I have used the Motorolas successfully for a number of years in two way spkrs, for home stereo as well as PA/musical inst use.

I am a saxophonist, have experimented for many years with various speakers for good vocal and wind inst reproduction.

(See my articles on Sax On The Web, http://listen.to/saxophone/ and there also you will find one I have, Playing With A Mic... general advice to wind players in using PA equipment.)

I first noticed the Motorolas many years ago at Radio Shack, and had seen the KSN1005a and KSN1001a (fluted 4khz horn, aka "Superhorn") and KSN1025 (2"x6" 1800hz horn) sold by them, and also used in a number of musical inst speakers. I was intrigued by the simplicity.

I had read some good remarks on the KSN1025 in Speaker Builder magazine's letters section. I was impressed with how flat these were, rivaling some much more expensive tweeters. I was less than impressed by the 5khz peak in the little KSN1005... a harsh one note cymbal sound.

Please refer to http://www.ctscorp.com/pzt/ffpzt-home.htm

You will also find a good piezo application article there, which tracks exactly with Wayne's advice.

Since my introduction to these tweeters many years ago I have concentrated on the 1800 hz unit for use in simple, yet effective 2-way systems.

CTS/Motorola has now expanded the 1800 hz driver line to other varients using this same basic driver:

A cheaper, and less satisfactory KSN1176 2"x6" horn similar to the 1025.

There is another 2x6 varient, the KSN1141b, that is a high power 2x6 1800hz unit that is part of their "Powerline" 400 wt (!!!) series. Now we are talking serious horsepower. Also in the Powerline series, KSN1141b 2x6 horn similar to the KSN1025, and a 4" square (outside shape, round horn) KSN1165a. These are all 1800 hz units.

They make a separate 1 3/8" x 18tpi screw in horn driver, KSN1142a, also in the 400 wt Powerline series. I have used this with the Motorola KSN1151a 10" x 5" horn lens. But it sounds quite similar to the 1025/1141 with built on horn lens... save your money.

I have had the same experience as Wayne Parham, and doubted the 92 db SPL's of these Motorola drivers. I had used them with good results with woofers rated 95-99 db/wt/m. Wayne tells me that by his actual measurement, the Motorolas measure 96 db/wt/m at 2.83v (equiv to 1 wt at 8 ohms). My golden ears agree (OK, laugh, but being a musician, I know what REAL instruments sound like).

Roll the woofer off at 1500-1600 hz with just a coil (6db) and zobel. I find it best to just wire the tweeters above with no other attached components, and choose a woofer of 95-99 db SPL. You may luck up on a likely woofer with a natural rolloff at this point. These Motorola 1800 hz units all have a built in 22 ohm 1/2 wt resistor. The two times I have smoked a KSN1025, the resistor was burnt, but soldering in a new one had it working again with no problems.

I have just recently purchased the larger KSN1188a driver. These extend down to 800hz... YES!!! 800 hz - 20 khz range. I have them teamed up with a larger 5"x15" horn lens (Parts Express #260-099, at $9 ea a real bargain!). So far, so good. New cabinets will soon be finished to mate these to some Pyle MH1560 15" woofers. So far, I just set them on top of existing cabs. But the sound is very promising.

I would be glad to hear, as per my other thread, of others use of the KSN1188a's, either for home or pro audio use. I know these have been on the market for a while and used commercially. Comments?

BTW, MDF does not cut it for "roadworthy" cabinets... I use birch ply. If there are resonances, I can't hear them... and certainly the strength of the ply vs MDF weighs heavily in this decision. MDF does not hold up well, in my experience, in equipment that must be moved around.

Have you guys seen spray on truck bed liners? That stuff makes a great finish for road gear! Looks like black wrinkle vinyl from a few feet away. A commercial sound company in the next town had 15 pair sprayed by a local outfit, after first trying it out for several months on a pair of their rental PA speakers. Give this stuff a consideration for your next project.

One more note, I have also wired 8 ohm resistors across the terminals of piezos, making them appear to be 8 ohm dynamic units electrically, and used them with L-pads and 6 db (caps) xovers, crossing them from 1800 hz up on up to 6000 hz. This works well, with little or no SPL loss.

• CTS/Motorola

I am listening to the Studio one Pi shipped by Wayne and am very pleased with the sound. I am driving it with low power 300B SE tube amplifier.

I'd like to know, from your experience, how much time is needed for the tweeter to properly run in? The sound improves quite a lot after 20 hours of playing. Should I expect more improvement? How much more run in is recommended?

My second question is, are they made of tight manufacturing tolerances? Do you see the need to match them?

I like the simplicity of the tweeter implementation, and my friends are all impressed with the good clean sound it delivers. Almost forgot, it is so cheap to own.

