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6n6p for tremolo
6n6p for tremolo
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Old 8th February 2020, 09:04 PM   #1
alex0terry is offline alex0terry
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Default 6n6p for tremolo

Hey guys!
I have a couple of 6n2p (Russian 12ax7?) and I wanted to add a bias shifting tremolo to a mic preamp based on two 6au6 pentodes that I built out of an old Akai tape recorder.
Im a bit frustrated after hours of messing around with it.. Just cant get that tube to oscillate
I tried different feedback caps and resistors for the RC stages, and also experimented with the cathode cap and resistor values and still nothing..
I have 320V for a B+.

Would appreciate any help to get that LFO up and running

Last edited by alex0terry; 8th February 2020 at 11:04 PM.
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Old 8th February 2020, 09:27 PM   #2
stenak is offline stenak  Norway
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The Russian 6N2P is the 12ax7 with 6,3v heaters?
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Old 8th February 2020, 09:33 PM   #3
alex0terry is offline alex0terry
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Exactly. Different wiring was applied in order to lit it up
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Old 8th February 2020, 10:49 PM   #4
PRR is offline PRR  United States
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> I tried different feedback caps and resistors

Did you try "plagiarizing" (research) the many-many-many 12AX7 tremolo oscillators in guitar amplifiers?
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Old 8th February 2020, 10:52 PM   #5
kodabmx is offline kodabmx  Canada
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6n6p for tremolo
6N6P is not anything close to a 12AX7. Stenak called it, the 6N2P is the 9AJ version of a 12AX7.

6N6P is close to an ECC99 though.
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Old 8th February 2020, 11:04 PM   #6
alex0terry is offline alex0terry
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Oh sorry I just saw now that I wrote 6 instead of 6N2P,
What I have is the 6N2P (sorry for the mistake)
Anyway.. I replaced the resistor and capacitor on the cathode with a LED, and it blinks real fast (thats a progress I guess) and I read a small voltage movement on the anode ( varies from 220-240v). strange, right?
Not sure what to do with the other half of the triode..
Any input would be appreciated !
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Old 8th February 2020, 11:11 PM   #7
kodabmx is offline kodabmx  Canada
Spreading triode love.
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6n6p for tremolo
I would suggest finding a circuit that uses the 12AX7 and basing it off of that. 6AU6 is a pentode after all... Much higher gain etc.
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Old 8th February 2020, 11:59 PM   #8
AllenB is offline AllenB  Australia
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6n6p for tremolo
Thread moved to Instruments and Amps
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Old 9th February 2020, 05:16 PM   #9
alex0terry is offline alex0terry
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So it seems I get an oscillation now, Just wondering how and where to inject it in the 6au6 preamp. Any advice on that?
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Old 13th February 2020, 08:24 PM   #10
Gnobuddy is offline Gnobuddy  Canada
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Quote:
Originally Posted by alex0terry View Post
...how and where to inject it...
"Bias wiggle tremolo" circuits that I've seen inject the tremolo signal into the (pentode) control grid.

Wiggling the screen grid voltage should also work on paper, but this is a less sensitive electrode, and will need more volts of "wiggle" to do anything.


-Gnobuddy
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