With no amp load or line input, just the PS-2A connected to a speaker cabinet, I put the device in “Operate”, there is a low level rustling noise coming out of the speakers. The sound is random, like cloth rubbing against a lavalier mic or a dirty pot.
The sound occurs regardless of how the volume knob is set. Increasing the volume doesn’t make it any louder. I moved the speaker cable to a different cabinet. The noise persists. What could this be?
Hi @tpovilaitis and welcome to the community 
Great description—this sounds like the noises that failing tubes can make. You might also start to get some popping sounds.
How many hours do you have on the tubes?
Regards,
Dan
Hi dan @Team_Fryette
The unit has seen light duty around the house when I have time. Primarily used with line level devices such as Synergy SYN2 and/or Friedman IRX. Only recently pulled my old JMP 2204’s out of storage to try out the reactive load.
Purchased the unit new from VKLA in Burbank in August-September of 2003.
Replaced power tubes with a pair of Apex matched & burned in JJ 6L6GC’s. The “rustling” noise is gone. Thanks for the tip.
However, a new, loud buzzing noise appeared when putting the unit in “Operate.” It’s a physical noise coming from the PS-2A and not out of the speakers. It seems to be coming from behind the jack field. After several seconds, the buzzing noise goes away.
This “buzz on operate” condition occurred repeatedly where I powered down, let it cool for awhile , then tried again. After several attempts over several hours, the “buzz on operate” has stopped. It seems to have resolved itself.
What would cause the buzzing sound?
Hi @tpovilaitis
Thanks for posting the video; this makes it so much easier to understand and reply!
I honestly don’t know what could be causing this. The operate mode activates the high-voltage circuits that go across the tubes. I am wondering if the new tubes are the cause or if there are dirty tube sockets. The way the sound ends is very odd too; it just stops abruptly. Does the unit sound and play OK?
I need to get an opinion from @Gil or @DavidPhelge to see if they have seen this before.
Regards,
Daniel
The buzzing has stopped entirely. The unit works normally with a line level source (SYN2). Haven’t tried the load side.
I tested the new tubes with the chassis open. No buzz occurred. The unit worked normally. The buzzing began after I closed it up, replaced the rack kit, and re-mounted it in the rack.
I’m beginning think gravity might have something to do with it. Had to flip the unit over a couple of times to remove/replace screws. Maybe there’s some component on the load side that’s not quite snugged down (transformer)?
Initially, I could trigger the buzz by lightly pounding on the rack chassis.
The buzz is gone. I can no longer reproduce the scenario shown in the video. Vibrations don’t trigger it either. Whatever it was, it seems to have resolved itself…
Hmmm… OK then, the fact that this might be a physical vibration like a screw makes me feel a bit better. I wonder if this is something to do with magnetic energy causing a loose bit of metal to vibrate. I’m going to play your video to people in the shop later.
Regards,
Dan