What's an alternative to testing a speakers frequency response besides using
an anechoic chamber?

Could we use MLS to manage the effects of
room reflections What is MLS exactly ? What does it involve?

Do we need a special software package that outputs a pulse through the
soundcard for the speaker amp, and
listens through the mike for a set period, then applies fourier analysis to
the wave that comes back from the mike? Would anyone know of the following
method: putting a pulse through a speaker, and then gate
the mike off after 50 milliseconds, or whatever, before the echos are back.
But to use this method we'd need to feed the mike to the sound card and have
a fourier analysis software?
Anyone ?

Thanks for any help,
Mark

Mark,

putting a pulse through a speaker, and then gate the mike off after 50
milliseconds, or whatever, before the echos are back.

You nailed it. And you can do that with the terrific yet reasonably priced
ETF software. Go here to learn mo

www.acoustisoft.com

I use ETF to assess room response. I have not used the gate feature for
measuring speakers independent of the room, but it can do that too.

--Ethan

Mark,

putting a pulse through a speaker, and then gate the mike off after 50
milliseconds, or whatever, before the echos are back.

You nailed it. And you can do that with the terrific yet reasonably priced
ETF software. Go here to learn mo

www.acoustisoft.com

I use ETF to assess room response. I have not used the gate feature for
measuring speakers independent of the room, but it can do that too.

--Ethan

On Sun, 16 May 2004 10:00:33 -0400, "mark"
wrote:

What's an alternative to testing a speakers frequency response besides using
an anechoic chamber?

Could we use MLS to manage the effects of
room reflections What is MLS exactly ? What does it involve?

Also check :

http://bofinit.com/Manuals/WinAIRR/WinAIRR.html
which sells for $50.

The length of time that the listening window stays open affects
low frequency measurements, so these still require big rooms or
going outdoors.

Chris Hornbeck

On Sun, 16 May 2004 10:00:33 -0400, "mark"
wrote:

What's an alternative to testing a speakers frequency response besides using
an anechoic chamber?

Could we use MLS to manage the effects of
room reflections What is MLS exactly ? What does it involve?

Also check :

http://bofinit.com/Manuals/WinAIRR/WinAIRR.html
which sells for $50.

The length of time that the listening window stays open affects
low frequency measurements, so these still require big rooms or
going outdoors.

Chris Hornbeck

mark wrote:
What's an alternative to testing a speakers frequency response besides using
an anechoic chamber?

There really isn't one.

Could we use MLS to manage the effects of
room reflections What is MLS exactly ? What does it involve?

You can minimize the effects of room reflections, but your low end corner
is still going to be dependant on the size of the room. If you want low
end measurements, you're still going to have to make sure the first room
echo doesn't arrive before the end of the first cycle.

Do we need a special software package that outputs a pulse through the
soundcard for the speaker amp, and
listens through the mike for a set period, then applies fourier analysis to
the wave that comes back from the mike? Would anyone know of the following
method: putting a pulse through a speaker, and then gate
the mike off after 50 milliseconds, or whatever, before the echos are back.
But to use this method we'd need to feed the mike to the sound card and have
a fourier analysis software?

Yes, you will need a calibrated laboratory microphone, and doing impulse
and MLS testing is going to require a much better microphone than is
required for swept sine testing.

You can look into the MLSSA software, which seems to be popular in a lot
of facilities. It's not magic, but it does make a lot of routine testing
much easier than swept sine work.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

mark wrote:
What's an alternative to testing a speakers frequency response besides using
an anechoic chamber?

There really isn't one.

Could we use MLS to manage the effects of
room reflections What is MLS exactly ? What does it involve?

You can minimize the effects of room reflections, but your low end corner
is still going to be dependant on the size of the room. If you want low
end measurements, you're still going to have to make sure the first room
echo doesn't arrive before the end of the first cycle.

Do we need a special software package that outputs a pulse through the
soundcard for the speaker amp, and
listens through the mike for a set period, then applies fourier analysis to
the wave that comes back from the mike? Would anyone know of the following
method: putting a pulse through a speaker, and then gate
the mike off after 50 milliseconds, or whatever, before the echos are back.
But to use this method we'd need to feed the mike to the sound card and have
a fourier analysis software?

Yes, you will need a calibrated laboratory microphone, and doing impulse
and MLS testing is going to require a much better microphone than is
required for swept sine testing.

You can look into the MLSSA software, which seems to be popular in a lot
of facilities. It's not magic, but it does make a lot of routine testing
much easier than swept sine work.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

On Sun, 16 May 2004 10:00:33 -0400, mark wrote:

What's an alternative to testing a speakers frequency response besides using
an anechoic chamber?

Test them outdoors? A grassy field is fairly anechoic. Wind noise might
cause a few problems.

On Sun, 16 May 2004 10:00:33 -0400, mark wrote:

What's an alternative to testing a speakers frequency response besides using
an anechoic chamber?

