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Greg Stewart 30th November 2003 09:16 PM

Felt-covering planar speakers for diffraction/reflection redux?
I just recently covered all the exposed front face of my Eminent Technology LFT-VI's with Dynamat Extreme... nice improvement there, smoother response and a couple of levels of details were revealed, especially at lower levels. The amount of improvement surprised me, before I did the damping, I tried playing them loudly and feeling the areas I planned to damp and could not feel much if any vibration. If you have similar speakers (LFT-VIII's, Maggies, etc.) you def wanna do this!
Next step is to damp the back surfaces(I'll use regular Dynamat here to reduce the possibility that any resonances of the damping materials add) and to cover the front with felt to reduce sideways radiation, diffraction, and reflection off the speaker faces. Also I suspect it'll even damp it further. I got some carpet underlayment felt... from what I've read in the archives, it won't be the best available, but it was relatively easy to find, inexpensive, and will be a LOT better than no material.

My questions:

1. Anyone done this to this or a similar speaker? If so, what should I expect to hear and what should I watch out for?

2. I'm planning to use a combination of water-based contact cement on the felt and double-stick tape on the speakers to attach the felt. Good idea, bad idea, other suggestions?

3. I can choose to lay the felt just on the front face of the speaker and end at the edge or wrap it around the decorative wood edging. I think wrapping will provide more benefit by reducing reflections/refractions off the edges of the speakers and improve imaging and the speakers 'disappearing', but will be a LOT more work. Worth it or not?


Greg in Minneapolis

planet10 1st December 2003 01:11 AM

wool felt works better than synthetic felts, and a substantial thickness is recommended. I'd go to the effort of wrapping around the edges.


Greg Stewart 1st December 2003 03:48 AM


Thanks for your input.

I checked... I'm pretty sure the felt pad I got is synth, not wool... oh well, I suspect it'll still be a LOT better than a bare speaker. The material's about 1/4" thick, so I think this is good.

I'm with you, I'm thinking that wrapping the edges will be worth it. I think one very overlooked aspect of speaker performance is reflections off the speaker body... even indirect ones that have already come off the walls, floor, or ceiling. Reducing them should help minimize speaker localization, having the speaker disappear instead of drawing attention to itself.

I'll post again when it's done and report the results.

Greg in Minneapolis

Greg Stewart 1st December 2003 04:42 AM

Brought back memories!

I just checked out your website... your driver info reminded me of my 1st stereo project, a pair of KEF T27/B110-based speakers in a stepped-baffle truncated pyramid box... ugly things, but they made ok sounds. Then I decided they were too ugly and bought a pair of boxes that a friend of mine had made that looked like the head from a pair of old KEF 105's... at least these were painted!

That was back in 1978 or so... ancient history!

Thanks for jogging the memories!

Greg in Minneapolis

planet10 1st December 2003 04:50 AM

Re: Brought back memories!

KEF T27/B110

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