How Much Power There Is In Car Amps?

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A lot of higher power amps actually deliver close to rated power and sometimes even more, provided you can deliver the current. But almost 100% of the cheaper models NEVER deliver even close to specs sadly. When it comes to insane power rating of 3kW and above I am not sure who well specs match actual performance.
 
As a rule of thumb, whatever the power says on the amp, divide by 5 to find the real power.

Finally we get to the truth about car amplifier ratings.

About 16 yrs ago when on the bench we tested some high power car amplifiers both on the bench and in the car. With a bank of 6 fully charged batteries and a 250 amp charger piggy backed to the batteries the car amplifiers didn't come even close when driving a 1K sine wave. In the car setting we got about a 1/5th of the rated power into the dummy load also.

I guess it has to do with the ability to say to your friends that you have 1000 watt amplifiers and watch them as their jaws drop. In reality you would have to be really lucky to get 200 watts out.
 
Forgot you question about channels. I prefer active crossovers which means one channel per driver. At least subs/midsubs can kick insanely if you use a very steep band pass crossover. I once tried a 12" PA midbass speaker in a 50l sealed box. I had a power amp that gave me roughly 600WRMS @ 8 ohm and crossover ~50-125Hz. I am currently experimenting with an active 2-way design with fairly small amps for my car. So far I have modified the built in crossover from 15-300Hz stock to somewhere around 3kHz and it seem to be working great.
 
burnedfingers said:


Finally we get to the truth about car amplifier ratings.

About 16 yrs ago when on the bench we tested some high power car amplifiers both on the bench and in the car. With a bank of 6 fully charged batteries and a 250 amp charger piggy backed to the batteries the car amplifiers didn't come even close when driving a 1K sine wave. In the car setting we got about a 1/5th of the rated power into the dummy load also.

I guess it has to do with the ability to say to your friends that you have 1000 watt amplifiers and watch them as their jaws drop. In reality you would have to be really lucky to get 200 watts out.

The amplifier I use to drive my sub and my two front channels can easily deliver ~2x135WRMS + 1x500WRMS @ 8 ohms pink noise all channels driven simultaneously.
 
The amplifier I use to drive my sub and my two front channels can easily deliver ~2x135WRMS + 1x500WRMS @ 8 ohms pink noise all channels driven simultaneously.

I assume you used test equipment as opposed to someone's finely tuned ear?

I would guess that there has been some progress in the last 16 years.

Either that or some truth to the actual power ratings.
 
mehrdad said:
Would Companies Fool People With PMPO Watt Instead Of RMS?


Done all the time.

I recall repairing one guy's "high power" 2 channel amplifier. Fancy chrome chassis, this baby even had a large fan built in !! Must be a lot of power.

So I go into the amp to replace a shorted BJT. In the process of firing it up and performing checks, I discovered the power supply rails were +/- 45V.

Now someone please tell me how I can obtain a rating of 1000W into 4 ohms (bridged or not) with 45V rails? I see no more than 250W, with no doubt some ugly distortion.

The best part of it was, the actual power supply itself was essentially nonexistent in capacitance reservoir, telling me this would be peak watts, and certainly not rms. And the fan? HAHA, no need for it, the thing ran cool, because it wasn't really drawing high watts under load.

The marketing genius of car audio (and home audio, for that matter, is no different).
 
zigzagflux said:



Done all the time.

I recall repairing one guy's "high power" 2 channel amplifier. Fancy chrome chassis, this baby even had a large fan built in !! Must be a lot of power.

So I go into the amp to replace a shorted BJT. In the process of firing it up and performing checks, I discovered the power supply rails were +/- 45V.

Now someone please tell me how I can obtain a rating of 1000W into 4 ohms (bridged or not) with 45V rails? I see no more than 250W, with no doubt some ugly distortion.

The best part of it was, the actual power supply itself was essentially nonexistent in capacitance reservoir, telling me this would be peak watts, and certainly not rms. And the fan? HAHA, no need for it, the thing ran cool, because it wasn't really drawing high watts under load.

The marketing genius of car audio (and home audio, for that matter, is no different).


I opened a car amp that had a sticker saying it was rated at 80wrms @ 4 ohms X4 channels. I opened it up and the amplifier stages were two TDA1557 chips (2 channels, each were BTL into 4 ohms, not more than 22wrms) and a couple of op amps for high pass filters and A LOT of vacant space on the PCB.
 
It's like anything, you get what you pay for.

The more reputable manufacturers have gone over to the CEA-2006 standard, and usually include test sheets with their amplifiers that are pretty reliable and give repeatable results. The less reputable ones...well, are still putting out crap :)

A lot of manufacturers use "standardized" boards from Asian OEM's, and simply modify cases and small parts to their liking and application...Zenon out of South Korea supplies a lot of the multi-kW monoblock PCB's to a few companies.
 
djQUAN said:



I opened a car amp that had a sticker saying it was rated at 80wrms @ 4 ohms X4 channels. I opened it up and the amplifier stages were two TDA1557 chips (2 channels, each were BTL into 4 ohms, not more than 22wrms) and a couple of op amps for high pass filters and A LOT of vacant space on the PCB.


An externally hosted image should be here but it was not working when we last tested it.
 
if you buy from a reliable company such as arc audio, dls, JL audio, audison, you'll get at least the rms rating and in most cases you'll get a bit more. for example my alpine pdx 4.100 is stated to be rated at 100 x 4 @ 4 ohms but the birthsheet came out to 128 x 4 @ 4 ohms.

to whom ever says divide the number by 5, thats BS. depends on the company. if you buy from crappy companies like pyle, dual, pyramid, then yea most likely you are going to get junk period.
 
Power in amps

Hi all, I have building and repairing car amps since the mid 70s. (am I that old?) I argued with many a customer about power ratings. Even when shown the actual power output on the bench they still want to believe the labels. A 20 amp fuse and terminals that cannot handle anything bigger than 10 gauge wire should be the first clue about power output. I even found one amp with lead plates in the bottom to give it weight!
My rule of thumb was: $1 per watt of honest power. It held pretty true.
The cheap amps we refered to as ILS power rating: If lightning Strikes!:D The american manufacturers were almost always honest about power output and that is why they were the only ones I sold. I suggest checking the power connectors and fusing to get a good idea of power output. A look at the power supply is an even better way. A 1" toroid with 14 gauge wire wrapped around it would not be good for much over 100 watts.
 
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