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In the Forum: Horn-Loaded Speakers
In the Thread: New superlative horn build - ESD acoustic
Post Subject: Beryllium and inversed phase plugPosted by martinshorn on: 5/14/2018
Something they mustve obviously done better than others using beryllium. Judging the sound. In a positive way.
The lower 3 are titanium, but all upper 3 are 4/3/2 inch BE sourced from truextend.
The suspensenion however is soft and allows excursion.
In order to solve the field coil issue described earlier, along with long throat colorations, they mounted the horn onto the diaphragm side of the magnet.
This will not press the sound through the magnet but release immediately from the phaseplug free to the horn.
By using WE/goto oldfashioned phaseplugs however, the bandwidth suffers. Also the groupdelay on the upper knee.
This was improved in using a modern radial-multi-slid which is not possible on the front-firing-driver.
Their solution was to invert the dome towards the magnet, with a negative dome-shape pole-plate.
By that a normal slit-plug is used in a front-fire towards the throat, outside of the magnet.
As a next, they did not use standard slit-plugs. All industry is using conical constant widening phase-plugs.
Actually being more precise, the throat should start curved already as a continuation of the horn shape.
This was applied on all drivers, which is a lot more complex and expensive to manufacture.
The lower octaves are also tangerine plugs, while the upper are radial.
Theyre using non-standard metal plugs to keep resonance rining of plugs above their operating range.
The tweeters use heavy soft non metallic plugs with a resonance below operating range.
The faceplate is mounted on the horn in a way that the phase-plugs are immediately on the horn-throat.
It was nice to see the seemless transition with my torch.
The BE brakeup combined with soft long excursion suspension gives the drivers the advantage of huge bandwidth, used for one nice extra feature described later in the devices part (amps etc.).
It was nice to talk to the Son and engineer providing proud all details with glow in the eyes, instead of rejecting like other companies "this is proprietary secret". You can really see they love what theyre doing 
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