AD converter oscillating?

[scott2000]

Op amps are supposed to make very little difference once you arrive at a certain quality level and if implimented correctly, but from my own experience they do differ, in objective measurements as well as sonically. FWIW, I usually end up with NE5534/5532.

The old Mytek ADDA is easy to swap amps bc they still have sockets in them , as well as cut traces and jumpers, from still designing I'm guessing

Currently in the running (converter wise) besides the Sparrow there is the PCM4222EVM with my own input board (using NE5534) and the Lake People RS 04. I replaced the audio op amps in the Sparrow with new ones (you never know what happened with caps going bad etc.) and added decoupling. This seemed to clear up the sound a little and the Sparrow is currently the front runner. But I have to make more tests to be sure.

Unfortunately, converters seem to be a thing that is extremely hard to get right, and the really good ADCs are very expensive. Plus it's difficult to get in several of these units at the same time for comparison. Or you have to buy them first and check them out later.

Yeah, nothing more frustrating than getting the sound right and not being able to capture it exactly.........
Thanks for sharing ...Great info! That's interesting that the Sparrow is doing that well  for you..... Those others are supposed to be pretty good from what I've gathered....

 

[living sounds]

The old Mytek ADDA is easy to swap amps bc they still have sockets in them , as well as cut traces and jumpers, from still designing I'm guessing , and it's extremely obvious the differences between different combos.... In separation and especially low end....It's kinda funny....Want a tighter  low end, use this op amp combo.....Want a more loose sounding low end, use this one.... not sure the reason for this, maybe one day I'll learn what's going on..... almost like a low pass filter just for the sub frequencies while still keeping the other info.....

I don't think I'd ever use the AD side but the DA side still has some uses that I can't duplicate the same way.....

Yeah, nothing more frustrating than getting the sound right and not being able to capture it exactly.........
Thanks for sharing ...Great info! That's interesting that the Sparrow is doing that well  for you..... Those others are supposed to be pretty good from what I've gathered....

My goal with a converter is transparency. It's not easy. The differences you describe can be a malfunction of the op amp in the given circuit (overshoot, oscillation), they can be harmonic distortion, phase distortion and whatnot but they are hardly ever a good thing in a converter.

I don't remember how many times I changed op amps in my console and at first loved it, but latter realized it made mixing really hard and/or yield bad results. In analog circuits I have concluded that I like what I hear with a good PSU, proper decoupling, out-of-band filtering, AC coupling, sticking to NE5532/5534.

Maybe I'll try an NE5532 in the Sparrow. Got to be carefull with surface mount stuff though, once the traces are gone the unit is only usefull as a paperweight...


If you like I can PM you a link with a couple examples sent through the 3 ADCs vs. the original.

 

[scott2000]

My goal with a converter is transparency. It's not easy. The differences you describe can be a malfunction of the op amp in the given circuit (overshoot, oscillation), they can be harmonic distortion, phase distortion and whatnot but they are hardly ever a good thing in a converter.

Yeah it's just for effect not for any critical listening..... and iirc the ad part was pretty bad but it's been a while since I've used it.......

If you like I can PM you a link with a couple examples sent through the 3 ADCs vs. the original.

Yes...I'd like to listen to them...