Charlie, sorry for questioning this, i have 1000% in your design and of course your diaghphram coating, i just have to allways ask questions, thats just me, anxiuos and trying to be patient as this is a diy project, so respect to senior members and builders have my up most respect. sincerely, Mavric
According to the Acoustat factory tour file I've seen several places on the internet:
Acoustat, Acoustat Factory, Photo Tour
"The conductive coating is a proprietary mixture of several solvents, dissolved plastics, and carbon black."
You might try contacting Moray James.
From Audio Circuit, answers for all thing Acoustat
Acoustat
"Hello Andy. What did Acoustat use for the conductive coating on the mylar film? What is the stator to diaphgram spacing. Thanks in advance.
Andy Szabo (2004-02-23): The conductive coating was a proprietary formulation developed by a chemist under contract to Acoustat. I don't have the formula, and it probably remains the intellectual property of whoever owns Acoustat today. I do know it contained carbon black, several solvents, and dissolved plastics. The solvents and plastics helped the coating bond to the mylar diaphragm, and the carbon black was ground to yield a specific resistivity.
Incidentally, Acoustat's coating was re-formulated in the late 1980's to have a higher resistivity, and thereby operate closer to the ideal ”constant charge”. This allowed the speaker to produce higher dynamic peaks without ”crackling”, and eliminated the random discharges sometimes observed in high humidity conditions. Panels made with the ”new” coating have a bias wire that is yellow with a red stripe. Older panels had either a solid red or white/red striped bias wire. The new coating did not change the sonic character of the speaker, but did considerably increase its dynamic cabability, most noticeably on the smaller models. All Spectra models were produced with this new coating, as well as the very last of the predecessor models.
The diaphragm-to-wire spacing for Acoustat was about 2.5 mm."
Thanks Atom and Bolserst,
And yes I have read all the stuff at Audio Circuit.
I find it interesting that all manner of reverse engineering and speaker cloning exists in the most upper tier of high fidelity loudspeaker with no hint or very little that anyone ever gets sued for legal infringement, yet the "proprietary" formula for Acoustat coating is still a mystery. I wonder if it is indeed similar or almost exactly the oxide coating used in the high bias"chromium" magnetic recording tape of those days, since Jim Strickland worked in that industry if I'm not mistaken.
Anyway it is something I really would like to find out. As for "proprietary" technology owned by the current Chinese owner of Acoustat brand I'd say that it is many years outside of protection. So I'd really like to know the chemist/s or from Jim himself or anyone else who whipped up batches of the stuff just what it is. I really believe protecting old tech like this serves no purpose. Other than to drive up the demand and price of old Acoustat panels.
And yes I have read all the stuff at Audio Circuit.
I find it interesting that all manner of reverse engineering and speaker cloning exists in the most upper tier of high fidelity loudspeaker with no hint or very little that anyone ever gets sued for legal infringement, yet the "proprietary" formula for Acoustat coating is still a mystery. I wonder if it is indeed similar or almost exactly the oxide coating used in the high bias"chromium" magnetic recording tape of those days, since Jim Strickland worked in that industry if I'm not mistaken.
Anyway it is something I really would like to find out. As for "proprietary" technology owned by the current Chinese owner of Acoustat brand I'd say that it is many years outside of protection. So I'd really like to know the chemist/s or from Jim himself or anyone else who whipped up batches of the stuff just what it is. I really believe protecting old tech like this serves no purpose. Other than to drive up the demand and price of old Acoustat panels.
Acoustat coatings "look" thick. Maybe cause its so black.
When I put my DMM on VCR tape, both chromium dioxide, and metal I read zero, even when the probes are only separated by a mm.
Is this so, or does my meter not read sensitive enough.
Also wondering if extra thin coats increases resistance?
When I put my DMM on VCR tape, both chromium dioxide, and metal I read zero, even when the probes are only separated by a mm.
Is this so, or does my meter not read sensitive enough.
Also wondering if extra thin coats increases resistance?
Acoustat did not know what was in the coating they used. It sticks really well but it never (even the second version) had high enough resistance. It is all a mute issue as there are better products available today. It is way too heavy anyway so why would you bother with spending time on it? That coating worked at the time and it lasted so it did the job end of story. You could make up some of the liquid nylon that Quad used it lasts longer and has way higher resistance (low gig ohms) or you could buy a can of Lycron or or or. There is no mystical magic in the coating Acoustat used, it needs to be replace and there are a lot of good options available. To attempt to copy Acoustat's formula would be a step backwards.
I agree wth you on that moray james.
If I rememeber correctly,I had read a few articles back in 2003 about acoustat plauged with coating problems also ,such as, cracking and seperation from the mylar.
Which lead to articles of refurberation.
Which was how I actualy found out how they were built in the first place. jer
If I rememeber correctly,I had read a few articles back in 2003 about acoustat plauged with coating problems also ,such as, cracking and seperation from the mylar.
Which lead to articles of refurberation.
Which was how I actualy found out how they were built in the first place. jer
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