Tube Amp Archive

I removed the tubes and measured both legs of the OT. They were 42 and 47 ohms. Do the voltages that I previously measured seem reasonable? The amp is not noisy or unstable but it does not have the volume that it did before things changed. At one point cranking up the treble increased the volume qui...

Hi: Thanks for the responses. THe OT has about 47 ohms between the CT and the legs while still soldered in. The pin voltages are as follows. EL34 pin 3 400 pin 6 390 PI pin 1 189 pin 6 200 B4 260 B5 pin 1 204 pin 6 182 If I should measure differently please let me know. I am defininitely a newb. Tha...

I turned the amp on again today and it now has sound, but it is poor. The voltages are as follows.

403v before the 1K resistor
392v after the resistor
294v B3
277v B4
263v B5
32v Bias

Could it be a bad cap?

Thanks for all of the help.
Gary

Yes, you are correct it was -32v. I am using toneslut trannies. I played a gig with it and then thought I should probably set the bias correctly by measuring the current at the tube. When I first measured across one side of the OT it was above 50ma. To bring it down to 40ma I brought the bias voltag...

Hi: I finished my Express build and adjusted the bias voltage to 32v, fired it up and it sounded great. The best sound I have heard in a long time. I decided that I would adjust the bias by putting my meter in parrallel with half of the OT so I connected one side to the OT center tap and the other t...

Thanks for the reply, my question with respect to the heater leads is what does the ground do electrically? One side of the HT winding is used for the bias current but the heater leads are a complete circuit without the center tap grounding. I am a newb so please excuse the stupidity. If there is a ...

Hi:

I am using Toneslut trannies with a Ceriatone kit. I am wondering which of the PT secondary leads need to be grounded and why. I read Paul's page and am wondering about the center tap for the heater browns specifically. Any thoughts would be appreciated.

Thanks:

Gary

Thanks for the response!, I had read a post that said buying the trannies stateside was preferable, and since shipping from Malaysia is not cheap I thought that maybe it was a better alternative. I have also read that the chinese tubes are terrible. I guess there are as many opinions as ........also...

I apologize in advance for the newbie question! I want to build an Express. I am considering Ceriatone parts. Does anyone have an opinion with respect to his parts? Should I buy his board and get the trannies somwhere in the states? Is there a BOM that contains the trannies? Should I start with a cl...