its efficient design and filters are great. Also i must add that it must be underrated because it is pushing out way more than 651 rms.Infinity never fails to give yet another crowd pleaser.

I agree with all of the previous reviewers

Written By C, Dallas, TX on Tuesday, September 26, 2006

I bought this amp less than a month ago and started out by running an Audiobahn 10" 450W RMS DVC sub in a sealed Q Logic box. By the end of the very first day I had it all hooked up the coils of the sub were blown all inside the box. Destroyed that sub. Ok, so I then decided to upgrade to an MTX Thunder 7500 10" sub. Same configuration, running at 2ohms. The MTX has lasted me about 3 weeks, until today, and the REF611a blew that thing away, too. The sub locked right up, but not before it blew me away with some SERIOUS sound. About rattled my rear view mirror off. For both subs I had the gain set at mid level, the low freq tuned at about 150hz, the high freq tuned all the way down and the DBO at about mid level. Both subs shared the same fate. So, now I'm becoming somewhat nervous at to what sub out there can actually take the massive abuse that this amp has to offer. The MTX is covered under warranty but it clearly didn't withstand the output of this sucker so I'm going to have to upgrade tomorrow. Maybe a higher end MTX sub or a different brand all together. I've heard the Alpine type r's can really take a beating so I'm going to check that out. No matter what I'm DEFINITELY going to go with a single 12" instead of a 10". I have an '05 Civic Si hatchback and there isn't much room in the back so I really don't want to take up every bit of space I have for 2 subs. Just need one that can handle it.
So to sum it all up I would most definitely recommend this amp as it clearly offers the output power it states to produce. Just make sure your sub/s can definitely handle the 657W of juice it supplies. It's a monster. There's my two cents. :)


Written By Kevin, Cour D'lane, ID on Friday, September 15, 2006

... Alright, at first i had this amp hooked up to 2 Kappa Perfect 12.'s in a 1.25 (per sub) sealed box. And it POUNDED SOOOO HARD. Bout 3 days later I was at my friends house and we added his 2 10" subs in a sealed box. AND THIS AMP POWERD UM EXTREMELY NICE. Then I borrowed my bros old sub.. one 12" Infinity Reference sub and hooked it up the the amp also! So now i got 5 subs in the back of my Explorer!! OMG ive never heard anything so loud in my LIFE... shakes u senceless and hits all the highs and lows. I get it turned up to 12 on my Alpine deck and it rattles ur brain!!!!! IT IS TRUELY AMAZING.

--Infinity Kappa Perfects (350 RMS ea)
--Infinity Reference (300 RMS)
--10" subs (150 RMS ea)

This amp powers um EASY. If u want the loudest system ever and the clearest, GO WITH INFINITY... you will NOT be disapointed.

Infinity Reference 611a

Written By Dan, Orange County, California on Tuesday, September 05, 2006

I got this baby powering two amazing 12" Kappa Perfect subs in a 1.25 sealed box in a 1998 Ford Explorer. and these subs r LOUD. Out of all the systems ive heard, mine is the lousest and clearest. vibrates and shakes my explorer sooo much... plus its super clear. I got this amp bridged running 456 watts (hooked up with 4 guage wire) to both my subs. My subs r 350 rms each. But they r extremely loud. Infinity makes very high quality speakers/subs/amps. VERY VERY VERY N I C E.

-----------------I N F I N I T Y--------------

(thinkin bout adding 2 more kappa 12.1's with another 611a...hmmm)


Written By Cameron, Seattle, WA on Monday, September 04, 2006

--I bridged this amp up to my two 12" Infinity Kappa Perfect subs in a 1.25 cubic ft per sub sealed box. ANyways, this amp is amaaaaaaaazingly loud, powerful, clear, perfect. It is sooo sooo loud. I havent been able to make my subs distort... and ive tried. Ive owned a lot of amps and tried out some of my friends amps... and NONE of them compare to this amp.

