Bottlehead Forum

Bottlehead Kits => Crack => Topic started by: drewhaynes on June 26, 2020, 07:16:01 PM

Title: Help with noise floor.. chaotic
Post by: drewhaynes on June 26, 2020, 07:16:01 PM
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?!
Title: Re: Help with noise floor.. chaotic
Post by: drewhaynes on June 26, 2020, 07:56:35 PM
Just to preemptively provide some info.. just tonight I've swapped out other 6080 and 12AU7 replacement tubes. Same issue.
Title: Re: Help with noise floor.. chaotic
Post by: Doc B. on June 26, 2020, 08:18:44 PM
Is the noise there with the Crack volume turned all the way down?
Title: Re: Help with noise floor.. chaotic
Post by: drewhaynes on June 26, 2020, 08:20:20 PM
No.. zero noise with Crack volume knob down. The noise scales with the volume knob!
Title: Re: Help with noise floor.. chaotic
Post by: drewhaynes on June 26, 2020, 09:13:12 PM
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.
Title: Re: Help with noise floor.. chaotic
Post by: Deluk on June 27, 2020, 01:05:09 AM
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
Title: Re: Help with noise floor.. chaotic
Post by: Tom-s on June 27, 2020, 05:19:09 AM
Quote from: drewhaynes on June 26, 2020, 08:20:20 PM
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.
Title: Re: Help with noise floor.. chaotic
Post by: drewhaynes on June 27, 2020, 07:45:09 AM
Quote from: Deluk on June 27, 2020, 01:05:09 AM
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...
Title: Re: Help with noise floor.. chaotic
Post by: drewhaynes on July 03, 2020, 07:30:41 PM
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!