Tube Amp Archive

There are no safety issues with such switches, as a preamp signal couldn’t cause injury. For signal switches in a preamp, voltages can’t really exceed 100Vac, and current levels will be a few mA. So pretty much any robust switch will work ok. Insufficient wetting current is a potential issue if som...

Greetings fellow tube heads! I was hoping for some clarification for safety's sake. I was looking to add a bright switch to an amp. Looking around the schematic I see the caps are rated for 630v and the only switch I see in the signal chain is a rotary switch rated for 1A, but no voltage listed. Non...

Thank you for all the replies gentlemen! Definitely food for though. I had read an article by Aiken Amps and thought there would be some benefit using a choke over the resistor. I might not be understanding the article fully. The amp sounds surprisingly good for the price but obviously corners were...

Thank you for all the replies gentlemen! Definitely food for though. I had read an article by Aiken Amps and thought there would be some benefit using a choke over the resistor. I might not be understanding the article fully. The amp sounds surprisingly good for the price but obviously corners were ...

As far as placement in circuit, I am assuming that R142 is a good spot or is there a better place for it?

Thank you for the replies gentlemen. I will look into a different choke option. As far as placement,would that be the best place to install it?

Greetings! Looking for some opinions on choke placement for an amp I currently have (Randall RH50T). I am looking at placing a Hammond 155H (which is rated at 5H 400v/50ma and 270 ohms) in place of R142 which is located right after the rectifing diodes and between two sets of filtering capacitors. A...

Thank you gentlemen for the responses! I didn't even think about R115. Not to mention for some reason I though I need to add resistance at the trimpots or after. I do appreciate the feedback.

Greetings! I have a Randall RH50T I recently acquired and was doing a bit of a check up on it. It currently has 6AC7 tubes in it with about 450v at the plates. The lowest I can get adjusting the trimpots is about 41ma on one tube and 39ma on the other.I am trying to get them down to about 35ma. The ...

Thank you sir! I had a feeling that maybe it didn’t but I am also a bit of a novice at this.

Greetings! I currently own a B52 ST60 that I am trying to install a resonance control on and am looking for a little help from you kind gentlemen. For the life of me I cannot identify the NFB resistor, or even the circuit for that matter, from the schematic. I tried comparing it to the AT100 schemat...