Speaker wadding advice

[stuart_morgan_64]

I have some speakers I picked up a few years ago, dropped them off at a woodwork chaps workshop, for various reasons the tidying up wasnt done.

The main drivers had been eaten by mice, have some replacement ones now.

My main question is, what can I use for wadding, looks like loft insulation. I dave thought of removing the fronts and restuff them, there is a lot of litter in them too. I fear they maybe be glues and screwed. Any advice, thanks.

Stuart

[paulsherwin]

Acoustic wadding goes in and out of fashion. You might want to see what they sound like with the wadding removed. You can use ordinary loft insulation, but there is also specialist stuff available which is presumably more effective (at a price of course).

You could just leave the old wadding in place.

[Sixer-h]

I would avoid using loft insulation or any insulation particularly fibreglass, if for no better reason than it is horribly dusty. Long haired wool used to be the favorite, but then man-made open cell quilts was used my many manufacturers. There are suppliers of this product in the UK such as Wilmslow Audio and Falcon Audio. The open cell foam sheets also do a nice job. it is important to get the volume right and not under or over stuff the cabinets.

[Edward Huggins]

I would definitely remove that old wadding as it looks infested/polluted.
"Dr Bailey's Long Haired Wool" (that surely date's me) used to be popular but - and as another suggested option - you could use BAF wadding which is clean to use and easy/safe to install.
Beware Fibreglass!
Is that an old IMF cabinet for use with KEF drivers?

[DonaldStott]

I'd agree with Sixer-h above - I'm no expert but those speakers do seem a tad over-stuffed?

You need to go back to first principles and ask why loudspeakers have internal wadding at all - the advice here from Wilmslow Audio is: -

"Place this wadding loose inside your cabinet to dampen internal surface reflections and control standing waves, which can create bass boom..."

https://www.wilmslowaudio.co.uk/baf-wadding-289-p.asp

Good luck with the restoration.

[Radio Wrangler]

IMF reference studio monitors? or TLS80?

http://www.imf-electronics.com/Home/...rence-speakers

They're transmission line designs and the damping material is critical to their operation.

General advice for all loudspeakers will inevitably be for sealed box or simple ported types. These are quite different.

The mass of the material is used to slow the speed of sound along the transmission line to the port to get it tuned to place the low frequency boost correctly, and it may be that the damping along the line is varied to selectively attenuate harmonics. I'm not sure if Fried was up to this trick, but the Chris Rogers transmission line design was.

you need to remove the material carefully, noting how much and where it comes out of so you can get materials of the right densities to put back.

With what those drivers cost nowadays, you'll want to get the things right.

David

[Dickie]

They certainly look over-stuffed with non-original material. I have a pair of IMF studio monitors that are similar to yours, using 8" round B200 woofers rather than the "race-track" B139s that yours use. Behind the woofers all the flat surfaces are lined with a couple of inches of open-cell foam that leaves a lot of fresh air but engulfs the high frequency drivers. This continues and disappears down the "throat" of the transmission line. At the far end of the line (ie the front of the speaker) this has become loosely stuffed horsehair. I don't know what happens in between, it needs some sort of inspection camera to have a look.

[paulsherwin]

There was a fad in the late 80s/early 90s to completely stuff speaker cabs with wadding.

[OscarFoxtrot]

Your local charity shop may be able to let you have a continental quilt which isn't of resaleable quality which will be a source of polyester fluffyness.

[Herald1360]

Don't get a feather or down quilt, though.......

[mark_in_manc]

I used to teach acoustics - a good while ago I had a (Swiss?) postgrad spend his summer investigating all sorts of cabinet wadding material for acoustic transmission-line purposes, using all sorts of methods which I suppose I could go on about if anyone is really interested. To my pleasure and his disappointment, the general result was 'so long as something's in there, it doesn't matter too much what it is'. You might spot small differences in measured cone velocity or total radiated pressure in a controlled environment (anechoic room?) due to changed 'alignment' - the filter function to which David alludes - but I doubt you'd hear it in normal use.

That 'slowing down' of the speed of sound is interesting - the air starts to act isothermally with lots of wadding as opposed to adiabatically in plain air, since the 'hairs' of the wadding conduct heat much better than air itself. Who knew?

[Diabolical Artificer]

If you leave the old wadding in smelling of mice etc it is an open invite to future mice being the equivalent of a good Trip Advisor review or chalk mark by your front gate as left by gentleman of the road and sellers of fortunes in the old days.

Some speakers used to have a woollen sort of felt in them, same as used in sofa's as padding. I've a bag full if you need any from the last settee' I killed.

Andy.

[rontech]

I acquired a pair of Lentek monitor speakers ( transmission line design ); from a friend back in 1986.

They were then about 12 yrs old. When I came to audition them, one speaker sounded somewhat distorted at low frequencies. On investigation of the interior, I found all the interior wadding in a heap at the base of the cabinet.

I made a trip to Wilmslow Audio ( It was in Wilmslow at that date ) and on their advice obtained a suitable quantity of what I think was long staple wool fibre.

Anyway this solved the problem and the speakers sounded very good indeed.

It looks as though getting the wadding right is very important.

[Silicon]

Avoid the itchy rockwool type of loft insulation.

Loft insulation made from recycled plastic bottles is easily available and user friendly.

If you have hamsters (or mice) it would be a good idea to fit a metal mesh to the acoustic port at the rear of the speaker.

[G8HQP Dave]

That 'slowing down' of the speed of sound is interesting - the air starts to act isothermally with lots of wadding as opposed to adiabatically in plain air, since the 'hairs' of the wadding conduct heat much better than air itself. Who knew?

I did. I remember reading about this many years ago; it helped that I had just finished a physics degree. It is possible to 'enlarge' the volume of an infinite baffle cabinet by adding the right amount of wadding. Too little and you don't get the adiabatic effect, but you may still get useful reflection damping. Too much and the wadding occupies too much space so consumes volume.

[stuart_morgan_64]

Thanks for all the advice, lots of it too. I will remove all the wadding, I won't replace it with the type in there, by the time I have finished I will have rashes and itch for a day or two. I shall cover up as much as I can.

I have read through all the comments. Removing the fronts seems not to be a option, what I thought were screws maybe nails. Will lay them on there backs and see how we go. I look forward to trying these out. I think I will keep them for many years.

[simpsons]

Call me a bit slow but why, when the internal view of the KEF TLS60 attached shows panels of sound absorbant material placed by the manufacturer in specific positions to optimise the design of the loudspeaker, are different ideas being mooted for the internal damping of the loudspeaker cabinet?

The fact that the previous owner has used what seems to be loft insulation doesn't mean that such a DIY approach has any merit. Marc in Manchester identified accoustical reasoning for the use of internal structure and dampening way beyond my understanding but KEF engineers, renoun for their expertise, certainly do.

[Dickie]

It will be interesting to see how much, if any, of the original stuffing there is behind the later additions.

[stuart_morgan_64]

I have just stuck my hands inside, now itching, it's only loft insulation inside, there is a label on the back of one.

[stuart_morgan_64]

It's going to be difficult to original, access.