Mini-Booster Question

[MicFarlow77]

Hi All,

I built Jack Ormans Mini-Booster a couple of weeks ago. I had to go out of town for the week due to work, so I let one of the other guitarists in the band test it out while I was gone.

He took it for a test drive and before he knew it, was heading to the closest place he could find to replace a pair of 12AX7's in the front-end of his amp.... turned out to be a $34 little trip.... he noticed that over a period of a few minutes, the sound quality of the amp was heading south. Turned out to be those two tubes....

They flat gave up the ghost.

As far as I can tell, there are no issues with the pedal. Followed Jacks parts selection to the letter. Garden variety J201's... didn't match them.. just put in a pair....

No Hums. No Buzzes. No Pops. No Tone Sucking. It is a great sounding pedal. Other guitarist has owned a Studio for 20+ years and he has so much gear, I'd be hard pressed to say he had it setup wrong... seeing how as there is only a volume knob...

I have a Line 6 DuoVerb and have had no issues... but it is not a Tube front end... so that is not an apples to apples comparison.....

He nor I am convinced that it was the pedal. There are 6 smaller tubes.. not sure what they all are, but just know the 2 Groove Tube ones went south. Not sure if the others are stock and are fine, or if the amp was originally shipped with Groove Tubes and those two finally went .... We are thinking they might have been on thier last legs and when he hit them with the booster, they finally gave up....

Has anyone else ran across the same type issue?

Thanks All.

Mick

[petemoore]

Has anyone else ran across the same type issue?
  Faulty 12ax7's.
  Yes. 
change input function].
  We are thinking they might have been on thier last legs and when he hit them with the booster, they finally gave up....
  This is enirely possible. Especially in combo amps, the mechanical vibration connection between speaker and input tube could certainly loosen up an input tube that's ready to be loosened up, simply because the speaker is slamming and the input levels are higher. [this would be chocked up in the 'bad tube found' category IMO.
  *sometimes you can tell they've gone microphonic by tapping lightly on 'em.
  other times they'll work fine under *certain conditions [technically 'bad' tube does good until conditions arent' change where they don't [like acting up when booster hit's em].
  Quick way to test an input tube is use a good input tube where you think there's a problem.
  Quick way to test an amp is try a different amp.