Bottlehead Kits > BeePre

BeePre 2 Modification for Highly Sensitive Systems

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Paul Birkeland:
For some users of the BeePre 2 with highly sensitive systems, the following modification will lower the noise floor of the preamp for the cost of a few resistors.  You will need four 27 Ohm Vishay PR-02 resistors.  I recommend part number PR02000202709JR500.

In the BeePre, install one resistor between 22U and 25U, another between 24U and 25U, another between 27U and 30U, then another between 29U and 30U.  I recommend positioning the resistors at 24/25 and 29/30 above the resistors already there so they are out of the way (see the attached photo). If you have trouble getting all the leads through 25 or 30, the unbanded lead of the 220uF cap can be moved to the lower terminal to make more space.

This will drop a bit of buzz that resides in the noise floor that I have a tough time picking up in any of the test systems I have here, but could certainly come through with headphones or highly sensitive speakers. 

Alby0521:
Hello

I’m getting the resistors today and will install them tonight.

I just wanted to double check one thing before installing. From the instruction you gave one goes on U22-U24 and the other on U24-U25. (Than mirrored on the other channel).
From the picture you attached it seems to me that one goes on U22-U25 and the other from U24-U25. Am I mistaken?

Thanks in advance.

Best

AB

Paul Birkeland:
You're correct, I just amended the original post to reflect that.

-PB

pechelman:

--- Quote from: Paul Birkeland on May 12, 2021, 05:42:18 AM ---You're correct, I just amended the original post to reflect that.

-PB

--- End quote ---

That's what I was attempting to tell you the other day. Guess I should have posted here instead.

-phil

Paul Birkeland:
Yeah, I immediately thought about that and figured out what you meant with that drawing. 

Incidentally it will be helpful to have your preamp visit on Friday, as I believe the second BeePre upgrade may naturally remove this noise on its own. 

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