Test them outdoors? A grassy field is fairly anechoic. Wind noise might
cause a few problems.

"Scott Dorsey" wrote in message
...
mark wrote:
What's an alternative to testing a speakers frequency response besides
using
an anechoic chamber?

There really isn't one.

Could we use MLS to manage the effects of
room reflections What is MLS exactly ? What does it involve?

You can minimize the effects of room reflections, but your low end corner
is still going to be dependant on the size of the room. If you want low
end measurements, you're still going to have to make sure the first room
echo doesn't arrive before the end of the first cycle.

Do we need a special software package that outputs a pulse through the
soundcard for the speaker amp, and
listens through the mike for a set period, then applies fourier analysis
to
the wave that comes back from the mike? Would anyone know of the
following
method: putting a pulse through a speaker, and then gate
the mike off after 50 milliseconds, or whatever, before the echos are
back.
But to use this method we'd need to feed the mike to the sound card and
have
a fourier analysis software?

Yes, you will need a calibrated laboratory microphone, and doing impulse
and MLS testing is going to require a much better microphone than is
required for swept sine testing.


You mean it hasn't been "re-calibrated"?

We are using a Earthworks M30 BX microphone.
It's calibrated from factory isn't it? And it's new. You'd send it for
re-calibration every couple of years, or once a year if you're really
really anal retentive.
Besides, the peaks and valleys in a speaker span a good number of decibels,
and most of the time there's nothing you can do about it; so does it
really matter if we we're off by plus or minus 0.2 dB here and
there? Can't even hear such subtle differences.

Do we still have to consider the room we do the test in. Or should we
consider doing it outside?
The floor at the back is a cement floor, firmly attached to the planet.
All we need is something soft to put under the speaker, like the foam pad?
Can we place the speaker box on the cement floor flush with a open garage
door and point the speaker box outside?

You can look into the MLSSA software, which seems to be popular in a lot
of facilities. It's not magic, but it does make a lot of routine testing
much easier than swept sine work.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

"Scott Dorsey" wrote in message
...
mark wrote:
What's an alternative to testing a speakers frequency response besides
using
an anechoic chamber?

There really isn't one.

Could we use MLS to manage the effects of
room reflections What is MLS exactly ? What does it involve?

You can minimize the effects of room reflections, but your low end corner
is still going to be dependant on the size of the room. If you want low
end measurements, you're still going to have to make sure the first room
echo doesn't arrive before the end of the first cycle.

Do we need a special software package that outputs a pulse through the
soundcard for the speaker amp, and
listens through the mike for a set period, then applies fourier analysis
to
the wave that comes back from the mike? Would anyone know of the
following
method: putting a pulse through a speaker, and then gate
the mike off after 50 milliseconds, or whatever, before the echos are
back.
But to use this method we'd need to feed the mike to the sound card and
have
a fourier analysis software?

Yes, you will need a calibrated laboratory microphone, and doing impulse
and MLS testing is going to require a much better microphone than is
required for swept sine testing.


You mean it hasn't been "re-calibrated"?

We are using a Earthworks M30 BX microphone.
It's calibrated from factory isn't it? And it's new. You'd send it for
re-calibration every couple of years, or once a year if you're really
really anal retentive.
Besides, the peaks and valleys in a speaker span a good number of decibels,
and most of the time there's nothing you can do about it; so does it
really matter if we we're off by plus or minus 0.2 dB here and
there? Can't even hear such subtle differences.

Do we still have to consider the room we do the test in. Or should we
consider doing it outside?
The floor at the back is a cement floor, firmly attached to the planet.
All we need is something soft to put under the speaker, like the foam pad?
Can we place the speaker box on the cement floor flush with a open garage
door and point the speaker box outside?

You can look into the MLSSA software, which seems to be popular in a lot
of facilities. It's not magic, but it does make a lot of routine testing
much easier than swept sine work.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Do we still have to consider the room we do the test in. Or should we
consider doing it outside?
The floor at the back is a cement floor, firmly attached to the planet.
All we need is something soft to put under the speaker, like the foam pad?
Can we place the speaker box on the cement floor flush with a open garage
door and point the speaker box outside?

We have no means of powering the equipment outside in a grassy field.
The oscilloscope, amp/crossover/speaker, frequency generator, fluke meter,
laptop?
Besides we have to lug a 2'x2'x4' 18" speaker box.
As well as a 2'x2'x2' 8" coaxial speaker box. And amps/crossovers/power
supply for both.

Should we have a quality soundcard for this test? Is an m-audio 2496
audiophile good enough for this kind of test?


"philicorda" wrote in message
newsan.2004.05.16.16.40.48.350073@nospnospamspaa mmntlworld.com...
On Sun, 16 May 2004 10:00:33 -0400, mark wrote:

What's an alternative to testing a speakers frequency response besides
using
an anechoic chamber?

Test them outdoors? A grassy field is fairly anechoic. Wind noise might
cause a few problems.

