ALK Crossovers

[wvu80]

This 12" SEOS waveguide (using a Crites A/4500 XO) worked great on my Khorns

 

[PrestonTom]

Let me provide a heretical perspective since I am not fully convinced that the crossover from the mid-range to the tweeter deserves this much attention. Yes, we can say "everything is important" but that ignores there reality that some things are very important and other things less so. 

 

My feeling is that the transition from the woofer to the mid-range is important and should be done with care and attention. On the other hand CW 3's are new and cost several thousand dollars. Right now folks are suggesting to yank the tweeter out of the cabinet and place it on top (any WAF has just gone out the window) and this will achieve time alignment (which may only show a rather modest benefit).

 

Is it worth it, or are there other areas you should spend your time and energy on? Let me propose a demonstration. Listen to some favorite music at a given level. Now, disconnect the mid-range and woofer so that you are now only listening to the tweeter output (do not change the volume control). Yes, you will hear something, but not much. Compared to the woofer and especially the mid-range, the tweeter contributes very little energy. 

 

Now settle down ... I did not say that the tweeter contributes nothing nor did I say that the tweeter is not critical for a sense of "air" and "crispness". What I am saying is that compared to all the that the woofer and mid-range provide, the tweeter has a relatively minor contribution.

 

Try the demo and see. After that try and convince yourself, and your significant other, that dismantling a set of speakers that cost you several thousand makes any sense.

 

Some suggestions have been made previously that you might want to try an equalizer or electronic crossover if you need to to tweak. Not a bad idea. Personally, I would first spend some time and systematically try some different speaker placement options (closeness to a corner or back wall, distance, toe-in etc). Heck, that won't cost you a dime.

 

In either case, good luck,

-Tom

 

Please, before you accuse me of being an idiot, please try the suggested demonstration first. It can give some perspective that might change some of your priorities.

 

[Chris A]

For me personally, I don't recommend that the OP "yank" anything actually (which is a bit of an emotive use of language).  But releasing the tweeter and moving it temporarily to the top of the cabinet is not even as invasive as replacing/refreshing a tweeter diaphragm. Perhaps that's worth consideration in your points, above.

 

Tom, I believe it is important to count the number of wavelengths of time misalignment woofer-midrange and midrange-tweeter crossovers in the Cornwall.  I believe that both your eyes and ears will be surprised...once you try it.

 

[To the OP--it seems as if your thread has been picked this morning for "more esoteric discussions" by others, and I apologize if all this extra discussion causes any confusion in your planning.]

 

Chris

[Chris A]

As a point of discussion, here is some data that I measured in my listening room with my left surround Cornwall (II not III as pictured) with intact factory crossover (EQed flatter using the Xilica):

 

[PrestonTom]

Chris this is simply folks chatting and besides I like emotive language. 

 

A mis-alignment can cause a couple of problems.First, over a spectral region where the two drivers are putting our similar amounts of energy, then the relative phase will not be fixed (it will vary with frequency). We both know this, but I wanted to get others up to speed if they have not been through this. 

 

If the relative phase is not fixed then it is tough to get the amplitudes of the two drivers to sum and give a flat frequency response. But this problem only occurs over a spectral region where the two drivers are delivering comparable outputs (one argument for steepish crossover filters). So yes, time alignment is beneficial over this spectral region, although the region may be narrow and not even contain much energy to begin with (hence my suggested demonstration). 

 

The second consequence of a time mis-alignment is that the delay, per se, may be audible. Under the best of circumstances, the delay would need to be about a couple of milliseconds  (which would be many wavelengths in this region) or a couple of feet of added distance from one driver relative to the other. 

 

What does all this add up to (after folks have tried the demo)? Well, don't yank the tweeter out of the cabinet yet. Rather, there are bigger fish to fry so lets work on room acoustics (speaker placement, toe-in etc).

 

As to the OP's question about extreme slope networks, all that I have mentioned is considerably less expensive.

 

[Deano1974]

Seems I have opened a can of worms - sorry

Please note all of your thoughts are greatly appreciated



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[twk123]

36 minutes ago, Deano1974 said:

Seems I have opened a can of worms - sorry

Please note all of your thoughts are greatly appreciated



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No need to apologize. Arguing over crossover design is a longstanding tradition here on the Klipsch forum. We generally have the steep slope camp, the just recap it camp, the paper in oil camp and the active digital multi amp camp. It may seem like people get riled up but its just part of the passion that drives the community and the fact we are all more than a little crazy about pursuing audio perfection. 

 

I do agree with Preston on the room, controlling primary reflections is probably going to yield far better clarity than tinkering with crossovers or driver placement. Depending on your room and WAF you can use curtains or dedicated dampening material. Parts Express actually has a new line for sale that is a pretty good deal.

