I recently mentioned the history of this amp in another thread.
Built entirely (including PT, starter and OPT) by a guy from my area (career soldier) who has now decided to retire from the world.
This amp partially burned 3 years ago, the power transformer having decided to transform into an independent heating system, it tried to get calories from anything that was flammable next to it (including the table on which it rested).
I requested information by email several times from this person to rebuild the amp in good conditions but have not had a response since he left the world.
I come here to ask for information about the schematic, to know if it is stable and/or if there are improvements/modifications to be made.
It was one of my favorite amps, I only found it a little short in the bass (for my taste, I never measured it)
Out of respect for this person, I have erased his name from the schematic, some French people will recognize his work, I do not want any controversy (there has been some in the past on his PP 845), please do not do it again.
I haven't bought a power transformer yet, I left this amp in quarantine in an isolated place in the house because it smells really bad.
It's a long-term project, but it's a start.
Before the incident
I have another amp made by him (copy of a pair of Leak TL25+ in a common chassis and common power supply) which has been performing well for years.
Built entirely (including PT, starter and OPT) by a guy from my area (career soldier) who has now decided to retire from the world.
This amp partially burned 3 years ago, the power transformer having decided to transform into an independent heating system, it tried to get calories from anything that was flammable next to it (including the table on which it rested).
I requested information by email several times from this person to rebuild the amp in good conditions but have not had a response since he left the world.
I come here to ask for information about the schematic, to know if it is stable and/or if there are improvements/modifications to be made.
It was one of my favorite amps, I only found it a little short in the bass (for my taste, I never measured it)
Out of respect for this person, I have erased his name from the schematic, some French people will recognize his work, I do not want any controversy (there has been some in the past on his PP 845), please do not do it again.
I haven't bought a power transformer yet, I left this amp in quarantine in an isolated place in the house because it smells really bad.
It's a long-term project, but it's a start.
Before the incident
I have another amp made by him (copy of a pair of Leak TL25+ in a common chassis and common power supply) which has been performing well for years.
The large transformer has a large field, also weight ..and... price. 700 milliampere is too much for 360 volts.
I think the OPTs are ok, but not yet measured, the 2e22, 6SL7 and 6SN7 are intact, everything near the PT is burned including the starter.
I'm going to take photos today.
That's one of the reasons why I want to bring it back to life, it was certainly a little short in the bass, but super clear and so open in the medium and treble.
I have never checked the actual values in the real amp, this will be the opportunity to do so.
I should be ashamed but I had never paid attention to the power indicated on the schematic but it is indeed very high compared to the output stage and the tubes used.
This amp was created and built by a person who created and built many (even if this one is unique), I never had the idea of doubting his skills, however I know that he had tendency to overuse components.
the thing that always intrigued me was that the amp had been on for barely 30 minutes and probably did not exceed 2W when it burned, I was busy on another amp that was giving me a hard time and a moment when I regained contact with reality I realized that the sound was less loud and that's when I saw the cloud above me then the smell.
It took half a day to cool down.
I'm impressed with your calmness and the fact that you are taking a video while the thing is burning. Kudos! I would probably be cr4pp1ng myself 🙂
Here is a simulation. I found a 2E22 model in the Spice Model thread, I have no idea how good is. Then I changed the voltage dropping resistors, to get the right DC values and take into account that two channels are being powered. I could not make the simulation stable with the 1K nFB resistor, best I could do was 2.7K. Transformer model used is 1650N (4.3K, close enough).
16W before clipping, a bit low for such output tubes. But, as usual, this is just a simulation.
16W before clipping, a bit low for such output tubes. But, as usual, this is just a simulation.
So, I took it out of its quarantine to take photos and it's not that bad.
Yes, it's heated well but it's quite local, the choke isn't even browned.
Yes, it's heated well but it's quite local, the choke isn't even browned.
My pleasure. In fairness, the amp has the same topology as mine, it was a bit of copy and paste 👍It's really very kind of you to have taken the time to enter the diagram into a simulation, I'm really very touched. 🙂