Repairing speaker cabinets.

Sep 12, 2012 23 Replies

I've bought a pair of BBC designed speakers which are quite kicked cabinets wise - one in particular - but still sound just fine. They are constructed from 12mm birch ply.



The worst one appears to have been dragged over concrete or whatever on a regular basis - the edges at the bottom are mostly rounded off as is near every corner. So what I was thinking of doing is routing a rebate all round and gluing in some hardwood strip to give me a good clean edge before veneering. Something like 5mm square after finishing would be enough to clean things up.



The construction seems to use a stepped joint which clearly shows at the back. so if I let in new wood to the same sort of depth will look the same



- the back itself is reasonable. And of course be covered with the veneer to the sides.



Would these joints be pinned as well as glued? Don't want to hit a pin with the router. ;-)



Any help gratefully received - this sort of cabinet work is new to me.



To put things in perspective, a perfect used pair of these would retail at



3000 quid plus. But would be extremely difficult to find as most come from studios so have cosmetic damage from normal day to day use. I gave up trying to buy decent ones as they were simply beyond my pocket - but would like to get these ones looking as close to original as possible.

Did you get these from the BBC auction? No idea about the construction, I'm afraid.

Some also had corner pieces inside as well. I'd have thought pinning was not done, but as you say, how to find out. You kind of need a mini metal detector!

Brian

A photo would help, to be sure, but...

Its probably a rabbet joint, and may well be pinned from both directions.

For example, this drawer's corner joint is done with a rabbet in the edge of the thicker rear section to accommodate the side panel:

formatting link
in doubt cut the corner out using two passes with a circular saw[1] set to a 5mm (ish) depth of cut (the saw blade will romp through the occasional pin without taking damage) - first with the saw resting on one face, then with it on the perpendicular face so that you cut out the corner. Note this will weaken the joint a bit until you get the repair strip in there.

[1] If you have access to a table saw, then even better.

Make up your repair strips a bit oversize, and glue and clamp them into the "corner" you have created. The trim it flush either with a plane or a flush trim bit on a router.

Another option would be overcladding the whole speaker with some thin birch ply...

Would a stud-finder be of any help there?

It might tell you there are pins there but what to do then ?

I'd work on the assumption that there are pins present. Get a cheap router= bit and have at it. My guess is that the router bit will fly through them = with no problem. If its a cheap bit its going to be the easiest way.=20

If you have a table saw then take a slight cut to depth but 1-2mm wide on o= ne corner. This will reveal the presence of any pins. Then you can go at it= with the saw or the router. The circular saw will have a kerf width of 3mm= so I would aim to cut to the correct width and depth (i.e.)5mm x 5mm. This= will leave a thin strip 2mm wide if the blade hasn't already broken it off= . You will need to finish with a router to get a good clean surface anyway. You might also like to think about lining the edges of the rebate with mas= king tape before gluing in the new piece. It would save on cleaning up afte= r.

Strong magnet

I've never tried one in this situation, maybe he needs to borrow one and embed a few pins in some scrap wood to see if they work.

Brian

What would worry me a little is this. Are the drivers being taken out and stored in a muck free place during all this, as otherwise i can see it ending in tears.

Brian

I think the sight of bits of woodchip dancing on the speaker cones would be a good conversation piece.

Don't need to borrow one - have three of them, assorted makes. Trying to find one which worked perfectly. ;-)

Typically of BBC practice, the entire baffle assembly detaches.

I have upward facing speakers in the rear of the old car. It went in to have a new rear wing welded on and I neglected to remove the speakers, but did strip out all the trim including the speaker grill. Ended up with metal swarf firmly attached to the magnet pole pieces. ;-) It's the sort of speaker with a post in the middle that the tweeters are attached to - a single cone unit would likely have survived, as they are sort of sealed in the middle.

On 12/09/2012 10:57, Dave Plowman (News) wrote: snip

Out of interest, which model are they? Might have a rummage in the attic :-)

Rob

Too big to go through the trapdoor. ;-) They are LS 5/8

That's probably easier to come by these days that you think. If you have a smartphone you can get a metal detector app, at least for android. Uses the magnetic sensor (compass), just tried the one I have and it finds the pins holding the architraves on no problem.

Oh to be retired and have no management...

Heh heh. It was the Bush House auction that got me started - looking through the online catalogue just out of curiousity. But all of those there went for far more than my budget. Got this pair off Ebay. There are more in the Phase 2 sale - cat is online now.

Yes, a small neodymium one should work.

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required