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#1
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Jansen electrostatic tweeter questions?
I've got an old pair of Jansen speakers with the electrostatic
tweeters. They're four array radiator types.( four inch square or so with four to a box.) I'm thinking about putting them in another speaker box project I'm working on and could use some advice from any who've had any experience with these type of tweeters. One of the individual radiators is badly damaged and I was thinking of paring them down from four to just three as it might be impossible to get replacement parts for anything this old. This shouldn't be a problem should it? Also they've got a heavy buildup of grime on them from extended storage. What's the best way to clean them off? (I was thinking a bit of simple green followed by rinsing with water, then blowing off with compressed air. Or would it be safe to use a contact cleaner? Thanks in advance for any info regarding these units. |
#2
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none wrote:
I've got an old pair of Jansen speakers with the electrostatic tweeters. They're four array radiator types.( four inch square or so with four to a box.) I'm thinking about putting them in another speaker box project I'm working on and could use some advice from any who've had any experience with these type of tweeters. One of the individual radiators is badly damaged and I was thinking of paring them down from four to just three as it might be impossible to get replacement parts for anything this old. This shouldn't be a problem should it? Also they've got a heavy buildup of grime on them from extended storage. What's the best way to clean them off? (I was thinking a bit of simple green followed by rinsing with water, then blowing off with compressed air. Or would it be safe to use a contact cleaner? Thanks in advance for any info regarding these units. ======================================= Please note, it's "Janszen" with a "Z", after their inventor, US Navy engineer Capt. Arthur Janszen. Some of the advertising even had the name as "JansZen" with a big "Z" so people be less likely to confuse the product with "Jensen." Do not use anything liquid on the screens. The polarizing voltage is 1100 volts and if there is any moisture left in them, you will risk arcing or damage when they are turned on. Brush them lightly with a soft brush to remove the dust, or blow them lightly with air. Dropping from four to three screens will drop efficiency, maximum output and power handling by 25%. Many of these, after long storage, will suffer from breakdown of the connection from the center terminal (on the inside of the screen) to the metalized mylar diaphragm. Symptom of this is low or no output. Don't be surprised if it doesn't work. The efficiency of those tweeters is relatively low. At highest output (which was adjusted by altering the polarizing voltage down from the maximum 1100 volts), they were barely a match for the AR-1w (the woofer section of the AR-3). I paired a set with a pair of old AR-2 (tweeters disconnected) once, just as an experiment, and the woofer predominated. Just about any modern woofer is more efficient, due to more powerful magnets and improved materials, and the use of ducted ports on most. Sometimes an old set may have bad rectifiers in the polarizing supply. Early ones had selenium rectifiers that have probably long gone bad. Just be aware if repairing it, that it's an 1100 volt supply. A common 1N4004 diode won't do the job, even though the current draw is minimal. And be very careful poking around inside, for your own safety. That said...if you have a good-working set of Janszen electrostatic tweeters, and they are well matched with your woofers, their performance is glorious, if somewhat beamy due to the four flat radiators. That was my preferred speaker system for years, and although they aren't hooked up now, I still have my two Janszen 130 tweeters, the pair of AR-3, and a pair of cast-frame AR 12-inch woofers which I bought secondhand, for "just in case" replacement parts. -GP |
#3
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Gene Poon wrote about the JansZen electrostatic tweeters:
Many of these, after long storage, will suffer from breakdown of the connection from the center terminal (on the inside of the screen) to the metalized mylar diaphragm. Symptom of this is low or no output. Don't be surprised if it doesn't work. I should have mentioned that in many cases there is a low-cost fix. When the JansZens were popular, I fixed quite a few by installing an external contact to the diaphragm. -GP |
#4
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On 17 Apr 2005 15:13:40 GMT, Gene Poon wrote:
