A
Anonymous
Guest
Then there is really really hot.........
I got myself a CCV-100 recently and it started playing up when powering up in the high power mode, it started making a loud cracking noise like a gunshot within 30 seconds ish of it being taken off standby so...
I decide to check the bias on all four power tubes
The amp came to me with four JJ power tubes in it and when I checked the bias the cathode current draw at idle was between 80ma - 85ma on each tube !!
it was biased so hot that it was pulling the plate voltage down to 520 volts in high power mode
I put a set of new winged c in and biased it at 47 ma per tube and the plate voltage then settled in at 550 volts which is where I believe it should be and there are now no more cracking gunshot type noises...
Strangely enough the amp sounded great even when it was biased that hot ... weird.
I did try putting the used JJ back in biased cooler at aroung 47ma but they are still making the cracking sound and I could see the tubes arcing inside the glass envelope when it makes the gunshot noise so I think they are well and truly cooked ..... nevermind
I got myself a CCV-100 recently and it started playing up when powering up in the high power mode, it started making a loud cracking noise like a gunshot within 30 seconds ish of it being taken off standby so...
I decide to check the bias on all four power tubes
The amp came to me with four JJ power tubes in it and when I checked the bias the cathode current draw at idle was between 80ma - 85ma on each tube !!
it was biased so hot that it was pulling the plate voltage down to 520 volts in high power mode
I put a set of new winged c in and biased it at 47 ma per tube and the plate voltage then settled in at 550 volts which is where I believe it should be and there are now no more cracking gunshot type noises...
Strangely enough the amp sounded great even when it was biased that hot ... weird.
I did try putting the used JJ back in biased cooler at aroung 47ma but they are still making the cracking sound and I could see the tubes arcing inside the glass envelope when it makes the gunshot noise so I think they are well and truly cooked ..... nevermind