Emerald Physics

[JonasKarud]

Anybody out there who knows how the " Aperture Bass Propagation technology" works, mentioned here:

http://www.emeraldphysics.com/page9/page9.html

[Patrick Bateman]

Based on the pic, it looks like they're doing one of two things:

• There's a chamber in front of the woofer now. A chamber would roll off the highs physically. Basically a bandpass, but tuned differently.
• Or it's a 'real' dual reflex bandpass, with a vented front and rear chamber. This is something I've really wanted to explore using Akabak or Martin King's Quarter-Wave software. You can modify the directivity of a speaker using a vent, because the vent's aperture is smaller than the speaker.

[MaVo]

Judged by the size of this hole in front of the woofers, it should have no effect at all in the passband of the woofer.

The "Aperture Bass Propagation technology" works by impressing the customer with fancy words and by this raising the amount of money he will spend for the speaker. In its own way, this is an impressive technology.

[JonasKarud]

I know so much that it works as a dipole, no rear chamber.

I've done some simulating in Lspcad, as a dipole radiator on rear side of cone and a small box, 4 liters, with a short, 30mm port with 100 mm diam. on the front side of the cone. The simulated results can make a grown man cry......

[Patrick Bateman]

Originally posted by MaVo
Judged by the size of this hole in front of the woofers, it should have no effect at all in the passband of the woofer.

The "Aperture Bass Propagation technology" works by impressing the customer with fancy words and by this raising the amount of money he will spend for the speaker. In its own way, this is an impressive technology.

I've heard their previous products, they're very good. Lots of solid engineering at Emerald Physics.

A fifteen inch woofer's directivity will begin to narrow at 900hz, due to the diaphragms dimensions. My Summas take advantage of this to cross over to a waveguide which goes down to... you guessed it, 900hz.

By re-directing the energy of the fifteen inch woofer through a 6" port, the woofer will now begin to narrow at 2250khz. This change in the directivity allows the woofer to have a more consistent coverage pattern below AND above the crossover point.

Pretty clever I'd say.

[gainphile]

Hi, is there any measurements of Emerald Physics products out there? CS2 lets say...

[jamikl]

I'm at work and can't sim this now. It seems to be the same as a slot loaded box without the box. Could be modelled in Horn response with no rear chamber, front chamber same as speaker volume on inside of cone and surround and a conical horn with maybe 25mm length and no expansion. Might look good until combined response is done for back to front cancellation. I have been looking at slot loading an open baffle myself to keep the directivity higher. As I said, can sometimes look good until the cancellation comes into the sim.
jamikl

[MaVo]

Originally posted by Patrick Bateman
By re-directing the energy of the fifteen inch woofer through a 6" port, the woofer will now begin to narrow at 2250khz. This change in the directivity allows the woofer to have a more consistent coverage pattern below AND above the crossover point.

Pretty clever I'd say.

You have to take into account that this box uses a 12 inch coaxial driver for mid, so the crossover point will be probably 3 octaves below this 2250hz and thats why the holes wont have much effect.

[gedlee]

Originally posted by MaVo

The "Aperture Bass Propagation technology" works by impressing the customer with fancy words and by this raising the amount of money he will spend for the speaker. In its own way, this is an impressive technology.

Thats my take on it too.

[Patrick Bateman]

Originally posted by jamikl
I'm at work and can't sim this now. It seems to be the same as a slot loaded box without the box. Could be modelled in Horn response with no rear chamber, front chamber same as speaker volume on inside of cone and surround and a conical horn with maybe 25mm length and no expansion. Might look good until combined response is done for back to front cancellation. I have been looking at slot loading an open baffle myself to keep the directivity higher. As I said, can sometimes look good until the cancellation comes into the sim.
jamikl

In some ways, it reminds me of a u-frame woofer as well. That was probably one of the most satisfying projects I've worked on. Easy to build, highly efficient, and sound great.