Do we still have to consider the room we do the test in. Or should we
consider doing it outside?
The floor at the back is a cement floor, firmly attached to the planet.
All we need is something soft to put under the speaker, like the foam pad?
Can we place the speaker box on the cement floor flush with a open garage
door and point the speaker box outside?

We have no means of powering the equipment outside in a grassy field.
The oscilloscope, amp/crossover/speaker, frequency generator, fluke meter,
laptop?
Besides we have to lug a 2'x2'x4' 18" speaker box.
As well as a 2'x2'x2' 8" coaxial speaker box. And amps/crossovers/power
supply for both.

Should we have a quality soundcard for this test? Is an m-audio 2496
audiophile good enough for this kind of test?


"philicorda" wrote in message
newsan.2004.05.16.16.40.48.350073@nospnospamspaa mmntlworld.com...
On Sun, 16 May 2004 10:00:33 -0400, mark wrote:

What's an alternative to testing a speakers frequency response besides
using
an anechoic chamber?

Test them outdoors? A grassy field is fairly anechoic. Wind noise might
cause a few problems.

Here's a plan:

Raytron's back | Back alley (East --)
|
|wall
|
|
|
| /
|/
/
#
/sonopan
divider --- #
/
#
/ |-ledge of garage door
#
_______________
#
| | |
#
| /
#
| speaker ) | -- 1 m -- =EX(mike) -------- 5
---//------ #
| (foam under) \
#
|_______________| |
#

#
\ |
#
\
#
\sonopan
#
\
#
|\
\
|

|

|

|

|

|

|

|

|

|

|

|
|
|
______________________|

The third sonopan panel not shown, it's above the speaker and tilted
forward.
by placing the speaker close to the north end of the garage door, we
maximize
distance to the south wall. It won't be as much as 5 meters though, but we
could place a lot of cardboard boxes tilted at 45 degrees, and covered with
blankets. At least it's only one wall to worry about.
Other walls and ceiling are 5 meters away or more, so if we gate at 3 mS
we're
laughing.
What the tilted sonopans are doing is reflecting lateral waves away from
walls
and ceiling, but also away from the mike. Some of the sound will get
through
them through, but the gating will ignore it anyways. Mostly there to reduce
minor reflections from objects closer than the walls and ceiling, rather.






"mark" wrote in message
...
What's an alternative to testing a speakers frequency response besides
using
an anechoic chamber?

Could we use MLS to manage the effects of
room reflections What is MLS exactly ? What does it involve?

Do we need a special software package that outputs a pulse through the
soundcard for the speaker amp, and
listens through the mike for a set period, then applies fourier analysis
to
the wave that comes back from the mike? Would anyone know of the following
method: putting a pulse through a speaker, and then gate
the mike off after 50 milliseconds, or whatever, before the echos are
back.
But to use this method we'd need to feed the mike to the sound card and
have
a fourier analysis software?
Anyone ?

Thanks for any help,
Mark

Here's a plan:

Raytron's back | Back alley (East --)
|
|wall
|
|
|
| /
|/
/
#
/sonopan
divider --- #
/
#
/ |-ledge of garage door
#
_______________
#
| | |
#
| /
#
| speaker ) | -- 1 m -- =EX(mike) -------- 5
---//------ #
| (foam under) \
#
|_______________| |
#

#
\ |
#
\
#
\sonopan
#
\
#
|\
\
|

|

|

|

|

|

|

|

|

|

|

|
|
|
______________________|

The third sonopan panel not shown, it's above the speaker and tilted
forward.
by placing the speaker close to the north end of the garage door, we
maximize
distance to the south wall. It won't be as much as 5 meters though, but we
could place a lot of cardboard boxes tilted at 45 degrees, and covered with
blankets. At least it's only one wall to worry about.
Other walls and ceiling are 5 meters away or more, so if we gate at 3 mS
we're
laughing.
What the tilted sonopans are doing is reflecting lateral waves away from
walls
and ceiling, but also away from the mike. Some of the sound will get
through
them through, but the gating will ignore it anyways. Mostly there to reduce
minor reflections from objects closer than the walls and ceiling, rather.






"mark" wrote in message
...
What's an alternative to testing a speakers frequency response besides
using
an anechoic chamber?

Could we use MLS to manage the effects of
room reflections What is MLS exactly ? What does it involve?

Do we need a special software package that outputs a pulse through the
soundcard for the speaker amp, and
listens through the mike for a set period, then applies fourier analysis
to
the wave that comes back from the mike? Would anyone know of the following
method: putting a pulse through a speaker, and then gate
the mike off after 50 milliseconds, or whatever, before the echos are
back.
But to use this method we'd need to feed the mike to the sound card and
have
a fourier analysis software?
Anyone ?

