Tony Reed Posted July 18, 2003 Share Posted July 18, 2003 I'm considering using a Pyramid TW12 piezo tweeter for a project of mine. (MCM1900) It's the only tweeter I've found that is physically the right size. (5 3/4" x 2 5/8") These tweeters (5) must fit in the tweeter box, so size is a factor. Opinions wanted, good or bad. Thanks, Tony Quote Link to comment Share on other sites More sharing options...
hwatkins Posted July 18, 2003 Share Posted July 18, 2003 Motorola KSN 1038 is a very good reasonably priced unit. All fall short of horns, but i have used this unit in a couple of projects and it is good enough for my first born to use... Quote Link to comment Share on other sites More sharing options...
Tony Reed Posted July 18, 2003 Author Share Posted July 18, 2003 My problem is that to fit the tweeter box (that contains 5 identical tweeters) I need a rectangular horn tweeter that measures 5 3/4" x 2 5/8" exactly. 5 3/4" x 2 3/4" won't fit. Any recommendations? Thanks, Tony Quote Link to comment Share on other sites More sharing options...
michael hurd Posted July 18, 2003 Share Posted July 18, 2003 How about building a new tweeter box ? Don't destroy the old ones just in case you want to return them to stock configurations. Then you could fit in whatever size rectangular tweeters you like. If you don't have the tools and equipment necessary, i'm sure a buddy or local wood shop would be more than happy to help you out for a small fee. Quote Link to comment Share on other sites More sharing options...
Tony Reed Posted July 18, 2003 Author Share Posted July 18, 2003 Michael, This is for my MCM1900 project, so it has to stay as "original" as possible. These are old Klipsch tweeter array boxes that originally came with 5 Motorola piezo tweeters inside. (what model I don't know) Since this is sort of a restoration project, I'd like to use the original boxes. Thanks, Tony Quote Link to comment Share on other sites More sharing options...
lynnm Posted July 18, 2003 Share Posted July 18, 2003 Opinions needed on Piezo Tweeters Two words They stink. Quote Link to comment Share on other sites More sharing options...
TBrennan Posted July 18, 2003 Share Posted July 18, 2003 There are many piezo models and some sound pretty good. Like with most drivers most of it is in the implementation. Piezos generally sound better if a crossover is used, even though they can be used without crossovers. The CTS website has info on using piezos properly. One trick is to wire an 8 ohm resistor across the terminals and then use a cookbook 8 ohm highpass filter. To identify the piezo Klipsch used go www.partsexpress.com and look at the piezos there. I think the one Klipsch used was the small rectangular horn that somewhat resembles an EV T-35 tweeter. Didn't Klipsch use a vertical array of 5 of the tweeters? Maybe DJK will jump in here, he's very astute about piezos. Quote Link to comment Share on other sites More sharing options...
IndyKlipschFan Posted July 18, 2003 Share Posted July 18, 2003 Yes, Klipsch did use the piezo tweeters, as well as K 77's(not sure but feel this is right the real deal in the K horns) in the high end pack for the MCM system. The k77's, of course, sounded a LOT better!! Quote Link to comment Share on other sites More sharing options...
Daddy Dee Posted July 19, 2003 Share Posted July 19, 2003 I once used RS (that's Redneck Shack if you're from Arkansas) piezo tweeters in some big speakers for spinning records at school dances. Listened to them at home, too. That was back when God was young and I thought they sounded good. Those were sweet years, spinning records on weekend nights and getting paid for it. Used to think, "Man this is great, I'm doing what I'd be doing anyway, listening to music LOUD, and getting paid for it, too!!!" Dee Quote Link to comment Share on other sites More sharing options...
Tony Reed Posted July 19, 2003 Author Share Posted July 19, 2003 Yes, Klipsch did use a verital array of 5 tweeters. My problem with the Parts Express tweeters is that they are all 5 3/4 x 2 3/4. The box will only accept 5 3/4 x 2 5/8. It's a tight fit, no extra room. I've got to buy 10 of these, so I want to get it right the first time. Recommendations, please. Thanks, Tony Quote Link to comment Share on other sites More sharing options...
Marvel Posted July 19, 2003 Share Posted July 19, 2003 Klipsch used the KSN1016 model. CTS has the KSN1016B listed on their pages: http://www.ctscorp.com/components/piezoelectric/piezoelectric_speakers.htm Hope this helps out Tony. Marvel Quote Link to comment Share on other sites More sharing options...
