Rogers LS6 bass driver - glued to cabinet? Unscrewed, not shifting

[mhennessy]

UV is bad for many plastics, and I know that polypropylene isn't the best for UV resistance, but it's just that I've never seen it before with a speaker diaphragm. Until now, perhaps

Not all pp is equal - some will have additives to improve the UV resistance. I wonder if this drive unit was made from a sheet that didn't?

I'll raise the issue with a couple of industry contacts when I next speak with them - they might know more about this, given that they were making drive units with pp back in the '80s

[mhennessy]

Originally Posted by blotblot

Successfully dropped the driver out, and started to carefully dust where I had gently sanded the polycarbonate cone …. and THE BRUSH WENT STRAIGHT THROUGH!. AARRGGGHH! (Photo attached)

More fragile than I had imagined!

You've nothing to lose by trying a repair, but it's probably worth keeping an eye out for a s/h donor drive unit, sadly.

I suspect that any repair that changes the stiffness of the cone will change the way it sounds, especially in the midrange. It might not be a problem to you - but if it doesn't sound right afterwards, that'll be why.

Either way, please let us know how you get on

[Refugee]

I just looked at the thumbnail and wrongly assumed it was the rubber flexy part.
Well I will be wary of any speakers with plastic cones now.

[Ted Kendall]

Originally Posted by mhennessy

I can't recall an instance of sun damage, either.

Neither have I - but most BBC speakers have not been used in such extreme conditions, and usually have the grilles kept on. Agreed, it could have been a duff batch...

[mhennessy]

Yes, natural light is rarely found in BBC cubicles

I was wondering to myself how much protection a grille would provide, and I'm honestly not sure. Looking through an LS7 grille now, it's striking just how open a weave Tygan is - hence its application, of course. Later on, Rogers switched to cloth for the non-BBC speakers - it's possible the OP's are new enough for that. I'm not sure cloth would have been much better at blocking sunlight. So I'd suggest that leaving the grilles off is probably not something to feel unduly guilty about, but they might have helped a bit...

The LS5/8 and 5/9 had a layer of black fabric in the grille, mounted immediately behind the Tygan. My understanding is that it was cosmetic rather than acoustic - it was intended to stop the white polypropylene diaphragms being visible through the Tygan if a light was aimed at the front of the speaker - but it might additionally provide a small degree of UV protection at the same time. Though as those were studio loudspeakers that would quite literally never see the light of day, that's unlikely to have been a significant concern...

[blotblot]

As requested, some closeups showing the odd structure, crack progression and a comparison with the undamaged speaker (side by side) showing the change in opacity.

I will also post some pictures of the repair using the 3M DP8005 polypropylene glue (quite thick, so did not run, but a bit gloopy for a smooth finish. Still smells too strongly to have inside the house and to test (sweet chemical smell - I may have to add some paint to seal it).

[blotblot]

Some pictures of the repair using the 3M Scotch-Weld (TM) Structural Plastic adhesive DP8005 polypropylene glue (quite thick, so did not run, but a bit gloopy for a smooth finish but could probably improve with practice!

Still smells too strongly to have inside the house and to test yet (sweet chemical smell - I may have to add some paint to seal it).

Used the minimum to attach the reinforcement. And a little on the back too.

Have also included some shots of my home-made glue applicator from a caulk gun and some nails - didn't fancy paying £50 for the 3M twin plunger and £20 for the mixer nozzle...

It will be interesting to compare to the un-repaired speaker - I have a tone generator so will give it a go when I do manage to get the speaker inside, as well as musicality test.

Would still prefer an original Rogers/Swisstone LS6 bass driver if I can source one for sensible money!

[derekheeps]

Originally Posted by blotblot

The polypropylene bass driver of one of my mid 80's Rogers LS6's (label attached) has sun damage (very silly!) resulting in an elongating crack about 0.5 to 1cm inside the outer edge, now 50% of the way round (see attachment). Beginning to sound buzzy - playing only very gently until repaired!

Hoping not to have to replace the bass driver as I cannot find a source of genuine Rogers replacements for the LS6 bass driver, although one bass driver was replaced by Rogers/Swisstone in Mitcham about 20 years ago.

So I am looking to see if I can add a fairly thin layer of M3 DP8005 repair on both sides of the cone. I have the glue, have rubbed down with fine sand paper, and want to do the other side too.

Having unscrewed the four screws, it seems WELL STUCK.

< Is this glue, or a degraded gasket/rubber? >

< Do I just pull really hard somehow, or apply heat first, or.... ? >

< Any ideas on how to remove, as I don't want to damage the cone, the woodwork or the metal chassis?? >

Getting a grip on the metal chassis is also proving to be tricky as it is recessed into the wooden front panel.

Very keen to try the glue option having received it, and if it works I may apply to both speakers so they are balanced!

< Also sources for a genuine replacement driver, if it doesn't work, as LS6 driver repairs/spares appear to have less mentions online than the LS3/5a that I also use. >

What you could do is look for some automotive trim removal tools : these are plastic prybar type tools , designed to pry parts loose without doing damage ; alternatively , wooden spatulas ( spatulii ? ) from your kitchen might be introduced into the edge under the drive unit and used to pry it loose .

You should , with care , be able to remove the unit .

Have you tried phoning Rogers for advice ?

Edit , I read further and see that you got it out .

If the repair is not satisfactory then a replacement unit may be the only option .

[Radio Wrangler]

Polypropylene in the form of cheap rope certainly degrades fast in sunlight.

David

[blotblot]

Originally Posted by derekheeps

What you could do is look for some automotive trim removal tools : these are plastic prybar type tools , designed to pry parts loose without doing damage ; alternatively , wooden spatulas ( spatulii ? ) from your kitchen might be introduced into the edge under the drive unit and used to pry it loose .

You should , with care , be able to remove the unit .

Have you tried phoning Rogers for advice ?

Edit , I read further and see that you got it out .

If the repair is not satisfactory then a replacement unit may be the only option .

Can I call Rogers? Is there a telephone number?? I thought that they had disappeared...

Quite a thought, to call them.

Do you think they might have a solution?

I'm sure I took one speaker to Swisstone near Colliers Wood area many years ago for a fix after an earthing fault on my turntable suddenly was heard very loud from upstairs in the house for about 10s..... then nothing...
Toast by the time I got there.

In the meantime my fix has made the speaker useable, apart from heavy choral choir singing which just exposes a faint buzz at a certain frequency. I may have a bit of adhesive round the back of the cone that's flapping a bit. If I'm feeling brave, I may go in with a scalpel, or a soldering iron to burn off the offending flapping bit it I can find it.

Thanks!!

[derekheeps]

I would have thought you can contact them , AFAIK they still exist - they have a website with a contact phone no listed . Indeed the website has been updated this year !

https://www.rogers-hifi.uk/contact-rogers

Your other place which might help is Wilmslow Audio , who most likely won't have the original drivers , but they are very good at providing substitutes ( of course you would need to buy a pair and replace both ) .

https://www.wilmslowaudio.co.uk

Your last hope is to find a genuine Rogers unit on eBay , but used drivers are an unknown quantity .

Please see the restoration and upgrades section on the Rogers website - they may be able to help .