Dick,

If those are the resuults you getm then you're not doing your filtering
properly.

I dunno - we set up a mike, played some tones, and that's what we got. What
else is there to do?

perhaps you might want to consider expanding your toolbox.

Actually, loudspeaker placement in rooms is of great interest to me too. In
fact, later today I'm going to do some tests of the response obtained with
speakers flat against a wall versus various spacings away from the wall.

Do you fear, sir, that I have snubbed you?

No, I just wanted to meet this mysterious man behind the curtain in person.

--Ethan

Dick Pierce wrote:
[...]
One final note: "minimum phase" has a very specific technical definition,
summarized above.

Another definition (one that I as an engineer familiar with Laplace
and z-transforms like) is that a minimum phase system is a system
that is stable and causal and whose inverse is also stable and
causal.
--
% Randy Yates % "...the answer lies within your soul
%% Fuquay-Varina, NC % 'cause no one knows which side
%%% 919-577-9882 % the coin will fall."
%%%% % 'Big Wheels', *Out of the Blue*, ELO
http://home.earthlink.net/~yatescr

Dick Pierce wrote:
[...]
One final note: "minimum phase" has a very specific technical definition,
summarized above.

Another definition (one that I as an engineer familiar with Laplace
and z-transforms like) is that a minimum phase system is a system
that is stable and causal and whose inverse is also stable and
causal.
--
% Randy Yates % "...the answer lies within your soul
%% Fuquay-Varina, NC % 'cause no one knows which side
%%% 919-577-9882 % the coin will fall."
%%%% % 'Big Wheels', *Out of the Blue*, ELO
http://home.earthlink.net/~yatescr

"Ethan Winer" ethanw at ethanwiner dot com wrote in message ...
Dick,

If those are the resuults you getm then you're not doing your filtering
properly.

I dunno - we set up a mike, played some tones, and that's what we got. What
else is there to do?

Well, gee whiz golly, Ethan, I reckon there tain't nothin'
else. It just seems me an' my buddies, we been wastin'
our time what with all these here fancy measurement microphones
an' them thar fancy measurement systems and all that high-
falutin' book learnin and all that.

Indeed, there's a LOT more to do. All due respect, but there's
a LOT more to it than just "set up a mike, play some tones."
Because if that's all you do, what you got ain't very useful.

But we've been through this, eh?

perhaps you might want to consider expanding your toolbox.

Actually, loudspeaker placement in rooms is of great interest to me too. In
fact, later today I'm going to do some tests of the response obtained with
speakers flat against a wall versus various spacings away from the wall.

Uh, to possibly overuse the analogy, what I meant by "expanding
your toolbox" doesn't mean going out and looking for more things
that might look like nails.

"Ethan Winer" ethanw at ethanwiner dot com wrote in message ...
Dick,

If those are the resuults you getm then you're not doing your filtering
properly.

I dunno - we set up a mike, played some tones, and that's what we got. What
else is there to do?

Well, gee whiz golly, Ethan, I reckon there tain't nothin'
else. It just seems me an' my buddies, we been wastin'
our time what with all these here fancy measurement microphones
an' them thar fancy measurement systems and all that high-
falutin' book learnin and all that.

Indeed, there's a LOT more to do. All due respect, but there's
a LOT more to it than just "set up a mike, play some tones."
Because if that's all you do, what you got ain't very useful.

But we've been through this, eh?

perhaps you might want to consider expanding your toolbox.

Actually, loudspeaker placement in rooms is of great interest to me too. In
fact, later today I'm going to do some tests of the response obtained with
speakers flat against a wall versus various spacings away from the wall.

Uh, to possibly overuse the analogy, what I meant by "expanding
your toolbox" doesn't mean going out and looking for more things
that might look like nails.

Dick,

Well, gee whiz golly, Ethan, I reckon there tain't nothin' else. It just
seems me an' my buddies, we been wastin' our time what with all these here
fancy measurement

Yes, you sure do like to portray me as an idiot. But as I recall you're the
guy who boldly stated it's impossible to have a room mode peak and null less
than half a wavelength away from each other! At least I was polite enough
not to call you an idiot for that incredibly ignorant statement. So much for
all your book learnin'. You need to get out of your ivory tower and into a
real room to do perform relevant tests.

