[BC] Looking For Mono To Stereo Conversion Software

[Robert Orban]

At 10:18 AM 5/26/2005, you wrote:
>From: Kirk Harnack <kirk at harnack.com>
>Subject: Re: [BC] Looking For Mono To Stereo Conversion Software
>To: Broadcast Radio Mailing List <broadcast at radiolists.net>
>Message-ID: <4295DBB3.2090505 at harnack.com>
>Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
>Danny Ray Boyer wrote:
> > Bernie, you are correct in what I need.  I have a mono wav file and want
> > to create a "fake" stereo image from the mono file. We have CoolEdit in
> > house and if it can do the conversion, I am unaware of it.
> > Cowboy, I will also try the Windows Sound Recorder.
> >
> > Danny Ray Boyer
> >
>
>You could do pseudo stereo yourself by this method:
>
>Import your mono file into Cool Edit Pro, then save as a stereo file.
>
>Reopen it and apply opposite EQ "cuts" the Left and Right channels of
>the file.
>
>For example, make the Left channel have three bandstop areas at, say
>300Hz, 1.5kHz, and 3kHz.  Make the Right channel have bandstop areas at,
>say 150Hz, 750Hz and 2kHz.  Get the idea?  If you can get the
>"crossover" points to match up, this will work better.
>
>This is similar to the basis of operation of Orban's stereo synthesizer.
>   I'm sure Bob Orban could advise you much better than the foregoing,
>but you get the idea.

My stereo synthesizer patent involved creating an L-R signal by passing the 
mono signal through an allpass filter. (You could also use a time delay 
instead of the allpass filter, although this was not part of my original 
patent, as this form of pseudo-stereo had been invented earlier by Mr. 
Hammond of Hammond Organ fame.) The left and right channels are created by 
matrixing the derived L-R signal with the original mono (treated as L+R). 
The resulting L and R channels have a so-called "complementary comb filter" 
response. This process produces excellent mono compatibility because the 
L+R signal is the original mono and the sum of the power spectra of the L 
and R channels is proportional to the power spectrum of the original mono.

Using graphic equalizers to approximate this process can get reasonable 
results, but one has to be careful to make the settings of the two graphic 
EQs as complementary as possible.

  I don't know of any plug-in that uses my process, but that's not to say 
that one doesn't exist.

Bob Orban