New build of P-P PCL86 Amp

[tubemax]

Hello everybody!

This is my first post, I wish to show my latest build of very fine sounding PCL86 PP amp which is fully based on Dissident amp ( Yvesm ) & Gingertubes ( Giant Killer ) designs but with some changes on biasing of output tubes ( I used LM317 as CCS instead of resistors per channel ), power supply ( 2 x toroid 12V power transformers with secondaries connected together ) and fitting a complete pre-amp stage with RIAA from Audio Innovations 300 series amp.

My goal was to build practical, compact en cheap integrated amp. Total cost is about 200,-Euro in parts with Toroid power transformers, Hammond 125D output, Philips NOS PCL86 & new JJ ECC83S.

What can I say - very musical & sweet sounding amp with great stereo and pin-point presentation. I used pentode mode connection mostly because of Hammond 125D limitations - btw. considering how small it is - it sound really good, except for very limited low-end.

Regards,
Max

[Matt.B.H.]

Nice looking build

Got any photos of the innards?

Cheers Matt.

[aardvarkash10]

niiiiiice! Schematic?

[mastodon]

Looks nice, well done! What are the measurements on the frequency response? That always worries me a bit with the Hammond 125's, especially since you remark that the low end is limited. I'm kind of curious as to how this actually works out in a practical implementation using this kind of power tube.

I find that when using power trannies for OPT's (yes, it's filthy, but it's an option...), the low end tends to be quite well-represented, extending to about 40Hz in a 6AQ5 PP triode-connected amp I use daily. However, above 10kHz, performance tends to degrade quite badly. How do the Hammonds perform in your amp for high frequencies?

[tubemax]

Hello,

Thanks for kind words, to be more specific I used cheapest Hammond PP-output transformers model-125D for output duty and two standard toroid power transformers 220V/12V 200 WATT connected with secondaries together to form one high voltage ( about 230VAC ) transformer. It works very well with about 285 Volts on anodes of output tubes.
Only Hammond 125D are not really made for hi-fi use, there is not much power in the low-end, but mid & highs are excellent!
I based amp on proven design from DIY audio members ( look for Giant Killer or Dissident ECL86 amp ) and is probably best pentode sound I ever heard.
I used first two drawings to combine one that works for me and from third I picked LM317 CCS biasing...
At the moment I can't measure linearity of output transformers... I have no means to do so...

Max