Working on two new SissySITs , first one is finished, soon to make happy my Webhamster Mikorist (short Miko).
It started not by plan , but by chance ….. several (or even more than several) months ago , I tried to help one of our Greedy Boyz at Diyaudio.com/Pass Labs subforum , to improve things with his Aleph X monoblocks.
Problem was simple but not so simple ……. in first incarnation , amp was sounding divine , but it was unreliable and eventually it gave up in flames ……. or at least with some gray smoke puffing out .
As usually ……. ZM at work :
Few vids from my attending of BAF 2011
Well , here and there these questions are popping on Diyaudio.com – how to check/adjust bias (Iq) ,offset(s) and gain on my X(A)xxx.? PL amplifier; this tutorial will address that.
Take in account that older PL amps are having (small) mosfet based output stage biasing generator , while later ones are having TL431 generator iteration – with some specimens finished without NTC compensation – exactly as amp shown in pictures.
However, I’m sure that you’ll find same logic (shown here) applicable also to earlier models.If not ,and you need some info regarding earlier models, contact me either through blog e-mail thingie , or on diyaudio.com.
Amplifier shown here is X150.5 , late issue (circa 2007 , according to pcb text) , being in possession of DiyA fella known under witty Old’n’Cranky moniker.