I am going to build a passive preamp soon. I would also like to add an USB DAC to the package. Are there any kits or plans available? I want the DAC to be powered from the USB port of a computer...i.e. no other power supply to power the DAC. I tried Google but got a lot of junk with one good lead.
Any help at all would be appreciated.
Thanks....Jim
Any help at all would be appreciated.
Thanks....Jim
JimOfOakCreek said:
You should pop in an idea of budget etc...
As for powering from the USB, this puts a limit on yur quality level and selection of kits. The PC is considered a dirty source, so a good number if not most of the USB dacs tend to favour their own cleaner supplies for power.
I just built the dddac1543 Kit from Doede. It is an incredible sounding device for the price,
Doede publishes schematics etc from his web site as well...
Search on DDDAC and you will find plenty of details.
TwistedPearAudio are just bringing out their USB DAC right now, though I have not heard it. Their preamp kit is very good quality though, I would expect the same from the dac. And they are stateside.
Bus powered vs sellf powered...
One thing to keep in mind is that if you use the USB interface as a digital only device(I2S out), and leave the digital to analog conversion to a separate DAC with its own power supplies (digital and analog) then you need not concern yourself too much with the supply for the USB device. The analog performance is key, and will be dominated by the dedicated DAC instead of the USB device.
Most modern PC supplies are also are far better then they were even just a couple years ago. So power supply issues while not to be ignored, are not always the nightmare they have been in the past.
The on board DACs of the most common USB devices (PCM27xx 29xx etc) are usually much worse in terms of dynamic range then even a middle of the road standalone DAC. Self powered (dedicated power supply) or bus powered the difference is not really significant.
I have taken a very modular approach to the DAC choosing to create separate modules that utilize I2s inputs and outputs. The USB module I have designed will work stand alone just fine as a midrange DAC, but works even better when mated with a DAC that can accept I2S input like the Opus.
Cheers!
Russ
One thing to keep in mind is that if you use the USB interface as a digital only device(I2S out), and leave the digital to analog conversion to a separate DAC with its own power supplies (digital and analog) then you need not concern yourself too much with the supply for the USB device. The analog performance is key, and will be dominated by the dedicated DAC instead of the USB device.
Most modern PC supplies are also are far better then they were even just a couple years ago. So power supply issues while not to be ignored, are not always the nightmare they have been in the past.
The on board DACs of the most common USB devices (PCM27xx 29xx etc) are usually much worse in terms of dynamic range then even a middle of the road standalone DAC. Self powered (dedicated power supply) or bus powered the difference is not really significant.
I have taken a very modular approach to the DAC choosing to create separate modules that utilize I2s inputs and outputs. The USB module I have designed will work stand alone just fine as a midrange DAC, but works even better when mated with a DAC that can accept I2S input like the Opus.
Cheers!
Russ
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