Will this work? - Cornwall Mod

[classic5]

My sister gave me a set of cornwalls recently. In my current house, they are very intrusive size-wise. I'm looking for a way to integrate then into a wall of built-in cabinets. The cabinets have countertops with doors below and bookshelves above. The house cabinets will take the cornwall cabinets on their side, at floor level. I came up with this idea and I wanted to run it past the forum. I have read a lot on this forum, but haven't researched this exhaustively. If this has already been covered, just point me there - thanks.

Briefly about the speakers and me:

The speakers are cornwalls birch raw with the flush fronts (no grills or grill recess) the cabinets are lined with the "tissue" padding and cotton cording and the woofers have the square magnets. Any ideas on what age ? (I can post the serial no.s later).

I have been a Klipsch fan since the mid 70's. I ,off and on, delivered systems for the Klipsch dealer here. I have owned two sets of heresy models. I don't think I know anywhere near the math and physics that go into speaker design, but I'm basing this idea on some principles I think are sound - namely, bass frequencies are percieved as omnidirectional, the cabinets are designed mainly around the woofer (back air volume, resonance, porting etc.), a good stereo "stage" is set with speakers (high freq.) toed-in 45 deg., horns disperse better horizontally than vertically.

My idea is to remove the squawker and tweeter assemblies from the cabinets, seal the enclosures with a block of plywood covering the horn cutouts from the back, pass the wires from the crossover through this board using terminals similar to the main terminal in the back, and run these leads to the horns mounted in a separate enclosure. This would allow me to place the cornwall units in the bottom part of the built-in cabinets and mount the horns above them in the book cases. This would make the cornwall disappear almost and hopefully the sound would still be much better than almost anything else I could buy.

Notes, questions and Issues:

- I read about people putting Altec voice of the theater in small rooms by having window seat-like bass enclosures and the horns higher up.

- Khorns come in two pieces although they are bolted together when setup.

- I would build the horn enclosures to look like a smaller versions of the Khorn top.

- Would the signal degrade if the mid and high leads were 6-8 ft. from the cross over.

- The cabinets would be on their side - ok for bass, right? - but that is why I want to move and "aim" the high end.

- should I mount the crossover with the horns and run the bass lead to the cornwall boxes?

- I can completely undo this "mod" if I get more space later.

- will the abscence of the horns and compression drivers make a big difference air volume-wise?

- Will this sound "worth a dern"?

Thanks for reading - Please reply if you get a chance.

[colterphoto1]

Got some good ideas and theories there! First, congrats on your acquisition of Cornwalls- the price was certainly right and you will be amazed at the sound you get from these babies. Applause on your innovative approach in including these in your main listening room despite archetictural obstacles.

From an acoustical standpoint, your ideas are 'sound'. You are right about low end being primarily omnidirectional, but I'd try as much as possible to maintain some sense of the stereo soundstage by putting your horizontal 'bass bins' under or on the sides of your mid bins. The horns of the cabinet are not a substantial % of the interior volume of the cabinet, so you shouldn't need to compensate for this ( horn volume is about 12x4x3 inches approx is only about 144 in3/ cabinet interior volume of 11,388 in3 based on my actual measurements= 1%) Your concept of mid cabinet orientation/placement is correct. Horns should oriented as they were originally in cabinet (note that some horns actually have better dispersion when placed vertically), with their height and toe-in appropriate for the listening room (ie, usually toed- in slightly to avoid the Bosian approach of reflecting sound off nearby walls)

From a construction standpoint, BEWARE!!! First, when modifying your Cornwalls, be certain that they are vibration free and that you can restore them to original design and cabinet finish. For that reason, seal the mid/high openings carefully, with lots screws and perhaps a non-hardening type of sealant such as rope caulk, thin cork, or foam. Be certain that the built-in cabinets you install the bass bins in are well constructed and free of vibration. Beware if you are using a turntable (used to play old-fashioned vinyl discs reported to contain muscial information), as the Corn's may create vibration that is picked up by the turntable.

Pad the shelf of your built-ins prior to sliding in the bass bins, to avoid scratches. The distance between the bass bins and mid/high units is not so critical from an electrical distance timing standpoint as is the distance between each of these cabinets and your listening position. You will hear a timing 'blur' if the distance between each bass/mid and listening position is substantial.

Good Luck and hope this helps, Also check out the post for Updating/tweaking Cornwall I's, with many helpful hints on electrical and mechanical updates to your units.

[JohnA]

The crossover point to the squawker is 600 Hz. That's well above the open second string of a guitar. The point is that a substantial portion of sounds labeled midrange comes from the woofer. You should not obscure the woofer because you will reduce it's output in the critical voice region.

Removing the horns should not make a critical change in cabinet volume. I don't think you will hear a change in the bass output.

[WMcD]

I agree with the above in general. My overall thought is that if this is a way you can accomodate CWs, a few compromises are worthwhile.

One issue is what will be the situation of the cabinet door. Will it have opennings to allow the woofer and vent to radiate. A slatted door might not be enough. Having opennings or some open frame and covering them with grill cloth would put you in the same situation as any other baffle.

Remember there is some nice cane stuff out there. White too. I find a big back surface tends to dominate a room.

I agree the volume (geometry) of the removed horns should not be a problem. I'd think a plywood plug will be a rigid as the mouth of the horn. Padding of some sort may prevent the box in the cabinet from moving around. This depends on what you feed it and how much you feed it. Smile.

Probably the crossover should stay in the bass bin area. I say that because you'll probably want to run the feed wire from the amp to the cross over in come hidden fashion. Three feet of wire from the x over to the horns shouldn't hurt anything.

There is an issue displacing the bass and mid by the distance we're talking about.

The bad point is that bass is said to be non directional. That is a bit of a can of worms in description. 1) Bass drivers radiate non directionally up to some frequency depending on size of the radiator. 2) Our ears can't "locate" bass below a certain frequency. This is mostly due to distance between our ears. (No comment.)

In any event, the 700 Hz crossover frequency is getting above both. That is why the "normal" design puts the drivers in a cluster. At least they are aligned in the vertical plane. This is certainly the case in the K-Horn.

There is one paper in the Klipsch collection which discusses, briefly, how high a crossover can be used if you want one (1) bass driver. The author (Snow?) opines that 400 Hz is the limit. I don't have it here. That gives some hope that things will not be too bad even though the issue isn't quite the same and you're above that x over point.

You may not be getting corner reinforcement of the bass as you would in a corner. Still, CWs are darn good.

Overall, this is terra incognito. I would not discourage you. You're the pioneer.

Gil

[ben.]

Contrary to Home Theater propaganda, we can localize frequencies above 60-80Hz. Also, 15" drivers' dispersion patterns tend to get beamy towards their upper limits of frequency response. Good luck with the project. It certainly seems a worthwhile endeavour.

[IndyKlipschFan]

Please send pics on the progress too. Sounds wonderful!