Noise in one channel - BHK preamp - tube rolling tribulations


#1

Hi,
I’ve been tube rolling with my BHK Preamp. I have received tubes from a variety of sources and I always clean the pins with deoxit and generally clean them off prior to use, even if they look clean. Today, in a rush, I grabbed a new set of National 7JD8’s and put them in. I realised afterwards that I had not cleaned them. When I started up the preamp I noticed a loud rushing sound from the preamp… I then swapped out the National 7DJ8’s for a pair of Tungrams 7DJ8’s (that I was using previously and I know are good) and sure enough, there is the rushing sound, only in that channel.
I thought it must have been a result of the dirty pins as it only started after the Panasonics went in and it is still evident in the same channel with other good tubes.
So have I got grunge in the socket? If so, is there a safe way to clean them out? A tool or some other trick and if so, can I use deoxit / alcohol or something to assist the cleaning?
Any help is appreciated.


#2

Sounds like either a faulty tube or a fault with the preamp has developed. As you have tried different tubes it could well be the preamp. As for dirty pins, the swiping action of inserting and removing the tubes would clean the contacts. Make sure the tubes are fully seated…


#3

Well since I tried other tubes that were working fine up to that point and they are now making noise then it wasn’t the tube. I sincerely hope one dirty tube can’t damage the preamp. I was under the impression that the design is quite robust. I am always careful to let the power drain and pull the power plug prior to taking the tubes out.
I am hoping for some technical input from PS Audio.

Mark


#4

And I did make sure that the tubes were well seated. A visual inspection doesn’t show any dirt or damage on the socket holes.


#5

I can’t see the pins being that contaminated as to cause a major problem. How many people clean the pins with deoxit before inserting them… For peace of mind liberally coat the pins on a pair of tubes and insert them / remove them / do this few times to clean the socket connections. It sounds like the preamp has developed a fault ! Only guessing on my part - and just going by what you’ve described, but I cant see it being down to dirty pins unless the pins were badly contaminated and / or badly damaged…


#6

Has anyone else reported this kind of fault? I remember reading a few comments on the BHK Preamp protoype thread that suggested some people had noise occur in one channel but I guess I assumed this was a dirt issue simply because I powered off the unit and waited about 4 minutes before inserting the new tubes.
Again, if anyone inside PS Audio can comment i would be appreciative. Actually I currently have a warranty issue with the headphone output that makes a buzzing sound in one channel. Are the 2 related??
I am waiting on word back from the authorised seller about what the fix is on that issue.
Looks like I m going to lose my preamp for a while…


#7

Start with the simple things first. Are all the jumpers in their correct positions?


#8

If it’s a clicking noise you are hearing in one channel, I had the same problem.


#9

Yes, jumpers are 6V, 5A. I was running another set of 7DJ8’s prior to that without incident. Put these in, problem started, pulled them out, back in with the other 7DJ8’s and the issue is still there :frowning:


#10

@nortonkp, NortonKP, was your’s a production model or a prototype?


#11

1-800-psaudio


#12

I live in Australia…


#13

Phone Mike Kirkham at Magenta…


#14

I’ll talk to the dealer that I bought it off tomorrow.


#15

If its a clicking noise in the left or right channel. You are at least the fifth person with the issue. It’s a main board issue. My preamp was purchased in August 2016 and is a regular production unit.

PS. I just use the stock tubes now.


#16

There is whooshing / tube rush through the main preamp and the headphone has a constant buzz.


#17

Well this is all very odd and a bit embarrassing perhaps. I got into my office this morning, where I keep my music system at the moment and i put the Tungsram tubes back in as I had left them out last night. I start my preamp up and the rushing sound has gone today. So what magical change happened overnight? Did the gods of music look down upon as I fretfully lay awake worrying last night? It certainly seems to be back to normal - I’ll keep an eye on it for a bit.
Thanks for everyones’ input.

Mark


#18

The sockets may have just had a chance to dry out without the tubes in place if you had coated the pins.


#19

Hi,
Yeah, I’m open to all theories at the moment! Good that it’s sorted itself out though - quite a relief.


#20

I just blame gremlins for these kinds of things. Especially if the problem does not reoccur. Lots of strange things just seem to happen randomly in this hobby.