New issues on my JTM45 build while testing tubes.

[gtrplayr1976]

I seem to remember having a 12AX7 that made that quiet motorboat noise, try subbing out each in turn with a good one.

Did it go away after warmup? This starts at a point during initial startup ,then fads out when it settles? I will give that a go though. Can't hurt.

[pdf64]

It was a long time ago, sorry, can’t recall the detail, but it got worse and provoked me to track down the culprit. I was surprised it was a tube fault.
It may have been one of GTs ‘Mullard’ replicas from the early 2000s, I read they had a lot of problems and got withdrawn.

[gtrplayr1976]

It was a long time ago, sorry, can’t recall the detail, but it got worse and provoked me to track down the culprit. I was surprised it was a tube fault.
It may have been one of GTs ‘Mullard’ replicas from the early 2000s, I read they had a lot of problems and got withdrawn.

I gave it a shot. Still have the noise. I'll keep looking.

[gtrplayr1976]

True and motorboating typically sounds different. Let's see if its still there with the GZ34. You might even use a 5U4GB for a little lower voltages if your PT supports the higher heater current.

I just tried another set of power tubes ,and the puttering is gone on the first startup. I will try again shortly to verify that. I'm kind of shocked. I've never had an issue with a tube I have gotten from Eurotubes.

[gtrplayr1976]

It was a long time ago, sorry, can’t recall the detail, but it got worse and provoked me to track down the culprit. I was surprised it was a tube fault.
It may have been one of GTs ‘Mullard’ replicas from the early 2000s, I read they had a lot of problems and got withdrawn.

I just tried another set of power tubes ,and first startup the puttering is gone.