Crossover Question

[hornhead]

I just got K-horns from my Aunt for little money. I noticed that the caps are ozzing a bit and the transformer looks rusty so I want to redo the crossovers. I was originally going to tri-amp them but I have ruled this out after much research. I just donwloaded the ALK crossover design and did an archive search. I read a lot of rave reviews but everyone was using the the modified V (phase plug removed) or M drivers that rolloff at 6,000hz, with the ALK crossovers. I have a much older klipschorn with the spring terminals. I was told that my driver starts rolling off at 5,000hz. I was wondering if anyone can tell me what modifications I would need to do to compensate for this on the crossover? I guess I would want to bring the crossover point of the tweeter down 1,000hz to compensate? Is this advisable and what would the capacitor value be to achieve this. Any advice is appreciated. I'm pretty handy with electronics so I don't think I'll have a problem building them.

This message has been edited by hornhead on 08-11-2002 at 10:01 AM

[mace]

Hi,

Congrats on the new K-horns!

You may wish to post over in the "Upgrading Older Speakers" forum. Al K. himself hangs out there and will surely respond to your questions.

Mace

[Al Klappenberger]

Hornhead,

I don't think you need to worry about the K55s you have. The K55 with the push-pin connections has no phase plug and will go to beyond 6000 Hz fine. My Belles came with them and I ran curves on them to verify it. It's the K55M that has a hard time getting to 6000, but they do make it! The gremlin with the two push-pin K55s that I tested was a return "glitch" at 9000 Hz. The "M" and the "V" with solder terminals don't seem to have that problem. At least the ones I tested didn't.

AL K.

Correction: As djk pointed out, the early k55 has a phase plug. I should have said it doesn't have the phase plug modification. I have never opend an early model K55 and have not seen the early version first-hand and didn't think about it! The later one has a circular opening like a ring. I uploaded a picture of it.

This message has been edited by Al Klappenberger on 08-11-2002 at 05:12 PM

[hornhead]

Thanks,

I guess the guy at Klipsch didn't know what he was talking about because he was the one who told me that the driver, I have, was modified to extend its frequency out to 6,000hz. Your design looks interesting. Is it fair to say that you're trying to isolate each drivers frequency range by using a high and low bandpass? Also, what is the 10ohm resistor for?

[djk]

All K55s have phase plugs. The only question is, is yours a one port or a two port? The K55V with push button terminals was a one port, the solder terminal K55V and the K55M are two port.

http://www.atlas-soundolier.com/techLib/slsheets/SL2.1551.PDF

The peak at 9Khz will be a little more pronounced in the K55V as Klipsch has Atlas reduce the spacing between the diaphragm and the phase plug.

http://www.atlas-soundolier.com/techLib/slsheets/SL2.1561.PDF

This driver is the same except it has a bigger magnet and more spacing between the diaphragm and the phase plug. Note that the dips from phase cancellations due to phase plug design are at exactly the same frequencies.

http://www.atlas-soundolier.com/techLib/slsheets/SL2.1552.PDF

A smaller phase plug spacing, note the dips are shifted higher in frequency.

[hornhead]

djk,

All K55s have phase plugs. The only question is, is yours a one port or a two port? The K55V with push button terminals was a one port, the solder terminal K55V and the K55M are two port.

http://www.atlas-soundolier.com/techLib/slsheets/SL2.1551.PDF

Mine has the push button terminals. The guy from Klipsch said that it only goes to 5,000hz but Al measured the response and says it goes to 6,000hz. Is the two port a better driver or just sounds alittle different?

[WMcD]

I don't quite understand the issue of "one port" and "two ports".

One of the EV designs have two accoustic ports. One for tweeter output, the other for the mid.

Some of the Atlas have a 70 volt line transformer built in while the others are normal 8 or 16 ohm input.

I recall PWK writing that he made the modification to the Atlas unit to reduce clearance between the phase plug and the diaphragm to increase high end output. Perhaps Atlas did this later too?

Gil

[hornhead]

I called Klipsch again and I guess I didn't understand them the first time. I was told that the older K-55-V driver goes to 6,000hz and that the modifier version goes to 7,000hz. Because the modified version has a higher frequency range the transition over to the tweeter is suppose to be a little smoother. However, it sounds like they are very similiar and not worth the bother of swapping out the older drivers for the newer ones. They must have made the older version for quite a while since I have them in these old Klipschorns I just got and a pair of 77 Heresys. I think the Klipschorns are from the 60's.

[JohnA]

You're correct. It's generally not worth the bother to swap to the solder terminal K-55-Vs. I can't hear the difference in mine. Others can. How high the -V can go depends on the horn and how forgiving you are; the response is falling after about 3k. I'm sure you noticed. The horn can trade dispersion at high frequencies to get on-axis gain at those frequencies. Klipsch' K-400 does that.

John