Thanks for any help,
Mark

Here's a plan:

Raytron's back | Back alley (East --)
|
|wall
|
|
|
|
|
/
#
/ sonopan
divider --- #
/
#
/ |-ledge of garage door
#
_______________
#
| | |
#
| /
#
| speaker ) | -- 1 m -- =EX(mike) -------- 5
m ---//------ #
| (foam under) \
#
|_______________| |
#

#
\ |
#
\
#
\sonopan
#
\
#
|
\
|

|

|

|

|

|

|

|

|

|

|

|
|
|
_____________________|

The third sonopan panel not shown, it's above the speaker and tilted
forward.
by placing the speaker close to the north end of the garage door, we
maximize
distance to the south wall. It won't be as much as 5 meters though, but we
could place a lot of cardboard boxes tilted at 45 degrees, and covered with
blankets. At least it's only one wall to worry about.
Other walls and ceiling are 5 meters away or more, so if we gate at 3 mS
we're
laughing.
What the tilted sonopans are doing is reflecting lateral waves away from
walls
and ceiling, but also away from the mike. Some of the sound will get
through
them through, but the gating will ignore it anyways. Mostly there to reduce
minor reflections from objects closer than the walls and ceiling, rather.

"mark" wrote in message
...
What's an alternative to testing a speakers frequency response besides
using
an anechoic chamber?

Could we use MLS to manage the effects of
room reflections What is MLS exactly ? What does it involve?

Do we need a special software package that outputs a pulse through the
soundcard for the speaker amp, and
listens through the mike for a set period, then applies fourier analysis
to
the wave that comes back from the mike? Would anyone know of the following
method: putting a pulse through a speaker, and then gate
the mike off after 50 milliseconds, or whatever, before the echos are
back.
But to use this method we'd need to feed the mike to the sound card and
have
a fourier analysis software?
Anyone ?

Thanks for any help,
Mark

Here's a plan:

Raytron's back | Back alley (East --)
|
|wall
|
|
|
|
|
/
#
/ sonopan
divider --- #
/
#
/ |-ledge of garage door
#
_______________
#
| | |
#
| /
#
| speaker ) | -- 1 m -- =EX(mike) -------- 5
m ---//------ #
| (foam under) \
#
|_______________| |
#

#
\ |
#
\
#
\sonopan
#
\
#
|
\
|

|

|

|

|

|

|

|

|

|

|

|
|
|
_____________________|

The third sonopan panel not shown, it's above the speaker and tilted
forward.
by placing the speaker close to the north end of the garage door, we
maximize
distance to the south wall. It won't be as much as 5 meters though, but we
could place a lot of cardboard boxes tilted at 45 degrees, and covered with
blankets. At least it's only one wall to worry about.
Other walls and ceiling are 5 meters away or more, so if we gate at 3 mS
we're
laughing.
What the tilted sonopans are doing is reflecting lateral waves away from
walls
and ceiling, but also away from the mike. Some of the sound will get
through
them through, but the gating will ignore it anyways. Mostly there to reduce
minor reflections from objects closer than the walls and ceiling, rather.

"mark" wrote in message
...
What's an alternative to testing a speakers frequency response besides
using
an anechoic chamber?

Could we use MLS to manage the effects of
room reflections What is MLS exactly ? What does it involve?

Do we need a special software package that outputs a pulse through the
soundcard for the speaker amp, and
listens through the mike for a set period, then applies fourier analysis
to
the wave that comes back from the mike? Would anyone know of the following
method: putting a pulse through a speaker, and then gate
the mike off after 50 milliseconds, or whatever, before the echos are
back.
But to use this method we'd need to feed the mike to the sound card and
have
a fourier analysis software?
Anyone ?

Thanks for any help,
Mark

mark wrote:

What's an alternative to testing a speakers frequency response besides using
an anechoic chamber?

Could we use MLS to manage the effects of
room reflections What is MLS exactly ? What does it involve?

Do we need a special software package that outputs a pulse through the
soundcard for the speaker amp, and
listens through the mike for a set period, then applies fourier analysis to
the wave that comes back from the mike? Would anyone know of the following
method: putting a pulse through a speaker, and then gate
the mike off after 50 milliseconds, or whatever, before the echos are back.
But to use this method we'd need to feed the mike to the sound card and have
a fourier analysis software?
Anyone ?

Thanks for any help,
Mark




Don't you really want to test them in the room? If you're building
speakers, why not use a chamber, or at least approximate one.

--
Les Cargill

mark wrote:

What's an alternative to testing a speakers frequency response besides using
an anechoic chamber?

Could we use MLS to manage the effects of
room reflections What is MLS exactly ? What does it involve?

Do we need a special software package that outputs a pulse through the
soundcard for the speaker amp, and
listens through the mike for a set period, then applies fourier analysis to
the wave that comes back from the mike? Would anyone know of the following
method: putting a pulse through a speaker, and then gate
the mike off after 50 milliseconds, or whatever, before the echos are back.
But to use this method we'd need to feed the mike to the sound card and have
a fourier analysis software?
Anyone ?

