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Peter Larsen[_3_] Peter Larsen[_3_] is offline
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Default time aligning a spot microphone the simple way

Hi Guys,

here is how to get a spot microphone just right if you again forgot measure
or record a clap near it:

1) know the order of magnitude of the required delay so that you start out
close to right

2) pan suitable main pair microphone fully left or right

3) pan spot mic fully right

4) get volume reasonably balanced

this does it!

5) adjust delay for proper center image of spot microphone sound source

/this does it!

6) add a few milliseconds if spot microphone sound source protrudes when
properly mixed.

Note: adjustment sensitivity is single milliseconds. May for some be easier
when listening via headphones and for some be easier when listening via
loudspeakers, not fully verified what works best, try both!

Kind regards

Peter Larsen





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Frank Stearns Frank Stearns is offline
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Default time aligning a spot microphone the simple way

"Peter Larsen" writes:
Hi Guys,


here is how to get a spot microphone just right if you again forgot measure
or record a clap near it:


1) know the order of magnitude of the required delay so that you start out
close to right


2) pan suitable main pair microphone fully left or right


3) pan spot mic fully right


4) get volume reasonably balanced


this does it!


5) adjust delay for proper center image of spot microphone sound source


/this does it!



Not sure I follow... Step 2: you mean, just one of the main pair mics? What flavor
of stereo pair are we talking about? AB? ORTF? NOS? XY? MS? (etc)

Step 3: should the spot pan be opposite pan of the selected main pair mic (assuming
you're just using one from the main pair).


If I understand it correctly I like the approach, but anticipate some little
gotchas with this method. Want to make sure I fully understand it and then try it.

I used to take clicks and clacks but found that it's just easier to start with your
steps 1 and 4, then single-sample step a delay on the spot channel and listen for
the best results. Once found, the spot level is often pulled back, lessening any
remaining artifacts.

Often as I do the initial step-through of delay values there will be more than one
delay that will sound good. I'll note them all then do a second pass to winnow
those delays to the absolute ideal.

Once in a while I'll even automate a delay factor as the same delay might not sound
as good in one piece as in another (featured instrument/voice picked up by the spot
has shifted their position, changing the spot/main pair geometry).


6) add a few milliseconds if spot microphone sound source protrudes when
properly mixed.


Yes, you can do this to push the spot out of comb filtering. Just don't hit the Haas
boundary, unless you want the effect.

Note: adjustment sensitivity is single milliseconds. May for some be easier
when listening via headphones and for some be easier when listening via
loudspeakers, not fully verified what works best, try both!


If it's a good room with good monitors free of their own time problems, speakers
generally are a little more revealing for this.

I find millisecond steps can be too large; single sample steps can be better. Quite
often the ideal delay is only 3 samples wide (44.1K); go one sample out on either
side and you lose the good sound.

Thanks for the idea; will be interested in clarifications.

Frank
Mobile Audio
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mcp6453[_2_] mcp6453[_2_] is offline
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Default time aligning a spot microphone the simple way

Remind me why it is necessary to time align a spot microphone. I understand your
procedure, and it makes a lot of sense, but I don't know when or why you would
use it.

On 1/28/2012 12:50 PM, Peter Larsen wrote:
Hi Guys,

here is how to get a spot microphone just right if you again forgot measure
or record a clap near it:

1) know the order of magnitude of the required delay so that you start out
close to right

2) pan suitable main pair microphone fully left or right

3) pan spot mic fully right

4) get volume reasonably balanced

this does it!

5) adjust delay for proper center image of spot microphone sound source

/this does it!

6) add a few milliseconds if spot microphone sound source protrudes when
properly mixed.

Note: adjustment sensitivity is single milliseconds. May for some be easier
when listening via headphones and for some be easier when listening via
loudspeakers, not fully verified what works best, try both!


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PStamler PStamler is offline
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Default time aligning a spot microphone the simple way

On Jan 28, 3:01*pm, mcp6453 wrote:
Remind me why it is necessary to time align a spot microphone. I understand your
procedure, and it makes a lot of sense, but I don't know when or why you would
use it.


Google "comb filtering".

Peace,
Paul


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Tom McCreadie Tom McCreadie is offline
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Default time aligning a spot microphone the simple way


here is how to get a spot microphone just right if you again forgot measure
or record a clap near it:

Pretty much how I work (Your description (3) was clearly truncated, though).

