Sanity check for Seymour Duncan PowerStage 700 Issue

SixRails

Member
I have a whining sounding coming from my PowerStage 700 (not the speakers) and I wanted to check with other fellow owners to see if this noise is normal or not. The sound isn't loud but can be heard when sitting 10 or more feet away in a quiet room. If this is not normal then I want to have the problem taken care of while the amp is still under warranty. The sound only happens after the amp has been on long enough to get hot.

I've been talking with Seymour Duncan's tech support group and they said I can send the unit in to have it looked at but it would take 6 to 8 weeks to get it back. I don't really want to be without an amp for that long if I don't have to, so before I send it back, I want to check with other PowerStage 700 owners to see if this sound is normal or not.

Please play the video below, turn the volume up, and listen in a quiet space. Ignore the sound that sounds like 60 cycle hum, you are only hearing that because I had to crank the gain on the microphone to amplify the sound for the recording. Listen for a high pitch sound that sounds like a whine or computer noise. This cycle of whine noise with fan turning off and on repeats about every minute or so.
  • From 00:00 to 00:02 You will hear a high pitch noise that sounds like a whine or computer noise
  • At 00:03 The fan starts and high pitch noise disappears
  • At 00:20 The fan starts turning off and the whining noise / computer noise starts coming back
Thanks in advance.

 
To me it sounds like noise is injected probably through the mains connection due to a loop... use a three to two prong adapter to disconnect the ground and see if it disappears.. if it does, then either fix the problem or leave it alone..

I have a hiss/buzz that comes through my GB Streamliner900 that is caused by the USB connection to the Axe-FxIII and is injected into the signal.. a$50 fancy USB noise eliminator just eliminated my $50 but not the noise, but a 99c outlet adapter did.

essentially start disconnecting stuff till it disappears..
 
To me it sounds like noise is injected probably through the mains connection due to a loop... use a three to two prong adapter to disconnect the ground and see if it disappears.. if it does, then either fix the problem or leave it alone..

I have a hiss/buzz that comes through my GB Streamliner900 that is caused by the USB connection to the Axe-FxIII and is injected into the signal.. a$50 fancy USB noise eliminator just eliminated my $50 but not the noise, but a 99c outlet adapter did.

essentially start disconnecting stuff till it disappears..

That would be easy and cheap to test, I'll give it shot. Thanks for the idea.
 
To me it sounds like noise is injected probably through the mains connection due to a loop... use a three to two prong adapter to disconnect the ground and see if it disappears.. if it does, then either fix the problem or leave it alone..

I have a hiss/buzz that comes through my GB Streamliner900 that is caused by the USB connection to the Axe-FxIII and is injected into the signal.. a$50 fancy USB noise eliminator just eliminated my $50 but not the noise, but a 99c outlet adapter did.

essentially start disconnecting stuff till it disappears..
Eliminating the physical ground from a device designed for one is a bad idea.

Recommending it to someone else is a worse idea.
 
Eliminating the physical ground from a device designed for one is a bad idea.

Recommending it to someone else is a worse idea.

I'm going to eliminate the ground temporarily purely for diagnosis reasons. If the problem disappears when the ground is disconnected then I know I have some kind of issue at the location that I'm plugging into.

I was once shocked at a gig by a microphone due to bad grounding where my guitar amp was plugged in. That was not fun!
 
Eliminating the physical ground from a device designed for one is a bad idea.

Recommending it to someone else is a worse idea.

You are welcome to your opinion, however in this specific case I frankly do not agree with it for one second, as:

1. If this was a tube amp your comment would have increased validity. This is a class D amp, with low voltage, isolated outputs and multiple safety mechanisms..
2. You assume that the device needs a ground for safe operation. This is a poor assumption.
3. For there to be any safety issue, to a person or the gear itself, there has to be at least one additional failure mechanism in place already.
4. Any potential safety issue resulting from a failure mechanism needs to be judged in line with the impact potential..ie tube amp? "interesting!" lol, but class D amp?.. "meh".

I would appreciate a refocus on the issues facing the OP where I suggested that he could isolate the ground for diagnosis purposes, and suggest that if you wish further discussion to do so offline.
 
SixRails, did you have any resolution to your issue? I just received a Powerstage 700 and it does exactly as yours.
 
SixRails, did you have any resolution to your issue? I just received a Powerstage 700 and it does exactly as yours.
The Seymour Duncan representative set me up to send the amp back to them for repair. However, I've been dragging my feet and haven't got around to it because quite frankly they say it will take 6 to 8 weeks for the repair to be completed. I'll have to just do it. I'm currently using an Orange Pedal baby for my amplification needs so there really wasn't a huge rush for me. If you end up sending yours in please let us know how it goes.
 
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