B&O M100.2 – Info, repair, measurements

[sandevsound]

Hello,

Two weeks ago, I bought Bang & Olufsen Beovox M100-2 speakers, and I’m writing this thread to share some info and challenges that I came across.
Speakers were bought in Italy and driven back to Croatia, Zagreb.

Cosmetically, they are in great shape. Just one spot and some scratch on the veneer. There are two small dents on one tweeter but negligible. They came with their original stands.

The speaker is a 4way with 5 drivers. All the drivers and the box looks really well-made.

Both the crossovers measure identically (wrong).
Unfortunately, both super tweeters (Celestion) are not working and for now I’m attempting to repair the first one. Also the rivets from the Seas woofers fallen of so I will use a screw and some thread locker glue.

The impedance measurement is in the attachment for both speakers with open super tweeters.

The surround on the phase filler has been changed from foam to rubber. The driver should be Peerless KU45 MRF with resonance around 90 Hz?! The first driver with the rubber surround measures Fs exactly around that, so I’m happy to see that. The wires are soldered and really short, so it was measured in hand next to the box.

I managed to find broken voice coil wires on both super tweeters (Celestion HF 2000) and resolder them or extend the wire to the solder point. I re-glued the diaphragm of the firt super tweeter back and measured the impedance. The Fs was around 1.6khz which should be ok. Dc resistance is around 8.6ohms, which should also be ok according to the information on the internet.

I was already having a smile on my face looking forward to getting out of this problem easily, but then the other day I measured the second Celestion super tweeter and the DC resistance was 4.6ohms… 😔

My guess is someone in the past blown one of them and replaced it with the wrong one. I think the driver should be 8ohm.

The crossovers are the same. I ordered new capacitors from Danish sound parts because half of the capacitors were off value by double or more. Both carbon 330ohm resistors on the crossover cracked, so I will replace them also.

I asked Martin some questions, and he answered quickly and was helpful, so I will use this opportunity to thank him again. 🧡

I’ll put some measurements and pictures for now if someone is interested, or it will help them in the future.

I’m thinking of:

• buying new diaphragms from Ninomusic (ebay, france). Does anybody have experience with them?
• buying new voice coils from Ninomusic and try to keep the original diaphragm.
• try to find a working second hand Celestion HF2000, 8ohm

Some pictures…

Attachments:

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Location: Zagreb

Favourite Product: Beovox M100-2

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