_-ive tryed out Audiobahn, Sony, Kenwood, Bazooka, and a MTX amps. THe only one that came slose was the MTX... But the MTX costs over $200 MORE!!! Ive tried amps that have WAY more wattas then this amp... But still dont sound NEARLY as good as this Infinity! Mostly because they r cheap and low quality. BUT INFINITY IS THE BEST>>> ILL HAVE NOTHING ELSE BUT INFINITY FROM NOW ON


Written By Matt, Rock Island, IL on Tuesday, May 02, 2006

I have this amp running to one 12d vq infinity sub and it sounds marvelous. I had same sub before with the 400rms audiobahn amp and it is nothing compared to this amp. I recommend the bass remote also it is very convienient.

Infinity Reference 611a

Written By Anonymous, Buffalo, New York on Sunday, April 30, 2006

Crutchfield Customer Review (What's this?)

Wow, this amp is really amazing. It seems much more powerful than what it is rated at. I have it powering two 12 inch infinity perfect single voice coils and it is one of the loudest systems I have heard.

Infinity Reference 611a

Written By Brad, Crystal Lake, IL on Friday, March 03, 2006

This is awesome! I have it pushing two MTX 5512s. The sound is VERY clean (as you would expect from infinity). It runs cool, even after hours of continuous use. If your thinking about this amp trust me you will not be dissappointed.

HoLy CrAp

Written By infinityisgreat, Oxford, MS on Sunday, February 19, 2006

this amp is bad. i have it pushing one infinity kappa perfect 10d vq wired at 2 ohms. so im pushing about 657 watts to it. its in a q-logic vented box. this sub WANGS! i have it in a 99 2 door i have plenty of air space. i have beat my back windsheild off my back glass so it doesnt even touch my window any more..and i had a 20 oz pepsi in my cup holder..and when i opened it it spewed from all the vibrations. Infinity is the best!


Written By RemMax, Indiana on Monday, January 23, 2006

I bought this amp and a pair of Kicker Comp 12" Subs Christmas 2005, By Jan 2006 I have now blown my second Kicker with this one was literally SMOKING at the end! It is paired with a Kenwood 7028 Head Unit having 3 sets of Pre-Outs (Front,Rear&Sub)with a Sirius Tuner attached and a Infinity 7541 that is hooked to 2 sets of Infinity component speakers 5010cs's in Q Form Kick panels and 6810cs's in the back of a Ford Ranger Extended Cab. When the speakers are working it is I think the Cleanest amps I have ever owned and is VERY VERY LOUD
And people think I am hard of hearing from the Gun Range!! Yea Right!:> These amps are LOUD! Now if I can just find a set of Subs to handle the power they put out I will have it made! These are the best amps I have ever owned!

Infinity Reference 611a

Written By Mikee, DC area on Wednesday, October 19, 2005

Crutchfield Customer Review (What's this?)

I put this in a '01 QC Ram. I have it driving a JL Audio Stealthbox. A bit much, but gives me the room to adjust. I have the input being fed by an Infinity Reference 7541a for my front and rear speakers. The two amps look beautiful next to each other. The sound is incredible. A vast improvement over the factory Infinity system.


Written By steven02_35th, Texas on Friday, July 15, 2005

Crutchfield Customer Review (What's this?)

I bought this mono amp to power my Infinity Perfect 10" Sub... Does a perfect job, more than enough power to put out some massive hard hitting perfectly clear bass... If you wanna have one of the clearest best systems, get this Infinity Amp to power an Infinity Perfect 10" or 12" sub and you are good to go!! Love everything about Infinity! wouldnt go with anything else now that i went all infinity in my car!!


Written By Brady, PITTSBURGH, PA on Friday, June 03, 2005

This amp has got to be the most amazing thing that had ever happened. Not too powerful to crush your subs but you hear the loud low thud with the clear crisp sound. This amp is a must!

Infinity Reference 611a

Written By Big T, Haiku, Hawaii on Saturday, April 16, 2005

This Amp is the BOMB.

