OO1 Posted June 20, 2023 Share Posted June 20, 2023 The 6P15P will also bias lower Quote Link to comment Share on other sites More sharing options...
henry4841 Posted June 20, 2023 Author Share Posted June 20, 2023 Not according to Frank's tube specs compared to a JJ EL84. Actually higher, one can run more current through the tube. Personally I am in the camp of Modjeski preferring high voltage and less current on a tube. With a higher voltage you have more voltage to swing the signal in. Running less current also extends the life of the tube. https://frank.pocnet.net/sheets/113/6/6P15P.pdf https://frank.pocnet.net/sheets/163/e/EL84.pdf Quote Link to comment Share on other sites More sharing options...
henry4841 Posted June 24, 2023 Author Share Posted June 24, 2023 On 6/20/2023 at 1:34 PM, tube fanatic said: Keep in mind that the suppressor is only needed for pentode operation to keep the secondary electrons away from the screen. Since the screen is tied to the plate in this amp, I think we are dealing with an academic point (obviously, triodes don’t have a suppressor since one is not needed). So, it can’t hurt to have the mod in place as it will have no effect with the EL84 in the socket. If anyone builds one of these, it would be an easy matter to put a switch across the cap to allow instant comparisons while the music plays when using a tube with the suppressor brought out to the socket. Maynard If I am seeing this correctly as the Zen is sold with the 6P15P-EV with the hazen mod cap on the suppressor grid, if one installs an EL84 tube in place of the 6P15P-EV you will have in effect a pentode amplifier where the suppressor is tied to the cathode, being in the EL84 the suppressor grid is tied internally to the cathode, bypassing the hazen mod cap. I do not see how the cap would have much if any effect if one uses an EL84 but rather turn your SE into pentode operation. Not necessary a bad thing but. Quote Link to comment Share on other sites More sharing options...
82 Cornwalls Posted June 24, 2023 Share Posted June 24, 2023 I think someone is confused. Maybe Maynard can help. It is triode strapped with either tube. Quote Link to comment Share on other sites More sharing options...
henry4841 Posted June 24, 2023 Author Share Posted June 24, 2023 2 hours ago, 82 Cornwalls said: I think someone is confused. Maybe Maynard can help. It is triode strapped with either tube. Just not familiar with a tube amplifier being pentode operated. Maynard, in a private message stated since the screen grid is attached to the plate it will still be as you said, still triode operated. I should have checked a schematic of a pentode amplifier before posting. Clearly shows 13K resistance between the plate and screen and not attached to the screen as in the Zen schematic. The resistance and inductance of the OPT isolates the screen as well. Example below. I can only remember building one pentode amplifier and it was with a Chinese kit I purchased years ago. Thanks for posting my error in thoughts. 1 Quote Link to comment Share on other sites More sharing options...
Flevoman Posted July 5, 2023 Share Posted July 5, 2023 On 6/24/2023 at 9:27 PM, henry4841 said: Just not familiar with a tube amplifier being pentode operated. Maynard, in a private message stated since the screen grid is attached to the plate it will still be as you said, still triode operated. I should have checked a schematic of a pentode amplifier before posting. Clearly shows 13K resistance between the plate and screen and not attached to the screen as in the Zen schematic. The resistance and inductance of the OPT isolates the screen as well. Example below. I can only remember building one pentode amplifier and it was with a Chinese kit I purchased years ago. Thanks for posting my error in thoughts. Please keep us updated with this project Quote Link to comment Share on other sites More sharing options...
henry4841 Posted July 5, 2023 Author Share Posted July 5, 2023 It is here. https://community.klipsch.com/index.php?/topic/217039-new-amp-project/ Quote Link to comment Share on other sites More sharing options...
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