Spendor BC3 New Surround

gbCambridge

New Member
Hi,
I have reacquired my BC3 speakers...lent to my son when he went to Africa 11 years ago. He is back and so are the speakers, both slightly the worse for wear.
The HF2000 had separated due to humidity.. the surround came apart. I have repaired those and they work very well.
As far as I can tell right now, all other units, apart from one bass unit are working well. On this particular unit the surround is separating from the cone and the cone produces a scraping noise when pushed in / out.
I have found a company which produces rubber surrounds and will actually make one to measure for the BC3....at http://sickenshop.de/ecombase/index.php?cPath=282_284_452_456
So, has anyone any experience of their surrounds? I am grateful for any advice I can get on replacing the surround on these Bextrene drivers. The speaker that I have working sounds great and I am looking forward to doing a substantial renovation on both.
Thanks for any help

George
 
Hi,

Separate the surround completely and then reglue it, shoud work.
Repeat on the other bass driver if showing signs of failure.
Generally inverting old bass drivers is a good idea.

rgds, sreten.
 
Hi,

Separate the surround completely and then reglue it, shoud work.
Repeat on the other bass driver if showing signs of failure.
Generally inverting old bass drivers is a good idea.

rgds, sreten.
Hi,
Thanks for that advice.
The situation has got slightly worse...it seems that rubber surrounds witht the reversed (concave) roll, as used by Spendor are not available. So, with nothing to lose I have ordered a surround with a view to experimentation. The original surround is actually torn. it might be possible to rejoin and use it, as you suggest. As you can tell, I am in a "nothing to lose " siutation with this. At least one speaker is working fine..it seems that just one bass unit needs fixing and all will be OK :)
 
Welcome to AK!

Well, if the surround is torn, then it may be academic. but if you're game, you might try some rubber cement (which when dry, is pliable) on the surround to seal the crack or tear first. Normally, we would suggest removing the surround entirely from the frame, then reglue the inner diameter of the surround to the cone (is it black bextrene cone or polypropylene - different glues for that purpose) Then use a 50-60hz tone played at low volume to center the cone and then try to clam down the outer edge of the surround with clothes pins - this is temporary. once all the edges of the surround are fastened down, and the tone is still clear (but not loud), then take off 25% (like from 12 to 3 oclock), and glue that to the frame, re-tone test, then clamp and move on to the next section. Once completely around the frame, then clamp, test once more, then let dry for 24 hours, same for the surround repair.

If you can, shoot some pics for us of the woofer and the damaged section of the surround.
 
Welcome to AK!

Well, if the surround is torn, then it may be academic. but if you're game, you might try some rubber cement (which when dry, is pliable) on the surround to seal the crack or tear first. Normally, we would suggest removing the surround entirely from the frame, then reglue the inner diameter of the surround to the cone (is it black bextrene cone or polypropylene - different glues for that purpose) Then use a 50-60hz tone played at low volume to center the cone and then try to clam down the outer edge of the surround with clothes pins - this is temporary. once all the edges of the surround are fastened down, and the tone is still clear (but not loud), then take off 25% (like from 12 to 3 oclock), and glue that to the frame, re-tone test, then clamp and move on to the next section. Once completely around the frame, then clamp, test once more, then let dry for 24 hours, same for the surround repair.

If you can, shoot some pics for us of the woofer and the damaged section of the surround.

Hi,
well apart from the humidity or whatever, which lifted the glue, I have since found out that the African audio "specialist" tried SuperGlue and possibly compounds obtained from the local witch doctor (who actually do advertise in the small ads in the local paper!).
You can see from the pics that the surround no longer has sufficient collar to fit on the frame, so I think the repair method, which I was keen to try, is not going to work. I hope the cone edge is clean enough to work on. The cone is Bextrene. Can you recommend an adhesive to try on this material?
The replacement surround is on its way from the Netherlands. It is a long shot but I don't see what I have to lose with this. The centering might be a bit more problematic, depending on the fit. We shall see. Spendor have said they would help...by selling me two replacement bass units. I didn't discuss the price as their support guy started justifying the price by saying that when the speaker was new a mini cost around £650 and the speaker was £450 ...so be extrapolation....... no thank you.
 