Hands-on research

What's in the box?

Download owner's manual

  • Mono amplifier with two 30A fuses installed
  • 2 Spare 30A fuses
  • 4 Self-tapping screws (length=1")
  • Instructions
  • Amplifier Quick-Start Guide
  • Warranty/Product Registration card
  • Infinity window decal

Product Research

Inputs, Outputs, and Controls


Class D Design: The Infinity Reference 611a is equipped with a high-frequency Class D switching power supply, which is more efficient than traditional class AB power supplies, and draws less current from your vehicle's charging system.

CEA-2006 Compliance: The specifications given by Infinity for the Reference Series 611a amplifier comply with the new CEA-2006 Amplifier Power Standard from the CEA (Consumer Electronics Association). All manufacturers who comply with the standard can display the CEA-2006 logo on their product.

Protection Circuitry: The amp features 4-way protection, and will shut itself down in the following cases:

  • DC Output: DC voltage is detected on the amplifier output
  • Temperature: Amplifier is overheated
  • Over/Under Voltage: Voltage at the +12V (Battery) terminal is less than 8.5V or more than 16V
  • Short Circuit: Short circuit in speaker or speaker wire

Status LEDs: Three LEDs on top of the amplifier provide the status of the amplifier. The "Clip" LED indicates the amplifier is being overdriven, and the speakers may be in danger. The "Power" LED indicates the amplifier is on. The "Protection" LED flashes or glows to indicate the amplifier has entered the protection mode because of a malfunction.

Dynamic Bass Optimization (DBO): The Dynamic Bass Optimizer (DBO) is used to enhance low frequency reproduction in your vehicle. Conventional bass-boost circuits only increase bass at a fixed frequency, and cause the amp to consume considerable power. The DBO allows you to adjust the frequency (20Hz - 80Hz), as well as the boost level (up to 12dB), allowing you to fine-tune the bass in your system to optimize performance. The frequency control is a high-pass filter which can be used as a subsonic filter.

Low Pass Filter: The 611a has a variable 12dB per octave, 32-320Hz low pass filter.

Optional Remote Level Control: The amp has an RJ-11 jack for use with the optional 100rc remote level control module (item # 108RC100). This will allow the subwoofer level to be adjusted from the listening position.

Inputs, Outputs, and Controls

Left Side of Amp:

  • Preamp Output: 1 pair of gold-plated RCA jacks (amp provides a non-filtered signal for daisy-chaining additional amplifiers)
  • Preamp Input: 1 pair of gold-plated RCA jacks
  • Input Level: Rotary control to match the level of the preamp input signal
  • LP Freq: Rotary control to set the cutoff frequency of the Low Pass Filter
  • DBO:
    • HP Freq: Rotary control to set the cutoff frequency of the High Pass Filter
    • Boost: Rotary control to set the level of the boost
  • Remote Level Control: RJ-11 jack for use with the optional 100rc remote level control

Right Side of Amp:

  • Speaker Output: 4 Set screw terminals for connecting speaker wires; handles up to 8 gauge (16 gauge minimum recommended)
    • Note: There are two sets of terminals to make it easier to connect multiple subwoofers. The terminals are connected internally in parallel.
  • Fuses: 2 Slots for 30A fuses (installed)
  • Power:
    • +12V: Set screw terminal for power wire from battery; handles up to 4 gauge wire (6 gauge minimum recommended)
    • Remote: Set screw terminal for remote turn-on lead; handles up to 8 gauge wire (18 gauge minimum recommended)
    • Ground: Set screw terminal for ground; handles up to 4 gauge wire (6 gauge minimum recommended)

Our Product Research Team

At Crutchfield, you'll get detailed, accurate information that's hard to find elsewhere. That's because we have our own in-house Product Research team. They verify what’s in the box, check the owner's manual, and record dimensions, features and specs. We stay on top of new products and technologies to help people make informed choices.