I prefer headphones and - as with manual focus on my camera lens - I find it
helpful to go deliberately 'beyond the good point' then come back from the
other side. I may even oscillate to and fro between the two points where a sound
is just discernibly early or late, and note those time values as a sanity check
(final chosen time should lie approx half way). And I regularly swap channels,
as a precaution against bias or a too vivid imagination ;-)
--
Tom McCreadie
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hank alrich hank alrich is offline
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Default time aligning a spot microphone the simple way

Sean Conolly wrote:

"Peter Larsen" wrote in message
k...
Hi Guys,

here is how to get a spot microphone just right if you again forgot
measure or record a clap near it:

1) know the order of magnitude of the required delay so that you start out
close to right

2) pan suitable main pair microphone fully left or right

3) pan spot mic fully right

4) get volume reasonably balanced

this does it!

5) adjust delay for proper center image of spot microphone sound source

/this does it!

6) add a few milliseconds if spot microphone sound source protrudes when
properly mixed.

Note: adjustment sensitivity is single milliseconds. May for some be
easier when listening via headphones and for some be easier when listening
via loudspeakers, not fully verified what works best, try both!


This is one case where I prefer to use my eyes: in the DAW drag the spot mic
back (time delay) until it lines up with the main mics. You just have to
find a place in the music where the instrument being spotted is prominant
enough to see in the main waveform.

Sean


Works when using a DAW, but not for situations where one will be
capturing a stereo mix. It can be helpful in the latter setting to get
it as right as possible from the gitgo.

When in the DAW, I will use my eyes to get close, and then close my eyes
to listen until I lke it. Sometimes I will get down to nudging by the
sample.

--
shut up and play your guitar * http://hankalrich.com/
http://www.youtube.com/walkinaymusic
http://www.sonicbids.com/HankandShaidri
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Sean Conolly Sean Conolly is offline
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Default time aligning a spot microphone the simple way

"PStamler" wrote in message
...
On Jan 28, 3:01 pm, mcp6453 wrote:
Remind me why it is necessary to time align a spot microphone. I
understand your
procedure, and it makes a lot of sense, but I don't know when or why you
would
use it.


Google "comb filtering".

Peace,
Paul

And also Phase Coherence, which is the more important reason IMHO.

Sean


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Don Pearce[_3_] Don Pearce[_3_] is offline
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Default time aligning a spot microphone the simple way

On Sat, 28 Jan 2012 18:50:57 +0100, "Peter Larsen"
wrote:

Hi Guys,

here is how to get a spot microphone just right if you again forgot measure
or record a clap near it:

1) know the order of magnitude of the required delay so that you start out
close to right

2) pan suitable main pair microphone fully left or right

3) pan spot mic fully right

4) get volume reasonably balanced

this does it!

5) adjust delay for proper center image of spot microphone sound source

/this does it!

6) add a few milliseconds if spot microphone sound source protrudes when
properly mixed.

Note: adjustment sensitivity is single milliseconds. May for some be easier
when listening via headphones and for some be easier when listening via
loudspeakers, not fully verified what works best, try both!

Kind regards

Peter Larsen





I have two ways.

The first way is to stand where the spot-miked instrumentalist will be
and clap my hands. Alignment is simple.

The second is to do the job properly and measure the paths to the two
mikes. The speed of sound (just over 340 m/sec) then gives the delay
needed on the spot mike.

d
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Peter Larsen[_3_] Peter Larsen[_3_] is offline
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Default time aligning a spot microphone the simple way

Frank Stearns wrote:

Not sure I follow... Step 2: you mean, just one of the main pair
mics? What flavor of stereo pair are we talking about? AB? ORTF? NOS?
XY? MS? (etc)


I used just the one on that side - ie. the right one and panned the spot mic
left, dunno which to choose with MS, it was AB, 50 centimeters between
4006's, piano mic a single KSM 141. I ended up redoing it because it didn't
integrate properly when listening to the final 44.1-16 and moved the KSM 24
milliseconds instead of 22, so I don't really know.

Step 3: should the spot pan be opposite pan of the selected main pair
mic (assuming you're just using one from the main pair).


If I understand it correctly I like the approach, but anticipate some
little gotchas with this method. Want to make sure I fully understand
it and then try it.


My R44 gave me the idea when recording a piano quartet, there's no way to
pan on it and the time difference when listening with the spot mic on
channel 3 was very disturbing, but hearing it like that made it very easy to
move it around at the "far end" of the piano to get its tonal balance to
match the 4006 pair, not mine. The Fostex MR8-HD has better ergonomics, but
the R44 has more bits and more portability. That Fostex remains a
surprisingly bag for audio at a very nice price.