Thanks for any help,
Mark




Don't you really want to test them in the room? If you're building
speakers, why not use a chamber, or at least approximate one.

--
Les Cargill

You need to test frequency response, phase response, time offset, and maybe
more.

http://www.siasoft.com ,
http://www.prosoundweb.com/live/arti...artbegin.shtml ,
http://www.prosoundweb.com/live/labb...t/smaart.shtml ,
http://www.prosoundweb.com/studyhall/am_index.php


"mark" wrote in message
...
What's an alternative to testing a speakers frequency response besides
using
an anechoic chamber?

Could we use MLS to manage the effects of
room reflections What is MLS exactly ? What does it involve?

Do we need a special software package that outputs a pulse through the
soundcard for the speaker amp, and
listens through the mike for a set period, then applies fourier analysis
to
the wave that comes back from the mike? Would anyone know of the following
method: putting a pulse through a speaker, and then gate
the mike off after 50 milliseconds, or whatever, before the echos are
back.
But to use this method we'd need to feed the mike to the sound card and
have
a fourier analysis software?
Anyone ?

Thanks for any help,
Mark

You need to test frequency response, phase response, time offset, and maybe
more.

http://www.siasoft.com ,
http://www.prosoundweb.com/live/arti...artbegin.shtml ,
http://www.prosoundweb.com/live/labb...t/smaart.shtml ,
http://www.prosoundweb.com/studyhall/am_index.php


"mark" wrote in message
...
What's an alternative to testing a speakers frequency response besides
using
an anechoic chamber?

Could we use MLS to manage the effects of
room reflections What is MLS exactly ? What does it involve?

Do we need a special software package that outputs a pulse through the
soundcard for the speaker amp, and
listens through the mike for a set period, then applies fourier analysis
to
the wave that comes back from the mike? Would anyone know of the following
method: putting a pulse through a speaker, and then gate
the mike off after 50 milliseconds, or whatever, before the echos are
back.
But to use this method we'd need to feed the mike to the sound card and
have
a fourier analysis software?
Anyone ?

Thanks for any help,
Mark

mark wrote:

What's an alternative to testing a speakers frequency response besides using
an anechoic chamber?

Do it outside.


Could we use MLS to manage the effects of
room reflections What is MLS exactly ? What does it involve?

There aren't any reflections outside. Swept sin is better
than MLS because it discards any harmonic distortion
products. Both are better than any real impulse methods
because they contain so much more energy that they reject a
very large amount of any ambient noise that might trouble
the testing otherwise.


Do we need a special software package that outputs a pulse through the
soundcard for the speaker amp, and
listens through the mike for a set period, then applies fourier analysis to
the wave that comes back from the mike? Would anyone know of the following
method: putting a pulse through a speaker, and then gate
the mike off after 50 milliseconds, or whatever, before the echos are back.
But to use this method we'd need to feed the mike to the sound card and have
a fourier analysis software?
Anyone ?

Windowed methods for speakers is difficult because the
impulse response of the speaker itself can easily extend
beyond your window. But with the swept sin approach, you
can still window the impulse response after it is
calculated. Anything that results from the room still shows
as reflections. I use Acoustic Modeler that was once a
stand alone DX plug but now is integrated with Sound Forge.
It contains the necessasary sweeps and will do the impulse
response calculation from the measured response to the
sweep. I think there are other options these days but don't
know them off the top of my head.

Once you get the impulse response then you are right, an FFT
of it will show you the response.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

mark wrote:

What's an alternative to testing a speakers frequency response besides using
an anechoic chamber?

Do it outside.


Could we use MLS to manage the effects of
room reflections What is MLS exactly ? What does it involve?

There aren't any reflections outside. Swept sin is better
than MLS because it discards any harmonic distortion
products. Both are better than any real impulse methods
because they contain so much more energy that they reject a
very large amount of any ambient noise that might trouble
the testing otherwise.


Do we need a special software package that outputs a pulse through the
soundcard for the speaker amp, and
listens through the mike for a set period, then applies fourier analysis to
the wave that comes back from the mike? Would anyone know of the following
method: putting a pulse through a speaker, and then gate
the mike off after 50 milliseconds, or whatever, before the echos are back.
But to use this method we'd need to feed the mike to the sound card and have
a fourier analysis software?
Anyone ?

Windowed methods for speakers is difficult because the
impulse response of the speaker itself can easily extend
beyond your window. But with the swept sin approach, you
can still window the impulse response after it is
calculated. Anything that results from the room still shows
as reflections. I use Acoustic Modeler that was once a
stand alone DX plug but now is integrated with Sound Forge.
It contains the necessasary sweeps and will do the impulse
response calculation from the measured response to the
sweep. I think there are other options these days but don't
know them off the top of my head.

Once you get the impulse response then you are right, an FFT
of it will show you the response.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

mark wrote:

We are using a Earthworks M30 BX microphone.
It's calibrated from factory isn't it?

