[jason]

I recently recorded a 24-voice acapella group performing in a great-
sounding church.

When I make a recording like this, I set up early and record a minute or
two of "the room" before anybody's there. I've used that a bit to
eliminate low-freq rumbles from HVAC and the like, but this recent
performance didn't have any of that. There -was- a low-freq "room sound"
(sorry I cannot characterize that better). It wasn't hvac or ac hum; it
sounded like stepping into a spacious, empty room. I've experienced that
ambient background many places where I've made recordings.

For fun, I used an Audition plugin to convert the X-Y recording to M-S
because I wanted to see what the effect of "more S and less M" would do to
spread out the image. The result was very pleasing if I didn't push it
very hard. But I noticed something I can't explain: the M-S rendition had
much less of "the room" ambience than the X-Y recording. The vocals didn't
sound different except for being spread out some. I actually liked the
fact that silences during the performance were really silent compared to
X-Y.

What accounts for this or am I hearing things? (or not)

[Scott Dorsey]

Jason wrote:

For fun, I used an Audition plugin to convert the X-Y recording to M-S
because I wanted to see what the effect of "more S and less M" would do to
spread out the image. The result was very pleasing if I didn't push it
very hard. But I noticed something I can't explain: the M-S rendition had
much less of "the room" ambience than the X-Y recording. The vocals didn't
sound different except for being spread out some. I actually liked the
fact that silences during the performance were really silent compared to
X-Y.

Okay, you have L and R signals in a file.

You convert them to M and S.

Then, you adjust the levels in order to change the stereo image.

Then, you convert them back to L and R to play them back.

Is this the process you are going through, or did you omit one or more stage?
If you convert to M-S, don't change the gains, and then convert back to left
and right, you shouldn't notice any difference in sound at all. If you do,
there is a mathematical issue going on.

If you convert to M-S and then play the M-S signal through two speakers, it will
sound bizarre and not very useful.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[[email protected]]

The low freq room tone is probably almost
all mono in phase. Any processing you do
to that reduces the mono in phase component
and increases the out of phase difference
component will likely also reduce
the room tone. M

[jason]

On 29 Apr 2017 23:36:45 -0400 "Scott Dorsey" wrote in
article
Is this the process you are going through, or did you omit one or more stage?
If you convert to M-S, don't change the gains, and then convert back to left
and right, you shouldn't notice any difference in sound at all. If you do,
there is a mathematical issue going on.


I did that. The sound changed, so I think you're speculation about a math
issue is probably true.

[Scott Dorsey]

Jason wrote:
On 29 Apr 2017 23:36:45 -0400 "Scott Dorsey" wrote in
article
Is this the process you are going through, or did you omit one or more stage?
If you convert to M-S, don't change the gains, and then convert back to left
and right, you shouldn't notice any difference in sound at all. If you do,
there is a mathematical issue going on.

I did that. The sound changed, so I think you're speculation about a math
issue is probably true.

Well, that's no good. Let us know what software this is so we can avoid it.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Jason[_15_]]

In article , says...
Well, that's no good. Let us know what software this is so we can avoid it.
--scott


It is a freebie from Voxengo. I see now that there is a newer version. I
may see if it's any different. I can use the Channel Mixer in Audition
to do the same experiment (I'd forgotten about that), so I'll give that
a try.

[[email protected]]

On Saturday, May 13, 2017 at 12:40:06 PM UTC-4, Jason wrote:
In article , says...
Well, that's no good. Let us know what software this is so we can avoid it.
--scott


It is a freebie from Voxengo. I see now that there is a newer version. I
may see if it's any different. I can use the Channel Mixer in Audition
to do the same experiment (I'd forgotten about that), so I'll give that
a try.

I'd HOPE you could do everything in Audtion, since it's so costly and so filled with bells and whistles.

Feel everyone wants to be a Pro, so they must use what Pros use. So silly to think like that.

Just my two cents, no attack intended.

Jack

[[email protected]]

On Saturday, April 29, 2017 at 10:40:48 PM UTC-4, Jason wrote:
I recently recorded a 24-voice acapella group performing in a great-
sounding church.

When I make a recording like this, I set up early and record a minute or
two of "the room" before anybody's there. I've used that a bit to
eliminate low-freq rumbles from HVAC



Forced air? Steam? What makes "rumble"?

Jack


and the like, but this recent
performance didn't have any of that. There -was- a low-freq "room sound"
(sorry I cannot characterize that better). It wasn't hvac or ac hum; it
sounded like stepping into a spacious, empty room. I've experienced that
ambient background many places where I've made recordings.

For fun, I used an Audition plugin to convert the X-Y recording to M-S
because I wanted to see what the effect of "more S and less M" would do to
spread out the image. The result was very pleasing if I didn't push it
very hard. But I noticed something I can't explain: the M-S rendition had
much less of "the room" ambience than the X-Y recording. The vocals didn't
sound different except for being spread out some. I actually liked the
fact that silences during the performance were really silent compared to
X-Y.

What accounts for this or am I hearing things? (or not)