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[Brandon Wright]

Of all of the SH96HOs that have been sold-I must say this is the first time I have heard of this "issue".

I just did a quick model.

I am not sure what the "other" plots were done it-but this is from our software.

It is a SH96HO turned vertical (so as to see the vertical orientation  coverage)

THe mics are 40' from the speaker.  THe black one is on axis- the blue one off axis-but in the "lobe" pattern.

The coverage plot is at 4Kz.

You can see the overall freq response in the mic positions to the left.

The greatest deviation is at 1500Hz, which is +/-1.5dB.

This is nothing that I would bet upset at.

What I find amusing is that when coverage plots are shown that have 15dB holes, somehow that is "accepted".

The other ones I posted were from the DDT Lite Ipad app (it is what I had in front of me at the time).

I get the same thing in the full direct software.

My plot is approximately 15 degrees off axis, and the one you posted is approximately 20 degrees, and yes, our scales are off.

But in 15 degrees, 4k went from being -1db relative to its adjacent bands to +5 or 6 db. That is a pretty significant change in the tonal characteristic of the speaker.

[Peter Morris]

If this is truly a characteristic of conical, straight horns it is worth discussing and further exploration. However, any compromises that are made in the synergy design are greatly outweighed by all of the advantages that you report (proximity of drivers, efficiency, pattern control, coherence, etc...)

Yes, conical horns have pattern control issues.  Those two lobes are typical at some frequency … not necessarily 4K.
 
Conical horn are however good at matching the required acoustic impedance for the various different sized drivers within the mouth of a synergy horn.

If you notice Danley’s horns while being fundamentally conical have some addition curves/angles in the flare.  I assume this is to find the best compromise between directivity and getting all the drivers to work well within the horn.

[Peter Morris]

I am not sure what the "other" plots were done it-but this is from our software.

Your software  for the Danley boxes, and the HF950, Ease focus II

[Ivan Beaver]

If you notice Danley’s horns while being fundamentally conical have some addition curves/angles in the flare.  I assume this is to find the best compromise between directivity and getting all the drivers to work well within the horn.

That "additional expansion" is what we call a "horn break".

It is used to reduce the reflections that occur when the horn suddenly physically stops (all horns and woofers do this at the edges) and helps to ease the transition at the lower freq of the pattern.

It is not about the loading of the drivers within the horn.

It is nothing new.  Constant directivity horns have been doing it for decades.

[Merlijn van Veen]

Hi everybody,

Lots of interesting reading.

I can only vouch that I measured on site what was predicted by the DSL Direct prediction software. A comforting thought and good indication of the degree of accuracy of Direct. The DSL CLF viewer underscored this behavior.

Regards,

Merlijn


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[Peter Morris]

Yes, conical horns have pattern control issues.  Those two lobes are typical at some frequency … not necessarily 4K.

Conical horn are however good at matching the required acoustic impedance for the various different sized drivers within the mouth of a synergy horn.

If you notice Danley’s horns while being fundamentally conical have some addition curves/angles in the flare.  I assume this is to find the best compromise between directivity and getting all the drivers to work well within the horn.

That "additional expansion" is what we call a "horn break".

It is used to reduce the reflections that occur when the horn suddenly physically stops (all horns and woofers do this at the edges) and helps to ease the transition at the lower freq of the pattern.

It is not about the loading of the drivers within the horn.

It is nothing new.  Constant directivity horns have been doing it for decades.

http://www.xlrtechs.com/dbkeele.com/PDF/Keele%20(1975-05%20AES%20Preprint)%20-%20Whats%20So%20Sacred%20Exp%20Horns.pdf

[Mark Wilkinson]

http://www.xlrtechs.com/dbkeele.com/PDF/Keele%20(1975-05%20AES%20Preprint)%20-%20Whats%20So%20Sacred%20Exp%20Horns.pdf

Peter, thx for the link......GREAT paper

[Peter Morris]

Peter, thx for the link......GREAT paper

It’s an old but good paper.  Horn design has moved on quite a bit from there now with computer modelling. A couple of my friends supervised a PhD on this subject and there is a related patient.
 
http://data.mecheng.adelaide.edu.au/avc/publications/public_papers/2008/preprint_morgans_optimization_2008.pdf
http://www.google.com.au/patents/US8494815

Although the SH96 does have a bit of a bump at around 4K, given there is typically a L +R stack with overlapping patterns, I don’t think it would difficult to achieve a relatively smooth power response across the coverage area.
 
(FWIW I wanted to use one of David’s horns the DIY but it was too deep)

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