Got a DAC-AH today
May 13, 2006 at 2:16 AM Thread Starter Post #1 of 6

tennisets

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I was in a pretty bad mood due to the depressing weather here, so seeing the package slip in my mailbox was a nice little pick-me-up since I wasn't expecting it until next week. Also, Pacific Valve was really quick. I payed on Monday, and they informed me they ship on Wednesday and Friday. So they shipped my package on Wednesday and it arrived today (which I suppose isn't too surprising since I live only about an hour away from where the package shipped from, but still it was nice).

Anyway, the dac only has a couple of hours on it now, but it sounds good. It seems to mate really well with the SR-404s; it tones down the highs a little bit and brings out the bass. Just what the doctor ordered! The tonal balance is really nice. Natural.

However, thus far at least, it exhibits a significant amount of grain in the midrange and treble. Hopefully burn-in will partly clear that up, but I suspect that the grain is mostly coming from the opamp output stage. I'm planning on bypassing the opamps with some ASC oil caps so hopefully that will clear up any midrange and treble grit.

Also, I'll definitely have to post pictures after I put the ASCs in; they're about 1.75" in diameter and 3.75" tall, and mount to the outside of the chassis. I was pleased to see that the top of the chassis is just a flat plate. It'll be easy to put a couple holes in there for the caps. Anyway, I'm guessing those big caps will look pretty sweet sticking out the top of the dac. I really like oil caps for coupling purposes, so hopefully they'll do the trick in this dac as well.
 
May 13, 2006 at 3:21 AM Post #2 of 6

Jahn

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Quote:

Originally Posted by tennisets

Anyway, the dac only has a couple of hours on it now, but it sounds good. It seems to mate really well with the SR-404s; it tones down the highs a little bit and brings out the bass. Just what the doctor ordered! The tonal balance is really nice. Natural.



Natural is the word I'd use too. It really take away any perception of electrostatic etch from my Lambda Pros, leaving only a beautiful bass, warm mids, and smooth highs.
 
May 13, 2006 at 3:44 AM Post #3 of 6

Samgotit

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I also found it "grainy", and I had the upgrade version with Blackgate NX caps and fancy opamps in the output stage. The grain went away after I was taught how to modify it to incorporate a passive output.

I can only assume the grain came from either the opamps or electrolytic caps. It has been noted that grain is a characteristic of electrolytic capacitors. A passive output cured that problem for me.

I really miss it!
 
May 13, 2006 at 3:52 AM Post #4 of 6

Jahn

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oh yeah i forgot to say, mine's modded so no grain here - passive output, new caps and stuff in there etc etc!
 
May 14, 2006 at 6:35 AM Post #5 of 6

Xakepa

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Even BG caps have a lot of grain and it takes a lot of burn-in to improve.

DAC-AH's output is a little cluttered IMO - bypass the opamp, go for a passive LPF, replace decoupling caps with good film/oil, replace the I/V res with stable one.

That's about it, enjoy

eggosmile.gif
 
May 14, 2006 at 7:02 AM Post #6 of 6

Samgotit

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Quote:

Originally Posted by Xakepa
DAC-AH's output is a little cluttered IMO - bypass the opamp, go for a passive LPF, replace decoupling caps with good film/oil, replace the I/V res with stable one.


That reminds me, you may want to check your regulators. Mine came with LM7806s where the board and schematic called for LM7808s. I have seen varying opinions on feeding the TDA1543s 6V or 8V.

I have also read where others adjust Vref (Trim pot at VR1) by ear?

Be aware, I did not get around to either modification.


Good Luck!
 

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