Problems with car amplifier; Computer PSU

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Aug 21, 2018
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Hi, I just subscribed so I could get help from someone here. I have a really peculiar situation here and have found nothing like this in the web. Please help me, it's been like 3 days of me messing around with this and no results. (I'm a little bit out of practice with my English, so sorry for cringy accent)
https://youtu.be/XA184x8ZbOg
 

Ralston18

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Please list the various components (PSU, Amplifier, speakers, etc.) by make and model along with their respective specifications.

Would not expect that a PSU would be capable of truly supporting the power requirements of the car amplifier.

Can you provide a simple sketch of your devices and the connections you are using? Include wattages and voltages.


 
Aug 21, 2018
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220v 1 PCYes 750w (it supplies about 670w on 12v rail) 80+ bronze PSU (only 1 12v rail, I cut off all other wires and left 13 12v and like 22 GND wires) , 1 Soundigital sd800.4d amp, 1 pair of JBL Club 6520 50w (120w peak) (3ohm), 1 subwoofer FBaudio 250w (1000w pmpo). I thought the PSU would do just fine. Also, one strange thing that I noted was when I turned on the amp with the PSU on +12 and GND, and a notebook charger on REM, the REM voltage went to -9v when measuring with the GND plug.
 
You are hardly the first person who's trying to do this.

First off, there is a procedure to make computer PSU function without the computer, normally can't.

Second, very simple, how many amp is the 12v rail providing you? Cannot use an amplifier that takes more amp that PSU is capable.

p.s. don't forget the remote turn-on wire.
 
Aug 21, 2018
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12v rail on psu: 670w and 56A.
Amplifier Ampere consumption:
40A musical, 78A peak (9v to 16v op range)

Edit: the sub is 4ohm and I will use it in bridge mode.
I plugged a 12v wire from the PSU to the amp, and something is happening and it's making the PSU flick on and off, like I showed on the video
 

Ralston18

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That "something" is probably that the PSU is just not able to do the job.

Or, if so, likely to die for good early on.

Will leave it to the more audio inclined to delve into voltage, amps, and wattages, etc.. with respect to any issues therein.

Very much in favor of DIY etc.; however, there is a point where some things will simply not work out.


 
Even if your PSU is rated for 650Watts, I doubt you can get all of them over single 12VDC rail. CHeck the label on your PSU, it lists loads on all rails (3.3, 5, 12).

That flickering you see - it's most probably an indication you're overloading your PSU.
 
Finally watched your video, all u keep saying it doesn't work, doesn't inspire confidence.

For the little I know about this subject, a computer PSU has a pin labeled as POWER GOOD and that pin needs to be hooked up a certain way for this to work. Am really surprised u have not found other sources/video that explains this.

Now this maybe obvious but not all 12v rail on a computer PSU are the same, u want to use the 4/8 pin CPU connector rail, typically this is the rail that carries the most current.

Anywoo. That's all I have.
 
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