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New Cornwall Midrange Horns


greg928gts

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The grills on the cornwalls I have were missing when I got them. I will make new grills to fit the horns I end up using. I would be interested in Greg's horns but I wonder what the difference would be compared to some PH800s at $75 a pair?

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I found them for $40 a pair.

http://www.kcnproducts.com/KCN-Products-MG-Electronics-PH-800-p/kcn-ph-800.htm

Three problems: There's no real data sheet on that horn -- they call it a "diffraction lens" and tell us it's a 120 x 90 horn -- but nothing about what kind of horn it actually is (tractrix, exponential, etc.). The model number tells us that it probably has a 800Hz cutoff. If there was a real data sheet on the thing, it would probably have a recommended crossover point of either 1200 or 1600Hz. You could cross at 800Hz with a steep filter like Al's ESN -- it would be hell on a driver with a first order filter like the Type B.

If I owned a pair of Cornwalls that I wanted to upgrade I wouldn't be dinking around with cheap plastic horns from a company that provides no data.

http://www.mgelectronics.com/productdetails.cfm?productid=112

Really nice work on that horn and the installation. The only criticism I have relates to mounting it to the rear of the motorboard. Still, it's an outstanding retrofit that undoubtably sounds worlds better.

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Dean,

Wrong PH-800 horn. The one he is talking about is made from a different material and is a 500hz horn. Lots of Cornscalas have been built with these horns and crossed at 500hz.

Bob

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Guest David H

Dean,

Wrong PH-800 horn. The one he is talking about is made from a different material and is a 500hz horn. Lots of Cornscalas have been built with these horns and crossed at 500hz.

Bob

Bob, does this mean you have a data sheet? I couldn't find one anywhere what is the Fc? what kind of flair? Or have you run any curves on it?
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Dean,

Wrong PH-800 horn. The one he is talking about is made from a different material and is a 500hz horn. Lots of Cornscalas have been built with these horns and crossed at 500hz.

Bob

Bob, does this mean you have a data sheet? I couldn't find one anywhere what is the Fc? what kind of flair? Or have you run any curves on it?

No data sheet on these. I just bought some and tested them. Manufacturer does state an Fc of 500hz, but that is about all they tell me. I verified that Fc with my own testing.

Bob

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Guest David H

Nice work Gothover. Let me know what you find out on the grills, I don't have any here to work with.

Greg

Greg, I tried a few way to cut the grills yesterday, the best by far is a dremel with a cutting blade, 2nd the tin snips work well but requires left and right handed to complete the job, and is time consuming, I also tried router cutting with a small trim router works ok, really need a guide to keep straight, and lastly I tried scribing with a utility knife, this was far too much work.

Dremel tool was best and is a very common household tool.

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Nice work Gothover. Let me know what you find out on the grills, I don't have any here to work with.

Greg

Greg, I tried a few way to cut the grills yesterday, the best by far is a dremel with a cutting blade, 2nd the tin snips work well but requires left and right handed to complete the job, and is time consuming, I also tried router cutting with a small trim router works ok, really need a guide to keep straight, and lastly I tried scribing with a utility knife, this was far too much work.

Dremel tool was best and is a very common household tool.

Was it difficult to pull the cloth away from the grill frame? Did you use blocks of wood to hold the cloth away? Any pictures?

Thanks.

Greg

PS - My experiences with a Dremel tool have not been very good. There were times when I thought I could do more damage to a piece of wood with my Norelco shaver!

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Guest David H

Nice work Gothover. Let me know what you find out on the grills, I don't have any here to work with.

Greg

Greg, I tried a few way to cut the grills yesterday, the best by far is a dremel with a cutting blade, 2nd the tin snips work well but requires left and right handed to complete the job, and is time consuming, I also tried router cutting with a small trim router works ok, really need a guide to keep straight, and lastly I tried scribing with a utility knife, this was far too much work.

Dremel tool was best and is a very common household tool.

Was it difficult to pull the cloth away from the grill frame? Did you use blocks of wood to hold the cloth away? Any pictures?

Thanks.

Greg

PS - My experiences with a Dremel tool have not been very good. There were times when I thought I could do more damage to a piece of wood with my Norelco shaver!

The grill cloth pulled away from the center easily, I slid a piece of cheap thin plastic cutting board up through the woofer opening to protect the cloth. I did not take any pics, I am working with an old grill and raw materials. I really need a decent grill to work with. This one was falling apart when I got it.
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Has anyone calculated if this larger horn respects the cabinet volume for proper woofer loading...........or..........do you technically really need to increase the volume of the cabinet?



By the way, I should have started with some complements. The horns came out looking great. The response curve looks pretty good too. I bet they are smoooooooth.

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Guest David H

Has anyone calculated if this larger horn respects the cabinet volume for proper woofer loading...........or..........do you technically really need to increase the volume of the cabinet?

By the way, I should have started with some complements. The horns came out looking great. The response curve looks pretty good too. I bet they are smoooooooth.

I did make some rough estimations and didn't feel it would make that much difference. The real test for me was the listning test. Kevin, the guy I installed them for is thrilled with the sound. He described them as smooth and detailed, he also said he zero'd his tone controlls, no longer needed. I should get him to join the forums and comment for himself. I will send him a link.

Thanks for the comments.

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Has anyone calculated if this larger horn respects the cabinet volume for proper woofer loading...........or..........do you technically really need to increase the volume of the cabinet?

By the way, I should have started with some complements. The horns came out looking great. The response curve looks pretty good too. I bet they are smoooooooth.

That is a good question....but the volume difference between this horn and the K601 is fairly small. It could change the tuning point ever so slightly...would be hard to notice.

I have dunked a K55 and K600 in water for check volume displacement...if someone is nuts enough to do it with this combo...we can compare notes.

jc

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Guest David H

I have dunked a K55 and K600 in water for check volume displacement...if someone is nuts enough to do it with this combo...we can compare notes.

I have not done the water test, however I have made some rough measurement and find the new horn is nearly a 33% larger than the K-600 so literally a .25" thick box gasket on the rear cover would easily accomodate the volume loss of this horn, However I still don't think it necessary.

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Guest David H

Need to get back to solving the grill cut-out issue. I received this pick of a cornwall grill last week, I am not sure if it is an original, as mine do not share a common cutout for midrange and tweeter.

I had him check this grill to see if the cloth is glued to the front pannel and it is. Does anyone elso have a grill they would be willing to check?

The objective here is to see if it is possible to slip a protector throught the woofer opening between the grill and masonite backing to protect the grill cloth while cutting the backing board.

post-24405-13819464338944_thumb.jpg

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Guest David H

Here is another possible use for the Fastrac Cornwall paired up with a Crites CT-125. This wont be quite as good as internally mounted but sounds good regaurdless.

post-24405-13819464591294_thumb.jpg

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