none wrote: I've got an old pair of Jansen speakers with the electrostatic tweeters. They're four array radiator types.( four inch square or so with four to a box.) I'm thinking about putting them in another speaker box project I'm working on and could use some advice from any who've had any experience with these type of tweeters. One of the individual radiators is badly damaged and I was thinking of paring them down from four to just three as it might be impossible to get replacement parts for anything this old. This shouldn't be a problem should it? Also they've got a heavy buildup of grime on them from extended storage. What's the best way to clean them off? (I was thinking a bit of simple green followed by rinsing with water, then blowing off with compressed air. Or would it be safe to use a contact cleaner? Thanks in advance for any info regarding these units. ======================================= Please note, it's "Janszen" with a "Z", after their inventor, US Navy engineer Capt. Arthur Janszen. Some of the advertising even had the name as "JansZen" with a big "Z" so people be less likely to confuse the product with "Jensen." Do not use anything liquid on the screens. The polarizing voltage is 1100 volts and if there is any moisture left in them, you will risk arcing or damage when they are turned on. Brush them lightly with a soft brush to remove the dust, or blow them lightly with air. Dropping from four to three screens will drop efficiency, maximum output and power handling by 25%. Many of these, after long storage, will suffer from breakdown of the connection from the center terminal (on the inside of the screen) to the metalized mylar diaphragm. Symptom of this is low or no output. Don't be surprised if it doesn't work. The efficiency of those tweeters is relatively low. At highest output (which was adjusted by altering the polarizing voltage down from the maximum 1100 volts), they were barely a match for the AR-1w (the woofer section of the AR-3). I paired a set with a pair of old AR-2 (tweeters disconnected) once, just as an experiment, and the woofer predominated. Just about any modern woofer is more efficient, due to more powerful magnets and improved materials, and the use of ducted ports on most. Sometimes an old set may have bad rectifiers in the polarizing supply. Early ones had selenium rectifiers that have probably long gone bad. Just be aware if repairing it, that it's an 1100 volt supply. A common 1N4004 diode won't do the job, even though the current draw is minimal. And be very careful poking around inside, for your own safety. That said...if you have a good-working set of Janszen electrostatic tweeters, and they are well matched with your woofers, their performance is glorious, if somewhat beamy due to the four flat radiators. That was my preferred speaker system for years, and although they aren't hooked up now, I still have my two Janszen 130 tweeters, the pair of AR-3, and a pair of cast-frame AR 12-inch woofers which I bought secondhand, for "just in case" replacement parts. -GP Thanks for all the info. I had these things collecting dust in the back of my warehouse for years and thought it'd be nice to put them in a pair of studio monitors I'm building. Someone had tried to pry out one of the units and cracked it along the edge, it did straighten out though and physically looks fine. They're 5 inch square with the patent # 2,896,025 on the edge if that helps ID them for you. They're really grimey from the long storage and will have to be taken apart for cleaning if you could give me details on how to do that. (I've done alot of electronic repair in my time so it's not beyond my ability, just need the details on these particular electrostats.) If you have links to any sites on these tweeters it'd be a big help. I think they may be the 130's(I've stripped all electronics/drivers out of the boxes). There was nothing on the boxes themselves to indicate model. The power supply/comtrol unit is all solid state with 12 caps, 2 5000 ohm resistors various other small resistors/diodes as well as a transformer coil and the choke coil and cap for the woofer. The control pot is a 20meg wire wound. Hope this helps. I do still have the woofers that came in the boxes and they are in near mint condition. 12 inch with a rubberized 5 pleat edge and heavy cone. They test out really good for being as old as they are. I'd put them up against most made today, will probably put them in some smaller boxes in some future project. Thanks again for all the info. |
#5
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none wrote:
Someone had tried to pry out one of the units and cracked it along the edge, it did straighten out though and physically looks fine. They're 5 inch square with the patent # 2,896,025 on the edge if that helps ID them for you. They're really grimey from the long storage and will have to be taken apart for cleaning if you could give me details on how to do that. (I've done alot of electronic repair in my time so it's not beyond my ability, just need the details on these particular electrostats.) If you have links to any sites on these tweeters it'd be a big help. ===================== I don't know of any sites about repairing them, but that's mostly because I haven't really looked. I just sort of jumped in, years ago. The JansZen screens can NOT be disassembled for cleaning. They're glued together permanently. All you can really do is to lightly brush or vacuum them to get as much dust out from between the stators and the diaphragm, as you can. -GP |
#6
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Incidentally, there are two different versions of the JansZen
