Name: RetroSound Quad4
Brand: RetroSound
SKU: 068QUAD4
Price: 219.99 USD
Availability: InStock
Rating: 4.5 (20 reviews)

by Crutchfield's Bob Bihlmayer

More power, Captain

You've got a classic car with a RetroSound radio installed, but you want more power for your front and rear speakers. Enter the RetroSound Quad4, an ultra-compact 4-channel amplifier rated at 45 watts RMS per channel, which offers plug-and-play hookup to any RetroSound radio. You can connect other aftermarket car stereos via the Quad4's low-level RCA inputs.

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More power, Captain

Big sound, small package

At roughly the size of a large candy bar, the tiny Quad4 delivers a mighty sound, while its dimensions allow mounting almost anywhere, including under seats and behind the dash. If you're using a sub in your classic ride, you can activate the built-in high-pass filters to remove the low bass from your full-range speakers so they play louder and cleaner. The Quad4 also features advanced thermal and short-circuit protection so you'll be able to enjoy your sound for years to come.

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Product highlights:

ultra-compact 4-channel amplifier
45 watts RMS x 4 at 4 ohms
direct input/output connection to all RetroSound radios
RCA inputs available for non-RetroSound receivers
switchable high-pass filters (110 Hz, 12 dB/octave)
frequency response: 10-40,000 Hz
advanced thermal and short-circuit protection
fuse: 15A
10-gauge power and ground leads recommended
dimensions: 7-3/16"W x 1-13/16"H x 2-15/16"D
warranty: 1 year
MFR # Quad4

What's in the box:

RetroSound Quad4 owner's manual

4-Channel amplifier
4 Mounting screws
User's Manual

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Researched by Crutchfield's Mark G.

Features & specs

Performance
RMS Power Output (Watts x Channels)	45 x 4
Peak Power Output (Watts x Channels)	55 x 4
Power at 2 Ohms (Watts x Channels)	N/A
Bridged Power (Watts x Channels)	N/A
Minimum Impedance Bridged	N/A
Minimum Impedance Unbridged	4
Minimum Impedance	4
Best Frequency Response	10-40000 Hz
THD at Rated RMS Power	0.2%
Signal to Noise Ratio	90 dB
Input Voltage	14.4v
Features
Amplifier Class	D
Low-Pass Crossover Frequency	N/A
Low-Pass Slope (dB/octave)	N/A
High-Pass Crossover Frequency	100 Hz
High-Pass Slope (dB/octave)	12 dB/octave
Bass Boost	No
Bass Boost Frequency	N/A
Fan Cooled	No
Fuse Rating	15
Speaker Level Inputs	Yes
Preamp Outputs	No
Width (inches)	7-3/16
Height (inches)	1-13/16
Depth (inches)	2-15/16
Parts Warranty	1 Year
Labor Warranty	1 Year

Product Research

Features

Quadraphonic 4-Channel Amplifier: The RetroSound Quadraphonic (QUAD4) is a full-range Class D (digital) power amplifier featuring 45 watts x 4 RMS power. The Quadraphonic amplifier offers exceptional dynamic range and low distortion for the best possible sound reproduction from your car audio system.

Direct RetroSound Connect & Low-Level RCA Inputs: The Quadraphonic (QUAD4) plugs directly into any RetroSound radio. Low level RCA inputs also allow the Quadraphonic amp to be used with practically any aftermarket car stereo system.

Built-in High-Pass Crossovers: The RestroSound QUAD4 has built-in high-pass crossovers for the front & rear channels. The high-pass crossovers are defeatable if you desire a full-range setup.

Front & Rear Gain: Front & Rear gain control allows you to match the input sensitivity of the amplifier to the output of your RetroSound radio or other aftermarket stereo.

Compact Chassis: The RetroSound Quadraphonic (QUAD4) amplifier's diminutive size means you can install it virtually anywhere, including behind the dash.

Power & Ground: Regardless if you are connecting the QUAD4 amp directly to a RetroSound radio or other aftermarket stereo, you will need to connect the constant +12 volt (yellow) lead to the battery, and the ground lead (black) to the chassis of the vehicle.

Advanced Protection Circuitry: The RetroSound Quadraphonic (QUAD4) offers advanced protection circuitry with thermal and overload protection.