--Ethan

Dick,

Well, gee whiz golly, Ethan, I reckon there tain't nothin' else. It just
seems me an' my buddies, we been wastin' our time what with all these here
fancy measurement

Yes, you sure do like to portray me as an idiot. But as I recall you're the
guy who boldly stated it's impossible to have a room mode peak and null less
than half a wavelength away from each other! At least I was polite enough
not to call you an idiot for that incredibly ignorant statement. So much for
all your book learnin'. You need to get out of your ivory tower and into a
real room to do perform relevant tests.

--Ethan

"Ethan Winer" ethanw at ethanwiner dot com wrote in message ...
Dick,

Well, gee whiz golly, Ethan, I reckon there tain't nothin' else. It just
seems me an' my buddies, we been wastin' our time what with all these here
fancy measurement

Yes, you sure do like to portray me as an idiot. But as I recall you're the
guy who boldly stated it's impossible to have a room mode peak and null less
than half a wavelength away from each other!

Mr. Winer, now you have stooped to the level of fabricating out-and-out
lies. I DARE you to quote memaking the statement you so dishonestly
state that I did.

"Ethan Winer" ethanw at ethanwiner dot com wrote in message ...
Dick,

Well, gee whiz golly, Ethan, I reckon there tain't nothin' else. It just
seems me an' my buddies, we been wastin' our time what with all these here
fancy measurement

Yes, you sure do like to portray me as an idiot. But as I recall you're the
guy who boldly stated it's impossible to have a room mode peak and null less
than half a wavelength away from each other!

Mr. Winer, now you have stooped to the level of fabricating out-and-out
lies. I DARE you to quote memaking the statement you so dishonestly
state that I did.

(Carlos) wrote in message

I'll try to be more specific: I would like to know whether the final
system (closed sub with Q=0.707, F3 = 37 Hz, 4th order LR crossover @
100 Hz) will have noticeably worse transient response than the current
one (vented boxes with 37% larger than maximally flat box volume,
tuned 22% lower than maximally flat, F3 = 40 Hz, 19.5 dB/Oct. slope),
assuming that the filter is well implemented, the levels are matched
and the distance from listening position to main speakers and sub is
the same (+/- 10 cm) and, for the sake of simplicity, the sub and main
speakers have substantially flat frequency response within their
respective passbands.


The final system, with the closed box subwoofer and a 4th order L-R
crossover, will have a slightly better transient response than the
current vented box does by itself. Actually, the two systems are very
close.

The (100 Hz) 4th order, LR crossover degrades the transient response,
but the close box woofer has a good transient response by itself.
Together they are not too bad. As I said, they will be about the same
as the vented box alone.

Bob Stanton

(Carlos) wrote in message

I'll try to be more specific: I would like to know whether the final
system (closed sub with Q=0.707, F3 = 37 Hz, 4th order LR crossover @
100 Hz) will have noticeably worse transient response than the current
one (vented boxes with 37% larger than maximally flat box volume,
tuned 22% lower than maximally flat, F3 = 40 Hz, 19.5 dB/Oct. slope),
assuming that the filter is well implemented, the levels are matched
and the distance from listening position to main speakers and sub is
the same (+/- 10 cm) and, for the sake of simplicity, the sub and main
speakers have substantially flat frequency response within their
respective passbands.


The final system, with the closed box subwoofer and a 4th order L-R
crossover, will have a slightly better transient response than the
current vented box does by itself. Actually, the two systems are very
close.

The (100 Hz) 4th order, LR crossover degrades the transient response,
but the close box woofer has a good transient response by itself.
Together they are not too bad. As I said, they will be about the same
as the vented box alone.

Bob Stanton

Dick,

I DARE you to quote me making the statement

Yes, that was paraphrased from memory. Fortunately Google Groups saves all
this stuff. Here's exactly what you said: "False, what you are claiming is a
physical impossibility. If you have a dip at 75 Hz, the CLOSEST a peak could
be is 1/4 wavelength away. You have to go through 90 degrees of phase
rotation for this to occur."

