The BHK Pre has been making a popping (glass tinging) type noise when I turn it on/off. The sound is a little delayed, it’s not right when I turn it on and off.
It looks like I ordered my BHK Pre August of 2021, which means I probably got it in September 2021. It’s about 1.5 years old now. This is my first tube item ever… does this mean anything? Is it time to replace the tubes? I haven’t heard any degradation in the sound.
I would probably try some new tubes, especially if you just started noticing the problem.
His many hours on the tubes? (The unit keeps track.)
I didn’t know that. Let me read the manual.
These little guys are typically good for 10,000 hours.
If the sound is fine, the tubes are OK.
And I like the tinkling sound of cooling tubes. 
I haven’t noticed it with my PS Audio equipment but my prior all-tube preamp pinged pretty loudly once or twice when the tubes were first warming up. Happened pretty regularly and through multiple tube changes. Didn’t hurt anything and I just got used to it.
Mine had some bad popping before changing the tubes, as well as some low-grade hiss. As I was waiting for my new tubes, one of them even got bad microphonics - if I so much as touched the chassis it would ring a high B-flat. New tubes cleaned everything right up
You could try taking the tubes out and putting them back in, sometimes this works.
…or swapping them left to right, right to left.
Problem is you don’t notice the degradation in sound as the tubes slowly degrade. I’ve been replacing the tubes in the BHK pre and 250 every 1000 hrs, and have noticed an improvement in sound quality after doing so.
Tubes get hot when they’re on and cool when they’re off. Expansion and contraction, can’t get away from it
Get a spare set of tubes. Swap them in and if you hear an improvement in sound quality, leave them in and keep your old ones as spares.
If they don’t sound better than the originals, swap them back and keep the newer ones as spares.
Repeat after approx 5,000 hours.
I’ll run small tubes for 2500 or so, swap them out for something else tasty, and eventually take the tubes I took out over to a local shop and have them tested. With six sets (currently) for the Pre I always feel like I am in a sweet spot. Every now and then a set ages out or one of them simply fails, but that’s not very often.
At the end of a listening session I always turn in stand by mode (blue button on the front panel) my gear.
From both M1200s and BHK Pre I can hear a “click” 5 seconds after I pressed the blue button.
Since I bought them and no matter how old are tubes or different tubes used too.
No clicks at all when I switch them on, only when they are going in stand by mode.
How hot do the tubes get in the BHK preamp? I have a tube preamp with a separate power supply and the only tubes that get too hot to touch are the 3b22 rectifier tubes which have a 6amp heater current. When I use 866a mercury rectifiers they don’t get near as hot, the audio tubes are just warm to the touch.
They are small signal tubes. They are warm when operating, not hot.
I wouldn’t touch them until they cool off.
If it isn’t an electrical pop, just a mechanical ting due to the tube glass expanding and contracting as it heats up and cools, you don’t have a problem. Is the Pre still sounding good? Leave it be. I’ve heard the glass envelope ting in a wide variety of tubed equipment over the years at power up/down (especially power amps). Not an issue.
I was looking in the manual but didn’t see anything about this. Did I miss it?
Press and hold the button to go into setup, click through until you see tube hours.
Awesome! Thanks! I’m only at 3741 hours