This is the video related to the amp , on youtube My new Circlotron OTL power AMP. ( Part one ) - YouTube . The camera fail to reproduce the bass of the amp well .
Hi Dimitris,
as for PCL82 vs. PCL200: Having a glance at the output curves of the triode sections of these tubes we see that the PCL82's triode is very similar to one half of a 6SN7, and for this I agree with you that it isn't useless at all! The PCL200's triode roughly corresponds to one half of a 12AT7 or the EC92/6AB4 and also can be very useful. Finally it is combined with a small power video output pentode having a large gm, thus making it a very good cathode follower. So one can easily decide which tube to choose.
If you are still looking for the PCL 200, you can buy it for € 2.50 in Germany. Is that too much?
Best regards!
Hi Kay , the triode section of the PCL82 have amplification factor of 70 and anode dissipation about 1W , and the 6SN7 have amplification factor of 20 and plate dissipation 3.5 W each triode so they are different tubes , and yes the triode section of the PCL82 isn't useless at all in this we agreed , the pentode section of the PCL200 have much larger gm than the pentode of the PCL82 and of course is better as cathode follower in this we agreed too , and its cheap as you say . Thanks for your comments .
Very well,-- Increased rails to 195V sounds great as usual, but I await some 30V zener-diodes at the moment to set up the cathode-mosfets, to try in place of resistors...
Thats good news . By increasing the voltage rails so you have to lower the bias of the output tubes of course , how much current now for them ?
Thank you Kevin , as for the schematic maby some day I will post it , but not now , all the project is at experimental phase now .
Taki se evxaristo , thank you , of course I will call you to hear it , thanks .
Last Sunday I make some improvements in the amp . I lower the value of the cathode resistors in the triode sections of the two PCL82 Rk1 &, Rk2 ( which is second diff. gain stage and drivers - cathode followers ) in other words I bias those triodes harder and the gain is increased a little bit , after that I increase the supply voltage from 310V to 322 V . I add one more capacitor 470μF/ 400 V in the power supply . The amp now sounded with more powerful bass , and all the other good things that it have before the improvement . Now it delivers 24 W into 8ohm load ( I have an increasement of 4 W ) after this modification . I measure the output impedance again with 1Khz sinewave at 20 Vp-p into 8 ohm load and its 1.2 ohm ( 23 Vp-p with no load ) which is pretty good .
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Yeah right. If you wanted to be open about it you would have been. What you do is just tease people. At least be honest about it.
Why you are angry like that ?, take it easy , I am not trying to tease anyone , this is only your feelings and you better keep it for yourself .