I once heard someone describe a tedious but effective way of cancelling
microphone bleed (by editing tracks) when recording vocals and acoustic
guitar at the same time. Would someone explain this procedure? Thanks!

John Mercer wrote:
I once heard someone describe a tedious but effective way of cancelling
microphone bleed (by editing tracks) when recording vocals and acoustic
guitar at the same time. Would someone explain this procedure? Thanks!

Use a figure-8 mike. Put the vocal in the null of the guitar.

Do the same thing for the vocal.

For the most part, guitar bleed into the vocal mike isn't as bad as
vocal bleed into the guitar mike. If the guitar has a little comb
filtering, it's not as annoying as if the vocal does.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Phase reversal and summing?

On Tue, 03 Jan 2006 13:18:11 -0800, Andy Eng wrote:

Phase reversal and summing?

I've found that makes the both the guitar and vocal sound a bit weird. As
if you had scooped out the lower mids with an eq.

This might work..

Copy the guitar track to a new track. Shift it a few ms so it lines it up
with the guitar spill on the vocal track. Put it out of phase. Eq and
adjust the level till it does some useful cancelling of the guitar spill
on the vocal track.

Probably still sound weird though.

philicorda wrote in
news
On Tue, 03 Jan 2006 13:18:11 -0800, Andy Eng wrote:

This might work..

Copy the guitar track to a new track. Shift it a few ms so it lines it up
with the guitar spill on the vocal track. Put it out of phase. Eq and
adjust the level till it does some useful cancelling of the guitar spill
on the vocal track.

Probably still sound weird though.

In theory, woulkd the combination of these two tracks then be copied to a
new track that resulted in little or no bleed of the guitar? If the same
procedure is then done to the guitar track, would it provide two separate
tracks with no significant bleed of either guitar or vocal?

(Scott Dorsey) wrote in
:


Use a figure-8 mike. Put the vocal in the null of the guitar.

Do the same thing for the vocal.

For the most part, guitar bleed into the vocal mike isn't as bad as
vocal bleed into the guitar mike. If the guitar has a little comb
filtering, it's not as annoying as if the vocal does.
--scott

Unfortunately, I look down at the guitar while singing because of lots of
movement withing the music. The bleed that is causing me the most grief is
vocal into the guitar mic. I am going to try the figure 8 suggestion and
hope for some placement that will work in my not so very forgiving
environment. Thanks for the suggestion.

"Andy Eng" wrote in
oups.com:

Phase reversal and summing?


I tried this and it seemed to color things to much for my liking. Thanks
for the suggestion.

John Mercer wrote:

Unfortunately, I look down at the guitar while singing because of lots of
movement withing the music. The bleed that is causing me the most grief is
vocal into the guitar mic. I am going to try the figure 8 suggestion and
hope for some placement that will work in my not so very forgiving
environment. Thanks for the suggestion.

Looking down isn't a problem at all. Put the mike right where you
sing at, so you're singing directly at the side of the mike where the
null is.

Or, if you can get away with it, use a single mike for both guitar and
vocal. It can take a lot of placement care and it kills your flexibility
later on in mixing, but it can be a useful tool.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

philicorda wrote:

On Tue, 03 Jan 2006 13:18:11 -0800, Andy Eng wrote:

Phase reversal and summing?

I've found that makes the both the guitar and vocal sound a bit weird. As
if you had scooped out the lower mids with an eq.

This might work..

Copy the guitar track to a new track. Shift it a few ms so it lines it up
with the guitar spill on the vocal track. Put it out of phase. Eq and
adjust the level till it does some useful cancelling of the guitar spill
on the vocal track.

Probably still sound weird though.

Probably sound like an out of phase strat?

Reversing phase only works to null a signal if the two halves are
_identical_ except for the phase. Guitar pickups are a really good example
because that is exactly what happens with out of phase pickups. The couple
of inches difference in position between the two pickups means they pick up
slightly different vibrations (other wise there'd be no point in having
more than one - douh). So some frequencies get cancelled more than others &
some might even get reinforced.

