Does anyone have data they are willing to share about a thermal set procedure for Quad esl 57 diaphragms?
The quad esl rebuild sites make no mention of this process, but there are some references to it on the internet (including on this forum, in an old post).
I'm not referring to heat shrinking dust covers, or even tensioning by heat shrinking. As I understand it, Quad used a weighted jig to mechanically tension the diaphragm, before thermally setting (annealing) it in an oven, prior to elvamide coating, and stator glueing.
There is some information about weighted jigs, and a few kind people who'll share data about weights even - but far less information about thermal setting (so little, that I even wondered if it was a joke at first).
I've tried contacting DuPont, but never got a reply, so any information would be appreciated.
The quad esl rebuild sites make no mention of this process, but there are some references to it on the internet (including on this forum, in an old post).
I'm not referring to heat shrinking dust covers, or even tensioning by heat shrinking. As I understand it, Quad used a weighted jig to mechanically tension the diaphragm, before thermally setting (annealing) it in an oven, prior to elvamide coating, and stator glueing.
There is some information about weighted jigs, and a few kind people who'll share data about weights even - but far less information about thermal setting (so little, that I even wondered if it was a joke at first).
I've tried contacting DuPont, but never got a reply, so any information would be appreciated.
At this link:
http://www.onethingaudio.net/FOR/QUA/GEN/9512-QUA-GEN-HIS-RW.htm
You'll find this quote, from Ross Walker (son of Peter Walker).
"We stretch it up to the required tension and stick it in the oven. In its cold form, if you stretch it, it will creep. But by putting it in the oven under tension all the molecules will line up to the most stable position so the tension won't change. This is quite important because otherwise the resonance of the speaker would change and it is carefully designed to a particular value. If it was too slack it would hit the plates, too tight the resonance would be too high. Secret ingredient X is used as a damping layer on the Mylar and then we bond the frame to the electrode structure."
"So you stretch it, stabilise it then bond it to one side of the electrodes. It is a push pull device with two stators and one moving diaphragm in between."
There are also a couple of posts on this forum, and also on audioasylum somewhere. I emailed one person who claims to know about this, and they replied saying that they'd like to "keep the last secret of the professional rebuilders".
Fortunately another person I've contacted emailed me some details, that the diaphragm does indeed need to be heated after tensioning, but before it's glued to the stator.
I'd read the Ross Walker interview some years ago, and originally had thought that he was having some sort of joke, but later realised that he was quite serious, and that annealing the diaphragm is a part of the process recommended by DuPont to Quad.
http://www.onethingaudio.net/FOR/QUA/GEN/9512-QUA-GEN-HIS-RW.htm
You'll find this quote, from Ross Walker (son of Peter Walker).
"We stretch it up to the required tension and stick it in the oven. In its cold form, if you stretch it, it will creep. But by putting it in the oven under tension all the molecules will line up to the most stable position so the tension won't change. This is quite important because otherwise the resonance of the speaker would change and it is carefully designed to a particular value. If it was too slack it would hit the plates, too tight the resonance would be too high. Secret ingredient X is used as a damping layer on the Mylar and then we bond the frame to the electrode structure."
"So you stretch it, stabilise it then bond it to one side of the electrodes. It is a push pull device with two stators and one moving diaphragm in between."
There are also a couple of posts on this forum, and also on audioasylum somewhere. I emailed one person who claims to know about this, and they replied saying that they'd like to "keep the last secret of the professional rebuilders".
Fortunately another person I've contacted emailed me some details, that the diaphragm does indeed need to be heated after tensioning, but before it's glued to the stator.
I'd read the Ross Walker interview some years ago, and originally had thought that he was having some sort of joke, but later realised that he was quite serious, and that annealing the diaphragm is a part of the process recommended by DuPont to Quad.
Hi,
naaa, an additional coating wouldn´t do the job. The high Q of the tightly stretched membrane needs damping. This is often done with a felt mat or something similar to introduce mechanical damping into the system. ´secret ingredience X´ is probabely a piece of felt or cloth or foam on the backside of the panel.
jauu
Calvin
naaa, an additional coating wouldn´t do the job. The high Q of the tightly stretched membrane needs damping. This is often done with a felt mat or something similar to introduce mechanical damping into the system. ´secret ingredience X´ is probabely a piece of felt or cloth or foam on the backside of the panel.
jauu
Calvin
Frank,
With regard to this comment:
>>Secret ingredient X is used as a damping layer on the Mylar<<
I think it was a slip of the tongue (the interview seems to have been done while walking around the Quad factory). The "secret ingredient" is just the Calaton itself, in my opinion. In that case, he used the term damping layer incorrectly. Nowadays everyone knows about the nylon coating, but his other comments about the oven are more interesting, I think.
It's widely reported that Wayne Picquet makes excellent panel rebuilds, and I've seen it mentioned (on audio asylum I think) that he is one of the few people who anneals panels. Gary Jacobson also refers to Wayne using an "industrial secret" on his page. Seems to me that the "secret" is the thermal set process, which DuPont advised Peter Walker to use when making the original Quad ESL.
With regard to this comment:
>>Secret ingredient X is used as a damping layer on the Mylar<<
I think it was a slip of the tongue (the interview seems to have been done while walking around the Quad factory). The "secret ingredient" is just the Calaton itself, in my opinion. In that case, he used the term damping layer incorrectly. Nowadays everyone knows about the nylon coating, but his other comments about the oven are more interesting, I think.
It's widely reported that Wayne Picquet makes excellent panel rebuilds, and I've seen it mentioned (on audio asylum I think) that he is one of the few people who anneals panels. Gary Jacobson also refers to Wayne using an "industrial secret" on his page. Seems to me that the "secret" is the thermal set process, which DuPont advised Peter Walker to use when making the original Quad ESL.
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