BHK Preamp - noise

I agree, bad tube or dirty pins not making a good connection.

Is that noise coming from both speakers at idle? Did you try switching the tubes from left to right, etc? I did experience a face of strange noises on mine too, but everything stabilized/disappeared after break in. I have now properly tried 6,7,12 volts tubes without any problem and currently enjoying some marvelous Telefunken 6dj8.

Try reverting the tubes and checking that all the pins for voltage and bias are correct.

p.s. At night, I left my preamp at 100 with a repeat track of (XLO System Burn In) on my DS 100 too. Amp was on stand by so no noise or blowned speakers here. That seemed to help the preamp achieve full break in.

Definitely worth trying some new tubes. This is the exact sounds I expect to hear when the tubes are bad/old.

ok thanks. Elevated white noise is on both channels but this sound I recorded that sounds like rain on a roof is only on the left channel.
Since it’s a new BHK, and I spent only 40h listening with these tubes I did not yet replace them…
I had hoped they would last a year or so…:slight_smile:

I already ordered new tubes and I will try. Do you have any recommendation which low noise tubes sound good with the BHK?

Try interchanging the original tubes between channels. You might get rid of the funky effects on the left side. Psvane tubes are great tubes to start with, so let see if that resolves the issue of the extra noises before moving on to a different tube.

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When you swap the tubes from side to side, clean the pins with alcohol before replacing them.

While 40 hours is indeed low usage, tubes can fail at any time - like most things.

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ok, will do.

Any updates here?

I cleaned the tube contacts and switched the left and right channel tube but then I had the issue on the other channel.
I then replaced the tubes with an ECC82 S4A tube. Now the “raining” sound is gone.
Compared to directly connecting the DSJ to the M700 amps I would say that I still have an elevated white noise level but I guess this is to be expected with tubes.In any case it is much quieter than with the bad tube.
I think I will continue my search and try out other, and quieter tubes.

I saw the huge thread about BHK tube rolling…
Any recommendation for a very quite tube 12V tube?

All tube types have variability in noise, channel matching, etc. If you want the lowest noise examples you have to pay someone to match and screen them for those issues. I don’t know of anyone who takes more care to screen their tubes than: Common Small Signal Tubes – Vintage Tube Services

Andy isn’t the least expensive source for tubes, but you get what what you pay for in this case. I find it’s better to contact him by phone rather than email.

Chris, if you are hearing this from your listening position, then yes, work to eliminate that noise. But if you can only hear this with your ear up close to your speaker, forget it. You’ll drive yourself bats**t crazy trying to eliminate it.

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ok thanks.
With the new tubes it is ok so far. I can live with that but I’ll still looking for quieter tubes in the meantime. While I could not hear the “normal” white noise from my listening position at all when I directly connected the DAC to the PowerAmps, now I can hear it but very faint. Still bothers me but of course it is now much better than before.
There was also a hum which got louder when turning up the volume (with the new tubes) but this is also gone now after some burn in time.
@Photon46
Thanks for the recommendation, I will contact that guy.