It's not tracable to the NIST but it is more than flat
enough for your purposes. As you point out, the speaker
devaitions will swamp those from that mic.

Do we still have to consider the room we do the test in. Or should we
consider doing it outside?

If you want any kind of reasonable low frequency data that's
about the only way. With either MLS or my preferred method,
swept sin, the noise factor of being outside is really
pretty negligable. You will probably need a good wind
shield for the mic, though. The noise that comes from wind
is too great for the longer methods to deal with, especially
at the lower frequencies.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

mark wrote:

We are using a Earthworks M30 BX microphone.
It's calibrated from factory isn't it?

It's not tracable to the NIST but it is more than flat
enough for your purposes. As you point out, the speaker
devaitions will swamp those from that mic.

Do we still have to consider the room we do the test in. Or should we
consider doing it outside?

If you want any kind of reasonable low frequency data that's
about the only way. With either MLS or my preferred method,
swept sin, the noise factor of being outside is really
pretty negligable. You will probably need a good wind
shield for the mic, though. The noise that comes from wind
is too great for the longer methods to deal with, especially
at the lower frequencies.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

mark wrote:



We have no means of powering the equipment outside in a grassy field.

It would be a good aquisition. A reasonable quality
automobile amplifier and a 12V gel cell handles the drive
and a modest laptop with a Tascam US-122 will do both the
signal drive and the measurement. Once the data is in the
laptop you have all kinds of options for its analysis.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

mark wrote:



We have no means of powering the equipment outside in a grassy field.

It would be a good aquisition. A reasonable quality
automobile amplifier and a 12V gel cell handles the drive
and a modest laptop with a Tascam US-122 will do both the
signal drive and the measurement. Once the data is in the
laptop you have all kinds of options for its analysis.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

In article ,
"Tim Padrick" wrote:

You need to test frequency response, phase response, time offset, and maybe
more.

http://www.siasoft.com ,
http://www.prosoundweb.com/live/arti...artbegin.shtml ,
http://www.prosoundweb.com/live/labb...t/smaart.shtml ,
http://www.prosoundweb.com/studyhall/am_index.php

You should also consider WinMLS, by Lars Moriset: http://www.winmls.com/

The TEF analyzer is still alive and kicking, and the TDS swept sinewave
will provide pseudo anechoic measurements, with a high signal to noise
ratio. Also available for the TEF is Polar software, and MLS.

http://www.gold-line.com/tef/t-ship.htm
http://www.gold-line.com/tef/t-slsoft.htm


Soon to be available via Renkus Heinz, is EaseRA. This package was
developed by Acoustic Design Ahnert, the same group that created the
EASE modelling, and EARS auralization packages.

This is a very comprehensive measurement software, capable of performing
both MLS and TDS measurements.

http://www.renkus-heinz.com/news/news_easera.html

In article ,
"Tim Padrick" wrote:

You need to test frequency response, phase response, time offset, and maybe
more.

http://www.siasoft.com ,
http://www.prosoundweb.com/live/arti...artbegin.shtml ,
http://www.prosoundweb.com/live/labb...t/smaart.shtml ,
http://www.prosoundweb.com/studyhall/am_index.php

You should also consider WinMLS, by Lars Moriset: http://www.winmls.com/

The TEF analyzer is still alive and kicking, and the TDS swept sinewave
will provide pseudo anechoic measurements, with a high signal to noise
ratio. Also available for the TEF is Polar software, and MLS.

http://www.gold-line.com/tef/t-ship.htm
http://www.gold-line.com/tef/t-slsoft.htm


Soon to be available via Renkus Heinz, is EaseRA. This package was
developed by Acoustic Design Ahnert, the same group that created the
EASE modelling, and EARS auralization packages.

This is a very comprehensive measurement software, capable of performing
both MLS and TDS measurements.

http://www.renkus-heinz.com/news/news_easera.html

"philicorda" wrote in message
newsan.2004.05.16.16.40.48.350073@nospnospamspaa mmntlworld.com...
On Sun, 16 May 2004 10:00:33 -0400, mark wrote:

What's an alternative to testing a speakers frequency response besides
using
an anechoic chamber?

Test them outdoors? A grassy field is fairly anechoic. Wind noise might
cause a few problems.

Sounds like you need a room that is opaque to wind, but transparent to
sound. A big test tent.

dtk

"philicorda" wrote in message
newsan.2004.05.16.16.40.48.350073@nospnospamspaa mmntlworld.com...
On Sun, 16 May 2004 10:00:33 -0400, mark wrote:

What's an alternative to testing a speakers frequency response besides
using
an anechoic chamber?

Test them outdoors? A grassy field is fairly anechoic. Wind noise might
cause a few problems.

Sounds like you need a room that is opaque to wind, but transparent to
sound. A big test tent.

dtk

mark wrote:

You mean it hasn't been "re-calibrated"?