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Well, some luck...amazingly. Just keep in mind I had nothing to lose.
Firstly the original surround was torn in one place and its edging which glued to the speaker frame was very tattered and lumpy.I obtained a roll surround of close to the ideal size from the Netherlands. The first problem was that it was a convex roll and the Spendor need a convex surround. I found that I could reverse the new surround to give the concave shape ( a convex surround would have been in contact with the front panel, and anyway, it was supposed to be concave). Using a scalpel I cut away excess surround leaving enough to provide support for the (tidied) remains of the original Spendor surround.I managed to match the curvature of the two surrounds by being generous with the use of the scalpel. I used an adhesive from the US, "Aleen's Original Tacky Glue" to glue first the two surrounds and then the cone to the surround. I used the tone-signal alignment method for setting up this complex surround. The cone, being Bextrene, was predicted to have al sorts of problems with adhesive. Well, this adhesive works perfectly. It is tacky but takes some 10 to 20 minutes to dry. Being nervous, I gave it 4 hours!
At the end of all of this the speaker looks, from the front, completely normal. The first test brought no sound at all. It turned out that some pins on the crossover board were making intermittent contact. That got sorted by using a different contact point. And, first tests, it all sounds fine! Right now I am testing with no cabinet and the bass is taking the full output of a 60 watt amp. I am running 30, 40, and 100Hz tests and they all sound fine and certainly no scraping from the voice coil. The HF2000 repairs also appear to have worked... very clear and sweet sound. The reinstallation to the cabinet will happen soon. This is a bi-wired setup, whichI have found to be useful on low-efficiency speakers, not much good on JBL for example. So, by the end of the weekend I should have my pair of BC3's working again..having traveled some 8000 miles since I last heard them. Whether the bass of this speaker will match with the bass of the other speaker I shall only know when I get to the next stage. Right now both speakers stripped from their cabinets.
Thanks to those who made helpful suggestions on this fine old speaker.

George
 
congratulations on the repair!! Love to see comparison pics of both woofers. If you haven't already, you might carefully inspect the 2nd woofer and check its surround for integrity. If any question, then replace with a new surround as well. It will be easier and faster since you now have experience.

Regarding ordering, which of the stock surrounds did you use and trim, or were you able to get one made to your specs for a BC3 as you mentioned earlier? Do you have a pic of the surround before trimming?
 
Hi,

Well, I can give you some information and some photos of my butchering.
I ordered my surround from
Maroesjka Bakker & Myrko Schneider

Good Hifi V.O.F.

Tel: 06-40381232 / +31640381232 (Monday-Saturday from 9-18 [GMT+1]), e-mail preferred. They were very helpful people and good to discuss with.

The surround that I ordered had the title "
the “RUBBER RING, MEASURES 11 INCH, FOR A 21 CM CONE” This has ABCD sizes “ 30 - 27,3 - 21 - 19,5”", where A, B, C and D refer to common specification points for surrounds (see their website).

As I mentioned I had to reverse it as the roll was convex and I needed concave. As I still had the original edge of the old surround, the job was to mate the new surround with the old edging from the old surround and then to bond that to the cone. I cut the new surround with a scalpel so that if supported the old edge and glued the new surround to the speaker frame. Once set I then bonded the two surrounds. The last thing was to actually bond to the cone and this went surprisingly easy. There is no rubbing sound or scraping at all, where previously there was.
I have taken a few photos of the BC3 front panel with the bass speaker mounted. You will see a fair amount of glue around.. al I can say that I inherited this from the African repair shop. It took a long time to scrape off all that they had done so that the bonding worked.
Once I had to do the work as there was not sensible alternative it went relatively easily. And now I have a working pair of BC3 speaker !!!
 

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