Hi,
I´m searching for very thin layers of Polyurethane-foam with open pores(!)
Thicknes: ~1mm (1/25inch)
Pores: 50-100PPI
Material: Polyurethane preferred, Polyethylene possible
My inquieries up til now lead to the resut, that companies cutting a layer from a solid block of foam will sell at minimum 2mm thickness
Does anyone have infos about a source providing the very thin stuff?
Thanks
Calvin
I´m searching for very thin layers of Polyurethane-foam with open pores(!)
Thicknes: ~1mm (1/25inch)
Pores: 50-100PPI
Material: Polyurethane preferred, Polyethylene possible
My inquieries up til now lead to the resut, that companies cutting a layer from a solid block of foam will sell at minimum 2mm thickness
Does anyone have infos about a source providing the very thin stuff?
Thanks
Calvin
Hi Calvin,
the only i found is www.modulor.de
They have very open foams but lowest thickness is 3mm.
I guess you want to put the foam in between the membrane and the stator to damp the fundemental and other resonances.
I tried that on a 3mm distant stator-membrane ESL with the foam described above. Works in principle but depending on the losses of the foam material field densitiy in the air gap is significantly compromised.
Capaciti
the only i found is www.modulor.de
They have very open foams but lowest thickness is 3mm.
I guess you want to put the foam in between the membrane and the stator to damp the fundemental and other resonances.
I tried that on a 3mm distant stator-membrane ESL with the foam described above. Works in principle but depending on the losses of the foam material field densitiy in the air gap is significantly compromised.
Capaciti
Hi Großer ,-)
habe mal mit 2mm und kleiner Fläche (Europakarte) versucht, jedoch keinen nennenswerten Pegel erzielen können. Allerdings sind F-gang und Step besser als mit Luft-Dielektrikum. Die Grundreso fehlt völlig, dafür ein sauberer Anstieg/Abfall. Mit Schaum müssten sich eigentlich eine markante Vorteile ergeben. Ich weiss aber im Augenblik noch nicht, wo die Verluste herkommen sollen, die Du erwähnst. Mit epsilon deutlich unter 2 und Verlustwinkeln unter 0,05 sollten die Pegel eines Luftdielektrikums ebenfalls erreicht werden??!!
Habe jetzt eine Quelle entdeckt für offenporigen Silikonschaum bis unter 1mm Stärke.
Werde das weiterhin versuchen, weil die theorischen Vorteile beträchtlich wären.
Gruss
Calvin
ps: Deine ´blaue´ Beschichtung läuft gut und stabil ;-)
habe mal mit 2mm und kleiner Fläche (Europakarte) versucht, jedoch keinen nennenswerten Pegel erzielen können. Allerdings sind F-gang und Step besser als mit Luft-Dielektrikum. Die Grundreso fehlt völlig, dafür ein sauberer Anstieg/Abfall. Mit Schaum müssten sich eigentlich eine markante Vorteile ergeben. Ich weiss aber im Augenblik noch nicht, wo die Verluste herkommen sollen, die Du erwähnst. Mit epsilon deutlich unter 2 und Verlustwinkeln unter 0,05 sollten die Pegel eines Luftdielektrikums ebenfalls erreicht werden??!!
Habe jetzt eine Quelle entdeckt für offenporigen Silikonschaum bis unter 1mm Stärke.
Werde das weiterhin versuchen, weil die theorischen Vorteile beträchtlich wären.
Gruss
Calvin
ps: Deine ´blaue´ Beschichtung läuft gut und stabil ;-)
Calvin,
In case you might think that the open cell ESL construction is something new or unique - check the Stanton Isophase ESL!
I found one.
The foam was dead.
Rebuilt it with new foam.
Had similar issues finding thin foam.
Found that the foam impedes good bass reproduction.
Not so great across the range either...
_-_-bear
In case you might think that the open cell ESL construction is something new or unique - check the Stanton Isophase ESL!
I found one.
The foam was dead.
Rebuilt it with new foam.
Had similar issues finding thin foam.
Found that the foam impedes good bass reproduction.
Not so great across the range either...
_-_-bear
Hi,
You´re right As with most points regarding ESLs, nearly everything has been said or done sometime by somebody already before.
