Einstein help required. Possible preamp tube issue.

  • Thread starter Thread starter badgergman
  • Start date Start date
badgergman

badgergman

Member
Hello.

I seem to have jinxed myself buy asking for advice on where to buy replacement pre-amp tubes earlier this week.

Last night whilst rehearsing with my Einstein combo I noticed a high pitched overtone to notes and chords as I played. Like a microphonic tone, present in the background mostly.

I notice that if I lightly tap the top of the amp the tap is heard through the speaker. Much more prominent on Channel one modes 2 and 3, less so on channel 2.

I am suspecting that V1 preamp tube has gone microphonic? Luckily I have replacements (Ruby 12AX7AC5 HG+)on the way from Germany, but I have a gig tomorrow!!

Would anyone care to say is my diagnosis correct? If so would swapping it out with a Ruby 12AX7AC5 HG be okay, or would it be better to swap V1 and V2 around to get through the gig tomorrow?

Appreciate any help you can give guys.

Thank you in advance.
 
Swap V1 and V2. If it should be better, use a good tube in V2 then.

Einstein:

V1 Used by both channels
V2 Used by channel 2
V3 Used by both channels
V4 Mixer & Loop Driver
V5 Return Driver
V6 Phase Inverter
 
Thanks.

Will try that tonight.

Would being able to produce noise through the amp by tapping it on top be possibly produced by any other factors do you think?

Regards
 
Swapped V1 and V2 and this curious microphonic issue has stopped happening.

I notice when swapping the preamp tubes that the installed ones are Ruby 12AX7AC5 HG. Not the + version.

When I receive the Ruby 12AX7AC5 HG+ tubes I have ordered I will swap both V1 and V2 out do you think? Or are Ruby 12AX7AC5 HG okay for use in V1 and V2?

I note that Peter recommends the + version in V1 and V2 is all. Unusual that they weren't installed.

Thanks for your advice.

Regards
 
You must log in or register to reply here.
Back
Top