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Updated Cornscalas


Mike Dubay

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I have been planning an upgrade to my Cornscalas. A couple of things I want to address.

1)

With my current Selenium D250X midrange the

system does give some distortion at higher listening levels.

2)

Improve the visual impact of the system.

As you can see my Cornscalas give a somewhat

monolithic view.

post-33301-13819661866134_thumb.jpg

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To improve the aesthetics of the system the horns will be

exposed with no upper bin or speaker cloth.

The wood horn is a 200 hz horn. With the left and right side clipped by 1.5

inches will give an 2:1 (W:H) aspect ratio and will match the 25 inch width of

the bass bin. The horn was build with

oak laminated plywood and flexible 3/8 inch plywood. The horn was finished with an exterior spar

varnish. This helped fill in the voids

on the flexible plywood and gave an even honey tone to the different plywood. I also noticed that the flexible plywood

became more rigid after the 5 coats of spar varnish.

Here is the horn fresh from finishing.

post-33301-13819661883174_thumb.jpg

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The new midrange and tweeter fixed a few problems.

They do exhibit less distortion at higher levels, but I’m

letting the drivers run in before any high level listening. The reduced distortion appears to be most

pronounced with vocals. The highs are

also more clean and detailed.

The midrange is also more accurate in the vocal region; the

D205X gave to some extent a sound like the vocalist had maybe a nasal tone or speaking

into coffee cup tonets, esp at lower vocal frequencies. The 408 ti reproduced vocals much more

accurately in an effortless manner.

Currently the cross over is a simple 2nd order

cross at 5,000 Hz between the tweeter and squawker with no attenuation applied just

yet. I have a 50 uf blocking capacitor

for the squawker for protection from unintended DC spikes. The sensitivity of

the 408 (111 spl) vs the 220 (109 spl) is pretty close. A quick check with test tones with my spl

meter showed equal response from the tweeter and the squawker, so will leave it

for now.

What attenuation settings do other members use for either a

408/220 combo or the 405/220ti combo?

I do exhibit some hearing loss in the upper frequencies, so

maybe reducing the squawker about 2 db might be the trick. I’m going to let my drivers and crossovers to

continue to run in before making changes.

I’m very happy with the looks of the speakers now. This winter will continue with some cabinet

work, replacing the dark colonial cabinet and the pine dresser with matching

euro style birch cabinets.

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