Tube Amp Archive

Though this thread is long quiet, I thought I'd post my (hopefully) final results. I couldn't give up on this amp so easily, and from the suggestions here, it just seemed that more power supply noise was getting through with the new transformer. So I ordered a Hammond 156R filter choke and a JJ Elec...

It sounds very plausible that the new transformer is simply letting more 120Hz through. Looks like the filter cap is a 22/450. What would you recommend I increase it to?

Well, I put the old transformer back in, and lo and behold it quiets down. Put the new one back in, hum's there again. I again moved the output transformer all around the chassis to see if there was any effect, but there is no effect from its position. The hum does not change with the amp volume, an...

I discharge everything before I work on the circuit at all, but thank you for the extra warning. I will do a basic check of the caps. I did try another 6L6 which gave the same results. If the filter caps test reasonably, I'm thinking I agree that I will have to install the old transformer to check t...

It is 120 Hz, not 60 Hz. I hadn't paid close enough attention. I resoldered the connections and the hum is still just the same. I changed no other connections in performing this modification. The hum IS still there with only the preamp tube removed. It is NOT still there with the power tube out. Do ...

Thanks for all the replies. No sound at all with the power tube out. It's single-ended, so no center tap. I'm thinking I'll pull it out and resolder everything I touched, since I'm not the best at it. What components should I check that might have been damaged? The board traces for these connections...

When I moved the chassis away from the cabinet and speaker, there was no change at all in the hum, so I don't think the coupling is directly to the speaker. I first thought the coupling must be between the power transformer and the output transformer, which is why I tried moving the output transform...

I'm looking for some help as I get a little further into the hobby of modifying amplifiers. I've made some successful small modifications to a Crate V18, consisting of replacing resistors, reverb tank, and speaker. My question now concerns an Epiphone Galaxie 10 to which I've already added a speaker...