Stanley

The CTS/Motorola tweeters seem very consistent to me. I just buy them. There is a KSN1025 (2"x6", 1800 hz) available from Radio Shack, lacks the high power protection, but is still a sturdy unit, for those of you who want to check them out, experiment right away.

I agree with a posting elsewhere on here by Wayne that the harshness many hear is a mismatch of levels... these tweeters are more sensative than the advertised rating. And he gives a solution to this problem.

Mine was different, I used the 8 ohm resistor across the terminals, then used an L-pad, and used a 12 uf cap on the hot lead coming to the L-pad. Before discussing with Wayne the SPL on these, I had already dialed my L pad down -5db to match the 1165a's more realistic 96 db SPL to my woofers' 92 db SPL.

I see no apologies necessary over using these "cheap" tweeters... they perform!

This was a very informative post. I have also thought that the KSN1188a had a lot of potential. It looks like a good match with a 15" woofer. I’m curious as to why you chose the 270-099 (I believe this is the correct part#) over the 270-095 (made by CTS). Was it price or are there other considerations?

Dave

As far as the horns... (FYI other guys, the Parts Express 270-099 is a no-name ABS plastic horn appx 15.2" x 5.125" for a whopping $8.80. The 260-095 is a 16.5" x 6.25" horn for $23.80... still a great price. There is also the 270-095 10.3" x 4.9" horn from CTS, $14.25.)

I had never used the 270-099 before, but I figured, how bad could it really be? And at $8.80, I was curious. As it turned out, it is quite thick material, has an aluminum threaded insert in the throat. While it may not hold a heavy dynamic horn driver in daily pro use, the very light KSN1188a driver (or KSN1142a) should be no problem.

Well, these cheap horns look VERY good and sound just fine to me. I intend to use them again on future projects. I can see no reason to spend more on the very slightly larger 260-095 horn, or smaller CTS made 270-095. If I am going to a better horn, it will have to be a much, much more expensive unit.

I have also put these KSN1188a drivers on the CTS made 270-095 horn. They sound just as good on either horn. The 270-099 cheap horn is thicker, stronger looking than the smaller CTS horn. IF I were building a small PA or floor monitor, with 10" or 12" woofer, I would probably use the smaller Parts Exp 270-095 CTS horn with KSN1142a driver (1800 hz driver) with a 10" woofer, and either the 1188 or 1142 with the same small CTS horn with a 12" woofer... to better fit the baffle board.

So, for a mere $37 plus shipping, the KSN1188a and the 270-095 make a heck of a good horn/lens combo.

• http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7

Every time you introduce a new driver, you have phase and response issues. For transients, "time alignment" etc is important. Keeping the transients intact is difficult if you introduce a crossover and another driver right smack in the middle the audio spectrum where it really affects things (5khz on up).

Now if the crossover is down lower, where the wavelengths are longer, it is not as difficult to keep everything in line. AND if you can make it a 6db crossover, you are doing even better. Now, the issues here are power isolation for the tweeter, and if the crossover is low, a driver that can go low will usually not be able to produce the top octave.

Well, Motorola piezos to the rescue... no problem with low frequency energy as the impedance is very high down low, and the tweeter does not produce these frequencies. Also, these tweeters have plenty of top end range... in fact, in excess of what is really needed.

And on top of everything else, I like the KISS approach.

Mr. Moleski said the KSN1188a (800hz) driver will work in both lens equally well, no loss of low end response with the smaller 1151 lens. He commented further that all of their screw-on drivers will work on either of these lens.

Spec sheets are no longer available from CTS. Their spec sheets all say Motorola and they cannot give these out.

The piezo products division was acquired from Motorola by CTS in 1999, and it is the same product, made and sold by the same people. Nothing has changed but the sign in front of the building (and I suppose, who signs their paychecks!). But he assured me their products continue to maintain the same high quality.

It is my understanding that piezos are self limiting with regard to low frequency, that is, the impedance of the driver makes it act as its own high pass filter. This would make the crossover very simple. I think that you could get away with 1 inductor on the woofer and a resistor across the terminals of the piezo.

It's too bad that the spec sheets are not available. I'd like to see what rate the 800Hz piezo rolls off at. I'd also like to see how flat the response is. Of course, at the price its reasonable to just give it a try.

I’m not familiar with the Pyle Drivers but in looking them over, the PYM1555 (292-236), PYM15128 (292-240, a little pricey), and PYM1578 (292-238) all look like they might be a good match. Also, the Dayton "Cast Frame Driver w/ 4" Voice Coil" (295-080) looks like it would work well in this application. It's a little pricey but still in range.

Good info on the horn. My guess is that you would get the best performance with the 270-099 would sound best because it appears to have a much smoother transition in the horn.

I also like the KISS aroach.

Dave