Cambrudge R50/Ex Baobab speakers

Cambridge R50/Ex Baobab speakers

Although I do really like my Paralab 40s for some reason I have now become the owner of a pair of Cambridge R50s.
These appear to have had an unhappy past and now I am hoping to restore them to their former glory, lets wait and see.
These speakers were previously owned by a HiFi fan(?) and they are shown on his web site baobab-audio.com. Take a look. They were then sold to two others and now it is my turn. They arrived with me as cabinets only with R40 crossovers, fortunaly not the B&O ones previously fitted! Pictures will be added.
They look to be fairly original but with added speaker connections front and rear, none of them seem to be in line fully, the back ones will have to stay as they are drilled through formica and I am not going to make things worse.

If anyone knows how the fibrous panels were originally fitted please let me know and whether the R50s had the foam plug in the vent for the B110 chamber. The hole for the T27 has been butchered so will try to plug it and redrill it if I can get the original bass units.
 

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On Sunday night I was chasing a pair of Large speakers for my restoration, no names given so as not to alert too many people, After some frantic bidding I lost out and kicked myself for not putting in a larger amount sooner! Never mind I thought to myself I am bidding on some complete units which looked promising and some speakers with broken cabinets for the tweeters.

Hooray I won the complete speakers I wanted and then double checked the maker's Museum pages to discover that the speakers were rated at 15 Ohms, oh b***er I said to myself several times. Never mind they only cost me £25.00 plus £15.00 postage, less than the £45.00 before postage for the 2 I didn't win.

They arrived today, connected them up and for the size of the cabinet sounded quite good. Lets have a look inside, so undo all the screws and take off the backs remove the loft insulation and what do I see..... a lovely sticker that says 8 Ohms, someone is smiling on me at the moment. All shiny and as good as new!

Now if the broken cabinets arrive and the tweeters are good they will have cost me a fraction of the cost of others offered! Fingers crossed.

I feel sad that I will be breaking up a perfectly good pair of speakers but will try to sell on the T15s a a sensible price. Some of the most solid cabinets I have ever seen. :):):)
 
The R50 is the B.J. Webb TLS and according toe Webb one kg of lambs wool per cabinet evenly distributed is the damping. The Webb design states that a plug of open foam should complety fill the opening of the midrange pipe. No qualities or measures are given but on the drawing the plug appear to be about 6 cm deep

With the whole pipe filled the design will work as a closed box with some resisitive venting. And clearing the last half of the pipe of damping material will not give that much of quarter wave behavior as the final section is only 1/3 of the driver area I expect the pipe itself to have substantial resistive losses.
 
Thanks. It appears that, as the cabinets were built, not by Cambridge, that just the space behind the B139 and the last part of the line has wool in. The first part of the line has a thin layer of foam attached to the rear of the cabinet. I intend to staple foam carpet felt to the side walls and botton of the lower chamber in the hope it will help. I am still hoping that someone will answer my requests for pics of the inside of good R50s to help, lets wait and see.
 
Managed to clean up the baffle boards, getting the old wiring loom out of the slot cut for it was a pain, but I have managed to keep the cloth from the vents for the B110 ports. The wiring looms were pretty well built all neatly tied together.
 

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Just been flicking through some old hi-fi news' and the earliest Ad for Cambridge R50s seems to be March 1973, they were for sale at C C Goodwin for £98.00. They also sold the B139 for £12.22, B110 at £7.58 and T27 at £6.00. Herts Hifi had the R50s at £164 a pair so the Goodwins price may have been each!

Not found a price for the Coles 4001 so was probably only available at specialist shops.
 
Progress

I have now built up the new crossover from Falcon and started to put together the wiring while I get the drive units.
I have decided to make sure the baffle can be easily removed from the speaker so have bought some XT60 connectors. I think they are used in RC models bit are a gold plated and appear to have a very good current rating. Photos below.
Still looking for Kef B110s at sensible prices so, pehaps foolishly, I have ordered a pair of MONACOR SPH-135C units, but they were inexpensive. I can see myself getting a pair of new B110s from Falcon if all else fails and perhaps some new Coles 4001 as well.
 

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Slow Progress

I have managed to get a pair of B110s at a reasonable price, and also a spare one at £35.00 including delivery.

Problems with T27s, managed to buy two but appears I was sent the wrong two, one open circuit and not the fitting gaskets shown. Have obtained a promise for a full refund including return postage, PO has tried to deliver twice but no-one there, fingers crossed for tomorrow!

Decided to try a pair of Morel Cat 298s from Falcon, always great service, then managed a pair of the older type of T27s at under £28.00 inluding delivery! Lets hope they work as described.

Wired the crossover with 16 AWG silver plated copper wire for Bass units and 18 AWG silver plated copper for the high frequency units all held together with heat shrink and +ves marked.

Decided to try to be clever fitting the ctossovers so bought some M3 nylon standoffs and nylon short bolts for the crossovers and fitted to baffle with metal M3 bolts, no chance of shorts and seems to work well.

3 new pics
 

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Nearly There

Well after last entry things got interesting on two fronts.
Finally managed to get refund on the duff T237s that were sent, sorting office in London lost the package but it did turn up. Got payment a couple of days ago!
Also managed to get a full set of B139s, B110s and older T27s on ebay for under £60 inc delivery. They are early versions but work perfectly apart from a crap paint job! See pics below.

So this set of speakers as they currently stand cost:
Cabs £75 + petrol
Kef Units £58
Coles 4001s £30
Crossovers £85
Sundries £40

Not too bad, but I do appear to have spare speaker units now that I may have to sell.

I have managed to keep the original baffles, that were nearly murdered while with Baobab but have been rescued with the help of my son who made up some little threaded plates used to hold the T27s. Even the little bits of cloth covering the B110 ports is original.

I couldn't wait to complete the work on the cabinets so they went back together yesterday. Very different sound to my Paralabs, the top end on the R50s is more forward and not as delicate and the bass seems so much better and faster. I will live with them for a while and see if they grow on me. They sound better, this morning, than they did yesterday.
 

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