Tube Driver issue?

[Tom Lauten]

Hi folks.

I just finished my Tube Driver build (Toms variation) on the Tube Driver125B V1.2 PCB.

Everything worked great on the first go and MAN does this thing pump out some great tube of sound!

I am having one weird problem. When I play (and ONLY when a note has been struck) I get a noticeable static/fizzing sound along with the strings note. It's not CRAZY loud but it is there for sure. I switched tubes and it still happens. I played with the gain and it seems to make no difference.

Any Ideas what could be causing this static/fizz when it's playing a note. It is quiet as you would like when strings aren't being played.

I'm using a vintage Mullard ECC81 but it did pretty much do the same thing with a Shuguang ECC81 as well.

I also played with the trim pot a little but this didn't seem to effect it much if at all.

[glimmer_twin]

I have a similar problem with my Tube Driver. With a JJ 12AX7, depending on the biasing, there's some kind of oscillating noise as the envelope decays on the lower side -with the trimmer all the way right-, or a noisy-popping tail in the upper notes when it's on the left. Anywhere in the middle, you can dime one or the other, but you can't get rid of both. With a CEI 12AT7 tube the sound is huge, much better than with the JJ but a sine wave is always there, biasing changes the pitch of it, but doesn't disappear. I'm eager for any idea that could help.

[Zerro]

Any schematics for considering? I mean that Tom's variation? Where I can see it?

[glimmer_twin]

Sorry, it's a Musikding kit, and I did Tom's variation. The power supply is a cheap Harley Benton Power Plant. I'm gonna try to record.

Thank you for your answer!

[glimmer_twin]

I think I catured the funny things my unit is doing:


[soundcloud]https://soundcloud.com/aplastaarteche/fizzy-tube[/soundcloud]

[soundcloud]https://soundcloud.com/aplastaarteche/popping-tube[/soundcloud]

Thanks again!

[Zerro]

I guess that this it that schematics?  C18 and R2 are not used or assigned in my original document. Try to control it (and play around). C17 seem to me too low - I should use minimally 470pF and the same cap (for proper voltage) I should connect from anoda to grid of first triode. But, the biggest suspect I have to that charge pump, which have only 47n cond at the end where should be power for triodes (cca 60V). I would add there elyt cca 1-10uF/100V. Fuell will rise little slowly there at the start (seems like as the valve heating :-), but it will be more freq. stabilized.

[Zerro]

Here is orig doc I have, in pdf.
For an example I am sending Tube Head schematic too - notice that power branch for triodes. Three systems of 4049 from charge pump are connected as the power generator, able to work with elyts in charge pump. But over this all, there is elyt at the end to stabilize power from HF oscilations. Woe, my english is not too great, but I hope you understood :@)

[glimmer_twin]

Thank you!

checking the build, I just noticed that I did the stock version, not the Tom's. Didn't have time to do the mods, just removed R9, as it is optional, and to my ear the strange noises are slightly better, but maybe they stay the same. Will change components this week and see how it goes.

Thanks again!

[Zerro]

Finally, that's the best at this all (minimally for me :@) to play around and tune the sound!