A Monster Construction Methods Shootout Thread

[Sin Phi]

I assume it is something like this, https://www.amazon.com/ROSEROSA-Prof.../dp/B07Z32Z8WB

Though what is more typically used in speakers is the same stuff as cars, https://www.amazon.com/Noico-deadeni...dp/B00URUIKAK/

That is the 80mil version, there are thinner butyl layers like 50mil out there as well. I have yet to build a speaker box with the butyl, but cars and right behind my headboard of my bed outside is the water heater box. Really thin galvanized metal that just made an incredible racket in the wind and rain. Use that to fix it up right. Sound is reduced and what is left is lower pitch.

[augerpro]

Seems similar to the Resonix I tested

[jzagaja]

Alu with butyl is used for damping cars. Good damping is necessary for elastic plywood 5mm.

[Rnp73]

Newb(ish) suggestion...

I've been going off this for designing a new system: https://qualia.webs.com/newdampingfactors.htm

Which, when the info is put in order (and taking out anything over 300hz) looks like this:

material frequency damping factor
tungsten loaded putty 80 0.725
'Permali' 18mm 220 0.688
'Permali' 6mm 250 0.671
'Newplast' 160 0.635
bentonite filled resin 48 0.618
'Panzerholz' 150 0.599
lead filled resin 100 0.592
bentonite powder filled resin 100 0.518
glass 'Butacite' laminate 150 0.391
'Pyrotek' 6mm 100 0.376
recycled rubber crumb 109 0.348
glass 'Sentryglas' laminate 247 0.317
Page Lacquer' acrylic over mdf 100 0.315
Plasticine' 77 0.304
...

Tungsten loaded putty is available at fishing supply places but too expensive for a bulk coverage. Good for small area decoupling though! Similarly, Permali and Panzerholz is very expensive - not to mention tough to source. So I don't think they are worth considering given the parameters of this testing.

However, bentonite filled resin looks very interesting (and goes looooww), resin (isophthalic, in this case) is relatively cheap and the bentonite for the non-powder version is standard cat litter. Also cheap, and available everywhere. If it's possible to pour a reasonable thickness in the gap of the enclosures, or even make a quick box out of it, that'd be fascinating to see the results. I've ordered some resin anyway, so I'll be trying it out soon...

If I can find a cheap source of tungsten powder, I'm tempted to try a resin with that in as well.

Anyone else have experience with these materials?

[454Casull]

HiFiCompass talks about a method to reduce the port resonance here:

Puri Bliss - BeWg | HiFiCompass

Do a Ctrl-F for "N.B. Rozen"

[hollowboy]

Originally Posted by Rnp73

Newb(ish) suggestion...

I've been going off this for designing a new system: https://qualia.webs.com/newdampingfactors.htm

I've seen a similar list, which included more composite materials than this one. My main take away from it was that ANY hybrid material is much much better than the base material. e.g. MDF with a thin laminate was truckloads better than basic MDF.

That is: a cheap complex material can be better than a simple expensive one.

Also note that a complex shape (a box, with holes and bracing) probably has massively different damping compared to a flat test panel. e.g. a bell and a gun will ring very differently, even if they are made of the same metal.

Originally Posted by Rnp73

Tungsten loaded putty is available at fishing supply places but too expensive for a bulk coverage. Good for small area decoupling though! Similarly, Permali and Panzerholz is very expensive - not to mention tough to source. So I don't think they are worth considering given the parameters of this testing.

Also: a 31 litre box using 2 litres of cheaper kitty litter goo will probably work better (and be less wasteful of a valuable material) than a 30 litre box using 1 litre of tungsten goo.

Unless you are after exoticism for its own sake, or in a bling competition with a millionaire, I can't see any situation where the expense would be worth the marginal volume reduction.

Originally Posted by Rnp73

However, bentonite filled resin looks very interesting (and goes looooww)

Anyone else have experience with these materials?

I've tried a basic bentonite loaded mix (kitty litter and gloopy glue mixed in a slurry like concrete) to line a cheap ABS plastic PA speaker. In this application, it didn't make much / any difference when compared to an identical untreated speaker.

...but I'd rather be disappointed by $10 of materials than by $500 of materials

I've also done some building with a ply / bamboo laminate, because

1) bamboo has really good damping properties
2) it looks really good
3) it is good to work with (really hard surface, machines very cleanly).
4) the stuff I like comes as 2400 * 1200 * 5mm sheet. It is a single layer that is designed to be laminated to a base layer
5) that 5mm thickness is very forgiving of sloppy workmanship
6) it isn't crazy expensive like Panzerholz (I got 4 sheets for $500 Australian)

I like the aesthetics so much, I've done non-audio projects the same way (e.g. stripped old furniture and re-skinned with bamboo).

The only downsides are
- its hardness (and silicon content) makes it more work to cut, and it probably dulls tools more quickly
- it doesn't respond to tools exactly how wood does (e.g. you can't plane it with hand tools)
- the splinters are different to most woods (they can be really fine and really strong, so they go in deep and break off).

[augerpro]

Originally Posted by 454Casull

HiFiCompass talks about a method to reduce the port resonance here:

Puri Bliss - BeWg | HiFiCompass

Do a Ctrl-F for "N.B. Rozen"

So the last paper I referenced is that Rozen paper, which is the inspiration for the port(s) Harman developed in their paper, which is the basis for my Harman port here. hificompass utilized a rectangle port, and only used Rozen's curve in one dimension. I would like to try in a rectangle port also (but curved in both dimensions) since these ports look ideal for subs, and a rectangle port made with bender board should be easy enough to fabricate.

hificompass doesn't say much about how he tapped the port and dampened the energy, maybe he will chime in.