4P1L push pull amp with Lundahl zero global feedback

[Abszero]

Hi all,
I am happy to present my latest incarnation of a push-pull amplifier with the amazingly linear Russian pentode 4P1L. It uses Rod Coleman's regulators for the filaments of 4P1L. The final stage is pushpull parallel 4P1L driven through a LL1660/10mA Alt"V" by the 6H30P-EB. The amplifier measures a THD of 0.2% at 6.7W. Total gain is 17dB (X7.3). The sound is amazing, somewhere between SE and PP.
Best,
Radu

 

[Pano]

Um.... I don't think it's just the sound that is amazing. That's a very pretty build! Congrats. Will you be sharing the schematic?

 

[Abszero]

HI Pano,
Here are the schematics. Nothing unusual. Also, top plate is anodized aluminum 3mm gold CNCed by ProtoPanel.com. Cabinet is mahogany all sides and birch ply 1/2" bottom with more than 300 holes for heat management. More info at simplepleasuretubeamp.com. Thank you for your words of appreciation.

 

[Wavebourn]

Nice build. You could get about 40W / channel from this tubes, though.

 

[Abszero]

I guess I could if you imply using them in UL connection class AB. Actualy when I bought the OTs I was thinking of building a classic pushpull with 6P3s and I tried it but in the end I liked better the sound of triode strapped 4P1L. I guess it is just a matter of taste. I know that there is a lot of power wasted this way, but I couldnt help it. This is my first amp, and I aimed for simple, 2 stages, transparent sound.

 

[tim614]

SWEET!!!

 

[Wavebourn]

Congratulations! No doubt it sounds extremely nice.

 

[merlin el mago]

Congrats Radu looks really nice.

 

[Abszero]

Thank you everybody for the nice words. 🙂