And now I can see why there's some confusion. The concept of "peak" and
"null" is confusing in small rooms because there are so many reflections
bouncing off so many nearby boundaries. So suppose you locate a deep null
and then move away in one direction. If the level comes up and goes down
again, that doesn't mean the highest point is actually a peak that's related
to the same nearby null.

If you recall, I measured a null in my room and found a 15 dB change across
a span of only four inches. And that's what really matters - the fact that
this happens, not how or why. Back then we were talking about the futility
of trying to fix room acoustics with DSP. Now Carlos has embarked on an
equally futile mission of trying to solve his room acoustics problems with
speaker placement.

This past Saturday my partner and I did some tests of speaker placement, to
see how much the response could be improved by mere placement. We went to
the considerable effort to remove all of his acoustic treatment and even the
carpet, to maximize the room contribution. Sure enough, and no surprise to
anyone here, some speaker locations had a flatter low frequency response
than others. But the peaks and dips were very severe in all cases. Then we
put the speakers against the wall again (not the flattest response) and put
back his bass traps and mid/high absorbers. The improvement was FAR better
than the best speaker location we had found.

We still have some tests to do using our newer, better bass traps. When
that's done we'll post on our company site graphs comparing the flattest
response you can get with placement versus what you get with proper acoustic
treatment. Carlos, if you're interested let me know and I'll post a screen
capture of what we have so far with our older model bass traps. It clearly
shows that treatment beats placement hands down every time.

--Ethan

Dick,

I DARE you to quote me making the statement

Yes, that was paraphrased from memory. Fortunately Google Groups saves all
this stuff. Here's exactly what you said: "False, what you are claiming is a
physical impossibility. If you have a dip at 75 Hz, the CLOSEST a peak could
be is 1/4 wavelength away. You have to go through 90 degrees of phase
rotation for this to occur."

And now I can see why there's some confusion. The concept of "peak" and
"null" is confusing in small rooms because there are so many reflections
bouncing off so many nearby boundaries. So suppose you locate a deep null
and then move away in one direction. If the level comes up and goes down
again, that doesn't mean the highest point is actually a peak that's related
to the same nearby null.

If you recall, I measured a null in my room and found a 15 dB change across
a span of only four inches. And that's what really matters - the fact that
this happens, not how or why. Back then we were talking about the futility
of trying to fix room acoustics with DSP. Now Carlos has embarked on an
equally futile mission of trying to solve his room acoustics problems with
speaker placement.

This past Saturday my partner and I did some tests of speaker placement, to
see how much the response could be improved by mere placement. We went to
the considerable effort to remove all of his acoustic treatment and even the
carpet, to maximize the room contribution. Sure enough, and no surprise to
anyone here, some speaker locations had a flatter low frequency response
than others. But the peaks and dips were very severe in all cases. Then we
put the speakers against the wall again (not the flattest response) and put
back his bass traps and mid/high absorbers. The improvement was FAR better
than the best speaker location we had found.

We still have some tests to do using our newer, better bass traps. When
that's done we'll post on our company site graphs comparing the flattest
response you can get with placement versus what you get with proper acoustic
treatment. Carlos, if you're interested let me know and I'll post a screen
capture of what we have so far with our older model bass traps. It clearly
shows that treatment beats placement hands down every time.

--Ethan

"Ethan Winer" ethanw at ethanwiner dot com wrote in message ...

[snip]

Carlos, if you're interested let me know and I'll post a screen
capture of what we have so far with our older model bass traps. It clearly
shows that treatment beats placement hands down every time.

--Ethan

Ok Ethan, here's what we are going to do: since I offered to send you
LspCAD's predicted FR plots but you didn't take the offer, that means
that either you are afraid they will prove you wrong ot that you
question LspCAD's accuracy. Well, they do prove you wrong. But maybe
you're right, simulation is just simulation and there's nothing like
an actual measurement to see what's really going on. So, let's
measure, shall we?

