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Old 31st March 2003, 02:28 PM   #1
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Default car amplifier for home sub?

Would it be an ok idea to use a car amplifer like the cheap Pyramid Arctic PB101 (15-30000Hz, 2x120W@4-ohm) as an amplifier for a home sub? With the proper step down tranny, of course. The sub would have a low pass of 100Hz, 12dB/octave. Is this ok? The sub can only take 115W MAX anyway into 8-ohms. Could I parallel both channels of the amp onto the sub? I don't want to risk bridging it, but is it ok to parallel? I already have a 440W 12" sub and just want something to be a lesser counterpart, and want to spend way under $100. So far, total is around $50, minus amp, which would be around $30 more for this. I can build my own for the same price, but I figured if I can get somethign already built and heatsinked for less, in its own box, why not do it? Would it work ok?
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Old 31st March 2003, 02:37 PM   #2
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Would a 12VDC@1.2A power transformer be adequate for a car amp?
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Old 31st March 2003, 03:06 PM   #3
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Car amplifiers work on low voltage DC and draw high current.

A simple 75w x 2 @ 4 ohm car amp that is not 2 ohm stable
will be fused at 15 amperes.

Look at your amplifier's fuse rating to get a ballpark on
what you need. 1.2A is not even close to be enough.

12VDC x 1.2A = 14.4 watts
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Old 31st March 2003, 03:32 PM   #4
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thylantyr is right - you need plenty of current for a car amplifier. You might be able to use an old PC power supply as these have reasonable high current rating on the 12v rail (I believe PC PSU is rated at 12v @ 16A continious).

A PSU intended for PC wil be a noisy switcher, but car amps use switching supplies internally to boost their supply rails anyway.

Nice one,
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Old 31st March 2003, 06:11 PM   #5
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Look on ebay for some Astron supplies....good quality, high amps.
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Old 1st April 2003, 06:12 AM   #6
sangram is offline sangram  India
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Actually, you can use the little transformer to check how much voltage the car amp actually runs on (open up the amp and check voltages at the rails), and then build a nice 400 VA supply for it.

Or run off car batteries. The small transformer will make a nice charger.
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Old 3rd April 2003, 10:25 PM   #7
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i made some speakers that used a car amp about 4 years ago, worked well, i used a 300va tranny and some nice big caps, you can get away with a smaller power supply by adding large caps on the rails, you'd need to make an RC cirucit for them to charge at first switch on. there are some 1F caps out there going cheap atm.

The caps would be enough to supply a large amount of current in bursts without the need for a massive tranny. but a car amp at that power will draw loads of current, if it is opperating at say 2 x 100w thats 200w total output and amps are only about 40-60% efficient so you'd be looking at about 400w inputpower. which is a lot of power for 12 volts tho amps can be 24v too.
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Old 8th April 2003, 04:23 PM   #8
JBasham is offline JBasham  United States
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I did this once. It worked fine. But, I used a 25 amp Tripp-Lite power supply.
The only true thing in audio is what you hear with your own ears.
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Old 9th April 2003, 02:27 PM   #9
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why not use a batteryloader, they have massive loading currents?
or is there a problem like different steps in the loading or something?
I like turning knobs clockwise
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Old 9th April 2003, 03:29 PM   #10
karma is offline karma  Canada
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Red face amps

and a good fuze
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