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ALK Cornwall Crossover question


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Geeetings Al,

I notice your Cornwall crossovers are crossed over at 750Hz (for the squawker/woofer leg) in lieu of 600Hz when I downloaded your design. If I wanted to build a pair of your X-overs, how would I modify the design if I wanted to use a 600Hz crossover point, instead of 750Hz? I'm a tinkerer at heart and I'm getting an itch to build me a set of custom crossovers - all the praise for your designs are getting to me!

Thank you so much!

KG

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Thanks Al,

My calculations give 1.625mH and 48.75uF. Strange, I was looking at an original schematic for a B-2 crossover last night, and their values treat the 4 ohm K33 like an 8 Ohm driver (they use a 2.5mH inductor with a 20uF cap to get 600Hz). I wonder why they would do that? Anyway, thanks again for your help.

KG

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KG,

You'r values are correct. Just use 47 uF for the caps.

The value Klipsch use are not for a constant impedance network.

By the way, moving the crossover down to 600 just puts more load on the squawker driver and runs it closer to the lower limits of the squawker horn. The woofer will easily go beyond 1000 Hz. Why move it down to 600?

Al K.

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Greetings Al,

I may be wrong, but it seems to me that the classic Klipsch sound is acheived largely by the characteristics of the horn squawker. The lower the cut off point, the more "horn like" the speakers sound, in a good way. Ex: the K-horn and LaScala's squawkers cut off at 400HZ, the Cornwalls at 600Hz, and the Heresys at 700Hz. Each is low frequency cut off point is limited by the size of the horn lens - and you can definitely hear it.

It seems to me that PWK designed each speaker with a mid horn to reach as low as possible without making the speaker too ridiculously deep, the La Scala being borderline. Also note the higher cut off of the Belle when they used a reduced depth horn. I think PWK would have used an even deeper horn in the Cornwalls if the speaker cabinet would not have been so deep.

What I would like is to squeeze the low end ability of the Cornwall squawker to maybe even 550Hz, if it will give it to me (by the way, will it? Can I cross the woofer over slightly higher to compensate for the tapering low response of the squawker?) I just love the mids in the K-horn/Scala because they do reach a little lower. I realize most people want the mid to shut up a little bit, I want mine to sing as low as possible.

As far as power handing, since the K55V was designed for full range paging applications, and will handle 30W under said application, a 550Hz - 600Hz cut off wouldn't seem to be much of a problem, especially with 6.7dB of attenuation already in the circuit from the autoformer. I've never even heard of someone frying a K55 voice coil. But I guess anything is possible.

Maybe the woofer is better equipped to handle the low mids. I've never seen a reponse curve from K55V/K600 squawker. Is something ugly lurking below 750Hz? I do not want to work hard on a crossover design only to wind up not using them due to bad sound.

Al, I really do appreciate your help here, and repsect your careful work, design, and advice on your Klipsch crossovers. I just have a custom crossover in mind based on the careful work of your design. Remember, imitation is the sincerest form of flattery.

Regards,

KG

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Klipschguy

Wont the original crossovers, loose some sound qualitys due to age?

Deterioation of some of the caps?

I havent messed with mine at all yet, but they did kinda look ancient!!

Als crossovers look really nice, but my klipsch wouldnt be original, if i mess with them, if i got Als crossovers i would still keep the originals !

Sounds to me, like your against it!

Im really in no hurry , i just keep seeing all the great replys on them!! And if we ever need crossovers the owners are selling their old ones on e-bay!!

Regards Jim

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Jim,

I would definitely keep my old crossovers, so I could change back if I wanted to. I love the sound of my Klipsch, I just wonder if I can squeeze a little more performance while getting to tinker in my workshop at the same time - I always need to have a project going. My biggest fear is losing that "Klipsch sound" that I like so much. I would want my crossovers to make my Cornwalls more closely approximate a K-horn type sound. I like the idea of a constant impedance crossover. By the way, the old caps are likely to degrade very slowly. I doubt I could her the difference if I replaced the caps with exact copy new ones.

Al,

Any advice is appreciated. I really do want a good result.

KG

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Jim and KG,

I agree about keeping the original Klipsch xovers. I still have the "AA"s that came with my Belles.

The difference in crossover between 600 and 750 Hz is pretty small. I just wanted to keep the 600 Hz squawker horn roll off below the networks crossover. I doubt if it's important, but crossing it at 600 makes 12 dB / aciave on the woffer and 18 dB / Octave on the squawker (roughly) considering it's natural roll off is added to the networks slope. I wanted to operate the squawker well within it's comfortable range. The danger to the driver itself is small.

Al K.

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Jim, saw your recent posts about building the CW networks yourself. Al is being a bit understated in his replies, just because he's modest and a gentleman and won't say otherwise. I'll offer the caveat personally, however, that to build a set of networks the way Al does would take A LOT of practice and experience. The experience piece is where you will save money by not making the mistakes while you learn (unless you do this for a living, and if that's the case, I take this all back Smile.gif )

You're better off just setting a few bucks away every month 'til Christmas and then let Santa send you a pair Smile.gif

------------------

Denon AVR-4800

McIntosh MC-2105 (Fronts)

Toshiba SD-3109 DVD

Klipsch Cornwall I's (LF/RF)

Belle Klipsch (Center)

Klipsch Heresy (RR/LR)

Klipsch KSW-12 sub

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Al, did you ever send a pair of ALK crossovers to a foreigner, let's say in Europe for example, and if you did, how much was the added cost??

I'd really like to improve the sound of my scalas, though i'm not in a hurry (still have to buy a new preamp, a second power amp to bridge them in mono, and also need to dynamat the horns...Wink.gif).

The only thing that i'm afraid of is, will I like the sound of your cross-overs? I'm sure your crossovers objectively IMPROVES the sound of the scalas by making them smoother, but maybe i'll miss the "wrong things" of the scalas! If I lived in the US i'd listen to a pair of already improved scalas to see if I like what it does to the sound.

That said, I think I'll order you a pair one day because everyone just seems so happy with them...Smile.gif

Frans

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Hello Shock-Late!

Al had sent a pair of crossovers to me in germany. Sure, you have to pay the shippingcosts, but also you must pay some taxes: custom tax and "Mehrwertsteuer" (i don't know the word in English or French). I've paid about 65$ for the taxes in Germany and the custom procedure.

I hope, this will help.

regards,

Dieter

------------------

Bass: Klipschorn

Mids: Fostex H220 + Fostex D221

High: Fostex T825

X : ALK

Pre : Rotel RC 995

Amp : AudioValve PPP 30

CD : NAD 520

Cine: Yamaha DSP E 1000

Cent: LaScala

Rear: DIY EV

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Hello Frans,

I like the Rotel, i think it's a good preamp for the money. Yes, it has XLR-output and 2 cinch-outputs.

Dieter

------------------

Bass: Klipschorn

Mids: Fostex H220 + Fostex D221

High: Fostex T825

X : ALK

Pre : Rotel RC 995

Amp : AudioValve PPP 30

CD : NAD 520

Cine: Yamaha DSP E 1000

Cent: LaScala

Rear: DIY EV

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