Tube Amp Archive

Hi Bill,

Interesting infos I need to digest. Many thanks!!

You are a master Martin, but you already know. Great, more shopping to come. Would you recommend to change any other cap in the meantime? I was also advised (not sure it was you) to replace the diods with better ones so that I can remove half of it. Not sure in what that would sound better. I see so...

Hi Martin, Hope you're doing well! I played a lot in my new sounding amp, very nice saturation I have never heard before! But I have a question. When I roll down the master volume knob to the minimum, I still have plenty of sound, like if it was on 1/10 on simple volume. Is it normal that the sound ...

THANK YOU THANK YOU THANK YOU! My plate voltage is 475 v, I could perfectly balance and set the bias to 44.2 ma to both tubes, and the master volume works perfectly, this is just AMAZING, a new amp is born! Master volume at 4, volume at 7, I have a great sound I never had in ten years I own the amp!...

I will have two bias probe to hands, they look pretty simple kit to mount but I'll test the connectivity before using it


So you would also do the measure of the voltage (450v) with the pin3 and ground? (so not using the bias probe, which is taking the pin 8 and 1)

You will have to set the bias to test the amp. To make it a bit easier you could meter across the outer lugs of the balance pot and adjust the balance for zero volts. Then use the DC resistance of the OT and the voltage drop across it to calculate plate current and set the bias level. Ok so if I un...

Exciting, will try tomorrow hopefully then! Thank for the info. I'm learning a lot! Yes, the MV to board wires were my first try, I tightened bias to MV a bit more. Easy to re-adjust, I may do so tomorrow.

(Would you re-wire in phase pin2->pin2 and pin7->pin7)

Time to sleep here

Hi Martin! Here some news! I couldn't wait buying wire with another color so... But now I need to wait for the 2.2M and another color for grids. As you can see, I had an issue with one pin wire... The solder meets it... S****... So I must replace that one. It goes from pin2 on one tube to pin 7 of t...

I know I'm going to cause cringes, but I converted my AA864 Bassman to Blonde several years ago. I played it that way until I converted it back when I sold it. I know Blackfaces are supposed to be great, but I loved the Blonde so much more. It did everything the Black did, but did it better. I didn...

Hello there, Hi Martin, Me again :D Now the bias mod is (hopefully) finished and the power plug simplified, the next step is to wire the master volume. Before doing so with the non most adequate parts, I would like to check what should I use: - at the pot, I see the 2.2M on the schematic: is that re...

Hi Martin, I think I'm done with the Bias mod! But I prefer to check with you before switching the beast on! Here are the pictures below. So I finally placed - Resistor Metaloxide 2 Watts / 470 Ohms - Resistor Metaloxide 1 Watt / 1 kOhms - Trimmer pot Piher 5K Does the layout look correct to you? Sh...

Exactly what I started to do as the two legs to diode and cap fit in the board

Ok let's go for the metal then.

Yes, looks like the trim will go in existing eyelet! Thanks for the advise, I have alligator clips.

The thing is I've got only cheap metaloxyde resistor, should this do the job for bias and larmar volume or should I buy carbone stuff?

I'm french, living in Germany, just at the border with Luxembourg where I work. Yes, Andy is quite famous here as you can imagine in such a small country! I hope he will be able to do the TDF, last year was a pretty sad story... I get the pictures right now! Yes the bias is what you think I'm sure. ...

Hi Martin, Here we go! I simplified the power entry: I removed the ground switch and its capacitor, removed the plug as it is wired to a transformateur 110->220, and installed a plate for the future master volume. You can see the Piher I bought, 5K. Now, I'm not 100% sure how should I connect the Pi...