diyAudio

diyAudio (https://www.diyaudio.com/forums/index.php)
-   Pass Labs (https://www.diyaudio.com/forums/pass-labs/)
-   -   The BA-3 as preamp build guide (https://www.diyaudio.com/forums/pass-labs/258022-ba-3-preamp-build-guide.html)

Zen Mod 27th July 2014 08:25 PM

"across" , pretty important part of the puzzle

delecoy 27th July 2014 08:29 PM

Now have both channels at 55ma across R10...still no offset across R12. The circuit is not responding to P2 at all.

Zen Mod 27th July 2014 08:41 PM

offset is not same as voltage

so , you're looking for voltages at some nodes (ref. to gnd) or voltages across some parts ......... but offset is ( by consensus) usually voltage at output , ref to gnd

gimme voltages at both Jfet drains , ref to gnd , same as voltages at both JFet sources ...... P3 in mid position

delecoy 27th July 2014 08:54 PM

Channel 1: Q2 drain to ground is 23.8V, Q1 drain to ground is -21.6

Channel 2: Q2 drain to ground is 23.8V, Q1 drain to ground is -21.6

The exact same?

Zen Mod 27th July 2014 08:56 PM

sources ?

delecoy 27th July 2014 09:08 PM

Channel 1: Q2 source to ground is 60.1V, Q1 source to ground is -68.8V

Channel 2: Q2 source to ground is 61.4V, Q1 source to ground is -68.0V

Offset on channel 1 at the RCA output is bouncing around 0 - 20 mV

Offset on channel 2 at the RCA output is bouncing around 0 - 20 mV

Zen Mod 27th July 2014 09:22 PM

60V ?????

something's very fishy there !

you didn't mixed PSU rails ?

delecoy 27th July 2014 09:23 PM

Starting over measuring offset in volts at output

Zen Mod 27th July 2014 09:25 PM

take a break , proceed tomorrow

or , maybe it's just me - I can't follow and find any logic , if trusting in #26

delecoy 27th July 2014 09:47 PM

Im thinking you had it in #23. I was looking to measure offset in the wrong place, increased the bias without decreasing offset, and may have zapped my jfets. Now measuring 0 at the source.


All times are GMT. The time now is 08:01 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 16.67%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Copyright ©1999-2021 diyAudio

Wiki