Acoustic reflectors and piston drivers

[markus76]

I'd like to invite everybody to a technical discussion about simple shaped reflectors/deflectors mounted in front of common piston drivers. Here's an example:



What is its task?
What are the working principles?
Are there any real world measurements that confirm functionality?
How does shape, size and distance from driver affect the performance?
How does the driver affect performance?
Can the behavior be modeled?

Any references and measurements are welcome.

[DrDyna]

Do these count?

Entry Speaker

I'm not sure about measurements, but the reviews seem favorable.

[jcx]

BeoLabs 5 speakers use "Acoustic Lens Technology"

claimed to be CAD optimized - in a talk it was stated it was more "fluid mechanics" than ray tracing

[weltersys]

Originally Posted by markus76

I'd like to invite everybody to a technical discussion about simple shaped reflectors/deflectors mounted in front of common piston drivers. Here's an example:



What is its task?
What are the working principles?
Are there any real world measurements that confirm functionality?
How does shape, size and distance from driver affect the performance?
How does the driver affect performance?
Can the behavior be modeled?

Any references and measurements are welcome.

The reflector’s ”task” is to provide 360 degree coverage in the high frequency range of the speaker.

The working principle is high frequency sound waves reflect like a ray of light off a mirror.
A simple cone shape as depicted will have a very narrow vertical dispersion at high frequencies.

The size of the reflector must be around a wavelength long to be effective, wavelengths longer than the reflector will diffract around the reflector rather than reflect.
Different shapes will reflect in different directions.

Different drivers will have different radiation patterns at different frequencies, emanating from different parts of the cone. The larger the driver, the lower the frequency that the speaker narrows in HF dispersion.

For a model to be useful, it would have to use the complex radiation pattern of a specific driver , which would require measurement of the driver prior to creation of the model.

[Bill poster]

Thanks for starting this thread because I've spent the last week trying to come up with original ideas for an acoustic lens/reflector.

[gedlee]

Hi Markus

Digging down deep for topics? I cannot imagine such a device working well. The B&O device didn't.

"Fluid mechanics" versus "ray tracing"!? Thats a new one. So "Acoustics" is now "Fluid Mechanics"? Well I guess that it always was, its just that Fluid Mechanics is mostly a static flow analysis and acoustics is a dynamic one where any static flow is ignored. So I guess that B&O is interested in the air currents arround the room and their effect on the sound?

[Bill poster]

Originally Posted by DrDyna

Do these count?

Entry Speaker

I'm not sure about measurements, but the reviews seem favorable.

Could have been a design classic without the hideous logo/font on the side. Oh well.

[DrDyna]

Originally Posted by Bill poster

Could have been a design classic without the hideous logo/font on the side. Oh well.

That rattle you just heard was me preparing my correction for that problem if I ever owned these speakers

[Bill poster]

Originally Posted by gedlee

Hi Markus

Digging down deep for topics? I cannot imagine such a device working well. The B&O device didn't.

Out of interest, do you mean the Sausalito lens?

[Bill poster]

Originally Posted by DrDyna

That rattle you just heard was me preparing my correction for that problem if I ever owned these speakers

lol!