converting M-Audio SuperDAC to 12v DC supply

[jv8]

I've got an M-Audio SuperDAC I'd like to use in a car audio system. The unit currently takes 9v AC 500 mA. I'd like to modify the PS on the board to take a 12v DC supply.

Can any of you DIY experts give me a few pointers on where to start? Can I get the board schematics anywhere?

Thanks
-Jon

 

[maczrool]

What does it currently use as a regulator? You might be within the regulator's specs to feed it 12 volts without modification, provided you have adequate heatsinking, as it will probably generate more heat than before. For example, if they are using a simple 7805 reg., then you can feed it up to 25 volts safely.

Stu

 

[Pjotr]

Hi,

The Dac-chip and digital parts use 5V only. But for the op-amps there is plus and minus 15V generated with the help of a voltage doubler from the 9V AC. You cannot feed the Superdac with 12V DC, then the voltage doubler will not work anymore. So you will need some DC-DC converter.

The other way around is to modify the whole amplifier section to a single rail supply system. Or leave out the whole op-amp section. The DAC chip themselve is balanced voltage out and can deliver 4V_pp into 600 ohms. Best is to use a good line transformer then (i.e. Sowter 3603).

Cheers

 

[maczrool]

Yikes! Good call. I missed the part about it having an AC input. Just ignore my post.

Stu

 

[jv8]

I saw the +/-15v regulators and started looking for a DC-DC converter. I like the thought of bypassing the op-amps, however. I'll look into the line transformer. I'm driving a standard unbalanced car audio amp RCA input.

If I go the DC-DC route, what should I look out for in the way of noise? I'm concerned about the switching power supply in those modules.

Thanks for the help... I'm more of a digital hardware guy. Analog stuff can be black magic at times.

 

[jv8]

Pjotr,

Looking at the DAC datasheet, the example output circuits use the op-amps as a LPF.

If I bypass the op-amps in the SuperDAC, will I lose a required LPF function?

Thanks,
Jon