The Amp Garage

The SSS bipolar driver supply board in the first post has been updated again. The bleeder resistor mentioned above has been reduced to 150k so the positive and negative sides of the supply will have balanced current draw, and the voltage on both sides will drain in about a minute after shut-down. Th...

That isn’t going to work because the grid can’t be lifted from a 220k leak to a 2M2 leak resistor no matter what. It has to retain the 220k resistance whether it’s a parallel of the MV control or a fixed resistor. It’s going to pop loudly also because it’s an open circuit while the contact switches...

GAStan wrote: ↑Sat May 25, 2024 2:35 am The bleeder is definitely a good idea. The +170 volt caps were still at 50vdc after sitting overnight before I added it.

Credit Tony D for that idea.

Looks great! Your questions and feedback have led to quite a few updates to the documentation, so there is some great synergy going on here.

Hope that solves it!

The speaker output should be in phase with the PI input.

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.