The Amp Garage

Hope that solves it!

Yours will be the first with the new resistors added to the bipolar supply. I’ll be interested to hear how that works in hardware.

I just found a really thorough introduction to Thermal Resistance and Heat Dissipation, and I wish I had found this a few years ago. basics_of_thermal_resistance_and_heat_dissipation_an-e.pdf If the Texas Instruments pdf above was too specific for your tastes, this Rohm Semiconductor lesson covers ...

Completed installation of bipolar power supply. Amp is now working again with better B+ and other voltages. Question: with the decreased voltage the bipolar supply provides V7 does this limit the clean headroom? Volume? Is there a noticeable tonal difference between the original and bipolar supplie...

Kagliostro wrote: ↑Tue May 21, 2024 7:17 pm Something like the dissipation of the single triode within the same envelope of a dual triode tube

ECC82.png

Franco

Yes. The mechanisms of the heat transfer are different, but it’s the same concept.

Once you have an arc occur there may be carbon tracking on the tube sockets which must be completely removed to prevent more arcing. If the socket material has been burned, replacing the socket may be necessary. So what caused the initial arcing? I think it was most likely an oscillation in the powe...

A 1kV 10n cap across the standby might help with the pop and increase the life of the switch contacts.

The better way to shut down is to turn the AC off first. That way the power supply caps will drain through the still hot tubes.

102 amp is still on, Operate, idle-no input. Transformer is very warm, I can only keep my fingers on it for 2-3 seconds. Similar in temperature to SSS transformer. This is after nearly 4 hours operation. Would your SSS run 4h and be at a similar temperature? It has four more preamp tubes, so 1.2A m...

IMO it would be better if you could get it to cross zero.

- The PAB isn’t quite as pronounced as my 102. Is this a function of the lift pot adjustment? Indeed. - I have the FET biased at a little over V1/Vdd=2 because of what I have on hand. If everything sounds good and there’s no noticeable voltage problems, how concerned should I be about finding the e...

You could do a shorted turns test on the one you have. See https://ampgarage.com/forum/viewtopic.p ... 11#p445611
Or if you have a power meter you could try energizing the primary with everything disconnected.

GAStan wrote: ↑Mon May 20, 2024 2:39 pm Does anyone know if Heyboer will rewind one of their transformers for a fee?

I’m thinking it would probably be cheaper to buy a new one. Interested to know if you find out.

That lead me to recall some prior discussions here that you are not really balancing the PI as much as the whole power amp. Is that a fair statement or am I misunderstanding? You are correct. The best approach is to arrange the power tubes to get the best DC balance, and then use the PI trimmer to ...

I think with 51k/47k plate loads and 22k tail as shown in the 2nd Gen layout, a perfectly matched 12AT7 would have very nearly balanced outputs. Any particular tube might be off in either direction, so keeping the original offset in place with a +/- capability via the trimmer would be the way to go.

Frankly, I'm sick of this. If you don't believe it or refuse to try it, good for you, whatever... Marc clearly heard a difference, as have numerous other folks, I applaud him for trying it for himself and making up his own mind. I have never said that I don't believe it makes any difference (and I ...

While waiting on some parts to arrive I "balanced" the PI. Scare quotes because with the 5K trimmer I installed and the tubes in the amp, I could get close using the ampeg method but not all the way to a 0v offset. It settled around 1.7. I do have another 12AT7 and may try that to see if it gets me...