Whistling Sound

I have bhk 300 monos, dsd, bhk preamp and a p20. When I bring the bhk preamp out of standby it also triggers the amps to turn on. About 10 seconds after the amps come out of standby, I hear a light whistling / wish sound. This just started a couple weeks ago. Anyone have any ideas what could be causing this. The sound last for about six to seven seconds. I also noticed that when I’m not playing any music if I put my ear up to the right speaker I hear a light put put put sound. It’s not audible from my list ending position which about 12 feet away but I can hear this initial whistling sound.

My first thoughts were the tubes. The bhk 300 monos are on their stock tubes and they are just over a year old. I replaced the tubes in the preamp and they have 1051 hours on them.

It is most likely tubes. You will probably need to swap them out to see for sure.

Thanks. The tubes in the bhk monos have about 3000 hours on them. Is this just the expected lifetime on them, or is it more than likely just a tube failure?

I’d say it’s time for tubes. I had a quad of Philips Miniwatt’s in my BHK 300’s and after about 2000 hours my music was getting a little lifeless. I put in a new Quad that I received from Joe Apperito on our Marketplace forum and boom! The sparkle was back. My BHK pre amp tubes are probably at 3000 hours and may soon need a replacement. In theory they should last up to 10000 hours in the BHK Pre but I’d replace them and see.

I don’t think there is an “expected lifetime” on an audiophile tube. They seem to lose their edge or get noisy at a very unpredictable rate. I have had them get noisy or lose their edge in a few hundred hours and others have lasted a couple thousand hours. The users who have a lot of tube knowledge and savvy have a lot of fun tinkering with them but they are a necessary PITA to me. I think because they are more “organic” than solid state devices their lifespan is not as predictable.

Is the noise out of both channels?

Sounds like either the amp or preamp tube on the right side is getting long in the tooth. If you have spares swap them in one set at a time and see if it goes away. That type of warmup noise is more common with preamps as is the put put noise.

The put put is coming out of the right side but the whistling sound is hard to tell. I would say probably both.

Hopefully it’s not the preamp since I just replaced those tubes probably around June or July this year. I’ll follow your advice and start swapping them out one by one.

Are either set of tubes Tungsrams?

Yeah the preamp has tungsram pc88 / 7dj8. The amps have the factory tubes in them.

The Tungsram’s are probably the problem then. I had a pair of their NOS 7DJ8’s and 12AU7’s exhibit the same symptoms in pretty short order. The 12AU7’s were actually a far better sounding tube but they made it about six weeks and then one of the matched pair started exhibiting the same behavior. I would swap the preamp tubes side to side first and see if the noise follows the bad tube. The pair in the 250 lasted problem free for almost three years.

You can remove the preamp from the circuit by running from your DSD directly to your amps.
Be sure to turn the volume down on the DSD before you connect it and use it’s volume control.
If the noise disappears, then you know it’s the preamp.
Also, look for any sign of white-ish coating inside the tubes. If you see white, likely that tube has a leak and is bad.

Casually, the BHK pre produces a whistle noise if I accidentally turn it off and back on a short while later. This issue was resolved by turning it off from the back rocker switch for 2 or 3 minutes and back on and the noise will just go away.

The first time I replaced the tubes in my BHK 250 it had a little over 1000 hrs on it, and I immediately noticed an improvement in the sound.
I’d say it’s time to retube your 300’s.

Hi Gary,
What brand did you use?

I replaced them with the stock tubes supplied by PSA.

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Then they’re Gold Lions. PSA provides one year warranty on tubes :+1:t2:

There is a fairly wide range of expected hours you can get out of the tubes, but I usually say it’s a good time to get the swapped out after 2500. I’m not terribly surprised that you’re having a little noise with about 3000 hours on the amp tubes.

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Welcome back. I hope you’ve enjoyed your brief break.

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