I find millisecond steps can be too large; single sample steps can be
better. Quite often the ideal delay is only 3 samples wide (44.1K);
go one sample out on either side and you lose the good sound.


! - certainly a point confirming the feel I'm slowly getting, one of
preferably using an ORTF type setup if spot(s) will be required in case of
AB. This also because that quartet in two other rooms is "just right" on my
C42's. It ended up being "too hi-fi" ....

! - also a point confirming my feel that using just one spot mic on piano is
less problems than using two. Comments appreciated.

Thanks for the idea; will be interested in clarifications.


I found it a time-saver. Now if onlý I had a big round button labed "time"
on the arm-rest for it - some computing is best done on a real chair sitting
at a real desk, but to me the best daw'ïng is via remote operating the daw
from an armchair using a laptop.

To those suggesting looking at the waveform: yes ... but there's nothing
obvious to look at with such a recording. I have a supersonic range finder
that uses a ""+20 kHz click"" - firing it near the spot could in theory be a
good method, but my ears always hurt after using it and it would certainly
annoy the practicing musicians.

Frank
Mobile Audio


Kind regards

Peter Larsen





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Peter Larsen[_3_] Peter Larsen[_3_] is offline
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Default time aligning a spot microphone the simple way

mcp6453 wrote:

Remind me why it is necessary to time align a spot microphone. I
understand your procedure, and it makes a lot of sense, but I don't
know when or why you would use it.


When actually recording stereo instead of building it from tracks. That
said, I rapidly ended up doing temporal alignment to get layering right when
practicing on the tracks from http://raw-tracks.com.

Kind regards

Peter Larsen


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Peter Larsen[_3_] Peter Larsen[_3_] is offline
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Default time aligning a spot microphone the simple way

Don Pearce wrote:

I have two ways.


The first way is to stand where the spot-miked instrumentalist will be
and clap my hands. Alignment is simple.


Should'a done, but plain forgot.

The second is to do the job properly and measure the paths to the two
mikes. The speed of sound (just over 340 m/sec) then gives the delay
needed on the spot mike.


I kinda do want a laser measuring device for that .... just never made it to
the top of the shopping list. Also at an AES meeting at DR (Danish State
Radio) they explained that they used the laser measured distance X 0.66,
that was what sounded right. To me that gives audible doubling ....

d


Kind regards

Peter Larsen


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hank alrich hank alrich is offline
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Default time aligning a spot microphone the simple way

Sean Conolly wrote:

"PStamler" wrote in message
...
On Jan 28, 3:01 pm, mcp6453 wrote:
Remind me why it is necessary to time align a spot microphone. I
understand your
procedure, and it makes a lot of sense, but I don't know when or why you
would
use it.


Google "comb filtering".

Peace,
Paul

And also Phase Coherence, which is the more important reason IMHO.

Sean


Right, but the lack of phase coherence results in comb filtering.

--
shut up and play your guitar * http://hankalrich.com/
http://www.youtube.com/walkinaymusic
http://www.sonicbids.com/HankandShaidri
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Frank Stearns Frank Stearns is offline
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Default time aligning a spot microphone the simple way

"Peter Larsen" writes:

Don Pearce wrote:


I have two ways.


The first way is to stand where the spot-miked instrumentalist will be
and clap my hands. Alignment is simple.


Should'a done, but plain forgot.


The second is to do the job properly and measure the paths to the two
mikes. The speed of sound (just over 340 m/sec) then gives the delay
needed on the spot mike.


I kinda do want a laser measuring device for that .... just never made it to
the top of the shopping list. Also at an AES meeting at DR (Danish State
Radio) they explained that they used the laser measured distance X 0.66,
that was what sounded right. To me that gives audible doubling ....



With all respect to those who want to simply measure to derive the delay factor (via
a tape measure, spikes on the waveforms, whatever), you're being a wee bit
simplistic.

And I include my earlier self in that group.

I used to all the time use and promote the use of a dog training clicker (makes a
nice visual on the waveforms; way better than a clap), but then reality eventually
caught up with me. w


Here are the problems with simple measurment:

- with a single, small point-source instrument, theoretically your measurements will
work, ASSUMING that the point source, spot, and main pair are in a line. (Somewhere
it was noted that DGG made sure that instruments, spots, and mains were each on a
line.)

But if they are not in a line (for any number of practical reasons), **and the
player or singer moves** the alignment veers as the player moves; then you have
variable comb filtering that can sound pretty wonky. If things are in a line, this
problem is mitigated, but things still might not be ideal.

