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andrea7617 19th January 2017 10:57 AM

BOSOZ balanced pre - for novice - questions
I would start the BOSOZ preamp.
Because I'm a novice, I have some doubt. I ask you!!!
First question is about the volume control. This is for me the most
difficult part of the project.
I use an unbalanced input (network player Pioneer N50) so I think I may use ALPS BLU RK27112 10K as input potentiometer (Pass calls it P1-P2 10 kohm)

I would do the simpliest solution, using only the input potentiometer.
Potentiometer P5
In this case, wich value of fixed resistor instead of potentiometer called
P5? :confused:The hole for this potentiometer are on board so I solder the resistance
in the hole (simple...)

Potentiometer P3-P4
This il the output potentiometer. If I don't use it, which resistor may I
use? Where in the board? Can I let the output without resistor? :confused::confused::confused:

Preamplifier gain.
I will use this pre with a diy Aleph 30 (that I'm building).
I can choose the gain of this pre using R15 value. Which is the best gain
for me. Default gain is 10. Is this the best value for my configuration?

Thank you for helping me!!!:D

Zen Mod 19th January 2017 12:13 PM


there is a recent thread with answers on same questions

Russellc 20th January 2017 02:49 AM

I still have this board unstuffed from back in the "Old Colony Sound" days...also the original Zen Amp board and matching Bride of Zen from the same source and era.

Once my Pumpkin Shunty is done, I may begin stuffing that one. Following.


Russellc 20th January 2017 02:56 AM

Zenmod, is this the thread?


Zen Mod 20th January 2017 07:05 AM

I believe it is some previous thread by Tony , or burst of his/our posts in previously existing thread

in any case - recent

Cambe 21st January 2017 02:34 PM

Maybe this one.

Zen Mod 21st January 2017 05:18 PM


andrea7617 24th January 2017 07:43 AM

I found the question about potentiometer.
Ok, Zen Mod says not to use P3-P4 and replace with 5k resistors. Perfect! First question (novice question...) Where shall I put this resistors? Directly in the signal cables that connect the pcb board to xlr/rca output (out+ and out- for each channel)? Or may I use no resistors in the cable output and only replace R11-R12 with 5k resistors instead your original value 100 K?

Second question. P5. I read that it can be shorted but I can be use a 500 ohm trimpot. Sorry for this stupid question... Trimpot has 3 legs and on the board there are only 2 hole...How can I connect correctly trimpot?

Zen Mod 24th January 2017 07:59 AM

1. solder them on board

2. just in case , post your reference schm

andrea7617 25th January 2017 12:28 PM

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