speaker internal damping.

[philv]

Hi.

I'm upgrading some speakers.
The upgrade plan i am following lists accoustic damping polyester cloth and also felt.

I am not sure if the felt is also for damping as a small amount is used on the back of the tweeters.

Is felt usually used with polyester for damping? Or justnpolyester?

Is the damping stapled in first and felt on top if felt is used aswell?
Or vice versa?

Should it cover the crossovers?

Thanks

[fatmarley]

Stapling something to the cabinet walls will do next to nothing. It's needs to be glued tight against the cainet wall. If you want to damp the cabinet walls properly, probably the best material is something like flashing tape or butyl rubber based stuff. I just bought some PeacMAT XR (https://www.ebay.co.uk/itm/20-Large-PeaceMAT-XR-Car-Sound-Deadening-Sheets-Vehicle-Audio-Speaker-Mat-Van/252645554812?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649) for my car and I will also buy some for my next speaker project.

Once you've done that you can line the walls with wool underlay (make sure it isn't sealed with plastic), acoustic foam (open cell) or polyester wadding (or all three). Just make sure you keep it well away from the midbass or bass driver and port. Otherwise you will lose bass. Done propery, I find it tightens up tha bass of a ported speaker.

[Macca]

Felt will damp down some high frequencies so that's why there is some stuck to the back of the tweeter, because it's a flat metal surface. But if you removed it then it's pretty unlikely that you'd notice any difference.


There's no hard rules with this sort of thing, Some advocate no damping at all. Some advocate stuffing the box full and then you've got all points in between. In my own experience designing and building some large-ish infinite baffles I tried the full range of options over the course of time and found no damping at all to give the best sound.

However the cab walls were pretty thick, 3 quarter inch all round. Many commercial speakers have cabs that are as light and flimsy as they can get away with so heavy damping becomes a necessary evil. In my opinion it reduces clarity and bass quality. But that's just my opinion/experience, plenty will disagree.

[YNWaN]

The felt on the back of the tweeters is just to absorb/damp internal cabinet reflections and will be extremely minimal in effect.

[philv]

Thank you or the replies.

Any recommendations for glue to use for felt?

[fatmarley]

https://www.amazon.co.uk/904-Roof-Felt-Adhesive-adhesive/dp/B0073S7AKA

I bet it stinks though and takes a while to go off (set)... Maybe a contact adhesive would be better.

[JohnG]

Can you supply the Speaker Model that you are planning on doing the work to.
There may be information known off that will benfit your plan.

[fatmarley]

http://www.troelsgravesen.dk/cabinet-damping.htm

[walpurgis]

http://www.troelsgravesen.dk/cabinet-damping.htm

Yes, classic form of damping. Much the same way as I do it. I'd give the bass port a bit more free space though.

[philv]

I'm thinking bostik carpet glue.
say sit is for felt underlay as well.

https://www.diy.com/departments/bostik-carpet-adhesive/3549212472603_BQ.prd

Not keen on spray contact adhesives.

[fatmarley]

I'd give the bass port a bit more free space though.

Agree. Too close to the port imo.

[philv]

Petroleum based.
The other half will love that.
They will instantaneously become garden speakers!

[philv]

Can you supply the Speaker Model that you are planning on doing the work to.
There may be information known off that will benfit your plan.

JBL L26.
I am upgrading to the Gravesen crossovers and replacing the internal damping as per his recommendations.

Jantzen 8mm felt, with jantzen polyester accoustilux on top.

All ordered....just can't get the glue he recommends in the uk.
Though he does recommend a bostik product.

[walpurgis]

All ordered....just can't get the glue he recommends in the uk.
Though he does recommend a bostik product.

Use any brand of aerosol carpet contact adhesive on both mating faces, let it dry until tacky and push firmly into place.

Try B&Q or ebay or of course a carpet shop, but they'll be pricey.

[JohnG]

I've had a look at the site your taking instruction from.
Are you going to the extent of the additional internal bracing shown in the 3 way version ?
The additional bracing will have a positive effect on the cabinet, and the removable front panel will aid any further exercises in the use of damping.
As the drivers in use should be run in, they will remain consistent in their presentation,this leaves scope to attenuate the speakers with use of your damping material to obtain your preferred end product.

[Chris]

When I built my WD25t speakers I used Arboseal GZ tape, as recommended by Peter Comeau in his kits, over all the inner faces of all panels and braces erc. Tedious but worth it I think, my boxes are extremely inert. My knuckles bear witness. I think it’s butyl rubber and self sticking by its nature, none of it has ever come unstuck..

[philv]

I've had a look at the site your taking instruction from.
Are you going to the extent of the additional internal bracing shown in the 3 way version ?
The additional bracing will have a positive effect on the cabinet, and the removable front panel will aid any further exercises in the use of damping.
As the drivers in use should be run in, they will remain consistent in their presentation,this leaves scope to attenuate the speakers with use of your damping material to obtain your preferred end product.

A Refoam, new crossovers/wirign/binding posts, and new damping material.
is as far as it goes.

[philv]

Hum.
So i felted the internal panels with 8mm felt.

But the polyester damping that arrived is only 10 to 15mm thick.
I was expecting 30mm.

Is 10 to 15mm going to be ok?
Not much different to the fibreglass original material i took out.