Ping

[Harvey]

I have recently purchased a quad of Mullard CV2493 tubes for my preamp, every time I mute the volume they ‘ping’ through the speakers. I had read about these tubes being prone to doing this (can’t find where it was now), it's not very loud and not really an issue with regards to sound quality as they don’t sound microphonic with music being played. I’m a complete newbie when it comes to tube rolling, should I worry about this, will tube dampers help?

While I have your attention, my preamp also uses two 6V6GT Electro Harmonix valves. There doesn’t seem to be much information about these in hifi applications and a limited selection available to choose from. Can anyone recommend a nice upgrade for these, I don’t want to spoil the sonic signature the Mullards bring to the party.

[DodgyConnection]

Not sure what it could be - I get a similar thing when I turn my valve pre off - a "tinking" sound through the speakers as it cools down - weird.

[Owen Young]

Dodgy, the tinkling sound is due, I think, to the thermal movement/shrinking of the internal tube elements (metal) as the tube cools down rapidly when the tube heaters suddenly switch off...normal.

However the only guess I can make about Harvey's 'ping' noise as the Mute switch is flicked, is that the switch has such a strong action that vibration hits a nearby tube. CV2493s are ECC88 types, which are close tolerance, 'frame grid' tubes - these tubes have have different noise characteristics & can be noisy in some designs. What preamp/amp?

6V6s are well known tetrode power tubes with a long history (from 1930s?) & still used in guitar amps I think.

[Harvey]

Looks like you are right Owen, I found a bit of talk about these being prone to 'ringing'.

Preamp is a BATVK3ix, I gave it tap on the front casing and it made the same pinging noise, from what I've read it is really only problematic if you have lot's of gain and very sensitive speakers, I have the former but not the latter. Should I try dampers anyway?

[Owen Young]

You could try dampers of some sort...just use rubber o-rings might the most economical trial approach. Personically I've never kept dampers on tubes, something sonically is lost, the last bit of air, sparkle, low level info, etc, but YMMV. Let us know what you think.