Experience with Spectra deflex panels?

[Rocky]

Does anyone have any experience using the Spectra Dynamics polyurethane Deflex panels and accessories? Are they worth their $$$?

[Rocky]

Or the "Black Hole 5" dampening sandwich? polyurethane based too.. My target application is a midbass chamber..

[ingvar ahlberg]

Black holes are no good in Your home, all loose stuff like carkeys, cash, Your glass of single malt and even the cat tend to dissapear into them.

[moving_electron]

I have used the panels on the back wall of a couple of pair of Fostex FE167E based bookshelf reflex. And was happy with them by themselves and they seemed to keep the detail while getting rid of the harshness problems of an empty box. But when I lined the rest of the walls with normal stuffing they sounded muted and not very detailed.

The deflex panels and some very light intermittent stuffing here and there on the walls was pretty much the best initially. Any additional stuffing mutted the detail.

But on the last pair though I put deflex panels on the back and Wispermat on the sides. This was by far the best. Seems odd since this seems counter to the experience in the same speaker design when I adding "stuffing" lining to the walls.

I have continued to use Whispermat for the next couple of pairs of speakers I built (without the deflex panels andd have been very happy with the results.

Wispermat is a foam+dampening mat similar to the Blackhole concept (but much cheaper). It is a commercial product for sound reduction. One has to buy at least a large sheet per order . I have used the sheet on three pairs of bookshelf speakers and still have some left. I'll bring some to the NWWA DIY if any one wants to check it out.

Here is what got me interested in Whispermat.

http://home.new.rr.com/zaph/audio/whispermat.html

[Rocky]

Electron:

How would you say impact on detail is on all-whispermat versus all-deflex? For me, on this project price is not a very big issue. Not because I'm rich, but because it's small 10 liter monitor speakers using very expensive drivers, thus there is no need to make cost compromises in dampening material..

I am planning on a quite thin enclosure structure though, to keep the monitor size down, using a sandwich of 6mm MDF/1mm viscoelastic glue/1mm lead/1mm viscoelastic glue/1mm lead/1mm viscoelastic glue/6mm MDF (total thickness of 18mm) and would also like my dampening material to consume as little space as possible, still with an absolute minimum of sacrifices.

Dampening material volume taken into consideration, would you say I am looking at the Spectra Deflex panels?

[Rocky]

I think I just stated that 6mm+5mm+6mm=18mm.. It's getting late.. but it was damn close though

[moving_electron]

Originally posted by Rocky
Electron:

How would you say impact on detail is on all-whispermat versus all-deflex? For me, on this project price is not a very big issue. Not because I'm rich, but because it's small 10 liter monitor speakers using very expensive drivers, thus there is no need to make cost compromises in dampening material..

I do not really have a direct comparison because I have not done and all deflex version. The all Whispermat version I have done is a different speaker with less detailed drivers so I don't have analytical data. So "unencumbered by the facts, I will speculate".

It seems to me that the Deflex panels and the Whispermat likely has different properties at different frequencies. So a mix is certainly appealing. It would seem that the deflex panel only would be somewhat suspect.

Whispermat only seems to work well. John Krutke uses it in his Seas L15RLYP / 27TFFC System. I believe these are generally regarded as drivers with a lot of detail, and the speaker seems to have gotten good reviews at DIY events.

http://home.new.rr.com/zaph/audio/audio-speaker12.html

Supporting evidence for this approach also is the Blackhole only implementations of some very well regarded designs (example MBOW1).

[i]Originally posted by Rocky [./i]

I am planning on a quite thin enclosure structure though, to keep the monitor size down, using a sandwich of 6mm MDF/1mm viscoelastic glue/1mm lead/1mm viscoelastic glue/1mm lead/1mm viscoelastic glue/6mm MDF (total thickness of 18mm) and would also like my dampening material to consume as little space as possible, still with an absolute minimum of sacrifices.

Dampening material volume taken into consideration, would you say I am looking at the Spectra Deflex panels?

Whether or not the Whispermat is thicker than the Deflex panel depends on whether or not you are counting the foam layer or not. If you are not counting the foam and just the damping layer then it is thinner than the Deflex panel.

I would worry that an all Deflex panel lining would only get at some frequencies. Again, speculation on my part. If I was not going to try a mix and was chosing one or the other, I would go with all Whispermat because this kind of approach seems reasonably well proven in these kinds of boxes.

By the way here is a note from the building instructions of the MBOW1 that might be pertinent:
"Do not run the BlackHole all the way to the front baffle. Leave at least an inch bare so that it does not interfere with the woofer's backwave."

[Rocky]

Forgive me for putting up such a critical point of view, but why would the Whispermat/blackhole reveal any more detail than conventional bitumen stuffing? despite the inner polyurethane layers, their outter foam layer still damp soundwaves in the usual stuffing manner? No?

Making the assumption I would find the whispermat fit for my project (I read the article, so I assume I can compare it to the BlackHole 5), And would follow the advice of leaving 1 1/2 inch space at the front baffle, would this 1 1/2 inch space (+ the front baffle), in your opinion, have a benefit of a non-foam polyurethane layer like the Deflex mat?

[pinkmouse]

Tried Deflex panels, they seemed to make no difference from an undamped box...

[sreten]

Some uf us regard the deflex panels as basically a con.

Reputable DIY retailers like Falcon Acoustics in the UK refuse to sell it.

Basically because it doesn't do what is says on the tin.

For reflex box's quality acoustic foam lining is best.

(Presuming you regard the lead damping as enough
mechanical damping of the enclosure walls.)

Bulk filling, Polyfill, Dacron etc can be used away from the port
exit to affect box airspace Q and bass damping to an extent.

sreten.