[BC] Looking For Mono To Stereo Conversion Software

[David Reaves]

Here's a way to use any basic audio editing program to create a simu-=20
stereo file that will sum back perfectly to the original in mono (you =20=

could also do this in analog with a few "Y" cables and a graphic EQ):

First, duplicate the original single-channel mono file so you have =20
two copies. Call them "A" and "B."

Take copy "A" and using your EQ make several relatively narrow (=B2 1 =20=

Octave) and relatively deep (=B3 8-10dB) notches across the spectrum.
This EQ'd version of the original will be your "channel 1."

To create "channel 2," make a copy of your newly EQ'ed "channel 1" =20
file. Flip its polarity. Do NOT change its level. Sum that with your =20
"B" copy of the original mono source, to make a new file. Call this =20
file "channel 2."

By using this method of subtracting the EQ'ed "channel 1" from the =20
original, your synthetic "channel 2" file will automatically have =20
corresponding "bumps" in its spectrum where the "channel 1" file has =20
notches.

Finally, use the "channel 1" and "channel 2" files as the Left and =20
Right channels to make your new "fake stereo" file.

If you do this procedure real-time rather than with WAV files, watch =20
your level meters while you listen, adjusting the EQ of "channel 1" =20
so that both channels get a similar amount of energy. Sweeping the =20
frequency and width of the notches around a bit should help you find =20
some settings that work best for both channels, and a satisfying =20
stereo effect... You may want to concentrate on the lower and upper =20
midrange, but settings certainly aren't critical.

By using notches and subtraction, you run no risk of creating =20
overloads. But you may need to normalize the final stereo file to =20
bring the levels back up to zero.

You could get a lot more elaborate than this. But any way you look at =20=

it, what you're doing is just a cartoon of the original. Though at =20
least with this method it will sound identical to the original when =20
summed to mono.

As well it should. :-)


David P. Reaves, III
TransLanTech Sound, LLC
Home of the Award-winning "Ariane Sequel" Digital Audio Leveler


On Thu, 26 May 2005 09:22:43 -0500, Kirk Harnack <kirk at harnack.com> =20
wrote:
<<
> Danny Ray Boyer wrote:
>
>> Bernie, you are correct in what I need.  I have a mono wav file =20
>> and want
>> to create a "fake" stereo image from the mono file. We have =20
>> 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 =20
> 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 =20
> synthesizer.
>   I'm sure Bob Orban could advise you much better than the foregoing,
> but you get the idea.
>
> Best,
>
> Kirk Harnack
 >>=