Question about DIY Cornwall

[IB Slammin]

On 8/10/2004 7:21:52 PM IB Slammin wrote:

I am humbled by your degree. Seriously.

I simply want to incorporate two Cornwalls per channel into a manageable (short) cabinet, utilizing a larger mid horn. Your expertise would be much appreciated.

I will admit I had to work hard for my degree, but I'm sure it should make one feel humbled.

First I want to ask why you want to use a larger mid horn? The Klipsch squawker (if wired correctly) should have no problem keeping up with two K33 woofers so why not use it? Going with something else only brings in a lot of uncertaintity and complicates things IMO. To start working on box shapes, you need to take some precise measurements of the Cornwall enclosure. I need to know the internal volume of the enclosure (or the internal measurements), the area of the port, and the length of the port. With that info I can determine the porting frequency.

Two years later.........LMAO, STL. None of us ever had to work for our degrees. You were the only one.

Precise measurements were done. The CW-DBB was designed and built. A larger mid horn? Ah, well....the K600 sucks. Can I say that? Well,let me say it again. Can you imagine a K600/K55 chewing your pant legs at 117db?

OK, OK. It is two years later. []

Done deal.

Terry

[IB Slammin]

On 8/10/2004 7:21:52 PM IB Slammin wrote:

I am humbled by your degree. Seriously.

I simply want to incorporate two Cornwalls per channel into a manageable (short) cabinet, utilizing a larger mid horn. Your expertise would be much appreciated.

I will admit I had to work hard for my degree, but I'm sure it should make one feel humbled.

First I want to ask why you want to use a larger mid horn? The Klipsch squawker (if wired correctly) should have no problem keeping up with two K33 woofers so why not use it? Going with something else only brings in a lot of uncertaintity and complicates things IMO. To start working on box shapes, you need to take some precise measurements of the Cornwall enclosure. I need to know the internal volume of the enclosure (or the internal measurements), the area of the port, and the length of the port. With that info I can determine the porting frequency.

Dude. This has been done.

Cornwall 84 internal dimensions H x W x D

34.25 x 23.75 x 13.375 = 10879.7265625 cubic inches (6.296138057002315 cubic feet)

1. This doesnt account for any of the internal contents.

2. Volume K-77 = 18.31 cubic inches

3. Volume K-57 and K601 = 112.89 cubic inches

4. Volume of base of crossover, parts, excluding wires = 107.01005481 cubic inches

10879.7265625 -18.31-112.89 107.01005481 = 10641.51650144 cubic inches. This is 6.158285012407408 cubic feet. This is the internal volume of the Cornwall minus the mid/high drivers and crossover. This doesn't account for the volume of the driver itself. It doesn't matter if yu use the K33 again for the project.

The port: H x W x D

3.38 x 22.25 x 9

There you have it. There is no error. I lived inside my Cornwall for several months.

The volume of my dbb cabinets (two K33's per cabinet) is 12.3 cubic feet. Yes you can use one tweeter and one midhorn.. piece of cake. All you need to do is use a type A network with duplicated low pass filters going to each woofer. Please note: In order for the dB match between the drivers, the woofers have to be wired in parallel. There is argument wheter this is just over 2 ohms or about 3.3 ohms presented to an amp. If you have a decent amp no problem.

jc

James,

What a gentleman you are. Now that the design/build is done, all I wanted to say was.....Na, Nan, nana, nana.......but thats just me....[]

Terry

EDIT: BTW, STL, many thanks for your expertise, and encouragement[]

[jwc]

Well, if "Na Nana nana" means "I told you so"....that is exactly right.

Guys. Look at Terry's (IBSlammin) Avatar. There is a reason that 511 is sitting on there. No it's not because his wife thinks it looks good (the Gargoyle). It is because it is smoke and blows better than the K600. Even if you keep the crossover of the midrange at 600Hz and get a better horn, it will sound much better.

Simple improvement is the Cornscala (non dbb). K401 instead of the K600. Immediate improvement with no XO changes.

To take the Cornwall to the utmost level, duplicate the K33 (total of 4), Altec 511B horn and JBL 2404 tweeter. The only thing I can think of to make the dbb the utmost experience is to use the Altec 902 driver....It will be done in time.

jc

[IB Slammin]

Well, if "Na Nana nana" means "I told you so"....that is exactly right.

Guys. Look at Terry's (IBSlammin) Avatar. There is a reason that 511 is sitting on there. No it's not because his wife thinks it looks good (the Gargoyle). It is because it is smoke and blows better than the K600. Even if you keep the crossover of the midrange at 600Hz and get a better horn, it will sound much better.

Simple improvement is the Cornscala (non dbb). K401 instead of the K600. Immediate improvement with no XO changes.

To take the Cornwall to the utmost level, duplicate the K33 (total of 4), Altec 511B horn and JBL 2404 tweeter. The only thing I can think of to make the dbb the utmost experience is to use the Altec 902 driver....It will be done in time.

jc

thats what IB talk'in 'bout......[]

tc

[3dzapper]

If'n you want to smoke that Quasimoto 511, try a trachorn. You'll be jumping around yelling "Molten metal! Molten metal!"

Rick

[DizRotus]

An off the wall thought on "stacking" Cornwalls.

Why not mount (bolt) one pair of Cornwalls to the ceiling positioned as a mirror image of the Cornwalls on the floor??

You then get the same coupling of the woofer to the ceiling as you get for the ones on the floor. It probably would work best with Vertical Cornwall II's on the ceiling.

Yes, yes I understand the construction issues, the WAF issues, sweet spot issues, etc.

But done right it would be COOL!!!

Mike

You might be interested in the photos of suspended Cornwalls attached to this and subsequent posts. They have appeared on the Forum before. The first series are those of Wendy Carlos of Switched on Bach fame. Her web address is:<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

http://www.wendycarlos.com/+sob.html

[DizRotus]

Another view.

[DizRotus]

The final photo was taken in a band practice room in the <?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" />University of Hawaii. When I questioned the band director about the Cornwalls he sent the following email (unedited).

<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

The Klipsch Cornwalls don't sound very good in that configuration. Our AV guy just went in and placed them up there and I wished he had consulted with me before doing it. I've spent years as an audio consultant and have designed speakers and used to do modifications to amps and stuff. Have not done the amps stuff recently and advances in amp design has left me behind. I love tube amps and there are only a few transistor amps that I think are ok. But I still do a lot of audio work. The Cornwalls don't work very well in its present location. The tweeter and midrange fire way over the heads of the students and they sound their best standing in the percussion section. They are spaced too far apart for good imaging. Because its on the balcony face the surface area does not give enough reinforcement to the bass and they sounds really thin. On my equipment it has a roll off around 110 so it sounds more like a midrange speaker. I sometimes bring it a subwoofer that I designed and it sounds much better. We have another set of Cornwalls in a different room and it sounds very good there. It has a very exciting sound with a bit of resonances here and there but they seem pretty controlled.

[D-MAN]

Only a complete idiot would not have turned them upside down, so the high frequency units are towards the bottom! What a maroon!

DM