CT 125 Tweeters

[BEC]

Erik,

Actually, the way I did the A/4500 crossover was to watch the outputs on a spectrum analyzer while tweaking in the values to get the curves I wanted to see out of it. There would be other ways to do it, this way just makes the absolute minimum changes to a Klipsch type A crossover.

Bob Crites

[fini]

Sounds like the KISS method.

[BEC]

Sounds like the KISS method.

Yes, minimizes the number of required steps for those who want to "DIY" the conversion.

Bob

[Erik Mandaville]

Bob:

Thanks, I thought that might be the case, and was just wondering if you had considered any alternatives.

Fini: Keeping things simple when possible is of course always a good thing. There may be a couple of positive outcomes to the way I outlined the change above, and was wondering if Bob had ever thought of trying something like it. Since an inductor is also added to his design, that portion of the modification only has to do with where it's placed in the circuit -- after the autoformer; in what I proposed: before the autoformer. As in his approach, mine also requires an increase in capacitance, and the only extra step in this really has to do with the relocation of one connection -- the tweeter off the autoformer at tap 5 to the input.

I've learned that there are those who are not used to seeing the tweeter connected that way, but it's really the more common way to wire a crossover. I've wired them this way according to published schematics for almost twenty years; and the early Klipsch Heritage networks, including the use of an autoformer for driver attenuation, is an exception rather than the norm (which is an observation, only, not a value judgement). There may also be a small amount of additive series resistance associated with the 13uf capacitor in front of the tweeter filter, most likely not very significant unless the capacitor is quite old and out-of-spec, and to my way of thinking it's more straightforward (or in another word, 'simple') to treat each branch individually. Al K's ES networks certainly wouldn't be a lesson in KISS, however with the right ancillary equipment, may offer some real advantages for some people.

Thanks,

Erik

[psg]

Guys, the modern Klipschorn has a crossover frequency of 4500 Hz according to the Klipsch web page. So the old AA had 6000 Hz because the older K77 couldn't go lower ?

I was considering the ALK Universal A kit, but perhaps I should inquire whether Al has a mod of his own for 4500 Hz. I wonder if the Universal A would sound better than going active on the cheap with a Behringer UltraDrive Pro DCX2496?

[Daddy Dee]

PSG,

Klipsch never used the K77 below 6000hz until they crossed it at 4500hz in the AK4 crossover. It would not be advisable to use the K77 at 4500hz in a type A or AA crossover. Bob Crites did so for a while, and did not blow up his K77, but it would be easy enough to do.

I don't understand the tech, but the first order crossover of the Type A is what puts the K77 at risk at 4500hz. The AK4 or other sixth order solutions are OK for the K77.

The CT125 frequency response is quoted at 3500hz or below maybe. It's power handling capabilities make it essentially bullet proof and it reproduces cymbal strikes and such with impressive realism.

[Groomlakearea51]

The CT-125 is as DD said, essentially bulletproof. I use them with an E/4500, an A/4500, and a few others thrown in as replacements for the K-77's in various applications. They are more versatile than the standard 77's. JMHO.

[psg]

Pehaps I omitted to say that I wanted an ALK Universal A modified to 4500 Hz because I do happen to have the CT-125 tweeters. []

But Al K doesn't make that mod. His next most-affordable solution is a AP12-350 and ES4000 combo, which runs at $664 + shipping + taxes into Canada. This is more than twice the price of the ALK Universal A kit, which I assume has crossover frequencies at 400 and 6000 Hz..

I was all set to spend $300+ for the Universal A kit, but now I wonder about the 6000 Hz vs 4000 Hz thing. $800 is another story I'd need to plan for.

[psg]

I don't understand the tech, but the first order crossover of the Type A is what puts the K77 at risk at 4500hz. The AK4 or other sixth order solutions are OK for the K77.

Makes perfect sense... Thanks.

[Deang]

Pehaps I omitted to say that I wanted an ALK Universal A modified to 4500 Hz because I do happen to have the CT-125 tweeters.

But Al K doesn't make that mod.

