[Mark]

Well large by my standards, the two pole mounted speakers are about 60
feet apart. I'm using rented equipment and running stereo to the two
FOH 12" pole mounted speakers. Something just didn't sound right to
me, and I suspected that somehow someplace the polarity (sometimes
incorrectly called phase) of one channel got switched. So I made up
an XLR jumper with a DPDT switch wired in to pins 2 and 3 so I can
flip the "phase" and A B the two settings. Now I have done this many
times in the past in a home setting and I know what it sounds like
when the speakers are switched in and out of phase in a normal home
sized room. It's pretty obvious which setting of the switch is
correct.

But when I tried this in the big room, I could hear a difference when
I flipped the switch, but it was not at all obvious which was
"right". (I used mono program material for this test to make it more
easy to hear).

So I've been thinking.... in a small room the speakers are on the
order of a wavelength or less apart at the mid-low frequencies and the
concept of phase definitely makes sense. But maybe in a large room,
the speakers are so far apart from each other that they are
"uncorrelated" and the phase relationship is randomized so there
really isn't a right phase and a wrong phase. I'm looking for
commnets... Is this true?

These are smallish (12") speakers on pole mounts and it's a PA
application, with a bunch of radio lavs, voice only, and I have
everything high passed at 100 Hz. No real bass in the program...

Mark

[William Sommerwerck]

So I've been thinking... in a small room the speakers are on
the order of a wavelength or less apart at the mid-low frequencies
and the concept of phase definitely makes sense. But maybe
in a large room, the speakers are so far apart from each other
that they are "uncorrelated" and the phase relationship is
randomized so there really isn't a right phase and a wrong phase.
I'm looking for commnets... Is this true?

If the speakers' outputs are subjectively "uncorrelated", it's because of
reflections/reverberation -- not because they're widely spaced. If you're
standing at equal distances from the speakers, you /should/ be able to hear
a difference between normal and reversed polarity. If you can't, something
is wrong -- eg, you're sitting in the speakers' reverberant field. Is that
what's wanted?

Ask yourself this question... If you were setting up the speakers in a movie
theater, would you deliberately wire the front left and front right speakers
with opposite polarity?

Trying to cover a large -- and apparently reverberant -- room with just two
speakers is "wrong" for a number of obvious (???) reasons. In large rooms,
PA systems use multiple speakers, driven at low volume, the signal to each
of which is delayed to match the time delay of the direct sound from the
rostrum. Given the delays, I'm not sure what the effect of random polarity
would be -- but, again, would you wire up the speakers without any regard
for polarity? Probably not.

[PStamler]

Have you tried testing the system with mono pink noise?

Peace,
Paul

[david correia]

In article
,
Mark wrote:

Well large by my standards, the two pole mounted speakers are about 60
feet apart. I'm using rented equipment and running stereo to the two
FOH 12" pole mounted speakers. Something just didn't sound right to
me, and I suspected that somehow someplace the polarity (sometimes
incorrectly called phase) of one channel got switched. So I made up
an XLR jumper with a DPDT switch wired in to pins 2 and 3 so I can
flip the "phase" and A B the two settings. Now I have done this many
times in the past in a home setting and I know what it sounds like
when the speakers are switched in and out of phase in a normal home
sized room. It's pretty obvious which setting of the switch is
correct.

But when I tried this in the big room, I could hear a difference when
I flipped the switch, but it was not at all obvious which was
"right". (I used mono program material for this test to make it more
easy to hear).

So I've been thinking.... in a small room the speakers are on the
order of a wavelength or less apart at the mid-low frequencies and the
concept of phase definitely makes sense. But maybe in a large room,
the speakers are so far apart from each other that they are
"uncorrelated" and the phase relationship is randomized so there
really isn't a right phase and a wrong phase. I'm looking for
commnets... Is this true?

These are smallish (12") speakers on pole mounts and it's a PA
application, with a bunch of radio lavs, voice only, and I have
everything high passed at 100 Hz. No real bass in the program...

