Archive for Nelson Pass related

Pass Labs X150.5 , checking/adjusting offsets ,Iq and gain

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.

X150.5 front

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Treshold Treasure …… while Papa was there : FET 9

 

Download files :

FET9 Service Manual

FET9e Gain Adjustment

FET9e Load Adjustment

FET9 Operating Manual

Treshold Treasure …… while Papa was there : 4000 (400a)

Papaface

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Treshold Treasure …… while Papa was there : 800A

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Treshold Treasure …… while Papa was there : 400A

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