GoodSoundClub - Romy the Cat's Audio Site

In the Forum: Horn-Loaded Speakers
In the Thread: Aporia - Silbatone Acoustics speaker

Post Subject: Back is part of the front (the back part)Posted by Joe Roberts on: 1/23/2009

Interesting concept but let me point out a few considerations.

The diffusor does performs a mild "equalization" function if you want to call it that but it is also an aid to dispersion. It is light "EQ"...3dB might be about right.

Without any diffusor, the front radiation of the Manger gets up in your face a bit and stands out from the horn. I believe that this is independent of frequency response issues and more to do with radiation angle characteristics and the perceptible texture of front vs. Backhorn radiation.

I tried taking it off and forget it. Ruins the coherency of the speaker and you can then hear front radiation + horn radiation. At the upper range of the horn, the speaker is fairly wide in directionality. At 150hz, the Manger unit beams. The illusion of a single source is lost.

Furthermore, the Manger driver is extremely fragile. There are small wires on the front and if these are disturbed, the $500 each (in large quantity) driver is finished. The diffusor protects the driver from mechanical damage.

A pic of naked driver is here:
http://spintricity.com/458/public/Vol1-3/page195

My Korean bud has the factory Manger system with 3 drivers per side in his bedroom. His wife likes their sound quite a bit and kidnapped these for her own listening pleasure (she is not a WE fan) while she is at the computer. One day his housekeeper decided to dust the speakers and that was the end of SIX Mangers in a single attack.

And the most important thing...IT LOOKS COOL!! Cant make any hair dryer jokes about a naked Manger.

Finally, as mentioned above, there are a number of issues with the back wave radiation that require playing with filters in that back pipe already. How this would interact with the compression chamber notion, who knows?

All in all, the diffusor is a decent practical solution in a number of ways. I fear that no matter what is done behind the driver, there is the issue of beaming and getting up in your grill that the front radiation poses. A bit TOO immediate and direct without the diffusor.

With this appliance screwed on the transparency of the Manger is maintained and the effective coherency of the system is enhanced.

Much practical experimentation and listening testing went into this diffusor design and, as you can see, it is a bitch to make with around 40 precision machined parts per side, so it is hard to play around with. I agree that such an approach would be near impossible to model or predict by pure mathematics and rests in the domain of "cut and try" experimentation.

Silbatone was formerly in a marketing partnership with Loth X, whose advance in Lowther-type back horn design involved a realization that the back chamber behind the cone must be roomy for optimal front radiation. The front and back of a cone are rather intimately related, after all. Most Lowther backhorns had a small chamber behind the speaker, which raised the Q of peaks and messed up the subjective character of the front radiation, while constricting low end response.

I don't remember the details of this argument, but the point is that you mess with the back, you're also messing with the front. The Manger front radiation is so fine and well behaved that I'd be worried about interfering with what the Manger does best.

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