Guide to Car Amplifiers

Herewith, a guide to car amplifiers, to help you make that big step from fibby headunit chip-amp watts to real phat RMS ones! Adding a dedicated power amplifier is the ‘big step’ in car sounds. Before that, you seek ever yet more powerful head units with higher wattage ratings. Maximum for a car radio is normally 4x50W. That’s just a true 23 watts of RMS power or ‘Root Mean Square’. Sony have an output stage with a tiny 4×100 watts Class D in one of their head units. But for real power to your sounds, you will need a dedicated amplifier. But which one?

Here’s the important stuff. Check out the power, the current draw, the sound quality and then the features count. 

The fairest way to rate amplifier power is RMS. Music is dynamic – it gets louder and quieter – thus true output of an amp can be hard to measure. The ‘peak’ ratings on amplifiers vary absurdly. There is a nasty cluster of fake products that look like real car amplifiers but are made to scam you. If it looks like too many watts for the money, it will be junk. We’ll talk about RMS power. Next, you need to know if you have the margin on your alternator to run the amplifier. Your ‘margin’ is the alternator’s ampere output above what your car needs to run its own accessories. The current draw may be too high for your car without upgrading your alternator or adding a deep cycle battery.

Lastly, check out the features. Does it have crossovers? Or filters? Or other stuff you like?

Guide to Car Amplifiers – Two/Four Channel Amplifiers

Alpine BBX F-1200 four channel

Better quality two (and multi) channel amplifiers can be ‘bridged’. This is when you connect one speaker wire to one channel (+) and the other to the paired channel’s (-). The use of a bridging switch is common but sometimes just hooking it up that way will work. It’s a way to suck more power, get better grip of the speakers and get more features for your money. We recommend you go straight for a four channel amplifier. More versatility and easier to resell if you upgrade.

This amp is a Class A/B MOSFET design and represents amazing value for money. Great fidelity and some real muscle for a low price from a top brand.

• Power Output: 4ohms 4 x 50W, 2ohms 4 x 70W, Bridged 4ohms 2 x 130W
• Current Draw/Fuse Rating: 40A
• Signal To Noise Ratio: 95 dB
• Features Rich? 50Hz – 500Hz highpass and lowpass filters and a 45Hz Bass EQ

Rockford Fosgate Power T-400 four channel

A serious slab of Americana, this amp has the famed Rockford PUNCH EQ and RF aughta be in any decent guide to car amplifiers. You can boost the sound at 12kHz and at 45Hz up to a whopping18dB. This can make your sound fatter and beatier. Great if you want some real thump and zing in your tunes. Less beloved of the fancy fidelity types but adored by the power hungry. Rockford talk more about raw power than super-fidelity. Two sets of crossovers, (up/down on each pair of channels) twice those of Alpine’s BBX, makes it more versatile.

Another Class A/B MOSFET design, Rockford Fosgate has a cluster of technologies they have been developing for decades just for car amps. This one truly rocks and will hold its value.

• Power Output: 4ohms 4 x 60W, 2ohms 4 x 100W, Bridged 4ohms 2 x 200W
• Current Draw/Fuse Rating: 60A
• Signal To Noise Ratio: RF quote less than 1% THD or Total Harmonic Distortion
• Features Rich? It has two sets of high and lowpass crossovers, and its own Punch EQ

JL Audio HD600.4 four channel

The HD600.4 has what JL call Single Cycle Control Switching. It’s a way of tightly regulating the power supply to the amplifier. A very high fidelity amp, it puts out the same 4×150 wattage at a wide range of impedance of load. So the 2ohm and 4ohm ratings are the same. That true power has amazingly high quality sound. It’s why this has a high price.

Described as having huge dynamics and astonishing resolution, JL dare you to compare it to any price product. JL are so good at high end amps that Alpine have been known to use them as performance comparison benchmarks. The HD600.4 is a full range Class D design.

• Power Output: 4ohms 4 x 150W, 2ohms 4 x 150W, Bridged 4ohms 2 x300W
• Current Draw/Fuse Rating: 50A
• Signal To Noise Ratio: >110 dB (A-weighted, 20 Hz – 20 kHz noise bandwidth)
• Features Rich? Remote level control and preouts but the quality is the main feature

Guide to Car Amplifiers – Multi-Channel Amplifiers

JBL Club A5055 five channel

Like the Rockford Fosgate T-400, this has big 4 gauge power wire terminals to deliver serious current. A fifty watter (65w at 2 ohm loads) with a decently large half-kilowatt bass amp section. This one amplifier can power a whole system. The unit’s crossovers span 32Hz to 320Hz for the main channels and there’s another the same, for the bass one. There is a bass boost set at 45Hz that can be lifted by as much as 12dB.

The main four channels are Class A/B and the subwoofer channel is Class D. This is cunning use of technology to keep the price keen. A great little unit for taking decent speakers to a whole new level.

• Power Output: 4ohms 4 x 50W + 1 x 320w, 2ohms 4 x 65W + 1 x 500w
• Current Draw/Fuse Rating: 3 x 30A fuses – BIG power at 90A
• Signal To Noise Ratio: Balanced Differential inputs cited but no figures quoted
• Features Rich? Comes with a remote level control knob. Crossover and bass boost.