I'm now building a subwoofer for a different project. It's vented
instead of closed but has the same F3 so for the purposes of the
experiment it will do fine. Once it's finished I will put it in that
good spot I found through simulation in my room and measure it at the
listening position. I use DLSAPro, an MLS system that gives 0.78 Hz
resolution. You claimed 1 Hz was the minimum required (BTW implicitly
assuming that I couldn't measure down to that resolution, for some
reason; well I guess since I'm just a clueless bass freak who wants
boom and thump I wouldn't have good measuring equipment). I will send
you the results and then we discuss again, ok?

Carlos

"Ethan Winer" ethanw at ethanwiner dot com wrote in message ...

[snip]

Carlos, if you're interested let me know and I'll post a screen
capture of what we have so far with our older model bass traps. It clearly
shows that treatment beats placement hands down every time.

--Ethan

Ok Ethan, here's what we are going to do: since I offered to send you
LspCAD's predicted FR plots but you didn't take the offer, that means
that either you are afraid they will prove you wrong ot that you
question LspCAD's accuracy. Well, they do prove you wrong. But maybe
you're right, simulation is just simulation and there's nothing like
an actual measurement to see what's really going on. So, let's
measure, shall we?

I'm now building a subwoofer for a different project. It's vented
instead of closed but has the same F3 so for the purposes of the
experiment it will do fine. Once it's finished I will put it in that
good spot I found through simulation in my room and measure it at the
listening position. I use DLSAPro, an MLS system that gives 0.78 Hz
resolution. You claimed 1 Hz was the minimum required (BTW implicitly
assuming that I couldn't measure down to that resolution, for some
reason; well I guess since I'm just a clueless bass freak who wants
boom and thump I wouldn't have good measuring equipment). I will send
you the results and then we discuss again, ok?

Carlos

Carlos,

I offered to send you LspCAD's predicted FR plots but you didn't take the
offer, that means that either you are afraid they will prove you wrong ot
that you question LspCAD's accuracy.

Sorry, maybe I read the posts too fast that day? I don't recall that offer.
I'm surely not afraid of being proven wrong! I have no attitude with any of
this stuff. My only interest is learning what matters and why. Heck, the
speaker placement tests I did the other day proved me wrong in one regard. I
had a theory that comb filtering caused by placing a speaker out from a
wall, due to low frequencies emitting from the rear of the cabinet, would
give a worse response than having the speakers flat on the wall. It turned
out flat against the wall did not give the best response. So I'm very glad I
did that test because I learned something. I don't need to be right! I'd
much rather know the truth about something than be right.

simulation is just simulation and there's nothing like an actual
measurement to see what's really going on.

Yes, I surely agree with that.

Once it's finished I will put it in that good spot I found through
simulation in my room and measure it at the listening position.

Sounds like a plan.

assuming that I couldn't measure down to that resolution, for some reason;
well I guess since I'm just a clueless bass freak who wants boom and thump

There's no need to be insulting. I never insulted you. Maybe you should stop
reading Dick Pierce's posts because he seems to be having a bad influence on
you. :-)

--Ethan

Carlos,

I offered to send you LspCAD's predicted FR plots but you didn't take the
offer, that means that either you are afraid they will prove you wrong ot
that you question LspCAD's accuracy.

Sorry, maybe I read the posts too fast that day? I don't recall that offer.
I'm surely not afraid of being proven wrong! I have no attitude with any of
this stuff. My only interest is learning what matters and why. Heck, the
speaker placement tests I did the other day proved me wrong in one regard. I
had a theory that comb filtering caused by placing a speaker out from a
wall, due to low frequencies emitting from the rear of the cabinet, would
give a worse response than having the speakers flat on the wall. It turned
out flat against the wall did not give the best response. So I'm very glad I
did that test because I learned something. I don't need to be right! I'd
much rather know the truth about something than be right.

simulation is just simulation and there's nothing like an actual
measurement to see what's really going on.

Yes, I surely agree with that.

Once it's finished I will put it in that good spot I found through
simulation in my room and measure it at the listening position.