Mark



Here's a suggestion: remove the high pass temporarily & play a
beautiful, full sounding solo kick drum (whose polarity is right of
course) and watch your 12" bass driver and see if on that initial whack,
if the speaker(s) first goes in or out.

Of course, it should go out.

(When I record drums I use the bass drum mic as the polarity/phase
master for all the other mics recording the drumkit.)



David Correia
www.Celebrationsound.com

[Arny Krueger]

"William Sommerwerck" wrote in
message

So I've been thinking... in a small room the speakers
are on the order of a wavelength or less apart at the mid-low
frequencies and the concept of phase definitely makes
sense.


But maybe
in a large room, the speakers are so far apart from each
other that they are "uncorrelated" and the phase
relationship is randomized so there really isn't a right
phase and a wrong phase. I'm looking for commnets... Is
this true?

I think you're headed in the right direction, but with 2 caveats.

(1) Large rooms can vary quite strongly in terms of how reverberent they
are. Listeners sitting in the reverberent field are going to have very
degraded perceptions of potentially audible effects related to phase and
timing.

(2) Whether a listener is seated the reverberent field depends primarily on
distance from the source, the reverberence (IOW, the Room Constant which is
a function of surface area and absorbtion) of the room and the directivity
of the source.

Reference: Acoustical reference data By John Eargle, pp 30-40

Sound sources that are directional at the lowest frequencies are rare
because they require quite a bit of intentional technology. Rooms with low
reverberence at low frequencies are also quite rare because absorbtion at
low frequencies also requires quite a bit of intentional technology.

Thus most listeners in large rooms are in the reverberent field particularly
at low frequencies, and their ability to reliably perceive the issues you
are considering is very degraded. However there are possibly some situations
that can go the other way.


If the speakers' outputs are subjectively "uncorrelated",
it's because of reflections/reverberation -- not because
they're widely spaced. If you're standing at equal
distances from the speakers, you /should/ be able to hear
a difference between normal and reversed polarity. If you
can't, something is wrong -- eg, you're sitting in the
speakers' reverberant field. Is that what's wanted?

Right. If you are standing between the speakers you are also quite close to
them, far closer than your typical listener in the audience. You might not
be in the reverberent field, even in a reverberent room.


Ask yourself this question... If you were setting up the
speakers in a movie theater, would you deliberately wire
the front left and front right speakers with opposite
polarity?

Of course not. But it happens all the time and often without disasterous
effects.

Trying to cover a large -- and apparently reverberant --
room with just two speakers is "wrong" for a number of
obvious (???) reasons.


Actually, accepted practice includes covering a large reverberent rooms with
just one source. That's because SR is generally not about preserving phase
and timing with any degree of accuracy. The first goals are to obtain
uniform coverage and hopefully good intelligibility.

In large rooms, PA systems use multiple speakers, driven at low volume,
the signal to
each of which is delayed to match the time delay of the
direct sound from the rostrum.

Nothing like a general rule. Distributed speakers with time delays is one
of many ways that are actually used, and one of many ways that may or may
not provide acceptable results, depending on the room. Distributed speakers
with time delays are solutions for very specific problems and are often
avoided with great suceess.

[William Sommerwerck]

Here's a suggestion: remove the high pass temporarily
& play a beautiful, full sounding solo kick drum (whose
polarity is right, of course) and watch your 12" bass driver
and see if on that initial whack, if the speaker(s) first goes
in or out.

The question was about relative polarity, not absolute.


Of course, it should go out.

Of course, it should go in.

For most (if not all) drums, the initial sound is a rarefaction, not a
compression. So, if you're worried about absolutely polarity, the driver
should move in, not out.

[Klay_Anderson]

On Feb 11, 6:34*am, "William Sommerwerck"
wrote:
Here's a suggestion: remove the high pass temporarily
& play a beautiful, full sounding solo kick drum (whose
polarity is right, of course) and watch your 12" bass driver
and see if on that initial whack, if the speaker(s) first goes
in or out.

The question was about relative polarity, not absolute.

