My DIY 2A3 amplifier

[bigbulb]

Hi all,

Here's my DIY 2A3 with plate choke loaded 6E6P driver.
I tweak a lot and finalised it recently and put to test. Plate choke loaded driver stage did give better dynamic and also huge soundstage.

http://audiophilediyer.com/2a3-se-amplifier/


Bigbulb

 

[Folsom]

Looks nice so long as you have banana plug speaker cables.

 

[bazelio]

Nice! Winding your own trafos!! Big props there.

Any hum as a result of using AC heating? Did you consider interstage trafos instead of coupling caps?

 

[bigbulb]

Hi all,
Thanks! I have no hum problem because I'm using DC filaments. I tried AC and need a multi-turn balance pot to null out hum .
Yes, I love interstage transformer. I'm winding my own interstage transformer now, prepare to build another 4P1L single ended.

 

[bazelio]

Ok, I wasn't sure from the schematic, but I guess that F1 box is a rectifer. Have you tried a filament regulator?

 

[bigbulb]

Ok, I wasn't sure from the schematic, but I guess that F1 box is a rectifer. Have you tried a filament regulator?

Hi. Sorry , I should mention thats a rectifier. will edit it now. thanks for pointed out my mistake! I have filament biased board I built my own. It was in my other 2A3 , In fact, I built 6SN7-2A3, 717A-2A3, and 6C45-2A3 , and now 6E6P-2A3. filament bias board ( filament constant current + capacitor multiplier , just like Rod Coleman DHT filament regulator )
The filament regulator did provide good dynamic, and this amplifier is just to try out plate choke loaded driver stage.

 

[bigbulb]

Looks nice so long as you have banana plug speaker cables.

Thanks. yes, I use banana jack to switch to others speakers quickly.

 

[bazelio]

Great!! It's a lot of fun to tinker with this stuff. I wish I had time for it. Speaking of Rod Coleman, have you seen his shunt cascode design? I'd love to hear an amp based on that very interesting topology. He found a Russian 6E5P DHT (I think) makes a great driver for 2A3 or 300b - very high gain and linear. Maybe I should commission a build from you! ;-)

 

[bazelio]

PS let us know when your good mic is working and you record this amp in action!

 

[bigbulb]

I have bunch of 6E5P as well, its nearly the same as 6E6P, both are very linear. 6E5Ps RP are slightly lower than 6E6P but I choose 6E6P because it last longer than 6E5P , This amp will ship to new owner one day, ( have to go, to fund my others project ) thats why I hope it can last longer. Thanks for the info about the shunt cascode design. I haven't try yet, but I did built something like constant current load for vacuum tube, a lot of fun to play with it.
Too many projects, too little time.
The new external microphone still on its way , I bought from Ebay, takes a long while to cross the pond. Hopefully it can provide me with better recording. Sure I will post an update here, thanks !