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Microphonic tubes

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Hi Guys,

Is it advisable to replace a microphonic tube if it is not misbehaving?

I recently purchased some NOS 6N8S (Soviet 6SN7 analogue) tubes for my preamp from a local guy here in New Zealand. One of the tubes is clearly microphonic.

The preamp is an sp14 from tubes4hifi which is an aikido design.
The preamp works fine. No issues with sound quality other ringing in the right channel if I bang my desk too hard.

To reiterate; is it necessary to replace a microphonic tube simply because it is mircophonic? or am I safe to use the tube until it presents a further issues?
 
It's not unusual that some tubes from a lot are more microphonic than others. Such tubes are not faulty. You can leave them in if you are satiesfied with the performance as long as the increased microphonics is the only issue with the tube.

To be safe, you may check the operating points in the circuit (voltages on gate, cathode and anode) and compare with the other less microphonic channel.
 
Hi Guys,

Is it advisable to replace a microphonic tube if it is not misbehaving?

I recently purchased some NOS 6N8S (Soviet 6SN7 analogue) tubes for my preamp from a local guy here in New Zealand. One of the tubes is clearly microphonic.

To reiterate; is it necessary to replace a microphonic tube simply because it is mircophonic? or am I safe to use the tube until it presents a further issues?
This is a GREAT tube for guitar amp.
For hi-fi audio you can use a tube damper as Herbie or similar.
 
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