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jasper9395 7th October 2012 03:20 PM

Bang & Olufsen S45 crossover
Hi there,

I am looking for anyone who can tell me the layout of the S45 crossover. Refurbishing a pair of these was the first speaker projects I did. One of the things I did while trying to improve them was fitting my own crossover desighn, I dont think it worked out well thou. I still have them sitting at home and would like to make a new crossover for them desighned the way B&O originally did but I have no idea the original layout and values. Hope someone can help. Thanks.

system7 7th October 2012 06:43 PM

2 Attachment(s)
Ah, I suppose it's natural to try and outdo B&O designer Jacob Jensen, after all, who he? You could have just replaced the ageing electrolytic capacitors, but no, let's IMPROVE things you thought...:rolleyes:

Where have you got to so far? What is the current network since the original is LOST in TIME, like TEARS in RAIN? :D

First thing is to establish exactly which model Beovox S45 you have. Is it this 2-way?
Beovox S45 |
I make that a 8" bass and 1" SEAS tweeter rather like the old dynaco A25 in a 16L closed box, but not too sure. It would be nice to know the DC resistance of the drivers. 4 ohm I guess. Probably crossing over quite low, say 2.5kHz.

Visaton make a 4 ohm crossover that might be about right:
Visaton - Lautsprecher und Zubehör, Loudspeakers and Accessories

It's also worth looking at a couple of B&O crossovers to get an idea. Right now I'm thinking 0.8mH bafflestep coil and the rest to follow. I'd like to see some measurements and photos to inspire me further to get you out of this hole. :cool:

balerit 7th October 2012 07:29 PM

I have a pair at my mom's place, will grab them and have a look.

The Book Worm - DIY Audio Ebooks and Manuals - Speakers, Moscode Amplifiers, Electronics, Map Reading, Free Capacitor Intro.

Bare 8th October 2012 12:01 AM

Don't be forgetting B&0 is PRIMARILY intent on pushing (their ) Stlye and ..price points.. by cunning skirting of 'marketplace legislations..true, but I digress :-).
Mid-Fi is an Honest descriptor of their Audio products. Zzzzzzzz stuff.
Hopefully with help (as in above) you can patch the thing and sell it on.
Then buy something with a future ?

sreten 8th October 2012 02:11 AM


The first version was a 2 way with a filler midrange to correct phase :
(i.e. 2nd order low pass, 1st order low/high pass, 2nd order low pass.)

Beovox S 45 6302 Speaker-P Bang & Olufsen B&O; Struer, build

Can't work out how to get a good diagram of the crossover.

Didn't take long to workout you could drop the filler driver if
phase was considered less of an issue which they duly did.

rgds, sreten.

Staxpatrick 7th September 2015 02:08 AM

The capacitors in the S45 are electrolytics 16uF 40V, not 15uF.

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