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 NEW  Matt presents bias and operation data for the 6V6 tube in SE operation - 6V6 Single-Ended (SE) Ultra Linear (UL) Bias Optimization.

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PostPosted: 12 Jan 2020, 22:18 
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Joined: 03 Jan 2017, 20:59
Posts: 41
lowhifi wrote:
We are Devo.

I remplace the 33uf capacitor before the choke for a 45uf and add the DC heater supply with a .1uf cap and now the preamp is very silent. The resistors where already installed at the end of the tube supply. An other successful build. Regards.

It's recommended to put a fuse when using a diode bridge to not fry the transformer if a diode is shorted.


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PostPosted: 22 Feb 2020, 22:00 
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Joined: 10 Jul 2015, 06:44
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Location: Melbourne Oz
Just a NOOB question, since the output signal is 180 degree out of phase, do I need to flip the speaker cable?

TIA


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PostPosted: 24 Feb 2020, 16:12 
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Joined: 06 Jun 2008, 18:23
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Location: Australia
If your power amp preserves absolute phase you may want to. One reviewer in Stereophile suggest see which way sounds best.

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Projects:"Illusion" - 6SN7 SRPP preamp in a plastic jiffy box | “Salt Cellar” - Mono 807 triode integrated amp |
"Rosso" - E88CC SRPP preamp | ”Salt Cellar II” - 6EM7 mono wine box triode amp |


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PostPosted: 24 Feb 2020, 16:24 
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Location: Melbourne Oz
I see, thank you Mark.


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PostPosted: 16 Apr 2020, 10:24 
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Joined: 05 Apr 2020, 10:39
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Location: Tuscany, Italy
Hi it's my first massage on this forum so greetings to all!
It's also my first attempt in tube DIY and i have a question: is it possible to use 12at7 tubes for both pre and buffer? I'm aware that it's not optimal but right now here in Italy i have problems to get 12au7 because of lock-down and since i have 2 12at7 tubes and A LOT OF TIME i would like to try... Can somebody tell me if some modifications must be done to the original design? Preamp will drive an T-Amp based on TA2024 chip, input impedance is about 20k. Thank you for any help and compliments for very interesting forum.


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PostPosted: 16 Apr 2020, 23:00 
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Location: Australia
Witek wrote:
Hi it's my first massage on this forum so greetings to all!
It's also my first attempt in tube DIY and i have a question: is it possible to use 12at7 tubes for both pre and buffer? I'm aware that it's not optimal but right now here in Italy i have problems to get 12au7 because of lock-down and since i have 2 12at7 tubes and A LOT OF TIME i would like to try... Can somebody tell me if some modifications must be done to the original design? Preamp will drive an T-Amp based on TA2024 chip, input impedance is about 20k. Thank you for any help and compliments for very interesting forum.

Should work OK.

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Projects:"Illusion" - 6SN7 SRPP preamp in a plastic jiffy box | “Salt Cellar” - Mono 807 triode integrated amp |
"Rosso" - E88CC SRPP preamp | ”Salt Cellar II” - 6EM7 mono wine box triode amp |


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PostPosted: 17 Apr 2020, 08:50 
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Location: Arizona, USA
Hi, Yes it ought to work, the gain will be more though. In the world of tubes you can often swap the 12AU7s with 12AT7s and the reverse. Not so much that they are alike, but frequently the settings work out the same. My phono preamp uses some in the cathode follower output stage and either type will do fine there. On the other hand, 12AX7 tubes will fit in the same sockets with the same pin connections but the settings are way different. It is true they do work, just way far from optiminal.

Good listening
Bruce

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PostPosted: 17 Apr 2020, 18:58 
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Location: Australia
In my 6L6 SE UL power amp, “Silver Supreme” , I use a 12AT7 Psvane as the driver tube. Tried other including my fav. U7 but always came back to the T7. The amp driver design was based around the 4ST and electrically it should work but it did more than that with the T7.

https://retro-thermionic.blogspot.com/2 ... ooden.html

P.S. Bruce I sent you a PM.

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Projects:"Illusion" - 6SN7 SRPP preamp in a plastic jiffy box | “Salt Cellar” - Mono 807 triode integrated amp |
"Rosso" - E88CC SRPP preamp | ”Salt Cellar II” - 6EM7 mono wine box triode amp |


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PostPosted: 17 Apr 2020, 21:52 
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Location: Arizona, USA
Hi Mark, No PM?

Good listening
Bruce

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PostPosted: 17 Apr 2020, 22:06 
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gofar99 wrote:
Hi Mark, No PM?

Good listening
Bruce

Oops, email.

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Projects:"Illusion" - 6SN7 SRPP preamp in a plastic jiffy box | “Salt Cellar” - Mono 807 triode integrated amp |
"Rosso" - E88CC SRPP preamp | ”Salt Cellar II” - 6EM7 mono wine box triode amp |


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