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Re: mono and pseudo-stereo?

Subject: Re: mono and pseudo-stereo?
From: Wild Sanctuary <>
Date: Tue, 15 Jun 2004 06:40:44 -0700
By copying the left channel to the right (assuming it is exactly the 
same material and aligned) you'll get two-track mono and not 
pseudo-stereo, Julie. There are, however, a number of processes, both 
analog and digital, from which you can derive pseudo-stereo - or at 
least a stereo illusion (a false sense of space from a mono track). 
The oldest is the Orban system (analog, 1968), which takes a mono 
track and divides the signal into 5 frequency bands. At each 
crossover point (the point at which a frequency band is separated 
from its nearest neighbor) Bob Orban introduced a 90 degree phase 
shift. Channels 1, 3, and 5 (the odds) were placed on the left. 
Channels 2 and 4 (evens) were placed on the right. The neat things 
about the Orban is that all of the controls are continuously variable 
(and/or voltage controllable) so that one can adjust the quality of 
the illusion to one's taste, and that by re-combining right and left 
channels, one can get an exact duplication of the original mono 
source. Later digital versions of stereo synthesizers, such as those 
available as part of multiple programs in the Alesis Quadraverb 
device (among others), offers variations on that theme. Some are 
really quite impressive given the mono source.

When I first began to record M-S in the late 80s, I brought into the 
field a martix (Schoeps) with which I was completely unfamiliar 
having received it just a day before I left for an African trip. 
During the entire time in the field, my mic cables were plugged into 
the wrong inputs on the matrix (which I didn't realize even though I 
thought I was monitoring correctly). Consequently, I lost a months 
worth of work at Jane Goodall's research site in Gombe. It was only 
when I got home that I realized that all I had was mono data. 
Horrified and embarrassed, I've spent the past dozen years trying to 
figure out how to derive stereo from those otherwise vaulable mono 
recordings. Using a carefully calibrated combination of analog and 
digital processes, I've managed to create a reasonable stereo 
illusion and recover some of the "space" present in that environment. 
It ain't the same. But it's better (different) than mono.

Bernie Krause

Wild Sanctuary, Inc.
P. O. Box 536
Glen Ellen, California  95442-0536
Tel: (707) 996-6677
Fax: (707) 996-0280
http://www.wildsanctuary.com

>Now I use only one Mic for my maranz, so my music file was mono. But
>then  what's the difference if I copy the left channel to right
>channel and make  it as a stereo file? It really occupy a lot of
>memory, but then what's the  difference of hearing btw the mono
>and "pseudo-stereo"?
>
>Thank you!
>
>A beginner, Julie
>
>
>
>
>
>"Microphones are not ears,
>Loudspeakers are not birds,
>A listening room is not nature."
>Klas Strandberg
>Yahoo! Groups Links
>
>
>
>


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