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Re: Fw: sursound: The pinna and Ambisonics/cross post (fwd)


I'm forwarding this response regarding subwoofers from Geoff Martin, who
is not on the list.

Jason Corey

---------- Forwarded message ----------
Date: Mon, 23 Oct 2000 19:28:41 -0400 (EDT)
From: Geoff Martin <martin@music.mcgill.ca>
Subject: Re: Fw: sursound: The pinna and Ambisonics/cross post (fwd)

> Regarding point 2, I wonder why audio engineers think that a single sub-woofer
> is a good idea these days. I find that they confuse the image compared to
> a conventional pair of stereo speakers. Multiple tweeters around the room
> seem like a good idea in view of 3) though.


Many audio engineers do not think that a single subwoofer is a good idea.
The specification for a single sub (the ".1" in "5.1") is intended for a
single driver dedicated to what is known as the Low Frequency Effects or
LFE channel. This is not to be used for anything other than special
effects such as explosions or spaceship engine rumble. For multichannel
music reproduction, even Dolby recommends the use of 5 matched full-range
loudspeakers and no subwoofer. (i.e. www.dolby.com/tech/5.1_mixing.pdf
- "In most music productions, there is unlikely to be a technical need to
use the LFE channel.")

Unfortunately the manufacturers of home audio components neglect this
recommendation and build 5-channel reproduction system which are based on
a low-frequency driver reproducing a signal summed from the 5 channels -
it's cheaper for them (and for you) but it by no means an optimal

I would reommend reading David Griesinger's and/or William Marten's work
on this issue:

Griesinger's home page

"Speaker placement, externalization, and envelopment in home listening
rooms" (DG)

"The Impact of Decorrelated Low-Frequency Reproduction on Auditory Spatial
Imagery: Are Two Subwoofers Better Than One?" (WM)
Proceedings of the AES 16th International Conference, 1999 April 10-12


                          Geoff Martin |
    http://www.music.mcgill.ca/~martin | "As long as people will accept
Multichannel Audio Research Laboratory |  crap, it will be financially
     Music, Media and Technology Group |  profitable to dispense it."
    McGill University Faculty of Music |            - D. Cavett