Tube Amp Archive

Dansamp, were the original tube(s) that failed from Sarge? Were these the Saratov versions he is selling currently for $94 a quad? no one Sovtek EH tube failed I have now purchased a full set of tubes from Sarge and the amp sounds great I was getting some 60 cycle hum that I traced to a weber coppe...

With a 50pF Treble Cap this might be normal, my express is the opposite, Treble has a MASSIVE range, bass/mid not much. Is the treble pot definitely connected to the bass pot and that .022uf cap? Littlewyan, thanks for asking all the right questions as I was cleaning up the routing of some of the w...

so, have to order new tubes from the Sarge but for the time being I wired it up with only two power tubes and all is well, no more redplating and the bias is as it should be , slight issue now is , treble pot is not as effective as I would expect it could be the cabinet I am using 5E3 cabinet with a...

well here is the proof

ok,
I think I have a bad tube

I swapped the tubes left to right and now the voltage on pin #2
has moved to the other side

reconnected the grid wires to the power tubes
and something is giving me 5.xx volts on pins #2 of the left side
power tubes
I have never seen this before

ok,
this is very strange
I disconnected the wires from the PI feeding the power tubes
I am getting 12 v. on pin two of the second power tube !!

so I am getting about 5 volts on pin #2 of the first pair of power tubes and 0 volts on pin #2 of the second pair of tubes so I am getting voltage coming out of the left side of the PI and 0 volts on the right side of the PI note sure if this makes sense I wouldnt expect much voltage since that shou...

by the way
my cathode resistor is 47 ohms

i didn't get a reading on pin #2

the OT center tap is on thew third cap
you can see in the pic
the first two caps are parallel
the screens are on the third cap to the right
its the green wire
and the choke is between those
its the thin red wires

yes I did check voltages see above post also with 5Y3 tube: power tubes are pin #2 = 10.57 v. pin #3 = 10.84 v. pin #7 = 220 v. pin #9 = 226 v. when I plug in the weber rectifier I don't have enough time to check voltages but doing a quick check before it redplates pin #3 = 8.0 v. pin #7 = 320ish v....

ok,
here is the latest,
I plugged the weber rect. cap back in and fired it up

same issue, only now the runaway tube issued moved to the second
power tube

the problem was present before that socket was replaced so I don't believe the condition of the current socket is an issue at this time I tried the amp with a 5Y3 rectifier tube and I was able to play it for a bit you could see just a faint red glow from that one power tube with 5Y3 : B+1 = 231 v. B...

The poo is silicone It was thAt way before I started on the amp I purchased the amp from eBay It was a two channel amp with reverb The guy said one channel worked and one was noisy But when I got it neither channel was functioning So I stripped the board and turned it into a rocket The power tube se...

Yes the socket has been replaced

It takes about 1 minute to red plate