converting M-Audio SuperDAC to 12v DC supply

jv8 · 23rd December 2003, 07:46 PM

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 · 24th December 2003, 02:43 AM

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 · 24th December 2003, 02:45 PM

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 · 24th December 2003, 02:53 PM

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

Stu

jv8 · 30th December 2003, 04:10 PM

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 · 30th December 2003, 05:28 PM

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

23rd December 2003, 07:46 PM	#1
jv8 diyAudio Member Join Date: Dec 2003 Location: Pittsburgh, PA	converting M-Audio SuperDAC to 12v DC supply 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

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24th December 2003, 02:43 AM	#2
maczrool diyAudio Member Join Date: Oct 2002 Location: Louisiana, USA	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

24th December 2003, 02:45 PM	#3
Pjotr diyAudio Member Join Date: Nov 2002 Location: Netherlands	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

24th December 2003, 02:53 PM	#4
maczrool diyAudio Member Join Date: Oct 2002 Location: Louisiana, USA	Yikes! Good call. I missed the part about it having an AC input. Just ignore my post. Stu

30th December 2003, 04:10 PM	#5
jv8 diyAudio Member Join Date: Dec 2003 Location: Pittsburgh, PA	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.

30th December 2003, 05:28 PM	#6
jv8 diyAudio Member Join Date: Dec 2003 Location: Pittsburgh, PA	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