Help with noise floor.. chaotic

[drewhaynes]

A while ago.. years for all I can remember.. I posted about my noise floor with a Crack+SB and HD650 being very chaotic. Just sounds like strange electrical nonsense going on in the background if I pause my music while the amp is turned up. Previously, some forum member suspected that my issue was my GrubDac which was using USB for both power and data. I replaced that with a Schiit Modi 3 and am using optical input from desktop and usb power from wall. Still.. when music is quiet or paused.. major background noise. I have a setup that is otherwise probably $1k but it feels ruined by the terrible noise floor.

What am I missing?!

 

[drewhaynes]

Just to preemptively provide some info.. just tonight I've swapped out other 6080 and 12AU7 replacement tubes. Same issue.

 

[Doc B]

Is the noise there with the Crack volume turned all the way down?

 

[drewhaynes]

No.. zero noise with Crack volume knob down. The noise scales with the volume knob!

 

[drewhaynes]

It's incredibly frustrating.. because the sound is otherwise world-class, better than most anyone is familiar with. But I cannot seem to rid myself of this background humming, which plagues all quieter passages. And.. it's pretty prevalent. A song has to be pretty raucous to drown out the background nonsense.

 

[Deluk]

Have you tried this mod? Cheap, easy and can be a miracle cure. Worked for me.
https://forum.bottlehead.com/index.php?topic=11676.0

 

[Tom-s]

No.. zero noise with Crack volume knob down. The noise scales with the volume knob!

So the noise is not coming from Crack but from what comes before Crack or a ground loop.

If the noise was coming from the amp itself, it wouldn't change with the volume control.

 

[drewhaynes]

Have you tried this mod? Cheap, easy and can be a miracle cure. Worked for me.
https://forum.bottlehead.com/index.php?topic=11676.0

This sounds like a possible solution! Going to try this...

 

[drewhaynes]

Just to close the loop.. I received my diodes and soldered them in between the power entry and ground lug... it's not FLAWLESS, but it seriously removed 90% of noise. BIG help. Thanks!