B&O BEOLAB 4000 ACTIVE SPEAKER PROJECT

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OSIB16

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B&O BEOLAB 4000 ACTIVE SPEAKER PROJECT
« on: 12 Jul 2019, 09:24 pm »
I just completed modifying a set of Bang & Olufsen Beolab 4000 active speakers, and wanted to document the progress on this forum. They are the more desirable Mark 1 versions (Class A/B built in power amps). Most people prefer them to the later Mark 2 which uses built in Class D power amps.
« Last Edit: 12 Jul 2019, 10:59 pm by OSIB16 »

OSIB16

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Re: B&O BEOLAB 4000 ACTIVE SPEAKER PROJECT
« Reply #1 on: 12 Jul 2019, 09:32 pm »
They are an odd shaped cabinet with solid aluminum build. Very beautiful to look at. Without the modifications the overall sound quality is quite good in my opinion (lots of potential), with balanced treble through to bass. The treble is smooth and clean,  and the bass is extended and powerful. Transparency is pretty good. However the downsides is that it is possible to hear a slight cabinet coloration. They go quite loud without distress, but bass becomes distorted when pushed to high levels.
« Last Edit: 13 Jul 2019, 02:38 am by OSIB16 »

OSIB16

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Re: B&O BEOLAB 4000 ACTIVE SPEAKER PROJECT
« Reply #2 on: 12 Jul 2019, 09:51 pm »
The unmodified circuit boards are shown in the photos...





OSIB16

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Re: B&O BEOLAB 4000 ACTIVE SPEAKER PROJECT
« Reply #3 on: 12 Jul 2019, 09:53 pm »



OSIB16

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  • Posts: 178
Re: B&O BEOLAB 4000 ACTIVE SPEAKER PROJECT
« Reply #4 on: 12 Jul 2019, 10:00 pm »
To cure the cabinet coloration I lined all the inside panels with grey adhesive backed 4mm thick wool fabric (shown in photo)...



 
« Last Edit: 13 Jul 2019, 02:31 am by OSIB16 »

OSIB16

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Re: B&O BEOLAB 4000 ACTIVE SPEAKER PROJECT
« Reply #5 on: 12 Jul 2019, 10:06 pm »
Ok now I’m going to show the circuit board modifications done. I swapped out all the junk wire for Neotech and Jupiter 6 nines copper, and Kimber.

OSIB16

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Re: B&O BEOLAB 4000 ACTIVE SPEAKER PROJECT
« Reply #6 on: 12 Jul 2019, 10:14 pm »
I Installed the following wires myself...

NEOTECH 12AWG PVC STRANDED COPPER (Power Input + Transformer Input).

KIMBER 19AWG VARISTRAND COPPER (Power Jumpers).

NEOTECH 16AWG SOLID CORE COPPER (Bass Midrange drivers).

JUPITER 23AWG SOLID CORE 6N COPPER (Tweeters).


(((((SPEAKER WIRING IS BARE COPPER, TREATED WITH DEOXIT GOLD & THEN COVERED IN PURE COTTON SLEEVE)))))








OSIB16

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Re: B&O BEOLAB 4000 ACTIVE SPEAKER PROJECT
« Reply #7 on: 12 Jul 2019, 10:48 pm »
I fitted the 2 large Mundorf AG capacitors onto the board myself. They are slightly taller than the old Samwha’s  and had to be slightly offset to fit into the cramped speaker cabinet. I extended the legs with OCC Copper 18AWG magnet wire...


OSIB16

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Re: B&O BEOLAB 4000 ACTIVE SPEAKER PROJECT
« Reply #8 on: 12 Jul 2019, 10:51 pm »
My local hifi repair guy installed all the Elna Silmic II electrolytic capacitors and ensured that the speakers were up and running...