He will not modify an existing Universal Type A (ALK) because most of the part values are different and it would be easier to build one from scratch. Al probably just doesn't remember, but he did do that design with a 4500Hz crossover point. If you want to build it I can supply the schematic.

[fini]

I don't understand the tech, but the first order crossover of the Type A is what puts the K77 at risk at 4500hz. The AK4 or other sixth order solutions are OK for the K77.

Makes perfect sense... Thanks.

It's a shame Klipsch had to order it six times before they got one that worked.

[Erik Mandaville]

The modifications needed for a type A or AA at 4-kcycles or 4.5k-cycles are not difficult to do. Those networks, as originally designed, are very simple in the sense that they do not use impedance compensation circuits, and so forth. They are designed around the desired crossover slope, desired crossover frequency, and the reflected impedance of the drivers used. I just find the type A as originally designed kind of curious.

At either of those lower crossover frequencies (with the above networks), it's important to use a tweeter that can handle it.

To me, the CT 125 sounds, as Dee indicated, even more open and clear when disconnected from the association with the autoformer and reconnected directly to the input of the crossover. That is in fact the way the majority of crossovers are wired, however some minor change in value of capacitance needs to be made.

Erik

[psg]

Pehaps I omitted to say that I wanted an ALK Universal A modified to 4500 Hz because I do happen to have the CT-125 tweeters.

But Al K doesn't make that mod.

He will not modify an existing Universal Type A (ALK) because most of the part values are different and it would be easier to build one from scratch. Al probably just doesn't remember, but he did do that design with a 4500Hz crossover point. If you want to build it I can supply the schematic.

That would be sweet! The email conversation I had with Al was specifically about ordering a modified Universal kit to which he replied:
I don't offer a 4000 Hz version of the Universal and recommended the AP12-350 and ES4000 combo. I can understand that he might not have the parts for the modded Universal around in kit form as well. I`m not sure that I'm ready for an $800 expense here.

[Daddy Dee]

Yeh. I would hesitate to attempt to modify the crossover points on an ALK design. (unless Al did it)

The modified Type A, AA, or Mandeville crossover would be a more economical solution.

Best compliment I ever got on my system was from Arkytype. Fini and I had spent two hours listening to Arkytype's system. He had ALK ES crossovers with Trachorns and Beyma tweeters driven with Mac gear. It did sound very good. We had intended just to stop by to pick up nametags for a Klipsch gathering. Ended up sitting down, sort of mesmerized with the sound and forgot the time.

Arkytype came to my house to hear my Khorns with modified type A crossovers and CT125 tweeters. He listened for about 25 seconds and said "damn you."

[Deang]

Peter, no he doesn't offer a 4500Hz Universal Type A, either built or in kit form. However, he did do the design for those interested in doing DIY.

http://forums.klipsch.com/forums/storage/6/720281/Alk_4500.gif

If you don't listen loud, it's difficult to get better sound than what the Type A or AA deliver. I've built the Universal Type A no less than three times for myself, and each time reverted back to the Type A. One of the really nice things about the Type A is that you only need four capacitors to build a pair, which means you can buy some really nice sounding caps; Mundorf, V-cap, etc.

[psg]

Well well. Now you have me back to square one.

I guess I didn't want to admit that I'm getting older and not listenning to super loud music very often anymore. Perhaps going to type A is a good idea after all.

[Daddy Dee]

Klipsch lore has it that the Type A was Mr. Paul's favorite.

That adds some cool factor, IMO.

I also suspect that he would like the way it sounds with the CT125 crossed at 4500hz.

[Deang]

I also suspect that he would like the way it sounds with the CT125 crossed at 4500hz.

Not necessarily .

[Daddy Dee]

[]Dean.

[seti]

Klipsch lore has it that the Type A was Mr. Paul's favorite.

That adds some cool factor, IMO.

I also suspect that he would like the way it sounds with the CT125 crossed at 4500hz.

I read that somewhere that the A was his fave before the day of tweeter destroying Solid State [:'(]

I have always liked the A crossovers. However if anyone out there has a pair of extreme slopes for Klipschorns I would love to give them a demo run.