Hertz HCP5D five channel

This is a hifi item. The HCP5D has a trio of both high level speaker input sockets and paired RCA inputs for signal level. It too can play a whole system of front/rear/sub. There is a button so you can run it three channel with two high power mains and the sub bass. One high end feature is the switchable subsonic filter fixed at 25Hz. Unless you are playing organ music or bass tunes, your power will not be needed down this deep. The filter stops the deep harmonics from going through the amp and using up the power where you cannot hear it. This serves to leave more oomph for the stuff you can feel.

The bass boost is at 50Hz and can be turned up by as much as 12dB. Also, there is an optional wired remote subwoofer level knob available. A very high quality single-box solution.

• Power Output: 4ohms 4 x 55W + 1 x 160w, 2ohms 4 x 90W + 1 x 280w
• Current Draw/Fuse Rating: 30A
• Signal To Noise Ratio: 100dB
• Features Rich? Yes! High pass, low pass and even band pass crossovers

Audio Control LC6 1200 6/5/4/3/2 channels

AudioControl call this the most flexible 6 channel amplifier on the market. As well as all the preamp inputs it has two sets of assignable preamp outputs. This means you can do all sorts of things up to and including running it fully active. It can run a high end set of three way component speakers and still feed signals onwards. The crossovers are sophisticated Linkwitz-Riley designs (meaning better than cheap ones) and there is a mass of controls on the top panel to sort all this. It is a bit of an expert product to install.

The power draw is hefty as this really makes some watts. AudioControl are the company that makes the Epicenter bass synthesiser, so they know their lows. It means they know about the power the lows need, too. A totally top end amplifier.

• Power Output:4ohms 6 x 125W, 2ohms 6 x 200w
• Current Draw/Fuse Rating: 3 x 40A
• Signal To Noise Ratio: 103dB
• Features Rich? Incredible, with proprietary AccuBASS® bass tech

Guide to Car Amplifiers – Single Channel Amplifiers

BOSS R2400D single channel

An inexpensive brand, this mono bass amp has some serious features, earning its place in our guide to car amplifiers. The maddest is that is strappable. You can use two to drive one huge power output. ‘Strapped’ power, bridging two R2400D at 2ohms, to show one ohm to each amplifier, claims an output of 4,800 watts. A bit overstated, I think. The low pass crossover is settable from 50Hz to 150Hz, and the subsonic filter is variable between 15Hz and 40Hz. This is a brilliant feature and allows you to play deep but without the crippling ultra lows sucking your power.

A Class D MOSFET design, there is a switchable phase control and the case has a groovy backlit logo. An awful lot of product and power for the money. You get a wired remote control and a special strapping ‘data link’ cable with it.

• Power Output: 4ohms, 1 x 450W, 2ohms 1 x 900W, 1ohm, 1 x 1800W
• Current Draw/Fuse Rating: 2 x 35A
• Signal To Noise Ratio:100dB
• Features Rich? For the price, this has bass boost, a crossover, a subsonic filter and more

JBL GTR-1001 single channel

A mighty Class D bass amplifier with a 2,600 watt peak rating. That means a true kilowatt RMS as the main oomph. This will require a secondary battery and ideally an uprated alternator on your car. The power of JBL big amps is legendary and this is an amazing amount of power for the money. In the old days a quid a watt for big amps was seen as good. Now, that is old fashioned as you can get a thousand watter for way under £500.

The GTR-1001’s lowish signal to noise ratio is irrelevant for huge bass. Meanwhile, this amp is the bass brother of other GTR models with incredible features. Any passenger may play their music into your system via the bluetooth sections on the other JBL GTR amps. Deeply clever, deeply cool, hugely potent, great value for money.

• Power Output: 4ohms, 1 x 700W, 2ohms 1 x 1,000W
• Current Draw/Fuse Rating:3 x 35A
• Signal To Noise Ratio: >80dB 
• Features Rich? Gain, frequency of crossover, bass boost and phase are the lot

Vibe BLACKDEATH M21K-V6 single channel

For the lunatic bass heads, the Vibe people go all the way. With absurd monster subwoofers to hang on them, this is their Korean-built bass monster. You could spend more with USA-made exotica and these mono monsters can get really crazy. This one is almost ‘normal’ by comparison to some. Able to drive huge speakers to ground shaking levels, this is the sort of thing bass competition systems need.

Incredibly, this is seen as good value for the true bass head’s spend. Amazingly enough, it also happens to be a sweet sounding ‘Ultra’ Class D amp. It can play full range if your speakers are big enough to cope. This can drive full-on public address systems and get you kicked out of car shows for drowning out the show P.A.

• Power Output: 4ohms, 1 x 3,470W, 2ohms 1 x 7,200W, 1ohm, 1 x 10,500W
• Current Draw/Fuse Rating: 1,000A
• Signal To Noise Ratio: 90dB
• Features Rich? Low pass/High pass crossover 10Hz to 15kHz