We are using a Earthworks M30 BX microphone.
It's calibrated from factory isn't it? And it's new. You'd send it for
re-calibration every couple of years, or once a year if you're really
really anal retentive.

You may want to consider using an IEC Type I microphone. I do not think
that the Earthworks comes close to meeting even the loose IEC Type II specs.

Besides, the peaks and valleys in a speaker span a good number of decibels,
and most of the time there's nothing you can do about it; so does it
really matter if we we're off by plus or minus 0.2 dB here and
there? Can't even hear such subtle differences.

With a sweep test it won't matter a bit, but with MLSSA or an impulse response
test, you need a microphone that has extremely good impulse response. The
problem with these methods is that they require much more accurate mikes
than sweep methods do.

Do we still have to consider the room we do the test in. Or should we
consider doing it outside?
The floor at the back is a cement floor, firmly attached to the planet.
All we need is something soft to put under the speaker, like the foam pad?
Can we place the speaker box on the cement floor flush with a open garage
door and point the speaker box outside?

If you're talking a place with a 50-foot ceiling, and you suspend the
speaker 25 foot in the air, then you can accurately work down to wavelengths
of 25 feet or so without having to treat the room significantly in any way.
The question is how far you can get your device under test from any
surfaces.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

mark wrote:

You mean it hasn't been "re-calibrated"?

We are using a Earthworks M30 BX microphone.
It's calibrated from factory isn't it? And it's new. You'd send it for
re-calibration every couple of years, or once a year if you're really
really anal retentive.

You may want to consider using an IEC Type I microphone. I do not think
that the Earthworks comes close to meeting even the loose IEC Type II specs.

Besides, the peaks and valleys in a speaker span a good number of decibels,
and most of the time there's nothing you can do about it; so does it
really matter if we we're off by plus or minus 0.2 dB here and
there? Can't even hear such subtle differences.

With a sweep test it won't matter a bit, but with MLSSA or an impulse response
test, you need a microphone that has extremely good impulse response. The
problem with these methods is that they require much more accurate mikes
than sweep methods do.

Do we still have to consider the room we do the test in. Or should we
consider doing it outside?
The floor at the back is a cement floor, firmly attached to the planet.
All we need is something soft to put under the speaker, like the foam pad?
Can we place the speaker box on the cement floor flush with a open garage
door and point the speaker box outside?

If you're talking a place with a 50-foot ceiling, and you suspend the
speaker 25 foot in the air, then you can accurately work down to wavelengths
of 25 feet or so without having to treat the room significantly in any way.
The question is how far you can get your device under test from any
surfaces.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Scott Dorsey wrote:



With a sweep test it won't matter a bit, but with MLSSA or an impulse response
test, you need a microphone that has extremely good impulse response. The
problem with these methods is that they require much more accurate mikes
than sweep methods do.

I don't believe this is true, Scott. If the mic is linear
the nature of the stimulus doesn't matter.

Both methods just form the cross correlation of the stimulus
with the recorded response to get the impulse response. The
main advantage of the swept sin over the MLS is the impact
of distortion products. With MLS they are distributed
throughout the cross correlation whereas with the swept sin,
they appear as little impulse responses separated from the
main one in time and in advance of it.

The other advantage which is exploited by Acoustic Modeler
is that time synchronization between the stimulus and
response can be removed as a requirement with the swept sin
because, being an analytic mathematical function, it can be
regenerated at a rate that will match the actual length of
the recorded response.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

Scott Dorsey wrote:



With a sweep test it won't matter a bit, but with MLSSA or an impulse response
test, you need a microphone that has extremely good impulse response. The
problem with these methods is that they require much more accurate mikes
than sweep methods do.

I don't believe this is true, Scott. If the mic is linear
the nature of the stimulus doesn't matter.

Both methods just form the cross correlation of the stimulus
with the recorded response to get the impulse response. The
main advantage of the swept sin over the MLS is the impact
of distortion products. With MLS they are distributed
throughout the cross correlation whereas with the swept sin,
they appear as little impulse responses separated from the
main one in time and in advance of it.

The other advantage which is exploited by Acoustic Modeler
is that time synchronization between the stimulus and
response can be removed as a requirement with the swept sin
because, being an analytic mathematical function, it can be
regenerated at a rate that will match the actual length of
the recorded response.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

Does "Speaker Workshop" software have any known issues doing gated mike MLS
measurements?

Does "Speaker Workshop" software have any known issues doing gated mike MLS
measurements?

"mark" wrote in message
...
: What's an alternative to testing a speakers frequency response besides using
: an anechoic chamber?
:
: Could we use MLS to manage the effects of
: room reflections What is MLS exactly ? What does it involve?
:
: Do we need a special software package that outputs a pulse through the
: soundcard for the speaker amp, and
: listens through the mike for a set period, then applies fourier analysis to
: the wave that comes back from the mike? Would anyone know of the following
: method: putting a pulse through a speaker, and then gate
: the mike off after 50 milliseconds, or whatever, before the echos are back.
: But to use this method we'd need to feed the mike to the sound card and have
: a fourier analysis software?
: Anyone ?
:
: Thanks for any help,
: Mark
:
Before I recommend anything it is important for me to understand what benefit an
accurate measurement of the speaker is expected to do for you. The answer will be
affected by the following.