Still though, if You plan on a panel for a hybrid ESL the usage of thin foam has some distinct advantages in theory, I´d like to proove in praxis. Higher efficiency, no ground resonance (You can design the freqency range and behaviour by the ´parameters´ of the used foam), less problems with standing wave effects --> lower distortion, translatory movement of diaphragm instead of bowing, improved dynamic headroom and easier to build and longer lasting since You wouldn´t need to take care much of diaphragm tension.
It almost sounds to good to be true, doesn´t it? And thats why I want to try out where the pitfalls lie ;-)
jauu
Calvin
You´re right
As with most points regarding ESLs, nearly everything has been said or done sometime by somebody already before.Still though, if You plan on a panel for a hybrid ESL the usage of thin foam has some distinct advantages in theory, I´d like to proove in praxis. Higher efficiency, no ground resonance (You can design the freqency range and behaviour by the ´parameters´ of the used foam), less problems with standing wave effects --> lower distortion, translatory movement of diaphragm instead of bowing, improved dynamic headroom and easier to build and longer lasting since You wouldn´t need to take care much of diaphragm tension.
It almost sounds to good to be true, doesn´t it? And thats why I want to try out where the pitfalls lie ;-)
jauu
Calvin
Hi,
the danger of developing leakages over time is there, alright, but so it is with any other ESL too. The foam can be treated, such that it has hydrophobic quality.
I´d like to know if anyone has made some positive or negative experiences with foam yet.
My first test showed excellent results apart from efficiency, which was exceptionally bad. Anyone suggestions what might be the prob (field density, field strength?)
jauu
Calvin
the danger of developing leakages over time is there, alright, but so it is with any other ESL too. The foam can be treated, such that it has hydrophobic quality.
I´d like to know if anyone has made some positive or negative experiences with foam yet.
My first test showed excellent results apart from efficiency, which was exceptionally bad. Anyone suggestions what might be the prob (field density, field strength?)
jauu
Calvin
Member
Joined 2003
Calvin,
The foam may be slightly conductive to begin with. Can you check potential on the film itself?
I once tried a very thin, very open, random weave polyester from a fabric shop (like batting except very thin). It worked, but the film slapped against the weave which obviously sounded terrible. This was with a full-range signal, so something similar might work with a high-pass filter.
Paul
The foam may be slightly conductive to begin with. Can you check potential on the film itself?
I once tried a very thin, very open, random weave polyester from a fabric shop (like batting except very thin). It worked, but the film slapped against the weave which obviously sounded terrible. This was with a full-range signal, so something similar might work with a high-pass filter.
Paul
Have you considered...
fluid damping of the outer edge of the diaphragm? This could be done with ferro fluid and some magnets. For the sake of discussion lets assume that you take necessary measures to keep charge away from the fluid.
Another old idea I had from a couple of decades ago was to use an out of phase periferal strip of stators. Just wide enough to off set some of the diaphragm energy. Just throwing some additional ideas into the pot. Regards Moray James.
fluid damping of the outer edge of the diaphragm? This could be done with ferro fluid and some magnets. For the sake of discussion lets assume that you take necessary measures to keep charge away from the fluid.
Another old idea I had from a couple of decades ago was to use an out of phase periferal strip of stators. Just wide enough to off set some of the diaphragm energy. Just throwing some additional ideas into the pot. Regards Moray James.
sure be calm...
just inserting some ideas that I honesly thought might interest you. You could try contacting Bill Perkins at pearl-hifi.com. Bill used open cell foam of the thickness you are interested in for the surround of his tweeter. I have called Bill but not had any response regarding this. So in the intrim I figured I would suggest some different ideas just to add some fule to the fire. Hope Bill can be of some assistance. In the mean time...
just inserting some ideas that I honesly thought might interest you. You could try contacting Bill Perkins at pearl-hifi.com. Bill used open cell foam of the thickness you are interested in for the surround of his tweeter. I have called Bill but not had any response regarding this. So in the intrim I figured I would suggest some different ideas just to add some fule to the fire. Hope Bill can be of some assistance. In the mean time...
Calvin,
By all means go ahead and experiment.
My brief foray into the rebuild of the Stanton Isophase did not have very excellent results.
If you expect the foam to be linear, like air, it is not.
Foam is much much stiffer than air.
If you expect to be able to have large excursions, you can't.
It might fly for an ESL HF section...
The main benefit is that you can curve it in theory.
