High Efficiency Speaker Asylum

Need speakers that can rock with just one watt? You found da place.

Use this form to submit comments directly to the Asylum moderators for this forum. We're particularly interested in truly outstanding posts that might be added to our FAQs.
You may also use this form to provide feedback or to call attention to messages that may be in violation of our content rules.

You must login to use this feature.

Inmate Login

By default, logging in will set a session cookie that disappears when you close your browser. Clicking on the 'Remember my Moniker & Password' below will cause a permanent 'Login Cookie' to be set.

Moniker/Username: The Name that you picked or by default, your email. Forgot Moniker?	Examples "Rapper", "Bob W", "joe@aol.com".
Password:	Forgot Password?
	Remember my Moniker & Password ( What's this?)

If you don't have an Asylum Account, you can create one by clicking Here.

Our privacy policy can be reviewed by clicking Here.

Inmate Comments

From:
Your Email:
Subject:

Message Comments

Original Message

Re: Holism and Reductionism - Fourier Series

Posted by Wayne Parham on September 9, 2003 at 02:31:42:
Tom -
Are you kidding me? Remember that I am skeptical of claims of perfect acoustic phase by loudspeaker manufacturers. I'm agreeing with Dawson's assertion that the perfect quadrature is non-realizable, at least in the approximated form you've likened it to as a direct radiator.
The mass/spring system forms a filter that changes phase with frequency. Reactive components used in the circuit also form filters that modify phase. The phase of the current through the circuit is relatively easy to find with reactive formulas, and it is non-zero over much of the audio bandwidth for every speaker motor and/or crossover discussed here. For that matter, it is also not a constant quadrature at 90^o.
Beyond this, the speaker's diaphragm is not a point source, but rather a planar source. It approximates a point source at frequencies where wavelength is large compared to diaphragm size and acts as a radiating plane above that. This creates a filter system too. And finally, we have cone flex to consider, which also creates a filter that isn't minimum phase.
Horn's are not exempt either - They suffer from all the same causes of phase shift as direct radiators, and they have some additional ones as well, such as path length, diffraction and other dispersion modifiers and additional resonances such as those caused by panel vibrations and those from 1/4 wave peaking. Sure you can limit those, and that's the hope of every designer. And sure a "perfect load" would be perfectly resistive, having no phase shift. But we're not talking about hypothetical perfect loads here, and to design with such an assumption is absolutely foolish.
So there's good reason to question claims of perfect acoustic phase from a design based on components using these technologies. Then again, there are a lot of good design choices and solutions that will work well. Dawson has given you some examples of those he has found. But academically speaking, there are complications that prevent optimizations of all criteria simultaneously. If this weren't so, we'd probably not be building such a variety of machines.
Wayne