Optimal Loudspeaker Beam

[thadman]

Assuming a waveguide is used, a beam of energy is produced. The waveguides direct the energy to a particular shape. The beams produced by waveguides vary (Geddes, Le'Cleach, etc).

What is to be considered the optimal beam shape that these waveguides attempt to achieve?

[brianpowers27]

Disclaimer, I am no horn guru.

Goal of directivity... To provide good coverage accross the inteded passband to all listeners. Note: Sometimes you want wide coverage but with a woofer matched to a horn you are likely trying to provide a system-wide power response that is smooth through the xo region.

Short answer: There is no single answer to this question. The best coverage patterns are found by simulating the power response of the total system.

[thadman]

Originally Posted by brianpowers27

Short answer: There is no single answer to this question. The best coverage patterns are found by simulating the power response of the total system.

Stereo, Position Independent Stereo, etc recordings require interference between multiple channels and assume a particular distribution of energy (ie a particular beam). This is not subjective, it is what the recording engineers design for.

[Robh3606]

This is not subjective, it is what the recording engineers design for.

How do they design for something they have no control over?? Speaker directivity is all over the map depending on the design of the speakers. Driver size and bunch of other factors all come into play. So there is no control over what someone hears in their room. There is no set directivity requirements for speakers used as monitors either.

Rob

[amiklos]

Originally Posted by thadman

This is not subjective, it is what the recording engineers design for.

Is there some requirement in place assuring that they all design for the same condition?

[soongsc]

Some research published at AES showed more beaming in thw lower frequency is desired.

[thadman]

Originally Posted by Robh3606

How do they design for something they have no control over?? Speaker directivity is all over the map depending on the design of the speakers. Driver size and bunch of other factors all come into play. So there is no control over what someone hears in their room. There is no set directivity requirements for speakers used as monitors either.

Rob

This is true.

A standard may not exist, however some patterns may produce a more desirable interference pattern with respect to the desired format (stereo, position independent stereo, surround sound, ambiophonics).

I believe Dr. Geddes may advocate consistent 90* dispersion with amplitude decreasing beyond that point to as low frequency as possible. If this is inaccurate or incomplete, I would appreciate feedback.

Phillips described a desired polar pattern for position independent stereo, however I'm having trouble sourcing the article again.

[CLS]

Originally Posted by soongsc

Some research published at AES showed more beaming in thw lower frequency is desired.

How?

Mega bass horn, cardioid, or dipole ?

I've never heard cardioid bass, while I do love BIG bass horn and OB bass very much.

[soongsc]

Originally Posted by CLS

How?

Mega bass horn, cardioid, or dipole ?

I've never heard cardioid bass, while I do love BIG bass horn and OB bass very much.

It diddn't say how, it only showed analysis results bassed on ITD and IID.
I would love to listen to a Mega bass horn if you have one set up.

[CLS]

Please forgive my ignorance, what are ITD and IID ?

About the big bass horn, here it is:
3way Horn

It's in a big studio of a university in southern Taiwan.