 

https://www.parts-express.com/sonic-barrier-fbp242-studio-acoustic-foam-bevel-panel-24-x-24-x-2-black-7-pack--260-549

 

[Deano1974]

No need to apologize. Arguing over crossover design is a longstanding tradition here on the Klipsch forum. We generally have the steep slope camp, the just recap it camp, the paper in oil camp and the active digital multi amp camp. It may seem like people get riled up but its just part of the passion that drives the community and the fact we are all more than a little crazy about pursuing audio perfection. [emoji3]
 
I do agree with Preston on the room, controlling primary reflections is probably going to yield far better clarity than tinkering with crossovers or driver placement. Depending on your room and WAF you can use curtains or dedicated dampening material. Parts Express actually has a new line for sale that is a pretty good deal.
 
https://www.parts-express.com/sonic-barrier-fbp242-studio-acoustic-foam-bevel-panel-24-x-24-x-2-black-7-pack--260-549
 

Thanks TWK123, I have already had the room acoustically designed by an ex BBC sound engineer (friend) that used to build studios, and the for the WAF she doenst care what i do as the room is dedicated for music [emoji4]

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[Tony T]

Whoa, I like those panels! Where did you obtain them? I especially like the difference in patterned design. Nice to the diversification instead of just bland flatness.

[Deano1974]

Thanks Tony, Actully they have been bought from a sound engineer when I lived in Malaysia 3 or 4 years ago, but you can source them from aliexpress in many different designs and colours


https://m.aliexpress.com/wholesale/pyramid-acoustic-foam.html?categoryId=200002937&channel=direct&gclid=EAIaIQobChMIpo_woOmh2wIVQoePCh2baArpEAAYASAAEgIfTfD_BwE

Whoa, I like those panels! Where did you obtain them? I especially like the difference in patterned design. Nice to the diversification instead of just bland flatness.

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[JohnA]

Deano, If I were you, I'd open the CWIIIs and see what sort of crossover they already have.  In the last 10 years, Klipsch has moved toward crossovers with steeper slopes and good components.  Your CWIIIs may already have such crossovers and thus gain nothing from Al's crossovers. 

[Deano1974]

Deano, If I were you, I'd open the CWIIIs and see what sort of crossover they already have.  In the last 10 years, Klipsch has moved toward crossovers with steeper slopes and good components.  Your CWIIIs may already have such crossovers and thus gain nothing from Al's crossovers. 

Okie dokie good idea, dont get me wrong they are amazing but as with most audiophiles we always wonder if things can be taken to the next level - tweekanitus [emoji44]

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[Don Richard]

On ‎5‎/‎25‎/‎2018 at 8:09 AM, Chris A said:

But releasing the tweeter and moving it temporarily to the top of the cabinet

 

One may be able to time align the tweeter/midrange for one listening position only. However,  the tweeter is being moved farther from the midrange driver. This will affect polars in the crossover overlap region more than if the tweeter was left in the stock position. What happens if the measurement mic is moved just 1 inch vertically? The measured phase will be different.

 

Time alignment will work much better on a coaxial or unity horn arrangement or, if the listener to source distance is greater than in the typical home,  in the case of a system with stacked drivers.

[Deano1974]

Hey guys, fyi I did remove the tweeter last night from the cabinet but the wire is too short, I can extend this quite easily but before doing so I wanted to enquire on what peoples experiences with this movement achieved on their opinion

What differences they heard

Thanks

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[Chris A]

On 5/25/2018 at 6:55 AM, Don Richard said:

Measure the loudspeaker first, see what it needs, then correct as necessary .

Here is a measurement of a Cornwall II impulse response (the left-side Cornwall in my listening room).  There is about 3.5 wavelengths of time misalignment between the tweeter and the midrange at 5 kHz (about 0.75 ms at 5 kHz):

 

 

Of course, the Cornwall III has different drivers and horns than the CW II but the general configuration is the same from a time alignment standpoint. The Cornwall III's midrange horn is reportedly shorter than the CW II, so the number of wavelengths of misalignment may be less than the 3.5 wavelengths of the Cornwall II.  I assume that the CW III is using a low pass filter on the midrange channel (something that is missing on the CW II), so the time misalignment due to the crossover filters alone will increase the time misalignment by approximately 90 degrees of midrange delay per order of the crossover filters used (starting at second order).

 

Experience has shown that you need to be within 1/4 wavelength at the 5 kHz crossover frequency to achieve coupling of tweeter to midrange driver/horns.  That's about 5/8 inch of total misalignment (including the phase delay of the crossover filters from high frequency to lower frequency).  I would guess that you will find that moving the tweeter back about 5.4 inches would be a good starting point to listen for the greatly increased sound stage and imaging performance point.  From that point, you can listen and move it back and forth by half inch increments until you hear when it goes into time alignment.

 

Chris

[Marvel]

On 5/26/2018 at 6:44 PM, Deano1974 said:

Hey guys, fyi I did remove the tweeter last night from the cabinet but the wire is too short, I can extend this quite easily but before doing so I wanted to enquire on what peoples experiences with this movement achieved on their opinion

What differences they heard

Thanks

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I put tweeters for my LaScalas in external baffles and aligned with the mids, as dave did on his Khorns.  Better imaging and a cleaner sounding, more coherent high end.

 

Of course, it's a greater distance on khorns/lascalas than on a Cornwall.

 

Bruce

 

PS  I move the lamp/diffuser when listening to the LS

[Deano1974]

Thanks Guys....

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