Of course, it should go out.

Of course, it should go in.

For most (if not all) drums, the initial sound is a rarefaction, not a
compression. So, if you're worried about absolutely polarity, the driver
should move in, not out.

Unless it is JBL then it is reverse from convention.

Text "Klay" to 50500 for contact info

-.- .-.. .- -.-- / .- - / -.- .-.. .- -.-- / -.. --- - / -.-. --- --
Yours truly,

Mr. Klay Anderson, D.A.,Q.B.E.

[Peter Larsen[_3_]]

William Sommerwerck wrote:

Here's a suggestion: remove the high pass temporarily
& play a beautiful, full sounding solo kick drum (whose
polarity is right, of course) and watch your 12" bass driver
and see if on that initial whack, if the speaker(s) first goes
in or out.

The question was about relative polarity, not absolute.

Of course, it should go out.

Of course, it should go in.

For most (if not all) drums, the initial sound is a rarefaction, not a
compression. So, if you're worried about absolutely polarity, the
driver should move in, not out.

The drum reference was to a kick drum. Not that all drums are not all
bipolar sources ...

Kind regards

Peter Larsen

[Peter Larsen[_3_]]

Klay_Anderson wrote:

For most (if not all) drums, the initial sound is a rarefaction, not
a compression. So, if you're worried about absolutely polarity, the
driver should move in, not out.

They are still bipolars ... and the reference was to a kick drum, notably a
recorded kick drum, usually that would imply close miked on the "customer
side" rather than on the operator side.

Unless it is JBL then it is reverse from convention.

Nah, only difference is the colour of the connection points. For a
compression driver their old way of doing it actually ensures that a
positive voltage produces positive pressure. My level of information is
however that they saw the light of a common standard back when the service
manual for my L100's was written, I vaguely recall a wording to the effect
of before and after some serial number.

Mr. Klay Anderson, D.A.,Q.B.E.

Kind regards

Peter Larsen

[Scott Dorsey]

Mark wrote:

But when I tried this in the big room, I could hear a difference when
I flipped the switch, but it was not at all obvious which was
"right". (I used mono program material for this test to make it more
easy to hear).

So I've been thinking.... in a small room the speakers are on the
order of a wavelength or less apart at the mid-low frequencies and the
concept of phase definitely makes sense. But maybe in a large room,
the speakers are so far apart from each other that they are
"uncorrelated" and the phase relationship is randomized so there
really isn't a right phase and a wrong phase. I'm looking for
commnets... Is this true?

You're also getting all kinds of reflections in a typical big room, so a
lot of what you are hearing is not direct sound... and that stuff is not
phase coherent.

The problems you are encountering don't have to do with the distance...
remember that if you're on the center line you are equidistant from them
so (barring room reflections) it doesn't matter how far away they are,
it just adds a delay.

The problem you're encountering is that the room is screwing the phase
relationships up totally.

Welcome to the sound reinforcement world. Unfortunately it's like that.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[William Sommerwerck]

Trying to cover a large -- and apparently reverberant --
room with just two speakers is "wrong" for a number of
obvious (???) reasons.

Actually, accepted practice includes covering a large reverberent
rooms with just one source. That's because SR is generally not
about preserving phase and timing with any degree of accuracy.
The first goals are to obtain uniform coverage and hopefully
good intelligibility.

Which was my motivation in making that statement. It isn't obvious to me how
one can get good intelligibility with a single speaker in a highly
reverberant room. (I don't want to push this thread OT, so don't feel
obliged to respond.)

[Peter Larsen[_3_]]

William Sommerwerck wrote:

Trying to cover a large -- and apparently reverberant --
room with just two speakers is "wrong" for a number of
obvious (???) reasons.

Actually, accepted practice includes covering a large reverberent
rooms with just one source. That's because SR is generally not
about preserving phase and timing with any degree of accuracy.
The first goals are to obtain uniform coverage and hopefully
good intelligibility.