electrostatic tweeter screens. Both are constructed like a sandwich; the diaphragm and fiber spacers are analogous to the meat in a sandwich, and the plastic frames and stators to the bread. On the earlier version, built until about the late 1960s or early 1970s, the plastic frames had the stator wires on the inside only. To the outside, what you saw was the square holes moulded into the plastic, with the stator wire grid behind the holes. In the later version, the stator wires were spiral-wound around the plastic frame. What you saw outside was the actual insulated stator wire; the square holes were still there, underneath them. Old JansZen speakers sent in for repair after the new design was introduced, would come back with the new screens. The factory considered them to be directly interchangeable. Power handling in the JansZen electrostatics was limited by another factor than the usual diaphragm-excursion characteristic of dynamic speakers. If driven too hard, the air between the stators and the diaphragm would ionize and the polarizing voltage would drain off. This resulted in the strange characteristic of increased power to the screen resulting in lower output, but still with low distortion. |
#7
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On 20 Apr 2005 23:59:40 GMT, Gene Poon wrote:
none wrote: Someone had tried to pry out one of the units and cracked it along the edge, it did straighten out though and physically looks fine. They're 5 inch square with the patent # 2,896,025 on the edge if that helps ID them for you. They're really grimey from the long storage and will have to be taken apart for cleaning if you could give me details on how to do that. (I've done alot of electronic repair in my time so it's not beyond my ability, just need the details on these particular electrostats.) If you have links to any sites on these tweeters it'd be a big help. ===================== I don't know of any sites about repairing them, but that's mostly because I haven't really looked. I just sort of jumped in, years ago. The JansZen screens can NOT be disassembled for cleaning. They're glued together permanently. All you can really do is to lightly brush or vacuum them to get as much dust out from between the stators and the diaphragm, as you can. -GP I must have the older ones as there are no external wires. I do believe I can get them apart though, with a bit of care. There are three brass rivets at the bottom which I'll drill out and the three bolt style conact posts holding it together at the top. I really need to get them apart as it's not dust but a heavy film of grunge that won't brush off. I'll use a mild solvent to loosen the glue that holds the plastic frame together. I have a pretty complete work bench of micro tools that I use for servicing micro-electronics in cameras and other electronic devices. I've talked with some diy'ers at an electrostatic forum who've been a big help on general ESL theory and construction tho' I'm still looking around for some sort of exploded diagrahm for these units.(Most have told me that if all else fails it's fairly easy to build a set of flat panels that'll run off the Janszen power supplies.) And from what I've read there are all sorts of improvements in both the mylars and coatings used in electrostats since these were designed. I wouldn't mind having a crack at upgrading these units if the origianal diaphrams are bad. Thanks again for the advice. |
#8
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Gene Poon wrote:
Incidentally, there are two different versions of the JansZen electrostatic tweeter screens. Both are constructed like a sandwich; the diaphragm and fiber spacers are analogous to the meat in a sandwich, and the plastic frames and stators to the bread. On the earlier version, built until about the late 1960s or early 1970s, the plastic frames had the stator wires on the inside only. To the outside, what you saw was the square holes moulded into the plastic, with the stator wire grid behind the holes. In the later version, the stator wires were spiral-wound around the plastic frame. What you saw outside was the actual insulated stator wire; the square holes were still there, underneath them. Old JansZen speakers sent in for repair after the new design was introduced, would come back with the new screens. The factory considered them to be directly interchangeable. Power handling in the JansZen electrostatics was limited by another factor than the usual diaphragm-excursion characteristic of dynamic speakers. If driven too hard, the air between the stators and the diaphragm would ionize and the polarizing voltage would drain off. This resulted in the strange characteristic of increased power to the screen resulting in lower output, but still with low distortion. Never heard of or saw these spiral jobbers - any pix on the web or jpegs you may have?? Also, you can't wash the JanZens because they have a graphite diaphragm, you'll wash that off and they won't work. _-_-bear http://www.bearlabs.com -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.308 / Virus Database: 266.11.0 - Release Date: 4/29/05 |
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