Vintage Unicorn - B&W / Bowers and Wilkins M1 Speaker Elliptical EMI & Celestion T692

[florin]

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Could be one of the speakers Bowers and Wilkins made in their humble beginnings.
B&W labels on the back with the model being marked as "M1" though it seems that it's been scratched into it rather than stamped like the serial number below it.
Judging by the huge aluminium capacitors in the crossover they could be early 60's.
Elliptical EMI paper cone main driver and two Celestion T692 tweeters of which I found nothing about online. By the looks of it the tweeters seem to be AlNiCo.
Cabinet made of three-ply lumber core panels. No padding inside, no seals on the back panel or around the drivers.
The screws that were holding the tweeters in place were different from one speaker box to the other and so was the wiring even though the speakers are consecutive serial numbers 564/1003 and 564/1004. They might have run out of screws and wire?!?
Also found a random screw dangling about in one of the boxes that was left in there accidentally as it was identical to the ones used in the crossover boards but there were none missing. Really?!? C'mon B&W . . quality control?!?
The inductors are shielded in what looks like ferrite but one is cracked.
The wire leaves the box through a hole at the bottom.
Sound wise they're rather lovely.
Even though the cabs they came in are about the size of DM3 (665x300x250mm / 26x12x10inch) I think they would fit well in a cab the size of B&W DM4 or some Radford Bookshelf?!? I don't have any experience with these EMI eliptical drivers. Are these meant to be used in a sealed box or open baffle?
I'm thinking of refreshing the crossovers and probably changing the inductors since one is cracked and move everything in a proper cabinet or fit them on two slabs of wood as an open baffle design? Can the EMI drivers be used in an open baffle design?

I've put up two videos on youtube. The second one is clearer.

1 - https://youtu.be/ahQXbxaVNY0
2 - https://youtu.be/gwdvgDmequU

[Macca]

The caps could date from the early 1960s but B&W weren't making speakers that early, I reckon these speakers would be from around 1969 or 1970.

I don't think those EMI drivers would be a good choice for open baffle designs.

Interesting old things though, thanks for posting.

[struth]

never seen that formation of drivers in bowers stuff. the old dm series had an eliptical driver but not 2 vertical small drivers. may be a test set

[walpurgis]

Apart from a sympathetic capacitor and maybe wiring and terminals upgrade, I'd leave the speakers completely standard. They are definitely rare and collectable.

The EMI drivers were generally only seen in sealed box designs, although I did use a large magnet set in big ported cabinets in the late seventies. Think I may have a pair of the Celestion tweeters.

[Lawrence001]

I had a pair of their first speakers the floorstanding P1 with the same driver lineup.

https://www.bowerswilkins.com/en-us/...s-how-it-began

[florin]

Many thanks for the input everyone.
Anything about these T692 tweeters?
I was wrong about the screw inside, It looks like it came off one of the tweeters and all the crews were loose on that one. It measured just under 11 ohm. All the others measured slightly over 11ohm.Screenshot 2023-05-06 at 14.39.49.jpg
I've taken all of the crews off and will have a look inside of the tweeter in the evening.
I've disposed of the cabinets already as they were quite shabby but will definitely keep the drivers and crossovers and move them a new cab.
Do you guys think the smashed on one of the crossovers matters much? Screenshot 2023-05-06 at 14.40.26.jpg

[Macca]

Probably be fine. do both speakers sound the same? If so you're good.

[walpurgis]

Do you guys think the smashed on one of the crossovers matters much? Screenshot 2023-05-06 at 14.40.26.jpg

If you mean the broken lip on the coil former of the inductor, it won't matter.

[florin]

If you mean the broken lip on the coil former of the inductor, it won't matter.

Yes. The shell of the inductor which looks like ferrite and it's actually missing a piece as shown in the picture.
Screenshot 2023-05-08 at 00.21.35.jpg
I had a look at the tweeter and managed to put the screws back on. It seems to have some sort of synthetic wool inside that had been covering the holes.