Thanks, good to know you enjoyed your design, at least for my observations the tubes only needed some 2 - 4 minutes to behave good, baking tubes can be a good alternative, I have seen lots of pictures of 6p1p´s with some thin blue beams of light, also mine do so, maybe thay are contaminated with oxigen or a kind of gas, but they seem to do well.
Also they are very good once they are warmed up, almost rock-stable.
I have been doing some experiments with topologies, with concertina, and grounded-grid push pull both do behave good, and at least no visible oscilations.
Also they are very good once they are warmed up, almost rock-stable.
I have been doing some experiments with topologies, with concertina, and grounded-grid push pull both do behave good, and at least no visible oscilations.
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The concertina phase splitter is a pentode. The resistances in the cathode lead (24K + 1K) and the anode lead (24K) are almost equal, but the screengrid current only flows through the cathode lead and, if I'm not mistaken, fluctuates with signal. How does this phase splitter give balanced signals? Maybe it's explained in the article but I can't read Polish.
The grid resistors of the power tubes are 1M. The datasheet for the 6P1P states 500K as the maximum value for the grid resistor.
I think it's better to start a new thread about this design so to prevent further thread jacking.
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@TheGimp, thanks much!
I did not mean to cause any special effort on your part. What you said confirmed expectations - “sounds about like 6BQ5 with a bit less power”. I have a bunch of nice Svetlana 6P1P-ev tubes and would like to build something with them, but I was surprised by the relative scarcity of published schematics for this tube in PP (on english-based websites), so your Sven will be my starting point.
I did not mean to cause any special effort on your part. What you said confirmed expectations - “sounds about like 6BQ5 with a bit less power”. I have a bunch of nice Svetlana 6P1P-ev tubes and would like to build something with them, but I was surprised by the relative scarcity of published schematics for this tube in PP (on english-based websites), so your Sven will be my starting point.
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Francois G,
No problem. I will still try to get the amp back to look at if I can.
I have pushed a pair to 15W in a guitar amp, so the 8W I got out of the PP amp was running them conservatively. I think 12W would not be pushing them badly (maybe 300 to 325 Vak vs the 250 I ran them at). I am running Svetlana 6P1P-EV tubes. I had several go Blue Flash on me with cathode stripping. I ended up baking the rest before using them. I think there is reference to that in this thread. If not I will try to look up what I did. I believe it was about 175C for a couple of hours. After baking them, I didn't see any more Blue Flash events.
No problem. I will still try to get the amp back to look at if I can.
I have pushed a pair to 15W in a guitar amp, so the 8W I got out of the PP amp was running them conservatively. I think 12W would not be pushing them badly (maybe 300 to 325 Vak vs the 250 I ran them at). I am running Svetlana 6P1P-EV tubes. I had several go Blue Flash on me with cathode stripping. I ended up baking the rest before using them. I think there is reference to that in this thread. If not I will try to look up what I did. I believe it was about 175C for a couple of hours. After baking them, I didn't see any more Blue Flash events.
Thanks! Also good to know you had success against “Blue Flash” after baking them. I assume that reactivates the getter to re-evacuate them. If you can track down your notes on it please let us know, it would be good to know what temperature and duration was your bake. Else I will search for it on diyAdio; I know I have seen it before.
Regarding “pushing the 6P1P-ev tubes”, diyA member kodabmx got “almost 20W out of a pair in tetrode at 340V B+, 56ma bias.” That’s around 17.5 watts dissipation. Yikes! See post #25 here:
https://www.diyaudio.com/community/...6p1p-4pp-amplifier.317395/page-2#post-5311684
Regarding “pushing the 6P1P-ev tubes”, diyA member kodabmx got “almost 20W out of a pair in tetrode at 340V B+, 56ma bias.” That’s around 17.5 watts dissipation. Yikes! See post #25 here:
https://www.diyaudio.com/community/...6p1p-4pp-amplifier.317395/page-2#post-5311684
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