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Car Speakers with PC audio amp?

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KevSteele:
Okay, it's "embarrasing true confessions" time...

I ran the voltmeter on the stereo, got about 6 volts output. Tried the PC amp outputs, got nothing...Decided that the PC speaker system had probably died. To make sure, I pulled it all out and took it over to another PC.

Surprise, the PC amp worked fine -- in fact, everything worked fine, including the car speakers!

Okay, now I'm thinking that I've somehow blown the onboard audio chip on my motherboard. I go back and check the volume settings, just to be sure.

Everything looks good, all the sliders are at reasonable levels, and...wait, what's that little checkbox? "Mute All"? Why is that checked? Aw, &*#$!

Bottom line is that everything is working great now, except possibly for my apparently malfunctioning wetware that caused this whole screwup to begin with!

Thanks for the help, though!  :-[

Kevin

MaximRecoil:
Glad you got it straightened out. I think we all have stories that we could tell like that. Missing something obvious is very easy to do.

MaximRecoil:

--- Quote from: SS427 on October 02, 2003, 09:29:10 am ---Use of a car amp: Not a very practical idea unless you have an inverter. Car amps want 12-14.4 volts and good quality inverters are expensive (the kind that they use in car audio shops for their display models).

You can also use a stand alone computer power supply instead of an inverter setup.  atx550w,,,20 bucks on ebay,,,,,,,,works great so far (amp and two 8" subs and two 4" speakers below the marquee)
--- End quote ---

That depends on the car amp. For a small one a big computer power supply can work but I tend to deal with amplifiers that pull 150 amps or more and put out 60+ volts across the terminals.

Let's say that you want a 100w x 2 @ 4 ohms car amp in your cab which is a pretty average size and comparable to the size of a typical home stereo receiver (in regards to power). The PC power supply will be supplying it with 12vdc. You would need a 17 amp power supply to support 200 watts. It is hard to know how much amperage a PC power supply will put out to its 12 volt rails because it also has 5 volt rails and 3.x volt rails so the total rating for the power supply is all of those combined.

This topic comes up fairly often on the car audio forums so I'll quote a post dealing with the similar topic of someone asking about using car amps for home theater:


--- Quote ---The problem with computer power supplies is that there is no one regulating them. If you come anywhere near the maximum output potential of an ATX power supply it will fry, and often catch on fire. Do not play without an extinguisher around.

I don't know which one it is, but tomshardware.com found one power supply that was able to actually output about 85% of its max power before it shut itself down. All of the tests were done by takeing an XXX watt power supply and pulling as much current off of each line as possible and then calculating the power with (current * 5v) + (current * 12v) .... and trying to get to the rated 650 watts or whatever. None of them made it, but one was close.

I work for an ATM manufacturing company and we have an ATM which is WinNT based. The power supply in the ATM for the PC is an ATX power supply, 250 watts. It is rated at 16 amps on the 12v line, when I tried to pull 11 amps on that line for a thermal printer, the output dropped to 7.7 volts. We had to change printers from a 12v@11 amps to a 24v@7 amps and use a different power supply.

I would highly suggest not using an ATX power supply to run a home theater on. They already can't handle their "rated" power, so I'd hate to see what would happen when you put a non-constant load on it like a car amplifier.

As for tricking an ATX power supply into working without a motherboard, IIRC, its as simple as shorting two of the wires together.
--- End quote ---

SS427:
Sorry, for the bright red background,,,,wasn't what I was expecting it to come out as when I picked shadow.

As far as the amp,  anything pulling that kind of amperage would be way to much for a computer power supply.  For consideration though on mine I was just wanting decent sound, but nothing that would rattle my cabinet apart and I had an old cheap amp laying around anyway.  Haven't tested the powersupply I got (rated at 24amps at 12volts), but that's been working fine for me (I;ll try to check when I get a chance).  Cost for me was the deciding factor (less than $50 for the speakers and power supply) were an inverter alone is significantly more costly.

From what I've searched and found it looks like the options are computer speakers, car speakers w/computer ps, car speakers w/inverter.  Cancellation magnets may or may not be needed depending on field strength an proximity to screen.

Kevin, (OT), I've been delayed on the led's, but when I get them I will get with you on shipping,,, ;)

ss

KevSteele:
SS427:

(OT: No problem about the LEDs. Whenever is fine.)

I don't have any obvious magnetic interference with the D9200 monitor, so I'm assuming I don't need cancellation magnets.

Sound is great from the car speakers I bought, and as a bonus the cones on the speakers are a translucent red plastic -- I'm already working out ways to illuminate them from behind!  ;)

Kevin

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