Which was my motivation in making that statement. It isn't obvious to
me how one can get good intelligibility with a single speaker in a
highly reverberant room. (I don't want to push this thread OT, so
don't feel obliged to respond.)

This is not OT, except perhaps bordering also on nearby newsgroups. The
issue is that a single source creates less temporal smearing, even if verbed
by the room, than the pathlength differences involved in having multiple
sources, also someone forgot the word "directional" and the concept of
aiming the sound souce(s) at non-reflective surfaces only, audience is
generally not reflective.

Multiple sources only get relevant in case reasonable max and min spl levels
can not be adhered to.

This also in my experience applies in open air, the difference being that
once the room is out of the math, then you can use secondary delayed
sources. Such would only aggravate the reverb time indoors.


Kind regards

Peter Larsen

[Richard Kuschel]

On Feb 11, 8:23*am, "William Sommerwerck"
wrote:
Trying to cover a large -- and apparently reverberant --
room with just two speakers is "wrong" for a number of
obvious (???) reasons.
Actually, accepted practice includes covering a large reverberent
rooms with just one source. That's because SR is generally not
about preserving phase and timing with any degree of accuracy.
The first goals are to obtain uniform coverage and hopefully
good intelligibility.

Which was my motivation in making that statement. It isn't obvious to me how
one can get good intelligibility with a single speaker in a highly
reverberant room. (I don't want to push this thread OT, so don't feel
obliged to respond.)

It isn't necessarily a single speaker, but it can be multiple speakers
in a "point source" array. Think of a center cluster in a gymnasium

When you have two speakers spaced apart, there will always be phase
problems except at one point in the room. At other points, there can
be so much delay from the far speaker that it will be hears as an
echo. if nothing else, the sound coming from two sources mears the
sound.

True stereo can only be heard from a set of spaced speakers in a hall
in a strip down the middle that is only about 7 feet wide and in the
near field.

[Klay_Anderson]

On Feb 11, 7:13*am, "Peter Larsen" wrote:
Klay_Anderson wrote:
For most (if not all) drums, the initial sound is a rarefaction, not
a compression. So, if you're worried about absolutely polarity, the
driver should move in, not out.

They are still bipolars ... and the reference was to a kick drum, notably a
recorded kick drum, usually that would imply close miked on the "customer
side" rather than on the operator side.

Unless it is JBL then it is reverse from convention.

Nah, only difference is the colour of the connection points. For a
compression driver their old way of doing it actually ensures that a
positive voltage produces positive pressure. My level of information is
however that they saw the light of a common standard back when the service
manual for my L100's was written, I vaguely recall a wording to the effect
of before and after some serial number.


Yeabut, if you place a battery positive to red and negative to black
on just about every brand of woofer *except* JBL, the cone will move
outward. If you perform the same on a JBL (red to positive, black to
negative) the cone will move inward.

Text "Klay" to 50500 for contact info
-.- .-.. .- -.-- / .- - / -.- .-.. .- -.-- / -.. --- - / -.-. --- --
Yours truly,
Mr. Klay Anderson, D.A.,Q.B.E.

[hank alrich]

Klay_Anderson wrote:

On Feb 11, 7:13 am, "Peter Larsen" wrote:
Klay_Anderson wrote:
For most (if not all) drums, the initial sound is a rarefaction, not
a compression. So, if you're worried about absolutely polarity, the
driver should move in, not out.

They are still bipolars ... and the reference was to a kick drum, notably a
recorded kick drum, usually that would imply close miked on the "customer
side" rather than on the operator side.

Unless it is JBL then it is reverse from convention.

Nah, only difference is the colour of the connection points. For a
compression driver their old way of doing it actually ensures that a
positive voltage produces positive pressure. My level of information is
however that they saw the light of a common standard back when the service
manual for my L100's was written, I vaguely recall a wording to the effect
of before and after some serial number.


Yeabut, if you place a battery positive to red and negative to black
on just about every brand of woofer *except* JBL, the cone will move
outward. If you perform the same on a JBL (red to positive, black to
negative) the cone will move inward.

