27 May
2008
27 May
'08
7:14 a.m.
Hi
A question came up on the chuck list today, regarding how to invert the
phase of one channel. The poster wanted to use this "trick" to widen the
width of the stereo image, and it sure does.
However now I'm thinking if it's a good idea in the first place. Besides
loosing mono-compatibility, I have a gut feeling that audio treated this
way will become very uncomfortable or even annoying to listen to after a
while.
Does anyone have any thought about this? Should this "trick" simply be
avoided or are there situations where using it on some parts of a mix
would be ok (keeping in mind that the tracks in question will disappear
in mono)?
--
peace, love & harmony
Atte
http://atte.dk | http://myspace.com/attejensen
http://anagrammer.dk | http://modlys.dk
27 May
27 May
7:36 a.m.
Hi!
Well I think it depends. If you're pretty sure, your mix will be around in
mono somewhere, then you should probably not do it. Otherwise: i didn't listen
to the effect, I'll try it.
But I would suggest using the SWH LADSPA plugins, they have a stereo-width
plugin:
matrix_spatialiser_1422.so
It simulates a different recording technique with two mics, on (I think
mono) directed towards the source and a figure-eight microphone orthogonal to
the other.
Kindest regards
Julien
--------
Music was my first love and it will be my last (John Miles)
======== FIND MY WEB-PROJECT AT: ========
http://ltsb.sourceforge.net
the Linux TextBased Studio guide
======= AND MY PERSONAL PAGES AT: =======
http://www.juliencoder.de
8:10 a.m.
Julien Claassen wrote:
But I would suggest using the SWH LADSPA plugins,
they have a
stereo-width plugin:
That would be besides the point. (I guess) He wants to keep it in chuck,
maybe for practical or educational purposes.
--
peace, love & harmony
Atte
http://atte.dk | http://myspace.com/attejensen
http://anagrammer.dk | http://modlys.dk
7:51 a.m.
On Tue, May 27, 2008 at 11:14:18AM +0200, Atte André Jensen wrote:
A question came up on the chuck list today, regarding
how to invert the
phase of one channel. The poster wanted to use this "trick" to widen the
width of the stereo image, and it sure does.
Bah, what you get is no stereo image at all, but some sort
of 'spatial soup'.
However now I'm thinking if it's a good idea
in the first place. Besides
loosing mono-compatibility, I have a gut feeling that audio treated this
way will become very uncomfortable or even annoying to listen to after a
while.
True.
Does anyone have any thought about this? Should this
"trick" simply be
avoided or are there situations where using it on some parts of a mix
would be ok (keeping in mind that the tracks in question will disappear
in mono)?
Just don't do it.
What you can do on selected tracks is to pan a bit 'outside the
speakers'. Normally if you pan e.g. hard right then L will be
zero, but you could make it negative. Most panners can't do this
but you get the same effect with
L' = R - a * L
R' = L - a * R
with 0 <= a <= 0.5.
Still not very good for mono compatibility, but if used with some
care, and on selected tracks, it works.
If you are listening with a normal stereo setup (angle between
speakers = 60..90 degrees) and feel the need to this, then there
is probably something wrong with your mix, and that should be
solved first. Could be it's missing some early reflections.
If the purpose of all this is to get a wider stereo image from
e.g. speakers built into a monitor, then there are other methods,
like crosstalk cancellation. But these should be applied at the
listeners's end, not in the mix.
--
FA
Laboratorio di Acustica ed Elettroacustica
Parma, Italia
Lascia la spina, cogli la rosa.
8:07 a.m.
Fons Adriaensen wrote:
Bah, what you get is no stereo image at all, but some
sort
of 'spatial soup'.
Ok, then we agree :-)
However now I reread the post more closely, and it seems his intentions
were a bit different. Here's what he wrote:
"feed the left channel back to the right with a short delay, inverted;
feed the right channel back to the left with a short delay, inverted;"
Actually it sounds to me like the inverting part becomes irrellevant.
When the delayed + inverted sound is output, the original audio has
moved on and the delayed audio is simply "something new" that's mixed
in, inverted or not.
Is this some kind of well known trick or am I right that inverting the
delayed signal doesn't do anything (good) for the result?
--
peace, love & harmony
Atte
http://atte.dk | http://myspace.com/attejensen
http://anagrammer.dk | http://modlys.dk
8:16 a.m.
On Tue, May 27, 2008 at 12:07:11PM +0200, Atte André Jensen wrote:
Fons Adriaensen wrote:
If the delay roughly corresponds to the path difference of one
ear to both speakers, and you do invert, then this is a primitive
form of crosstalk cancellation.
If you want to try the real thing (which can be quite good), get
jconv and use one of two EYCv2** configurations. More info in
the config files.
