The HOMster! (or How I Learned How to Fix a Horn)

[Patrick Bateman]

Originally Posted by gedlee

Sure sounds familiar to me.

Absolutely!

I was definitely inspired by your Summas

The thing that's enlightening about my experiments is that the three things mentioned in the previous post seem to be as important (if not more than) the shape of the horn itself.

Everyone seems to obsess about the shape of the horn, when those three things seem to matter a great deal also.

For instance, the majority of commercial loudspeakers don't have any diffraction treatment whatsoever. The roundover seems to make an extraordinary difference.

[ScottG]

Originally Posted by Patrick Bateman

• The off axis response of the treated device is better than the off axis response of the untreated device. This reinforces the theory that a significant fraction of the energy produced by the untreated horn is being generated by waves which are not traveling down the axis of the horn.
• I have treated oblate spheroidal waveguides with foam, and they experience a modest reduction in SPL. About 3db above 10khz, decaying to about 1db at 1khz. This horn, with a diffraction slot, is seeing a much greater reduction in SPL, with a foam plug which is smaller. My theory is that there are more HOMs in this diffraction horn than in an OS waveguide, and the foam is attenuating them.

I could be wrong, but I don't think that this is correct.

I think the reason for the treble loss is due to greater high freq. absorption from the foam relative to the OS design. (..Horn with a longer path length, less expansion, etc..) Furthermore, I'd expect it to have *less* effect lower in freq., exaggerating the upper freq. loss relative to the average. Diffraction throat or not, its a horn.

Anyway, whether either of us is correct or not, an excellent thread with good results!

[gedlee]

Originally Posted by Patrick Bateman

The thing that's enlightening about my experiments is that the three things mentioned in the previous post seem to be as important (if not more than) the shape of the horn itself.

Everyone seems to obsess about the shape of the horn, when those three things seem to matter a great deal also.

I hate to admit it but this is entirely correct. I have kept kind of mum about this realization (which I made quite awhile ago - it doesn't play well into my position) but its absolutely correct. More correct than I think that you would even guess. Its not good for business to give away all ones secrets, but there is more to all this than meets the eye. By hook or crook you are catching up to what I've found over the last six years of development. There are still some things that are hidden in the cracks, but you'll probably figure those out.

I mean "cut-off frequency" and "loading" -- who cares!!

[ScottG]

Originally Posted by Patrick Bateman

Absolutely!


The thing that's enlightening about my experiments is that the three things mentioned in the previous post seem to be as important (if not more than) the shape of the horn itself.

Everyone seems to obsess about the shape of the horn, when those three things seem to matter a great deal also.

For instance, the majority of commercial loudspeakers don't have any diffraction treatment whatsoever. The roundover seems to make an extraordinary difference.

..And this conclusion is rather different than what Earl has been stating. (EDIT: ..well up until just now!)

1. The dispersion pattern for instance isn't exactly the same as what an OS contour provides.

2. Neither is minimizing throat diffraction represented here.

Again, the emphasis is virtually all on the "mouth" (..which is far more representative of Jean-Michel's position.)

This begs a natural question: Have you had the opportunity to try a Le Cleac'h contour with a maximum round over for comparison? (..I know, ..absolutely worthless in a car environment. )

[Patrick Bateman]

Originally Posted by gedlee

I hate to admit it but this is entirely correct. I have kept kind of mum about this realization (which I made quite awhile ago - it doesn't play well into my position) but its absolutely correct. More correct than I think that you would even guess. Its not good for business to give away all ones secrets, but there is more to all this than meets the eye. By hook or crook you are catching up to what I've found over the last six years of development. There are still some things that are hidden in the cracks, but you'll probably figure those out.

I mean "cut-off frequency" and "loading" -- who cares!!

Well these aren't Summas by any means. I'm listening to my Summas as I type this, and I've been listening to them since 5am this morning. I'd love to see someone listen to a horn for fourteen hours straight without crying "uncle."