djk Posted July 19, 2003 Share Posted July 19, 2003 "Yes, Klipsch did use the piezo tweeters, as well as K 77's(not sure but feel this is right the real deal in the K horns) in the high end pack for the MCM system. The k77's, of course, sounded a LOT better!!" Well spoken by someone that has probably heard neither version of the MCM1900. "Opinions needed on Piezo Tweeters Two words They stink." One favorite line I heard in a movie was 'better than sex', the woman's reply was 'maybe you aren't doing it right'. My reply to detractors of the piezo: Maybe you aren't doing it right. The K77 will handle more power than the KSN1016 piezo, in every other way, shape or form, the piezo SMOKES the K77. In a Klipschorn/LaScala/Belle the KSN1016 when crossed properly will work with a 200W amplifier, do you need more power handlng than this? Piezo tweeters require application specific crossovers to get the best performance, the MCM1900 has such a crossover. The current KSN1016 mounting flange needs to be trimmed to fit the MCM1900 housing. I do this on a table saw , tape over the horn opening to keep clean. The motor assembley of the piezo has three mounting screws, two next to one side, one next to the other. Trim the side next to the two screws first, otherwise you will need to clamp a 1 X 4 to the saw top as an auxillary fence to do the other side. Persons wanting to know how to design proper crossover for piezo tweeters should do a search at: http://db.audioasylum.com/cgi/search.pl?searchtext=piezo&b=OR&topic=&author=djk&date1=&date2=&slowmessage=&sort=score&sortOrder=DESC&forum=hug Quote Link to comment Share on other sites More sharing options...
JohnA Posted July 19, 2003 Share Posted July 19, 2003 djk, The efficiency of the 1016 is shown at 92 dB/2.83V/1M. How do you get it to match output with the rest of a K-horn/Belle/La Scala? Quote Link to comment Share on other sites More sharing options...
djk Posted July 19, 2003 Share Posted July 19, 2003 "The efficiency of the 1016 is shown at 92 dB/2.83V/1M. How do you get it to match output with the rest of a K-horn/Belle/La Scala?" Same way Klipsch does(autoformer), the details are at the AA site. The KSN1016 is about 125 ohms at 10Khz, so it is really in excess of 104dB/W/1M. Quote Link to comment Share on other sites More sharing options...
lynnm Posted July 20, 2003 Share Posted July 20, 2003 In deference to djk whose opinions I greatly respect I will modify my original comment: Opinions needed on Piezo Tweeters Regarding every piezo tweeter I have ever listened to: Two words They stink. If djk says that there are nice sounding piezo tweeters then perhaps my opinion will change if I ever hear a really good one. My biggest issue with the piezos I have heard is that they sounded strident and had an almost metallic quality in the lower end of their range. Presumably - based on djk's comments - the better units do not exhibit that behaviour. Quote Link to comment Share on other sites More sharing options...
djk Posted July 24, 2003 Share Posted July 24, 2003 "My biggest issue with the piezos I have heard is that they sounded strident and had an almost metallic quality in the lower end of their range. Presumably - based on djk's comments - the better units do not exhibit that behaviour." We could actually be lisening to the same piezo tweeters. There are several issues here. Foremost is probably the fault of Motorola for saying these don't need a crossover. They really do, and the more complex the crossover is, the better the tweeter can sound. Another big issue is amplifier stability. Many cheap speakers had a half dozen of these all in parallel, a load of anywhere from 0.5µF~1.0µF It is popular these days to omit the output inductor in amplifier designs, Adcom is just one such example. These amplifiers become unstable driving this much un-damped capacitance on their outputs and tend to 'ring' on transients. This tends to make the high end sound like an electric shaver, 'metalic' or 'buzzy' sounding. The un-damped tweeter drive element itself has a 'ring' mode. Adding a series damping resistor de'Q's the resonance in most models that this is OK. I usually use values in the range of 47R~100R/2W, this also takes care of the amplifier instability problem too. Low frequency causes intermodulation distortion, and in severe cases, the diaphragm can hit the phase plug. This does not sound good. The high voltage from the low frequency can also cause cracks to develop in the piezo bender element, they sound very wierd after they crack. Motorola was obsessed with having a bunch of output in the 20Khz region so they ran very tight spacing on the phase plugs. Some companies trying for high quality sound actually took the tweeters apart and added a paper spacer ring to increase the clearance. Motorola screened all tweeters in house, the problem was that 'fall-outs' still got sold, just at a reduced price. If it made noise, they sold it. For constant amplitude output as the frequency goes down, diaphragm motion goes up a a 12dB/oct rate. Music program material content also goes up at a 6dB/oct rate as the frequency goes down, it flattens out below about 250hz. For this reason it is best for piezo tweeters to have an 18dB/oct minimum roll-odd rate, the bender element provides 6dB of this by being a capacitor, the extra 12dB or more must be provided by the user. A Zobel must be used to keep the impedance presented to the crossover reasonably flat. Since the piezo is capacitve the Zobel will have an inductor in it. This is the opposite of a driver with a voice-coil, they are inductive, so the Zobel has a capacitor in it. I have been able to get 104dB/2.83V/1M out of a single KSN1016 ±1dB from 4Khz~16Khz, rising another 2dB at 20Khz. This tweeter sounds much better than the old T35 too. Quote Link to comment Share on other sites More sharing options...
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