Noob question
If preamp tubes get microphonic do they usually get microphonic slowly or does this happen suddenly?
I have a JJ 803S in one of my amps for maybe 20h now. So far it is fine.
Might it happen that in lets say another 20h it suddenly gets microphonic?
The US military back in the day believed that if a tube functioned properly for 100 hours, it was very unlikely to fail catastrophically before it wore out.
So you only have 80 hours to go!
Seriously though tubes can go pop etc at any time for any number of usually unknown reasons. Especially new manufacture, but old ones will do it too.
If your tubes are not microphonic now, then the main reason for them to become microphonic is either from rough handling / dropping your amp or in the case of a combo amp, tubes rattling from mechanical coupling via the speaker to the tubes directly or via the speaker to cabinet to chassis to tubes.
BobW wrote:If your tubes are not microphonic now, then the main reason for them to become microphonic is either from rough handling / dropping your amp or in the case of a combo amp, tubes rattling from mechanical coupling via the speaker to the tubes directly or via the speaker to cabinet to chassis to tubes.
+1.. Pulling them moving them around putting them in different amps can contribute as wel..I know I am guilty of this!!
Tony
" The psychics on my bench is the same as Dumble'"
glasman wrote:
I have been testing the short bottle TungSols and have found some issues with them getting noisy and then KABOOM. I guess Alan Philips (CarolAnn) has seen the same issue. I will say while they lasted (< 15 hours) they did sound good. I have also tested the TS 5881's and found no issues. I not tested the large bottle TungSols.
But for right now, I will stick with WC's, expensive but never had any issues with them.
Gary
Thanks for this information!
Think I will skip the test
"KABOOM" is kaboom in terms of pieces of glas flying around or kaboom in terms of just crapping out?
KABOOM as in fried filament balancing resistors, cooked screen resistors and OPT with a new P/P impedance.
Others here have used them with here without incident, but the last set I tried started getting that nice "frying" sound and I yanked them and put in the junk tube box.
Located in the St Croix River Valley- Afton, MN
About 5 miles south of I-94
aka K0GWA, K0 Glas Werks Amplification www.glaswerks.com
glasman wrote:
I have been testing the short bottle TungSols and have found some issues with them getting noisy and then KABOOM. I guess Alan Philips (CarolAnn) has seen the same issue. I will say while they lasted (< 15 hours) they did sound good. I have also tested the TS 5881's and found no issues. I not tested the large bottle TungSols.
But for right now, I will stick with WC's, expensive but never had any issues with them.
Gary
Bummer!
I'll let you know what I think of them after a couple of shows.
<i> "I've suffered for my music. Now it's your turn."</i>
HI, I'm new but figured I'd put my 2 cents in; I got a a pair of the JJ 803's and a pair of the Tung Sol reissues recently to experiment with. Both JJ's are microphonic and rattled like maracas right out of the box (I baby my tubes when handling) Very disappointed. I'm trying one as a PI to try and salvage it. I'm very happy with the Tung Sol's although I'm wary of new-production long-plate tubes now.
prudens wrote:HI, I'm new but figured I'd put my 2 cents in; I got a a pair of the JJ 803's and a pair of the Tung Sol reissues recently to experiment with. Both JJ's are microphonic and rattled like maracas right out of the box (I baby my tubes when handling) Very disappointed. I'm trying one as a PI to try and salvage it. I'm very happy with the Tung Sol's although I'm wary of new-production long-plate tubes now.
Welcome prudens.
Curious if you bought your JJ tubes from Bob at Eurotubes?
glasman wrote:
I have been testing the short bottle TungSols and have found some issues with them getting noisy and then KABOOM. I guess Alan Philips (CarolAnn) has seen the same issue. I will say while they lasted (< 15 hours) they did sound good. I have also tested the TS 5881's and found no issues. I not tested the large bottle TungSols.
But for right now, I will stick with WC's, expensive but never had any issues with them.
Gary
Thanks for this information!
Think I will skip the test
"KABOOM" is kaboom in terms of pieces of glas flying around or kaboom in terms of just crapping out?
KABOOM as in fried filament balancing resistors, cooked screen resistors and OPT with a new P/P impedance.
Others here have used them with here without incident, but the last set I tried started getting that nice "frying" sound and I yanked them and put in the junk tube box.
Yeah those Tung-Sol 6L6 short tubes are a total POS. Red plate issues galore. I returned 72 of them after I had 4 or 5 sets blow up as soon as I put them though any sort of full power testing. Cost me a fortune in fuses.... The shitiest 6L6 ever.
JJ 6L6's are a bit iffy too at the moment and every one of their EL34's need severe buring in in order to stop them crackling on first power up.
Findiing Svets to be the best at the moment, though the JJ's are fine after breakin. Some guys don't like these in any Dumble type of circuit. They work well in the CA's though.
I never use JJ preamp tubes. THe long plates are nearly all microphonic as all hell and the short plates are way over the 12AX7 nominal gain spec and sound one dimensional. They have zero microphonics but make up for it with AC filament noise.
markusw wrote:So far the my JJ ECC803 is still working without problems. Probably 40-50h in total.
It's a "selected gold". Maybe they go through a better QC?
Update: my JJ ECC803S now runs a couple hundred hours in the PI position w/o troubles. Maybe it's really about the JJ selection procedure that makes them less likely to fail than their non-selected 803s? Of course this is just a single tube. Might also be sheer luck
Now I'm really glad that I went with the Winged C's 
