My rig has developed a static (hiss) issue on the right channel recently that I have been struggling to diagnose. I have followed Paul’s advice (How to Fix Hum Extended) with no success. I’ll outline my gear first, then describe hiss, then what steps I have taken. Really hope that someone here can guide me in the right direction and get this fixed:
Gear
• BHK Signature Preamp (less than 3 yrs old)*
• BHK Signature 250 (less than 2 yrs old)*
• Power Plant 15 (all components connected)
• Bluesound Node Vault streamer
• Rotel CD player
• B&W floorstander speakers
*stock tubes still in place
Hiss Basics
-Hiss sound is audible in right channel when standing in front of speaker and slightly audible from seating position when room is quiet.
-Hiss noise does not get louder with volume increase. It does stop when volume goes completely to 0 on the pre-amp.
Steps Taken
I completely disconnected all leads into the preamp -hiss continued
I shut off (unplugged) all nearby devices after disconnecting leads – hiss continued
I tried a cheater plug for both preamp and amp – hiss continued
I plugged both amp and pre into the wall socket bypassing the P15 – hiss continued
I switched tubes left to right in both the pre and amp -right channel hiss continues
I switched speaker cables left to right -hiss went to right channel
I don’t know what to do next. I am relatively new to high end and I think I’ve reached my capacity in understanding what might be causing the problem. Hope I do not have an equipment problem. Any suggestion appreciated!
How old is the amp?
Maybe an amp power supply issue, but I’d expect to hear noise in both channels. Maybe the affected channel driver and/or output stage are going bad.
Try to pull the small circuit boards behind the tubes in the BHK preamp and swap them side for side. Be aware that some of the BHK’s have the boards soldered in so it is not possible to easily swap them out.
Just removing and reinstalling the boards may also clear up the hiss.
My BHK had a similar hiss that went away just by pulling the boards, using a pencil eraser to clean the pins, then carefully reseating the boards. It seems like the pins were rather long so you have to be careful when putting them back into place.
I have no idea what they do but it did solve the issue.
Thanks Baldy, I’m a little reluctant to be touching anything in there but I’ll give this a look tomorrow and see if I can figure out what small circuit boards you are referencing.
Do you remember when the hiss began? Did the hiss appear after any changes? Did you move the mA jumpers in the preamp?
I would invest in some stock replacement tubes and try them. It might solve the problem and if it doesn’t, you have spare tubes, which is a good thing, so money not wasted.
Thanks Ron, last change was I replaced the stock power cable for the PP15 but that was before hiss developed. I have never moved the jumpers and still have the stock tubes that came with units. I have been thinking about replacement tubes even before this issue developed so I’m sure I’ll be doing that.
2 ideas/thoughts…. Have you tried bypassing the bhk pre and plugged the node directly into the amp using the nodes preamp outputs? Or have you had the amp on and the pre off/disconected? I’d be curious if the his continues. If it does you might be able to rule out the preamp.
If when you switched the speaker cable channels and the hiss followed have you tried different speaker cable?
Thanks club_pizzazz, I’ll try node directly into amp and see what happens. I did have preamp disconnected from the amp and the hiss stopped. So it appears issue is with preamp right? I can try different speaker cable as well. I’ll be back at it tomorrow and report back.
