Hi,
I am finished my new prototype amp with GU-15 tube. GU-15 is medium power (19W) DHT pentode. More information and some data: http://www.diyaudio.com/forums/tubes-valves/47108-magic-gu15.html.
I am finished my new prototype amp with GU-15 tube. GU-15 is medium power (19W) DHT pentode. More information and some data: http://www.diyaudio.com/forums/tubes-valves/47108-magic-gu15.html.
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Hello, Happy New Tear to all colleagues!
Can you please let me know some more details about the sound? Does it sound like a DH tube (airy and effortlessly)? Did you think about a comparison with 4P1L and/or 6P21S, or maybe even with #45 or 2A3?
From the circuit, I understand Ua is 435 Vdc while the drawn current is only 35mA. Why did you chose this OP?
I saw the docs which were published by Charm from Russian Federation. Do you think getting the tube closer to 19W Pdamax would not be safe?
Thank you very much!
Can you please let me know some more details about the sound? Does it sound like a DH tube (airy and effortlessly)? Did you think about a comparison with 4P1L and/or 6P21S, or maybe even with #45 or 2A3?
From the circuit, I understand Ua is 435 Vdc while the drawn current is only 35mA. Why did you chose this OP?
I saw the docs which were published by Charm from Russian Federation. Do you think getting the tube closer to 19W Pdamax would not be safe?
Thank you very much!
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Hi,
yes it sound like a DH tube -airy and effortlessly. Not so sweet as 4P1L, but with more body. I like this sound.
OP is around 290V/57mA - 16,5W. Where did you get 35mA?
yes it sound like a DH tube -airy and effortlessly. Not so sweet as 4P1L, but with more body. I like this sound.
OP is around 290V/57mA - 16,5W. Where did you get 35mA?
Thank you! I saw written 35 near the OPT primary, but now I think it’s the impedance (3K5).
Anyway, I’ll check the impedance on the diagrams already provided by our colleague
Anyway, I’ll check the impedance on the diagrams already provided by our colleague
35 is the inductance in Henry for the primary of the output transformer.
I simulated the schematic in LTSpice... I kinda still don't understand why it works 😛
I simulated the schematic in LTSpice... I kinda still don't understand why it works 😛
I am not decided to use this tube, I was only trying to find some more interesting DH tubes which may work in audio. To be sincere, I listened to a 6P21S SE, amplifier, to a 4P1L SE and to my 2A3/#45 amplifier. 6P21S, clearly sounds better than a usual indirectly heated penthode or tetrode, but not that refined as #45 does. 4P1L is much closer to the triode DH tubes.
Anyway, if I will find them for a reasonable price, I will take the chance to experiment
Anyway, if I will find them for a reasonable price, I will take the chance to experiment
Kinda off topic:
Saptemari... from your experience are DH tubes good for balanced circuits or just SE? I know that back in the day, because they did not have the concept of global feedback, only open loop, tubes were made with tighter tolerances then now.
I plan to design and build a balanced DHT preamp/line stage for my OTL monoblocks and I intend to use #26 triodes or 4P1L triode strapped.
Sanatate
Saptemari... from your experience are DH tubes good for balanced circuits or just SE? I know that back in the day, because they did not have the concept of global feedback, only open loop, tubes were made with tighter tolerances then now.
I plan to design and build a balanced DHT preamp/line stage for my OTL monoblocks and I intend to use #26 triodes or 4P1L triode strapped.
Sanatate
@Savu, I am not sure about how tight was the tolerance when talking about soviet tubes. For instance, 6C33C was used in MIG”s and their characteristics are very dispersed.
Anyway, I am quite sure your idea is good. I too want to build a push-pull amp using DH tubes. I only built SE amps until a month ago when I finished a PP amp with the classic EL84. It is sounding nice and the extra power made me think about a DHT PP.
I would suggest using a LM317 as a CCS for the cathodes (if using semiconductors is acceptable to you), like Mr. Heran did here: http://diyaudioprojects.com/Tubes/EL84-Push-Pull/ECC802S-SRPP-EL84-Push-Pull-Tube-Amp-CCS.png
You’ll be able to perfectly balance the current between the two tubes.
Sanatate!
Anyway, I am quite sure your idea is good. I too want to build a push-pull amp using DH tubes. I only built SE amps until a month ago when I finished a PP amp with the classic EL84. It is sounding nice and the extra power made me think about a DHT PP.
I would suggest using a LM317 as a CCS for the cathodes (if using semiconductors is acceptable to you), like Mr. Heran did here: http://diyaudioprojects.com/Tubes/EL84-Push-Pull/ECC802S-SRPP-EL84-Push-Pull-Tube-Amp-CCS.png
You’ll be able to perfectly balance the current between the two tubes.
Sanatate!
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