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7 questions already asked

I have the RetroSound Hermosa radio. The owners/install manual for this amp lacks any color coding for the various plugs coming from the amp... do I simply match the wire colors coming from the Hermosa to the wire colors coming from/going into the amp? Sorry for the newbie question, just don't want to fry the amp or the radio.

odie Aug 31, 2022

1 answer

If you purchased the product from Crutchfield, feel free to contact our Tech Support team. Our toll-free Tech Support number is printed on your invoice, and is also available under the "My Orders" tab in the "My Account" section of our website. If you did not purchase the unit from Crutchfield, then you may want to contact the manufacturer.

zachary Aug 31, 2022 (Staff)

Do they have a wire that connects to factory radio or a guide for wiring so I can splice into?

ira Aug 17, 2021

2 answers

Hi Ira T, I can't answer your question directly because I don't what vehicle you have. However, RetroSound does have a few different wiring diagrams for wiring this amp. You can go to RetroSound website to find the Amp drop down menu. Locate the amp and there should be an icon for owners manual to download. The owners manual should have the wiring diagram you need in the installation instructions.

ronald Aug 20, 2021

This will depend largely on your vehicle. For details on installation please contact an Advisor by phone (1-800-324-9695) or online chat. They will be able to pull up your vehicle and give you the details on what you will need for an installation.

kenneth Aug 18, 2021 (Staff)

So this plugs into my factory amp?.

jason May 04, 2020

3 answers

No it doesn't,It's designed to plug into a Retrosound radio and boost the output and connect directly to 4~8 ohm speakers

sam May 06, 2020

This is a amp plugs in to retro sound head unit

stuart May 06, 2020

Negative. This is an amplifier that plugs in directly on to a retrosound radio. It will need to be modified to be used with any others brand/radio.

victor May 04, 2020

Does this amp give true quantaphonic sound to the system?

lenny Apr 07, 2019

1 answer

Since I'm disabled and money is rather tight I haven't been able to install it yet.

jack r. Apr 15, 2019

Does this really have a sufficient constant power wire? The wiring diagram shows to use the yellow wire for constant 12v, but it looks kinda small to be 10 gauge even. It also says a 15 amp fuse is included, but the yellow wire in the pic doesn't show an inline fuse.

david Aug 16, 2018

2 answers

the wire is sufficient. You can cut it shorter and run larger wire to your battery if you choose. I think I used 10 ga all the way. You don't see the fuse because you always mount the fuse as close to the battery as reasonable. like within the first couple feet.

joshua Aug 22, 2018

Yellow wire only runs the clock function,only uses slight amt. Of power

roy l Aug 21, 2018

Will this amp work as plug and play with the Custom Autosound USA 230 radio, the way it does Retrosound radios?

scott Apr 04, 2018

2 answers

The RetroSound Quad4 amp only offers plug-and-play hookup to RetroSound radio models. However, you can still connect other aftermarket car stereos via the Quad4's low-level (RCA) inputs. For more details or to discuss further, please contact an Advisor directly by phone (888.955.6000) or online chat. Thanks!

david Apr 25, 2018 (Staff)

Scott. Not sure how to answer your question. I have installed the amp into my 1974 MGB but am still unable to get power to my radio through the amp. Still doing wire tracing and troubleshooting.

wayne e. Apr 24, 2018

Is there any difference in sound quality between using the RCA inputs and the direct connection with the RetroSound Newport radio? Just wondering if anyone had tried hooking up the amp both ways to hear any difference. Thanks.

jonathan d Sep 23, 2016

1 answer

I'm running a RetroSound Newport radio in my 1987 Buick Turbo Regal and actually using both RCA and speaker level outputs together and there is no detectable difference between the two. I just wanted a nice clear stock looking radio with Bluetooth and auxiliary input connections for cruising. My car has the Factory Concert Sound II 6 speaker system. I rewired the system so the door and dash speakers are not in parallel, then run the 3.5" RetroSound Dash tweeters and rear speakers (JVC 6X9 with adapters replaced the factory 4 X 10 units) on the 20 watt RMS amp in the radio. The 5.25 door speakers and a bazooka dual voice coil subwoofer tube are powered by a Rockford Fosgate 250 X 4 amplifier in the trunk using RCA outputs from the radio. I am not using the Quad 4, so I can't comment there. At my age, 15 on the volume scale is about all I can stand and that's plenty loud. Hope this helps

chris j Sep 23, 2016

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