1) are you building a loudspeaker and crossover?
2) are you attempting to equalize a room with a "manufactured" pair of speakers in
it?
3) What exactly are you trying to accomplish by measuring the speaker.
4) other than not having the expertise in measuring a loudspeaker, do you have some
specific expertise or experience in doing something with speakers that you want to
improve on.

I can provide a lot of answers, but I need to know what you are looking to
accomplish.

Phil Abbate
LspCAD Dealer
www.philsaudio.com

"mark" wrote in message
...
: What's an alternative to testing a speakers frequency response besides using
: an anechoic chamber?
:
: Could we use MLS to manage the effects of
: room reflections What is MLS exactly ? What does it involve?
:
: Do we need a special software package that outputs a pulse through the
: soundcard for the speaker amp, and
: listens through the mike for a set period, then applies fourier analysis to
: the wave that comes back from the mike? Would anyone know of the following
: method: putting a pulse through a speaker, and then gate
: the mike off after 50 milliseconds, or whatever, before the echos are back.
: But to use this method we'd need to feed the mike to the sound card and have
: a fourier analysis software?
: Anyone ?
:
: Thanks for any help,
: Mark
:
Before I recommend anything it is important for me to understand what benefit an
accurate measurement of the speaker is expected to do for you. The answer will be
affected by the following.

1) are you building a loudspeaker and crossover?
2) are you attempting to equalize a room with a "manufactured" pair of speakers in
it?
3) What exactly are you trying to accomplish by measuring the speaker.
4) other than not having the expertise in measuring a loudspeaker, do you have some
specific expertise or experience in doing something with speakers that you want to
improve on.

I can provide a lot of answers, but I need to know what you are looking to
accomplish.

Phil Abbate
LspCAD Dealer
www.philsaudio.com

Before I recommend anything it is important for me to understand what
benefit an
accurate measurement of the speaker is expected to do for you. The
answer
will be
affected by the following.

1) are you building a loudspeaker and crossover?

Yes. Crossover is in the preamp, phase coherent, subtraction type; we're
"tri-amping".
We're going to change the crossover to a Linkwitz-Riley soon; waiting for
the PCB's.

2) are you attempting to equalize a room with a "manufactured" pair of
speakers in
it?

No

3) What exactly are you trying to accomplish by measuring the speaker.

We want to:
1) Know how flat the 18" woofer speaker (bass reflex) cabinet response
really is.
Same for the 8" mid range. Same for the titanium tweeter.
2) Know how much we need to adjust gains to balance the SPL of the three
drivers
3) Know whether we need to reverse driver phases for smooth crossovers,
and/or
whether we need an all pass filter for phase correction on the tweeter
channel.
Then, once SPL and phase issues are settled, we want to
4) Verify how flat the whole speaker's response is, just on axis, for now.

4) other than not having the expertise in measuring a loudspeaker, do
you
have some
specific expertise or experience in doing something with speakers that
you
want to
improve on.

Our speakers sound good so far, but we maybe biased, since we built them ,
so we want to know exactly how good they are.

I can provide a lot of answers, but I need to know what you are looking
to
accomplish.

Phil Abbate
LspCAD Dealer
www.philsaudio.com




"anybody-but-bush" Anybody But wrote in message
hlink.net...

"mark" wrote in message
...
: What's an alternative to testing a speakers frequency response besides
using
: an anechoic chamber?
:
: Could we use MLS to manage the effects of
: room reflections What is MLS exactly ? What does it involve?
:
: Do we need a special software package that outputs a pulse through the
: soundcard for the speaker amp, and
: listens through the mike for a set period, then applies fourier analysis
to
: the wave that comes back from the mike? Would anyone know of the
following
: method: putting a pulse through a speaker, and then gate
: the mike off after 50 milliseconds, or whatever, before the echos are
back.
: But to use this method we'd need to feed the mike to the sound card and
have
: a fourier analysis software?
: Anyone ?
:
: Thanks for any help,
: Mark
:
Before I recommend anything it is important for me to understand what
benefit an
accurate measurement of the speaker is expected to do for you. The answer
will be
affected by the following.

1) are you building a loudspeaker and crossover?
2) are you attempting to equalize a room with a "manufactured" pair of
speakers in
it?
3) What exactly are you trying to accomplish by measuring the speaker.
4) other than not having the expertise in measuring a loudspeaker, do you
have some
specific expertise or experience in doing something with speakers that you
want to
improve on.

I can provide a lot of answers, but I need to know what you are looking to
accomplish.

Phil Abbate
LspCAD Dealer
www.philsaudio.com