Ciao,
--
FA
Laboratorio di Acustica ed Elettroacustica
Parma, Italia
Lascia la spina, cogli la rosa.
Bah, what you get is no stereo image at all, but
some sort
of 'spatial soup'.
Ok, then we agree :-)
However now I reread the post more closely, and it seems his intentions
were a bit different. Here's what he wrote:
"feed the left channel back to the right with a short delay, inverted;
feed the right channel back to the left with a short delay, inverted;"
Actually it sounds to me like the inverting part becomes irrellevant. When
the delayed + inverted sound is output, the original audio has moved on and
the delayed audio is simply "something new" that's mixed in, inverted or
not.
Is this some kind of well known trick or am I right that inverting the
delayed signal doesn't do anything (good) for the result?
8:24 a.m.
Fons Adriaensen wrote:
If the delay roughly corresponds to the path
difference of one
ear to both speakers, and you do invert, then this is a primitive
form of crosstalk cancellation.
So the delay part is crucial and the result can be good?
I don't understand how long the delay should be (although I know how
fast sound travels and how far apart my ears are).
Supposed I'm 10 meters away from a PA (speakers 10 meters apart), what
should the delay be? What if I'm listening at home, 3 meters away from
my home stereo (speakers 3 meters apart)? What if I'm listening through
headphones?
I'm starting to find this interesting :-)
If you want to try the real thing (which can be quite
good), get
jconv and use one of two EYCv2** configurations.
Maybe I should!
--
peace, love & harmony
Atte
http://atte.dk | http://myspace.com/attejensen
http://anagrammer.dk | http://modlys.dk
8:41 a.m.
On Tue, May 27, 2008 at 12:23:57PM +0200, Atte André Jensen wrote:
Fons Adriaensen wrote:
It's not supposed to work in those conditions. What you need is
two speakers that you see in an angle of about 20 degrees (so
much closer than normal), and a distance of around 2 to 3 meters.
The 'sweet spot' is quite small. Two or more listeners should
be behind each other, not besides.
The required delay is very small, around 100 us.
If the delay roughly corresponds to the path
difference of one
ear to both speakers, and you do invert, then this is a primitive
form of crosstalk cancellation.
So the delay part is crucial and the result can be good?
I don't understand how long the delay should be (although I know how fast
sound travels and how far apart my ears are).
Supposed I'm 10 meters away from a PA (speakers 10 meters apart), what
should the delay be? What if I'm listening at home, 3 meters away from my
home stereo (speakers 3 meters apart)? What if I'm listening through headphones?
Bad idea ! Xtalk cancellation is used to *replace* headphones,
while allowing the listener to turn his/her head w.r.t. the
speakers. Allowing this makes the image much more 'real' than
with headphones.
Ciao,
--
FA
Laboratorio di Acustica ed Elettroacustica
Parma, Italia
Lascia la spina, cogli la rosa.
8:48 a.m.
Fons Adriaensen wrote:
It's not supposed to work in those conditions.
What you need is
two speakers that you see in an angle of about 20 degrees (so
much closer than normal), and a distance of around 2 to 3 meters.
The 'sweet spot' is quite small. Two or more listeners should
be behind each other, not besides.
Ok, so that's why you were talking about it only being useful "at the
listeners's end, not in the mix".
Thanks for clearing everything up!
--
peace, love & harmony
Atte
http://atte.dk | http://myspace.com/attejensen
http://anagrammer.dk | http://modlys.dk
4:12 p.m.
Back on Tuesday 27 May 2008, Atte André Jensen was like:
Hi
A question came up on the chuck list today, regarding how to invert the
phase of one channel. The poster wanted to use this "trick" to widen the
width of the stereo image, and it sure does.
NOOOOOOOOOO. This stupid trick is EVIL.
However now I'm thinking if it's a good idea
in the first place. Besides
loosing mono-compatibility, I have a gut feeling that audio treated this
way will become very uncomfortable or even annoying to listen to after a
while.
It is VERY annoying. When listening to it with headphones, the side where the
phase is inverted causes my ear to "itch". It's very annoying and
uncomfortable, and I notice it immediately.
Does anyone have any thought about this? Should this
"trick" simply be
avoided or are there situations where using it on some parts of a mix
would be ok (keeping in mind that the tracks in question will disappear
in mono)?
Avoid this, and shoot anybody who tries to do this. It is annoying on
headphones, and causes all sorts of frequency cancellation problems when
played from stereo speakers.
-Reuben
6028
days inactive
6028
days old
linux-audio-user@lists.linuxaudio.org
9 comments
4 participants
participants (4)
-
Atte André Jensen -
Fons Adriaensen -
Julien Claassen -
Reuben Martin