Boston Acoustics takes much of the technology they developed for their top-of-the-line GT Reference amps, and uses it in their latest GTA Series amplifiers. The 4-channel GTA-704 amplifier puts out 70 watts RMS per channel — plenty enough power to rock two sets of speakers or components. You can also drive a pair of subs with 250 watts RMS each in 2-channel mode, or bridge the rear channels to send 250 watts to a sub while the front channels run your full-range speakers. Boston Acoustics' Q-Tune™ technology lets you bump up your bass, whether you're running a subwoofer or not. The inputs feature special noise-cancellation circuitry that ensures clean reproduction of your music all the way through to your speakers.

The amp's Integral Mounting System puts the mounting holes in each corner of the frame, instead of using protruding tabs that waste space. You'll find all connections and adjustment controls recessed on one side of the amp, for a neat installation and easy adjustment. Variable high- and low-pass filters let you tune the amplified signal so your system can sound its best. An optional wired remote control gives you the power to tweak the bass level from the front seat.

Product Highlights:

  • 4-channel car amplifier
  • 70 watts RMS x 4 at 4 ohms (125 watts RMS x 4 at 2 ohms)
  • 250 watts RMS x 2 bridged output at 4 ohms (4-ohm stable in bridged mode)
  • CEA-2006 compliant
  • variable high-and low-pass filters (50-200 Hz, 12 dB/octave)
  • Q-Tune technology switchable bass boost (6 dB at 45 Hz) on rear channels only
  • optional wired remote subwoofer level control
  • Symmetrical Signal Technology (SST™) uses asymmetrical balanced inputs for noise cancellation
  • frequency response: 10-50K Hz
  • preamp and speaker-level inputs
  • fuse rating: 25A x 2
  • 8-gauge power and ground leads recommended — wiring and hardware not included with amplifier
  • 14-1/8"W x 2-3/8"H x 8-5/16"D
  • warranty: 2 years
  • 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.

Hands-on research

What's in the box?

Download owner's manual

  • 4-Channel amplifier
  • Four 25-amp ATO fuses (two installed/two spare)
  • Four 3/4" Self-tapping screws
  • 3mm Allen wrench
  • 2mm Allen wrench
  • Two 12" Speaker input harnesses
  • Owner's manual (English)
  • Owner's manual (Spanish/ French)
  • Warranty information

Product Research

Features
Controls
Connections

Features

Multi-Channel Design: The Boston GTA 704 is a 4-channel amplifier, basically two independent 2-channel amplifiers built into one chassis. Either side can be bridged so it can be used as a 4-channel, 3-channel, or 2-channel amplifier. The amplifier is stable down to 2-ohms in stereo, and 4-ohms when bridged.

CEA 2006 Compliant: The GTA 704's power ratings are measured according to the Consumer Electronics Association CEA-2006 standards. These standards allow you to accurately compare the rated power output of all CEA 2006-compliant amplifiers, even different brands. Manufacturers who adhere to the standards can display the CEA 2006 logo on their products and packaging. The power output is measured from 20 Hz to 20 kHz using a 14.4 volt power supply:

  • Four-Channel (4-ohm): 70 watts x 4-channels into 4-ohms with no more than 1% THD+N
  • Four-Channel (2-ohm): 125 watts x 4-channels into 2-ohms with no more than 1% THD+N
  • Bridged (4-ohm): 250 watts x 2-channels into 4-ohms with no more than 1% THD+N

Controls and Terminals: All the controls and terminals are conveniently mounted on one side of the amp.

Controls

Gain: The amplifier's gain setting is adjusted using two independent rotary controls for the front and rear channels. The line-level input gain settings are continuously variable from 200 mV to 5.0 V; the speaker-level input gain settings are continuously variable from 400 mV to 10.0 V.

Crossover Switches: There are also independent crossovers for the front and rear channels; each can be set to HP (high pass), Off (full range), or LP (low-pass).

Crossover Frequency: You can independently select the crossover frequency for the front and rear channel crossovers; each is continuously variable from 50 to 200 Hz. The crossover slope is 12 dB/oct.

Q-Tune: Q-Tune bass boost can be applied to the rear channels; the boost is +6 dB at 45 Hz and can be turned off if you prefer.

Connections

Speaker-level Input: Front and rear speaker-level input harnesses (included) supply signal to the amp when the receiver has no RCA outputs.

Line-level Input: The front and rear amplifier sections have independent RCA input jacks.

GTA-RSL: RJ-14 port; connect an optional GTA-RSL remote level control (item number 065GTARSL, sold separately); the GTA-RSL is attached to the rear channels and only functions when the low-pass crossover is engaged.

Speaker Output: Four pair of set-screw terminals are provided for connecting the speakers; the terminals accept up to 10-gauge wire; the set screws are tightened/loosened with the supplied 2mm Allen wrench.