Text "Klay" to 50500 for contact info
-.- .-.. .- -.-- / .- - / -.- .-.. .- -.-- / -.. --- - / -.-. --- --
Yours truly,
Mr. Klay Anderson, D.A.,Q.B.E.

This very fact bit a system provider in the ass at an event to which
I've been consulting in Austin. They had a pair of side hangs of EAW
boxes with a JBL 43-something with a baby's butt horn as a completely
unnecessary center fill.

Amazing how much better it sounded with that JBL tunred off, because
they'd just gone by the terminal colors...

Next year there will be no center fill there.

--
shut up and play your guitar * http://hankalrich.com/
http://armadillomusicproductions.com/who'slistening.html
http://www.sonicbids.com/HankandShai...withDougHarman

[PStamler]

Meanwhile back on topic.

To the OP: you want to know if your woofers' polarities are matched?
Take a couple of microphones, the same model, and put them up against
the grille of one speaker. Plug them into a couple of mic preamps and
plug the preamp outputs into an oscilloscope, set for an X/Y display.

Play a recording of a mono kickdrum and look at the scope. If the
pattern's a /, then your test setup has identical polarities in both
channels; if it's a \, one channel has the polarity flipped, so fix
it.

Now move one of the mics to the other speaker. Play the kickdrum. /
means your polarity is cool, \ means it isn't.

If you haven't got a scope, record the results in a DAW and look at
the waveforms. But a scope is easier.

Peace,
Paul

[Peter Larsen[_3_]]

PStamler wrote:

To the OP: you want to know if your woofers' polarities are matched?
Take a ....

9 volt battery, or 1.5 - quite probably sufficient.

Paul

Kind regards

Peter Larsen

[PStamler]

On Feb 11, 1:57*pm, "Peter Larsen" wrote:
PStamler wrote:
To the OP: you want to know if your woofers' polarities are matched?
Take a ....

9 volt battery, or 1.5 - quite probably sufficient.

* Peter Larsen

Yes, but:

1. That only tests the woofers themselves; it won't find errors in the
cable, amp, or (electronic) crossover wiring. Out-of-polarity woofers
could be coming from a miswired XLR cable.

2. It also only works if you can actually see the woofers move. If
they're behind a really heavy grille, or in a horn-loaded cabinet, you
may not be able to see the cones move when you connect a battery.

Peace,
Paul

[Mark]

On Feb 12, 3:28*am, PStamler wrote:
On Feb 11, 1:57*pm, "Peter Larsen" wrote:

PStamler wrote:
To the OP: you want to know if your woofers' polarities are matched?
Take a ....

9 volt battery, or 1.5 - quite probably sufficient.
* Peter Larsen

Yes, but:

1. That only tests the woofers themselves; it won't find errors in the
cable, amp, or (electronic) crossover wiring. Out-of-polarity woofers
could be coming from a miswired XLR cable.

2. It also only works if you can actually see the woofers move. If
they're behind a really heavy grille, or in a horn-loaded cabinet, you
may not be able to see the cones move when you connect a battery.

Peace,
Paul

OK thanks to everyone for the replies...
yes I'm interested in the relative phase going through the whole
system, I'm not interested in absolute phase and I'm not interested in
testing just the drivers.

I tried the MONO pink noise again this time with an assistant flipping
the switch as I walked around the room and it became more clear that
the system is phased correctly, When I was in the middle between the
two speaker the normal (non reversed) setting sounded better... but
there is a large variation as you walk around and AT the sound desk it
is not as obvious.

So my conclusion is that it changes a lot around the room and having
two speakers far apart I can see is not the ideal situation, but it's
what I have to work with.

Th MONO pink noise is pretty good for a listening test. Using pulses
and visually checking the speaker cones movement was a good idea and I
tried that, but I can't see through the grill. Using a mic in front of
each speaker with a scope would work if I had a portable scope. I'm
ready to let this go as not an issue, If I want to obsess over it a
bit more, I can use a portable recorder and record the pulses from a
mic close to each speaker and analyze the results off line later. Or
make a little LED polarity indicating widget with a speakon connector
that I can play the pulses and stick on the back of each speaker and
verify the polarity is the same on both. That might be neat and
handy...

thanks for the discussion..

