Have any of you Parasound DAC owners tried these ASE-Audiotuning "upgrades"?

http://www.audiotuning.de/english/index.html?1-54-digital.html

It was discussed before in the other Parasound thread but nobody has heard them I guess. The ones with inferior digital chipses (1000,1500) probably better for this upgrade as they gain 24/96 capability (if the DAC chips are replaced as well with PCM1704U-K chips) while this is not available in the 1100 or 1600.

A Hungarian guy has a heavily modified 1100, I will probably try to organize a comparison between that and my stock 1600.

I first noticed the upgrade modules here.

Can't remember if Danc did something like this to one of his with the upgrade module. Maybe he did a comparison with the PMD100 also.

I'm pretty sure that Filburt and/or Danc found that the PMD100 was better. I think the biggest mod that needed to be made was the change to K chips and output stage.

Upgrading DF1700 to DF1704 seems OK, but going PMD100 to DF1704 seems a bit pointless to me. I guess if one had a large collection of well-recorded hi-rez that's better than equivalent redbook albums...

I just bought a D/AC 800 so I would be upgrading the stock NPC SM5813 which is a rebadged DF1700. I think it may prove a worthy upgrade based on some of the reading I've done but the cost of the upgrade will be more than the DAC itself. I have already pulled all the opamps in the output stage and replaced with sockets and have been rolling opamps with some success. Would it be fairly simple to skip the output stage and go passive with some nice film caps?

Upgrading DF1700 to DF1704 seems OK, but going PMD100 to DF1704 seems a bit pointless to me. I guess if one had a large collection of well-recorded hi-rez that's better than equivalent redbook albums...

...then one should probably just get another DAC.

No way you can just have film caps from the dac to the outputs, wont work. PCM67 has a 1.2mA output.

Edited February 16, 201016 yr by cetoole

No way you can just have film caps from the dac to the outputs, wont work. PCM67 has a 1.2mA output.

I was thinking of inserting the caps after the I/V stage (AD841). Would that be doable?

I was thinking of inserting the caps after the I/V stage (AD841). Would that be doable?

Yes, but why?

I know enough about this stuff to be really dangerous, but wouldn't a passive output sound better than an active one with all the opamps? I did something similar with my Lite DAC-AH and it sounds much better to my ears. Of course, the caps I used cost more than the DAC itself.

In any case, I'm moving ahead with the ASE-Audiotuning mods to swap out the stock Yamaha receiver (YM3623) and NPC filter (SM5813) on my D/AC-800. I'll report back when they've settled in.

I would just buy a whole new DAC instead of going with the audiotuning mods, as IIRC, they are really no less expensive than getting something like a DAC 1100HD. Anyways though, the PCM67 outputs 1.2mA centered around something like 3v (not looking at the datasheet right now), but also provides a reference voltage equal to that offset which the I/V opamps are almost certainly using for their + input instead of ground, which cancels the offset. You should measure, but coupling caps are probably not needed at all here. I would upgrade the opamps used, or change to some other I/V, but I wouldnt just pull and bypass the opamps entirely, unless you like how aliasing sounds. DACs like these need a LPF to properly reconstruct the original waveform.

Thanks, Colin. I've been reading up on different uses for opamps and was able to recognize that some of them in the D/AC 800 are used for a low pass filter. Parasound was nice enough to send me the schematic and I'm quickly realizing that what I did with the Lite is probably not transferrable to this DAC. Again, thanks for your help!

I know enough about this stuff to be really dangerous, but wouldn't a passive output sound better than an active one with all the opamps?

Not necessarily. There are lots of different ways to do a passive or active output stage, and both approaches can have an influence on the sound quality positively or negatively.