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Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum |
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#4171 |
Account disabled at member's request
Join Date: Sep 2004
Location: Madrid
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Same color combo than one of the amps above - still doesn't look right to me for some obscure reason. Maybe because of the wedding colors.... the beige, the red. Hmmm. Kinda makes me feel uncomfortable.
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#4172 | |
diyAudio Member
Join Date: Jun 2006
Location: Werr,i,bee,Australia
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Quote:
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#4173 | |
diyAudio Member
Join Date: Jun 2010
Location: East Coast, USA
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Beautiful amplifier Charlie! What a great wedding gift!
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My DIY Electronics Blog: DIYAudioBlog.com |
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#4174 |
diyAudio Member
Join Date: Feb 2010
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I built a prototype with a pair of QQE03/12 double tetrodes and pair of soviet 6F12P triode-pentode (which is a phenomenal tube).
Voltage amplifying stage is a CCS loaded triode and phase splitter is done with pentode section of 6F12P. Output stage has fixed bias and 10k to 8 ohms Indel output transformer. Anode voltage is 300 V and screen voltage 220 V. Both bias and screen supply are stabilized. Output power is 10 W with 1 % THD. With one watt THD is some 0.1...0.2 % with 10 dB GNFB. Input sensitivity is 600 mV. Hum level at the output is some 80 dB below max. Po. All heaters are done with AC. ![]() ![]() ![]() |
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#4175 |
diyAudio Member
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Esteban Bikić |
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#4176 |
diyAudio Member
Join Date: Feb 2010
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#4177 |
diyAudio Member
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Dear Artosalo, thankyou very much for the circuit. A couple of more questions. Does the +vcc at V3 plates 300V?
The tranies are from witch trade name? Best and thanks again.
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Esteban Bikić |
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#4178 |
diyAudio Member
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Did you try to direct coupled between the 6F12 triode and pentode?
Did you try to use the pentode like amp and the triode like a phase splitter?
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Esteban Bikić |
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#4179 |
diyAudio Member
Join Date: Feb 2010
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Supply voltage at the anodes of QQE02/12 is some 300...310 V. Optimum screen supply is about 220 V and quiescent anode current 30...32 mA.
CCS transistors are BF472 (PNP) and the NFET at power supply is IRF820. Direct coupling of the voltage amplifying stage and phase splitter requires that the anode voltage of 1st stage should be some 80 V. The circuit I used give lower distortion. I did not try to use pentode as 1st stage since the gain of triode section (mu = 100 ) was just what I needed. But ofcourse the pentode would work fine as an amplifier. |
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#4180 |
diyAudio Member
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Wonderfully cover, you are there, knowing your material your valves.
The 6f12 pentode like triode is so similar to the triode alone. They have both same transconductance and µ. Wavebourn likes this valve. Best Regards and thanks for your fast reply
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Esteban Bikić |
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