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June 16, 2021, 04:27:39 AM

Author Topic: BeePre 2 Modification for Highly Sensitive Systems  (Read 460 times)

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Offline Paul Birkeland

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BeePre 2 Modification for Highly Sensitive Systems
« on: May 08, 2021, 11:22:15 AM »
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. 
« Last Edit: May 12, 2021, 05:42:01 AM by Paul Birkeland »
Paul "PB" Birkeland

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Offline Alby0521

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Re: BeePre 2 Modification for Highly Sensitive Systems
« Reply #1 on: May 12, 2021, 05:35:20 AM »
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

Offline Paul Birkeland

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Re: BeePre 2 Modification for Highly Sensitive Systems
« Reply #2 on: May 12, 2021, 05:42:18 AM »
You're correct, I just amended the original post to reflect that.

-PB
Paul "PB" Birkeland

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Offline pechelman

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Re: BeePre 2 Modification for Highly Sensitive Systems
« Reply #3 on: May 12, 2021, 06:27:29 AM »
You're correct, I just amended the original post to reflect that.

-PB

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

-phil

Offline Paul Birkeland

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Re: BeePre 2 Modification for Highly Sensitive Systems
« Reply #4 on: May 12, 2021, 06:44:54 AM »
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. 
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Alby0521

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Re: BeePre 2 Modification for Highly Sensitive Systems
« Reply #5 on: May 12, 2021, 07:03:27 AM »
You're correct, I just amended the original post to reflect that.

-PB

Great Paul, I’ll install the resistor tonight and report back.

Cheers

AB

Offline debk

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Re: BeePre 2 Modification for Highly Sensitive Systems
« Reply #6 on: May 12, 2021, 08:39:59 AM »
 

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.
[/quote]

Will the BeePre upgrades be available soon?  If so I will wait for them instead of doing this mod

Debra
Debra K

Pearl 2 Phono amp
BeePre2, Psvane ACME 300b
Kaiju, Linlai Elite  300b
Sota Sapphire, Pete Riggle Woody Tonearm, Kiseki Purpleheart Cartridge
Rega P6 Ania Pro cartridge
Bob's Devices SUT
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Sotm SMS-200 neo
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Jager speakers

Offline Doc B.

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Re: BeePre 2 Modification for Highly Sensitive Systems
« Reply #7 on: May 12, 2021, 09:50:59 AM »
Yup, it's getting close.
Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.

Offline Alby0521

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Re: BeePre 2 Modification for Highly Sensitive Systems
« Reply #8 on: May 12, 2021, 02:39:49 PM »
Great Paul, I’ll install the resistor tonight and report back.

Cheers

AB

What an outstanding result!!! I couldn’t be happier. The noise dropped by a lot! To give an idea, before installing the resistors I had a -12db pair of attenuators into the Kaiju and I had hum at half way volume of be beepre2. Now I removed the attenuators and I get a slight noise at 3/4 of the volume pot (it would be impossible to even try to listen at that level).

To summarize, very happy!! Thanks PB and BH team.

Best

AB

Offline Toobuzz

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Re: BeePre 2 Modification for Highly Sensitive Systems
« Reply #9 on: May 13, 2021, 07:04:18 AM »
Great news, AB!  I'm so glad that this worked for you.  I'm over the moon with my BeePre2 as well.  I have slight hum too, but it's not a problem.  I'm using solid state amps and inefficient (87db) speakers so it's only audible between tracks when the volume > than 50% (which is approaching my maximum comfortable listening level).  I ordered these parts but will hold off until after the upgrades!!!

Offline Paul Birkeland

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Re: BeePre 2 Modification for Highly Sensitive Systems
« Reply #10 on: May 14, 2021, 02:13:19 PM »
The second upgrade will also take care of this issue.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Roamconstant

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Re: BeePre 2 Modification for Highly Sensitive Systems
« Reply #11 on: June 10, 2021, 07:54:19 PM »
Got my BeePree operational tonight.  I am experiencing a hum/buzz that sounds like the previously mentioned buzzy bees (sorry).  If I add these resistors, should they remain in place once the upgrade is released?

I hear the hum coming from all three sources on my efficient speakers.
It’s feeding a Kaiju that has been operational for a couple weeks.  The system hasn’t exhibited any undesirable background hum until I added the BeePre.  I definitely have to get this thing running quieter.


Offline Paul Birkeland

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Re: BeePre 2 Modification for Highly Sensitive Systems
« Reply #12 on: June 11, 2021, 06:07:39 AM »
Yes, just add them in and enjoy.
Paul "PB" Birkeland

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Offline Roamconstant

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Re: BeePre 2 Modification for Highly Sensitive Systems
« Reply #13 on: June 14, 2021, 01:56:22 PM »
This modification did exactly what I hoped.  The volume dependent buzz from the speakers was dramatically reduced.  It is only audible with full gain on the Kaiju and 3/4 volume on the Beepre and no audio playing.  Speakers are Klipsch Cornwall w/ fresh tweeter, mid horn driver, woofer, and crossovers from Crites Audio fwiw (96db I think).

This DEFINITELY increased the enjoyment in listening to the new equipment.  THANK YOU!