Having said that, the foam and the roundover makes a measurable and breathtaking difference. It's interesting that people have been using EQs to tame horns for decades, when this seems to work a lot better, *and* it's cheaper.

[Patrick Bateman]

Originally Posted by ScottG

..And this conclusion is rather different than what Earl has been stating.

1. The dispersion pattern for instance isn't exactly the same as what an OS contour provides.

2. Neither is minimizing throat diffraction represented here.

Again, the emphasis is virtually all on the "mouth" (..which is far more representative of Jean-Michel's position.)

This begs a natural question: Have you had the opportunity to try a Le Cleac'h contour with a maximum round over for comparison? (..I know, ..absolutely worthless in a car environment. )

No, but I'm open minded! If there's one in the states, point me in the right direction. If you want to hear some Summas, or my car, I intend to demo both this month at the PNW Audio Society.

What's really piqued my curiosity is the extraordinary improvement rendered to a rather mediocre horn. Look at this response above 2khz; it's ridiculously smooth, considering the horn is easily eight times too small, preposterously asymmetrical, and has a diffraction throat. Even the compression driver is beat up.



It really makes me wonder what you could get away with if you used an elliptical mouth and a 360 degree roundover. I have a feeling it would measure quite well.

[ScottG]

Originally Posted by Patrick Bateman

It really makes me wonder what you could get away with if you used an elliptical mouth and a 360 degree roundover. I have a feeling it would measure quite well.

I think you would be correct, AND it should give somewhat better low freq. extension. But it isn't well suited to a baffle, nor as a result a more common loudspeaker shape.

IMO though, the first thing you should do is decide what type of dispersion pattern you actually prefer.

In other words, is the OS's nearly "flat"/conical (diffraction free) throat profile with attendant uniform dispersion loss really the pattern that "works" for you? Or would you prefer increased horizontal dispersion, (..from a far better contour than the test here), with the typically resulting non-uniform loss in pressure vertically? Or perhaps you would prefer the narrowing/directivity loss in pressure at higher freq.s that the (Std.) Le Cleac'h profile provides? Lots of choices here, but like you - I think you have the most important element figured out.

[Robh3606]

It's interesting that people have been using EQs to tame horns for decades, when this seems to work a lot better, *and* it's cheaper.

Just curious but where in the frequency range?? Are you talking passive EQ for CD or EQ an in an equalizer??

Rob

[ScottG]

Originally Posted by Patrick Bateman

No, but I'm open minded! If there's one in the states, point me in the right direction.

Brandon's? Lynn's?

Really, I've seen precious little state-side (..and all where the air is thin.)

Yeah, I know.. useless.

So, how do you feel about that *131st* DIY horn? (..please, try not to throw the only partially depleted beer cans at me.)

[Patrick Bateman]

Originally Posted by Robh3606

Just curious but where in the frequency range?? Are you talking passive EQ for CD or EQ an in an equalizer??

Rob

In the car audio world there's a lot of reverence for "old skool" setups, and a lot of people are copying what worked in the 80s. Myself included, honestly.

In the 80s a standard setup was a set of horn-loaded compression drivers, driven by a good solid state amp, with a pair of 31 band EQs to tame the horns. These were ubiquitous:

If I'm not mistaken, USD, Image Dynamics and Crossfire were basically re-badging Rane EQs. I could be wrong, maybe Winslow will chime in.

The EQ can tame the horns to an extent, but the foam and the roundover is far more satisfying. Subjectively, the combination of horn and equalizer is satisfying in the short term, but grows fatiguing quickly. In this respect, it's almost perfect for winning sound off competitions, because when you first hear a good set of horns, it's a life-changing experience.

The problem is that they begin to grate on your ears. Slowly, but surely.

The foam and diffraction treatments make the horns sound like a good direct radiator, albeit a very efficient one, instead of a conventional horn.

It would be great to see a company like Image Dynamics license this technology.