Mr White's "Opus", designing a simple balanced DAC

[Luke]

The pics dont help guys?

[MrMajestic]

Originally Posted by Luke

Hi Russ,

cabling is quite minimal check it out on post #1759

Mr White's "Opus", designing a simple balanced DAC

What Im wondering is if the usb input on the dac is touchng the chassis grouns, is this ok or should I create a clearance and isolate them? Bar that I dont know how I would change the cabling routing. Do you think shorter wires would make a difference?

I think the cable routing looks fine. If you tilt the boards a bit so you can run it without the usb input touching the chassis then you will know if that is the problem.

[BrianDonegan]

Originally Posted by Luke

The pics dont help guys?

So, it worked fine, then developed a whine? Did anything change? Anything get moved?

[Russ White]

Regarding io's earlier post I deleted them because they are not relevant to Luke's problem.

Lukes DAC was working fine previously. This is a new issue not related to the DAC PCB.

As far as the scope shots io posted go, it looks like an apples oranges comparison. If you take a scope shot of one half Opus output without any BAL/SE stage such as IVY III or Ballsie Lite, it will look very much like what io posted. Also certain filter settings can make it look like that too. because of pre-post ringing. Not GND.

If you run the opus DC coupled through a proper output stage as recommended it will not look anything like what io posted.

Cheers!
Russ

[io]

hello
Russ

I suggest that you look at what causes it to appear at the exit of DAC is also independent of the following circuits.
You will see the same Opus board own, no problem, io

io

[Russ White]

hello io,

I do understand perfectly.

The Opus board is not meant to be used all alone. Especially SE output.

Cheers!
Russ

[io]

Unfortunately, the true problem

(Opus volumite-BALANCED output)

but let there be peace

[Russ White]

io really having a hard time following you. I am happy to consider your input but perhaps private email would be better. Then you can give me a more accurate description of what you are doing. I would love to be educated if you have something truly useful to show me.

I look forward to hearing from you.

[eclectic2k]

thanks for staying peaceful guys
io, I gotta admit, I'm also not sure what it is you're seeing an issue with. I'll let you work that out with Russ. Let us know whatthe results are if you have a good discussion.

Luke, I guess you say this was working well at some point, so that is strange.

- you're listening to SE outputs direct from the DAC? (hot & GND) or Diff? Same noise either way?
- have you checked all the settings? (I don't have time to review them now, but no loose connections on the receiver board or DAC?) Changed Fs, etc...
- FWIW, on my board I connected mute to the signal valid flag from the receiver so I don't hear junk when the DAC is not locked to a valid signal...

-CK

[Luke]

Originally Posted by BrianDonegan

So, it worked fine, then developed a whine? Did anything change? Anything get moved?

Nothing has changed, but its ok with music playing, its when you turn the volume down low, or stop the music. Its likely that I didn't acknowledge something was wrong from the start.