L'Amp: A simple SIT Amp

[juanitox]

Eventually, you'll want to get your voltage references working. These really shine with no degeneration, and I think you'd do well to focus your effort there. I have, after all, posted a working schematic which you can easily build on perfoboard.

michael , i came back with this but i want to be sure there is no misunderstanding , fig 11 without bypass cap on source res sounds very bad i agree but with a 47000uf and 22ufMKP on it , it's sounds as good if not better than my first version with negative bias..

anyway i will retry fixed bias cause i had not the CLC power supply that i have now

[Zen Mod]

@MR

I'm lazy ....... maybe because I have some nice xplanation handy ;

will post a link as soon I upload pdf to ftp

[Zen Mod]

in fact - I found it on line , with JR's blessings :

http://mmiworks.net/sprc/SP10-MaJeChi.pdf

tnx to wakoo bloger - (new adventures in) ultra‑fi: sound practices reading club /22

edit :

hey - I'm sorta Happy Camper ZM - term "signal energy preservation" I coined by my self , without any help .....

[Michael Rothacher]

Originally Posted by juanitox

michael , i came back with this but i want to be sure there is no misunderstanding , fig 11 without bypass cap on source res sounds very bad i agree but with a 47000uf and 22ufMKP on it , it's sounds as good if not better than my first version with negative bias..

anyway i will retry fixed bias cause i had not the CLC power supply that i have now

I understand. Have you considered the possibility that the difference might be attributable to a problem with your original voltage reference setup?

[juanitox]

sure it was because now even if the R-core still make a little mechanical noise there is nothing out with the head inside the 102db horn .. so perhaps it was the lm337 bias module which had ground loop with my ancient power suplly.

also when i turn on the new PS with this module they explose immediatly perhaps because it makes a short circuit somewhere , i'm lost...

as for the fixed bias VS auto-bias i'm used to that with SET tube amp , and i don't know why as in theory fixed bias is better in practice you get a more 'tubey" sound with bypass resistor on cathode..

[ra7]

Mike, I love your simple CCS solution.

Q. What controls the amount of current through the CCS? Is it the bias voltage on the SIT or the Vgs of the IXTH? Or both?

[Michael Rothacher]

@ZM Thanks much, ZM. I'm going to read over that tonight.

BTW, I love the term.

"Signal Energy Preservation" Copyright 2012, Zen Mod All Rights Reserved.

[Zen Mod]

naah ....... make that Copyleft ( as for few other terms/names I made during the years )



edit : signal energy preservation is , I think , main reason why Metaldasnke luves his Biiig Donut amps , same as Drek preamp

[Zen Mod]

Originally Posted by ra7

Mike, I love your simple CCS solution.

Q. What controls the amount of current through the CCS? Is it the bias voltage on the SIT or the Vgs of the IXTH? Or both?

CCS is self biased

it's depletion mode mosfet - biased via Vgs - voltage across source resistor

[nicoch58]

juanitox @ lundhal have nice filament choke....
catode bias drop the B+ on the catode resistor on transient a sort of limiter/compressor...fix don't have the big bad caps plus without the limiter can fly better...
not too expert but probably the tube sound are the elko on catode at last on my driver stage the silmic do this vs PP or oscon