OK, now *I* need some 'sound' advice

I hear that! The whole thing seems nuts to me.

Those peak power numbers these days don't mean much either. Heck the audio system in my old El Camino sounded great blasting out music camping and was plenty loud even at the river with ski boats everywhere. Eventually it vibrated every screw loose in the whole car to I think. lol

That amp's output was rated at 10watt's of clean RMS @8ohms x 4 channels.

Dan

Reply to
Danny G.
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Yup! The key word here is CLEAN!

You can have 1000 watts, but if the THD is 15%, your ears will bleed.

I pay the same or less for smaller amps with better specs...

Reply to
Hachiroku

!5% ouch. And I thought 1% was junk and 0.1% so-so.

Reply to
Danny G.

Ya gotta watch the specs!

0.1 is OK, considering the environment you're listening in. There is another measurement; I can't remember what it was, but it is the rating of total distortion the amp will put out, and then there is the signal to noise ratio.

The GOOD thing about inexpensive LOUD amps is, the ratings are at full rated power. So, if you have a 500 watt amp, but are only running it at about 70 Watts (get a watt meter and run an amp at 25Watts RMS and tell me if you can stay in the car...) then the noise figures are cut dramatically!

Back in my youth, they used to have ratings on Dept store stereos..144 Watts!!! Then in VERY small print (ipp). IPP is Instantaneous Peak Power. It means that for one millisecond that 5 watt amp in the thing can push

144 watts to your speaker, like a bass drum hit or an orchestra blast.

The FTC made them stop using all of these, and then started making them rate distortion figures at maximum wattage RMS. The car aftermarket was left alone for a few years, but considering the popularity and expense of car audio equipment they went after them, too, so that now all audio equipment is rated the same. So, that 1% THD rating is at the full RMS output power of the amp. If it is a very powerful amp, the THD figure will drop dramatically. And, if it's .1% to begin with, it will be negligible at normal listening volumes.

Reply to
Hachiroku

Here is a link to a current model Pioneer GM-D510M 1,000 watt mono amp that lists enough specifications to show those rules still don't apply to car audio.

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BTW: One of the hot rods a buddy of mine has is a older style van that's pretty much a spare no expense hot rod show car right down to the custom made rims. It has what he calls a "good

1,000 watt system" in it.

My point is that van's only real electrical load is the driving lights and the audio at night. Yet if it was on the open highway the audio must be shut off after about two hours because the 125 amp alternator can not keep up. Parked the audio will drain the battery even with his battery charger (10 amp I think) on it.

eeek

Reply to
Danny G.

Doesn't mention anything in there about +12V current requirements, and more important the quiescent draw - the power load with no signal going through. Use a bunch of equipment that draws a large load even when the volume is not turned up loud, and you will have power problems.

much a spare no expense hot

1,000 watt system" in it.

audio at night. Yet if it was on the

amp alternator can not keep up.

think) on it.

I'd check over that "125-Amp" alternator, there are a lot of them sold where they are over-rated at 'peak current' just like they lie about amplifier ratings - the power falls off a lot when they get hot.

Prestolite/Leece-Neville, Motorola Lester and Delphi (among others) make real truck alternators that will put out a true 140A, 200A, 300A and more continuous - but they are the larger frame alternators to allow room for windings and heat dissipation. But they are big enough to present a challenge installing them in a passenger car or light truck, and vans are going to be real stuff job.

And of course a 10-amp charger isn't going to keep up when parked - you need a 50-amp charger minimum for that. But battery chargers are notoriously noisy power, the hum will get into the stereo.

The better solution is to get a built-in RV Power Inverter/Battery Charger system that is designed for that use - you can split off the Stereo gear duty to a separate deep cycle battery. Some of the fancy ones like the "Heart Inverter" will give you 120V for a microwave oven or other appliances without needing a generator set to run them.

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Reply to
Bruce L. Bergman

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pretty much a spare no expense hot

1,000 watt system" in it.

audio at night. Yet if it was on the

amp alternator can not keep up.

I think) on it.

At least they list the "Continuous Power" Ratings. THAT they are forced to do by the FTC.

Of course, some 17 YO is going to say, WOW!!!! A THOUSAND WATTS!!!!!

Reply to
Hachiroku

pretty much a spare no expense hot

1,000 watt system" in it.

audio at night. Yet if it was on the

amp alternator can not keep up.

I think) on it.

Ya that thing is huge. But the car is all show and almost never on the road so the limited amount of audio time and short altenanator life is ok

It is kind of funny that one hour of audio kills a battery that has enough umf to leave the headlights on four four hours and have no problems starting the engine.

I guess I could be off a some but 100 amps @ 12 volts and 10 amps @120 volts both add up to about the same amount of power. volts * amps = watts

Random link to a charger rated 120 volt /1300 watt (10.8amp) input that has around 80 amps out to charge a battery or whatever.

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Reply to
Danny G.

This is why the auto industry went from 6V to 12V in the 1940's, and why most military vehicles went from 12V to 24V - drops the amps in half for the same amount of electrical work performed.

The new target for the automotive industry is 42V, whether they can get there is another question. Myself, I think anything past 24V is going to hit the law of diminishing returns. Besides, there's already equipment designed and available for 24V if they wanted to change over.

That would be a good solution for him, and he can build it into the car for aesthetics, no hood up and charger sitting on the driveway. They do make much bigger if that one won't keep up.

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Reply to
Bruce L. Bergman

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