Mark

[david correia]

In article
,
Mark wrote:

On Feb 12, 3:28*am, PStamler wrote:
On Feb 11, 1:57*pm, "Peter Larsen" wrote:

PStamler wrote:
To the OP: you want to know if your woofers' polarities are matched?
Take a ....

9 volt battery, or 1.5 - quite probably sufficient.
* Peter Larsen

Yes, but:

1. That only tests the woofers themselves; it won't find errors in the
cable, amp, or (electronic) crossover wiring. Out-of-polarity woofers
could be coming from a miswired XLR cable.

2. It also only works if you can actually see the woofers move. If
they're behind a really heavy grille, or in a horn-loaded cabinet, you
may not be able to see the cones move when you connect a battery.

Peace,
Paul

OK thanks to everyone for the replies...
yes I'm interested in the relative phase going through the whole
system, I'm not interested in absolute phase and I'm not interested in
testing just the drivers.

I tried the MONO pink noise again this time with an assistant flipping
the switch as I walked around the room and it became more clear that
the system is phased correctly, When I was in the middle between the
two speaker the normal (non reversed) setting sounded better... but
there is a large variation as you walk around and AT the sound desk it
is not as obvious.

So my conclusion is that it changes a lot around the room and having
two speakers far apart I can see is not the ideal situation, but it's
what I have to work with.

Th MONO pink noise is pretty good for a listening test. Using pulses
and visually checking the speaker cones movement was a good idea and I
tried that, but I can't see through the grill. Using a mic in front of
each speaker with a scope would work if I had a portable scope. I'm
ready to let this go as not an issue, If I want to obsess over it a
bit more, I can use a portable recorder and record the pulses from a
mic close to each speaker and analyze the results off line later. Or
make a little LED polarity indicating widget with a speakon connector
that I can play the pulses and stick on the back of each speaker and
verify the polarity is the same on both. That might be neat and
handy...

thanks for the discussion..

Mark


Fletcher when he owned Mercenary Audio had something he called a phase
clicker you could borrow. I googled the term and found this:



http://www.swee****er.com/store/detail/Cricket/




David Correia
www.Celebrationsound.com

[Peter Larsen[_3_]]

PStamler wrote:

On Feb 11, 1:57 pm, "Peter Larsen" wrote:

PStamler wrote:

To the OP: you want to know if your woofers' polarities are matched?
Take a ....

9 volt battery, or 1.5 - quite probably sufficient.

Peter Larsen

Yes, but:

1. That only tests the woofers themselves; it won't find errors in the
cable, amp, or (electronic) crossover wiring. Out-of-polarity woofers
could be coming from a miswired XLR cable.

True, but testing the entire chain correct does not exclude multiple errors
in it, so it remamains the answer to knowing the woofers polarity to check
the woofers. Electronics are supposed to be polarity preserving but not all
are, however to test the electronic devices: test them. To test the
xlr-cables: test them. It is vital to understand that you can not know
whether all devices and cables are correct by just testing the system.

To test the system: as you suggested: play male vox and listen on the
centerline, it is quite conceiveably correct in the reverberant field that
the difference is subtle. Improving the direct to reflected ratio if
possible is then a very good idea.

If it is not "your system" then on site testing can be what you can do, but
if it is "your system", my understanding is that this is a "your system
sitution", check all components before leaving home.

2. It also only works if you can actually see the woofers move. If
they're behind a really heavy grille, or in a horn-loaded cabinet, you
may not be able to see the cones move when you connect a battery.

Correct. As I recall the original question this sunday morning such
concerns, while correct, do not apply. Do not trust cable conductor
colouring too much if an electrician has installed fixed loudspeaker wiring
in a building .... as for whether you want to trust his wiring of the
electrics after finding the error is a different question. Yes, I am
referring to an actual AV installation.

