How low do they go -- JansZen ESL tweeter?
The subject gives the jist... i've a pr of the tweeters from a set of Z-500. Does anyone know where they were crossed and how low this ESL tweeter can go?
(sorry for my english)
very interesting solutions on this ancient speaker!
( 1970-75, right?)
If I well remember , a similar ESL are used in the Wilson Wamm(!) ,
3or 4 units as a "medium" i suppose. I don't know exact specs. of the crossover frequency & slope but I suppose Fr 800Hz 12dB/oct H/P minimum, depends of the power handling target.
Can you take some measurements of it?
From the size I presume a behaviour similar to a BG neo 8 , in the same radiation conditions of course ( without "double" horn).
Good chances of beautiful sound :)
best regards from Venezia
Ah, the familiar blue plastic! Radio Shack sold these for a while, too. They'll take a pretty hefty bias voltage.
I experimented with them some years back. JansZen never really got their crossover right, and no wonder- the unit really doesn't do well below 3-4K, then gets mighty beamy in the top octave. A tough match for a big woofer like they used. Arrays of them could probably do better, but I only had two.
I could see this in a dipole taking over from a full-range driver to cover the top octave and a half.
Iirc, the practical LF limit is 1500 Hz.
They are not little "squares" they are actually  rectangular lenthwise strips... as far as the internal cell construction.
I think 1500vdc is the practical bias limit.
They tend to fail where the center/diaphragm connection is.
They were graphite on mylar.
Once you get the bias too high they "fizz"...
They're not the cleanest ESL tweeters, and get worse the more you push them. Using a better *iron* for the matching xfmr might help in that regard. To replace simply measure the turns ratio and get some iron that is better with the same ratio...
Of course, with an ESL the ratio effects the relative sensitivity and the LF rolloff as well as the bandpass characteristic. So there is some yin/yang to play with in that area.
They were used in a number of notable speakers including the KLH ESL and cut in half in the Infinity Servo Static, later RTR adopted the 1/2 cell design in their blue tweeters...
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