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In the Forum: Horn-Loaded Speakers
In the Thread: New superlative horn build - ESD acoustic
Post Subject: The horn design from Bruce EdgarPosted by martinshorn on: 5/14/2018
So first in line, the horns.  
They stressed out that particularly the horn flares where not within the comfort zone of their own developer team.
That triggered the recruitment of Bruce Edgar. The design is only his, and they took it 1:1. Of course tooling is very expensive.
So initially the prototyping was done by wood due to cost reasons.  

Once final, they had their own molding tooling made for them. Actually 3 per horn. For an inner, outer, and inbetween form.
Theyre actually 3 layer sandwiched which has many advantages in production and rigidity later, such as leaving a cavity at the thickened mouth for gravel.
This is to dampen the horn as theyre not baffle mounted. A knocking confirms, the horns are more than silent. Quiet impressive. The finishing quality looks and feels marvelous. 

Now Bruce Edgar advised to vary the horn shapes depending on their usage.
He advised, not like LeCleach, to have one flare only, but rather use faster opening in the higher octaves, more narrow in the lower.
The fast opening is supposed to be benefitial for the sound perception in heights. So the upper 3 are tractrix, with 3 different opening rates or t-factors. The higher the octave, the smaller the t-rate. 

The fundamental horn is non tractrix but exponential. Though, the t-rate is much higher. 
That lowers the Q of the horn, and us such, smoothenes the group delay, and together with crossover gives a lower order roll-off.

In the base, Bruce chose to use a 3 meter hyperbolic with even higher t-rate.
Indeed the roll-off balances nicely most room modes and boominess (i can confirm it was very dry and clean transient in the lows).
Its supposed to stand close to a side-wall with hard stone / concrete to mirror the mouth. This makes the t-rate less than it looks. 

Different than LeCleach, who praised to always use horns as big as possible, with fast opening wide roll and XO 1 octave above the cuttoff.
Bruce Edgar decided to use the mouth and flare functions collaborating with the driver and crossover, shaping the final crossover Q's.

At least that much reached and remained between my ears. I receive this information. Though i remain critical to small mouth and slow opening profiles.Bigger are much more efficient. Though, the one that fits into your real-estate is still better than no-horn.I once owned a terrible undersized basshorn and it was no good.But, i did not spot any negative coloration here, that i could associate to this.Also i know and own the JBL 2312 horns with similar flare, which indeed confirm the lower Q to work properly. 


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