I found controlling the foam's shape was non trivial.
Also preventing compression of the foam and still mounting it was non-trivial.
Plus foam likes to disintegrate in the presence of O3, unless perhaps you find some specialized foam material in the required thinness...
A difficult thing to master, imho.
keep us posted!
_-_-bear
By all means go ahead and experiment.
My brief foray into the rebuild of the Stanton Isophase did not have very excellent results.
If you expect the foam to be linear, like air, it is not.
Foam is much much stiffer than air.
If you expect to be able to have large excursions, you can't.
It might fly for an ESL HF section...
The main benefit is that you can curve it in theory.
I found controlling the foam's shape was non trivial.
Also preventing compression of the foam and still mounting it was non-trivial.
Plus foam likes to disintegrate in the presence of O3, unless perhaps you find some specialized foam material in the required thinness...
A difficult thing to master, imho.
keep us posted!
_-_-bear
Hi,
depending on the shore value of the foam up to 50% of compression should be possible with acceptable linearity. Still though the stiffness could be too high to get conssiderably lower than ~1kHz, but it might be possible to use foam with a hole pattern in it -thinking of kind of a net structure (using quadratic holeshapes of less than 10mm sidelength). This would yield numerous very small and freely vibrating membrane segments and lots of soft supporting points.
A very serious point is O3 stability. Thanks, I´ll have to check on that!
Great Input from Your´s
jauu
Calvin
ps. couldn´t find any useful material about the Stanton Isophase yet, but I´ll keep on
depending on the shore value of the foam up to 50% of compression should be possible with acceptable linearity. Still though the stiffness could be too high to get conssiderably lower than ~1kHz, but it might be possible to use foam with a hole pattern in it -thinking of kind of a net structure (using quadratic holeshapes of less than 10mm sidelength). This would yield numerous very small and freely vibrating membrane segments and lots of soft supporting points.
A very serious point is O3 stability. Thanks, I´ll have to check on that!
Great Input from Your´s
jauu
Calvin
ps. couldn´t find any useful material about the Stanton Isophase yet, but I´ll keep on
From memory...
I think that Bill used a combination of siliconized Latex sealent (water based) mixed with India ink (to block UV) diluted with water. The foam was saturated in the solution then squeezed dry and left to dry. This means that you probably want to start with a lighter density foam as the sealant will stiffen it up some. You might also consider replacing the India Ink with a high SPF sun screen. You can expect a foam like this to last 10 - 15 years in use depending upon local conditions. There are a number of Bill's tweeters still functioning well that are older that this. Have fun. Regards.
PS: I would guess that current day production foams are superior to those made 20 years ago. All depends upon the intended application and exposure. Thin foams of the type you are looking for are commonly used as padded backings for vinyl films used to make them have a nice surface feel as on note book covers etc..
I think that Bill used a combination of siliconized Latex sealent (water based) mixed with India ink (to block UV) diluted with water. The foam was saturated in the solution then squeezed dry and left to dry. This means that you probably want to start with a lighter density foam as the sealant will stiffen it up some. You might also consider replacing the India Ink with a high SPF sun screen. You can expect a foam like this to last 10 - 15 years in use depending upon local conditions. There are a number of Bill's tweeters still functioning well that are older that this. Have fun. Regards.
PS: I would guess that current day production foams are superior to those made 20 years ago. All depends upon the intended application and exposure. Thin foams of the type you are looking for are commonly used as padded backings for vinyl films used to make them have a nice surface feel as on note book covers etc..
Hi,
I appreciate Your support very much, but some of it is really not understandable. You should realize that especially abbreviations that might be common in Your part of the world are not in a different part of the world.
e.g SPF! "Now introducing....S(uper)P)ower)F(orce) the new super hero team of Marvel comics"?
And who is Bill? Kill Bill´s Bill? Billy the Kid? Or a Dollar Bill?
Qs after Qs!
jauuu
Calvin
I appreciate Your support very much, but some of it is really not understandable. You should realize that especially abbreviations that might be common in Your part of the world are not in a different part of the world.
e.g SPF! "Now introducing....S(uper)P)ower)F(orce) the new super hero team of Marvel comics"?
And who is Bill? Kill Bill´s Bill? Billy the Kid? Or a Dollar Bill?
Qs after Qs!
jauuu
Calvin
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.