Tube Amp Archive

Seems fixed! I put the bias pot and power tube cathodes on the same ground, and also removed paint from the chassis around some of the transformer/choke bolts to get better grounding. Also put a good lock washer on the bias pot and really tightened all ground points. The amp is singing again and sou...

Thank you. I will consolidate the bias pot and cathode grounds and revisit the pot/chassis ground contact.

It’s a Classictone 40-18004, and yes, sorry, it is 440V at the plates when behaving

I don’t think so. Here are my readings on the bias pot lugs: No power, bias pot 1. 32.5k 2. 30k 3. 27k With power on (with and without standby) 1. -2 Mohm 2. -2 Mohm 3. -1.9Mohm I added a pic because I didn’t believe the reading. Also, I tried to adjust the bias pot when the amp went into the weird ...

Hey all, I've been trying to chase down an issue with my 102 build that happens after the amp is played through for 5-10 minutes. All readings (initially) seem reasonable (6L6 344V plates, Bias at 43mA). After playing a bit the sound cuts out and I'm measuring -120ish(!) volts on pin 1 of the 6L6's ...

Hi all, Just finished my build. Sounds great! I had troubles getting it to bias properly and finally realized the layout on page one seems to be missing a connection between the two 220uF caps in the power supply to place them in series (see attached where I've added it in red). Once that connection...

Sent another private message. Seems to be stuck in my outbox.

PM sent.

Thanks everyone. I just got done reading about bridge rectifiers and center taps = magic smoke

Will make all the changes. For what its worth, that golden time with the amp working was pretty fantastic!

Am I correct thinking that the over voltage on the relay could cause arcing across the relay which could burn up the transformer?

HI erwin-ve, Short answer is "I am now". I was only measuring ~5.8V at the regulator output, and made a dumb decision about which relay voltage based on not understanding relay voltages. I assumed a 12V relay needed to see 12V at the relay to switch. Would the overvoltage on the 5V relay potentially...

Hi all, Just (almost) finished a 102 build based on the ampgarage layout (attached). Played for close to an hour with no issue when the OD channel switched back to clean on its own, and switching became unresponsive. The voltages at the relay were normally ~5.8V but had dropped to 0.6V, and then the...

I received a set of resistors recently. They are excellent. Don’t hesitate to order if you are considering it.

Hello,

Is the last chassis still reserved? Interested in chassis and boards.

Thanks for the heads up! Have to use my phone to get the forum to work at all.

Hope they can get it worked out?