John Mercer writes:

"Andy Eng" wrote in
roups.com:

Phase reversal and summing?


I tried this and it seemed to color things to much for my liking. Thanks
for the suggestion.

Don't do the phase flip, just the time slip (or advance -- depends on
which track you're changing and which is one is the problem). Measure the
distances between the mics; calculate the acoustic time difference in
milliseconds. Sound travels at 1130 feet per second or so (with some
variation for temp, humidity, and elevation) so we're talking very roughly
10 mS here if your mics are a foot apart.

While listening, bump the timing of your calculated delay in 1/10 mS
steps. Go several steps in one direction and then the other to find a
"good" sound. (Once you get close you might even need to try some smaller
time steps.)

Once you dial in the "sweet spot" I think you'll find the sound quite
acceptable. I deal with this quite a bit, and the time slip thing can be
a good fix.

The problem is that the leakage you describe (where two mics are fairly
close together and with the same program at roughly the same level but
much closer to one mic than the other) is nothing more than a comb
filter, caused by the speed of sound v. the speed of electricity.

Once you time align, the worst part of those combs can usually be
taken care of. A bit of EQ can mitigate anything that remains.

Hope that helps,

Frank Stearns
Mobile Audio

--

Frank Stearns writes:

John Mercer writes:

"Andy Eng" wrote in
groups.com:

Phase reversal and summing?


I tried this and it seemed to color things to much for my liking. Thanks
for the suggestion.

Don't do the phase flip, just the time slip (or advance -- depends on
which track you're changing and which is one is the problem). Measure the
distances between the mics; calculate the acoustic time difference in
milliseconds. Sound travels at 1130 feet per second or so (with some
variation for temp, humidity, and elevation) so we're talking very roughly
10 mS here if your mics are a foot apart.

OOPS! Make that 1 mS.

While listening, bump the timing of your calculated delay in 1/10 mS
steps. Go several steps in one direction and then the other to find a
"good" sound. (Once you get close you might even need to try some smaller
time steps.)

Once you dial in the "sweet spot" I think you'll find the sound quite
acceptable. I deal with this quite a bit, and the time slip thing can be
a good fix.

The problem is that the leakage you describe (where two mics are fairly
close together and with the same program at roughly the same level but
much closer to one mic than the other) is nothing more than a comb
filter, caused by the speed of sound v. the speed of electricity.

Once you time align, the worst part of those combs can usually be
taken care of. A bit of EQ can mitigate anything that remains.

Hope that helps,

Frank Stearns
Mobile Audio

--

John Mercer wrote:

Unfortunately, I look down at the guitar while singing because of lots of
movement withing the music. The bleed that is causing me the most grief is
vocal into the guitar mic. I am going to try the figure 8 suggestion and
hope for some placement that will work in my not so very forgiving
environment.

This is exactly the problem that a figure-8 mic can help with. Remember
that the pattern is three-dimensional, like two balls on either side of
the mic. position the mic so that your mouth is aimed at the point
where the balls touch and that will be a very good null. The
"sensitive" direction of the mic will point toward your guitar.

You have to remember that the side opposte the guitar is just as
sensitive as what's picking up the guitar so watch out for reflectons
off the wall, of both your voice and guitar. But you can get very good
rejection this way.

I've used a single point stereo mic with the two mics set to
bi-directional to record a singer with guitar. With a little fiddling
around, you can get the voice in the null of one mic and the guitar in
the null of the other mic, and have plenty of isolation. Never enough
to do punch-ins without something else in the mix to cover up the
"ghost" but if you're recording a singer with a guitar backed up by a
band and the singer can't (or doesn't want to) sing without his or her
guitar, it's a good approach.

Thank you, Frank! I will experiment with this and see what I can come up
with.

Thanks, Mike. I will definitely spend some trying to get the figure 8 mic
placed corectly. This explanation helps. I really want to avoid playing and
singing at differnt times. I did have more last night then in the past due
to suggestions and information given to me by group memebers.