Paul

Kind regards

Peter Larsen

[Arny Krueger]

"Mark" wrote in message


Using pulses and visually checking the speaker cones
movement was a good idea and I tried that, but I can't
see through the grill.

What about the back sides of the drivers?

If you can put the speakers fairly close together, it should be easy to
check polarity by ear.

However, I get the feeling that these options aren't available to you.

[Scott Dorsey]

Mark wrote:

OK thanks to everyone for the replies...
yes I'm interested in the relative phase going through the whole
system, I'm not interested in absolute phase and I'm not interested in
testing just the drivers.

Play a click track with positive going pulses. Watch the woofers.
If they both move in the same direction, the whole system is in
relative phase.

Mercenary Audio will sell you some automated gadget that does this also.

I tried the MONO pink noise again this time with an assistant flipping
the switch as I walked around the room and it became more clear that
the system is phased correctly, When I was in the middle between the
two speaker the normal (non reversed) setting sounded better... but
there is a large variation as you walk around and AT the sound desk it
is not as obvious.

So my conclusion is that it changes a lot around the room and having
two speakers far apart I can see is not the ideal situation, but it's
what I have to work with.

This is just how lousy rooms are. The sound is reaching you from a lot
of different directions, over different paths of different lengths. So
the room part of the system isn't phase coherent at all.

If you used a center cluster with just one speaker at one point, you would
still have the same problems, because the problem isn't the sound system.

Sometimes if you get flutter echoes from curved ceilings, you can have
places in the room where the whole stereo image swings hard right to left
as you move your head a couple inches. That's a fun trick although not
much fun for the people who paid money for tickets to sit there.

Th MONO pink noise is pretty good for a listening test. Using pulses
and visually checking the speaker cones movement was a good idea and I
tried that, but I can't see through the grill. Using a mic in front of
each speaker with a scope would work if I had a portable scope.

A flashlight will help you see through the grille. The gadget Mercenary
sells fits in your hand and is easier to carry than a portable scope.

I'm
ready to let this go as not an issue, If I want to obsess over it a
bit more, I can use a portable recorder and record the pulses from a
mic close to each speaker and analyze the results off line later. Or
make a little LED polarity indicating widget with a speakon connector
that I can play the pulses and stick on the back of each speaker and
verify the polarity is the same on both. That might be neat and
handy...

It's an issue, and it's in fact a really severe issue. But the issue is
the room and you might not be able to do anything about that. Although
bringing in pipe and drape and covering the largest reflective surfaces
with banners can help.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[geoff]

William Sommerwerck wrote:
Here's a suggestion: remove the high pass temporarily
& play a beautiful, full sounding solo kick drum (whose
polarity is right, of course) and watch your 12" bass driver
and see if on that initial whack, if the speaker(s) first goes
in or out.

The question was about relative polarity, not absolute.


Of course, it should go out.

Of course, it should go in.


Only if you are, or are behind, the drummer.


geoff

[Richard Webb[_3_]]

Scott Dorsey writes:

snip

This is just how lousy rooms are. The sound is reaching you from a
lot of different directions, over different paths of different
lengths. So the room part of the system isn't phase coherent at
all.

Maybe I"ve missed this in earlier discussions, but what kind of events happen in this room?

If you used a center cluster with just one speaker at one point, you
would still have the same problems, because the problem isn't the
sound system.

WOuld agree with that. THis is why some houses of worship
try the pew back speakers, give everybody in the
congregation near field grin.

snip again
It's an issue, and it's in fact a really severe issue. But the
issue is the room and you might not be able to do anything about
that. Although bringing in pipe and drape and covering the largest
reflective surfaces with banners can help.

YEp, tapestries or similar, as the man says damp down those
reflective surfaces and go from there. iF intelligibility
of spoken word stuff is an issue I'd really talk to
management about something like that. That's why I queried
what sort of events happen in the room.


Regards,
Richard
.... Remote audio in the southland: See www.gatasound.com
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