ATO Fuse: Two 25-amp ATO-type fuses are located between the speaker and power terminals.

Power/Remote: The power, ground, and remote wires connect to three set-screw terminals. Each terminal accepts up to 8-gauge wire and the set screws are tightened/loosened with the supplied 3mm Allen wrench.

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 open the box, verify contents, 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.

Boston Acoustics GTA-704 Reviews

Average Customer Review:

8 reviews
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Im happy!

Written By chiludo, SATX on Wednesday, January 23, 2013

Crutchfield Customer Review (What's this?)

great amp to power 4 Polk Audio DXi6500 6.5" Component Speaker System speakers, a bit of a snug fit under a 08 tundra passenger seat but will fit.

Pros: great power

Cons: tight fit.

Good amp. Nice price

Written By Tim, EASTERN SHORE, MD on Thursday, November 01, 2012

Crutchfield Customer Review (What's this?)

Clean good sounding amp

Pros: Price, Clarity

Cons: None

A Terrific 4-channel Upgrade

Written By DMA, Dallas, TX on Monday, August 06, 2012

Crutchfield Customer Review (What's this?)

I was in the market for an upgrade for my trusty eight year-old US Acoustics USB-4065 (from Crutchfield, of course), as it was a bit beat up from daily trunk use (two of the RCA jacks were nearly snapped off, but it still worked), As my system is otherwise all Pioneer, I considered the Pioneer GM-D9500F, but I opted for the Boston Acoustics GTA-704 after reviewing the specs and hearing good reviews from friends and colleagues. What a great little amp! It was easy to install, easy to set, and it sounds terrific. The overall sound is very crisp and clear, and I swear vocals sound cleaner with no change to my Pioneer AVH-P3400BH's settings. To top it off, I caught it at a price break! If you're looking for a quality 4-channel amp at a great price, try the Boston Acoustics GTA-704.

Pros: Easy to install, lots of options, great price

Cons: None that I can think of...

Solid Amp

Written By DotRat, Boston, Ma on Monday, July 23, 2012

Crutchfield Customer Review (What's this?)

The amp packs a solid punch in a fairly small amount of real estate. It produces the range well and drives my front and rear speakers on the low end so well I don't feel the need for a sub. The unit produces significant heat but the aluminum case does a fairly decent job dissipating it. I wish Boston Acoustics still built their amp products on American soil because I feel like everything they have produced here had a greater attention to detail. Whether this amp will hold up to the drastic temp changes I see here in New England remains to be seen, but overall I am happy with my purchase.

Pros: Small Size, Decent Interface, Solid Sound

Cons: None Yet

Boston Acoustics GTA-704

Written By Jeff, Jordan,MN on Thursday, July 19, 2012

Crutchfield Customer Review (What's this?)

I purchased this amp to power a single 12 inch sub bridged with the adjustable gta-rsl. I feel the amp has adequate power however to run both channels bridged you have to split the input rca signal to feed both channel inputs, then once you do that the gta-rsl only works on the rear channel. This did not fit my application so I returned it. Once I had it up and running and tuned it did sound decent though. Probably would be better running a set of component speakers.

Great amp

Written By Wrenchspinner, Cleveland OH on Wednesday, June 27, 2012

Crutchfield Customer Review (What's this?)

I have had the amp for about a week. all I can say is wow! it sounds great and really makes my speakers come to life Great product! Highly recommend it

Pros: Geat power and price

Cons: none yet

Great Amp

Written By Frank, Texas on Sunday, June 10, 2012

Crutchfield Customer Review (What's this?)

This amp went great with my speakers! Installing was a breeze for me!

Nice Amp

Written By DanB, DE on Sunday, February 05, 2012

Crutchfield Customer Review (What's this?)

Nice amp, I am very happy with it, great price too thru Crutchfield's Boston Acoustics sale. Currently running two sets of speakers - front comps & rear coax's, well matched to the power output, no problem. I like it better than the previous 70W x 4 amp I was using, seems to handle music dynamics a little better.

Pros: Great price, nice sound, no noise, very well built, no overheating issues.

Cons: None.

Product reviews from the Crutchfield Labs

Boston Acoustics — a sound decision

When the offer came through to "audition" some new Boston Acoustics gear in my car ... well, I just couldn't refuse. After all, it'd been an awfully long time since my last upgrade, and I was eager...

What are the Labs?

Get everything you’ll need to enjoy your new Boston Acoustics GTA-704

You'll need an amp wiring kit to install your new amplifier, as wiring is not included.
Bring the music from your amp to your speakers.
Patch cables take the music from your stereo to the amplifier. Most amp wiring kits don't include them.
Helps protect your car's charging system and improves power handling. Required power and ground wires not included with cap.
The right tools will make the installation easier.
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T-Spec 16-gauge Speaker Wire

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T-Spec Capacitor

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