- with a wider source that you're spotting, say a wind section, choral section, even
a large piano, you might clap or click at just one place, but what about a few feet
to the left or right? Your path distances change, as must your delay -- but for
which location?

And if the spot and mains are not in a line, and your spotted source has depth, now
you have compromised settings forward and back as well.

- I too use 50 cm AB... So, which main pair mic should you align to? If to a phantom
point between the AB microphones, the alignment for both are wrong (and audible) and
becomes even more wrong (for at least one of the microphones) as the point source is
farther left or right.

Visualize those vectors in 3D; note the problems.


This is why I've switched to aligning by ear. Sometimes the alignment is close to
what distance measurements might suggest, sometimes more, sometimes less. Every now
and then you get a serendipity of comb filtering that actually helps the overall
tone (though rare).

More often the delay will be a bit more than what distance might suggest, but less
than Haas. You're out of the worst potential comb filtering whether the player moves
or not. The more-than-needed added delay can "outline" the spotted instrument so
that you can actually use a bit less in the mix and still get the highlight you
want. (And using a bit less is good, because you further reduce audibility of
residual problems.)

My $0.02. As always, YMMV.

Frank
Mobile Audio
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Default time aligning a spot microphone the simple way

On Sun, 29 Jan 2012 10:30:58 -0600, Frank Stearns
wrote:

"Peter Larsen" writes:

Don Pearce wrote:


I have two ways.


The first way is to stand where the spot-miked instrumentalist will be
and clap my hands. Alignment is simple.


Should'a done, but plain forgot.


The second is to do the job properly and measure the paths to the two
mikes. The speed of sound (just over 340 m/sec) then gives the delay
needed on the spot mike.


I kinda do want a laser measuring device for that .... just never made it to
the top of the shopping list. Also at an AES meeting at DR (Danish State
Radio) they explained that they used the laser measured distance X 0.66,
that was what sounded right. To me that gives audible doubling ....



With all respect to those who want to simply measure to derive the delay factor (via
a tape measure, spikes on the waveforms, whatever), you're being a wee bit
simplistic.

And I include my earlier self in that group.

I used to all the time use and promote the use of a dog training clicker (makes a
nice visual on the waveforms; way better than a clap), but then reality eventually
caught up with me. w


Here are the problems with simple measurment:

- with a single, small point-source instrument, theoretically your measurements will
work, ASSUMING that the point source, spot, and main pair are in a line. (Somewhere
it was noted that DGG made sure that instruments, spots, and mains were each on a
line.)

But if they are not in a line (for any number of practical reasons), **and the
player or singer moves** the alignment veers as the player moves; then you have
variable comb filtering that can sound pretty wonky. If things are in a line, this
problem is mitigated, but things still might not be ideal.

- with a wider source that you're spotting, say a wind section, choral section, even
a large piano, you might clap or click at just one place, but what about a few feet
to the left or right? Your path distances change, as must your delay -- but for
which location?

And if the spot and mains are not in a line, and your spotted source has depth, now
you have compromised settings forward and back as well.

- I too use 50 cm AB... So, which main pair mic should you align to? If to a phantom
point between the AB microphones, the alignment for both are wrong (and audible) and
becomes even more wrong (for at least one of the microphones) as the point source is
farther left or right.

Visualize those vectors in 3D; note the problems.


This is why I've switched to aligning by ear. Sometimes the alignment is close to
what distance measurements might suggest, sometimes more, sometimes less. Every now
and then you get a serendipity of comb filtering that actually helps the overall
tone (though rare).

More often the delay will be a bit more than what distance might suggest, but less
than Haas. You're out of the worst potential comb filtering whether the player moves
or not. The more-than-needed added delay can "outline" the spotted instrument so
that you can actually use a bit less in the mix and still get the highlight you
want. (And using a bit less is good, because you further reduce audibility of
residual problems.)

My $0.02. As always, YMMV.

Frank
Mobile Audio


You can still fine-tune by ear, but measuring will get you 99% of the
way very quickly. And of course comb filtering is always going to be a
problem - you just have to minimize it by making sure on mic is
dominant in the mix.

Whether tone filtering is a problem in practice depends on all sorts
of things, of course. If the mains are in a reasonably diffuse sound
field the phase is already pretty jumbled, and the spot will mix ok.
And it may be that the mains are positioned beyond the phase-coherent
distance of the source to start with. More than about 30 feet will do
that.

d
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