Sounds like a plan.

assuming that I couldn't measure down to that resolution, for some reason;
well I guess since I'm just a clueless bass freak who wants boom and thump

There's no need to be insulting. I never insulted you. Maybe you should stop
reading Dick Pierce's posts because he seems to be having a bad influence on
you. :-)

--Ethan

"Ethan Winer" ethanw at ethanwiner dot com wrote in message ...
Carlos,

I offered to send you LspCAD's predicted FR plots but you didn't take the
offer, that means that either you are afraid they will prove you wrong ot
that you question LspCAD's accuracy.

Sorry, maybe I read the posts too fast that day? I don't recall that offer.

I suspect that wasn't the only time you read one of my posts too fast.
7th message on this thread, last line of my second paragraph.

assuming that I couldn't measure down to that resolution, for some reason;
well I guess since I'm just a clueless bass freak who wants boom and thump

There's no need to be insulting. I never insulted you. Maybe you should stop
reading Dick Pierce's posts because he seems to be having a bad influence on
you. :-)

Me, insulting? read again: I'm just saying what you assumed, based on
what you said. Quote: "Not only will a subwoofer not solve the real
problem, it will likely make things even worse. However, it will give
you more "thump and boom" if that's all you care about."

Dick did tell me off once, years ago, after I happily told a fellow
DIYer that vented boxes were more efficient because they used the back
wave energy instead of dissipating it. If I had got all offended and
stopped reading his posts, I'd probably still believe that lie, and
others like multiple smaller vents have more friction so you should
correct the length, amps with 0.00001 ohm output impedance are much
better than with 0.1, etc. Don't get me wrong, I don't take what he
says as Gospel and do verify it with other sources and references, but
I have come to the conclusion that generally he does know what he's
talking about. You may not like his style, but I can take a "you're
talking ********" if I can learn from it free of charge.

Carlos

"Ethan Winer" ethanw at ethanwiner dot com wrote in message ...
Carlos,

I offered to send you LspCAD's predicted FR plots but you didn't take the
offer, that means that either you are afraid they will prove you wrong ot
that you question LspCAD's accuracy.

Sorry, maybe I read the posts too fast that day? I don't recall that offer.

I suspect that wasn't the only time you read one of my posts too fast.
7th message on this thread, last line of my second paragraph.

assuming that I couldn't measure down to that resolution, for some reason;
well I guess since I'm just a clueless bass freak who wants boom and thump

There's no need to be insulting. I never insulted you. Maybe you should stop
reading Dick Pierce's posts because he seems to be having a bad influence on
you. :-)

Me, insulting? read again: I'm just saying what you assumed, based on
what you said. Quote: "Not only will a subwoofer not solve the real
problem, it will likely make things even worse. However, it will give
you more "thump and boom" if that's all you care about."

Dick did tell me off once, years ago, after I happily told a fellow
DIYer that vented boxes were more efficient because they used the back
wave energy instead of dissipating it. If I had got all offended and
stopped reading his posts, I'd probably still believe that lie, and
others like multiple smaller vents have more friction so you should
correct the length, amps with 0.00001 ohm output impedance are much
better than with 0.1, etc. Don't get me wrong, I don't take what he
says as Gospel and do verify it with other sources and references, but
I have come to the conclusion that generally he does know what he's
talking about. You may not like his style, but I can take a "you're
talking ********" if I can learn from it free of charge.

Carlos

Carlos wrote:

I have come to the conclusion that generally he does know what he's
talking about.

Do not read specifics into this, generally if Mr. Pierce suggests that
you posting was not the penultimate wisdom on whatever subject matter
then a) he is right and b) he explains. Should a) not apply, and that
has occasionally happened - albeit rarely, then he will ackownledge it.

Carlos


Kind regards

Peter Larsen

--
************************************************** ***********
* My site is at: http://www.muyiovatki.dk *
************************************************** ***********

Carlos wrote:

I have come to the conclusion that generally he does know what he's
talking about.

Do not read specifics into this, generally if Mr. Pierce suggests that
you posting was not the penultimate wisdom on whatever subject matter
then a) he is right and b) he explains. Should a) not apply, and that
has occasionally happened - albeit rarely, then he will ackownledge it.

Carlos


Kind regards

Peter Larsen

--
************************************************** ***********
* My site is at: http://www.muyiovatki.dk *
************************************************** ***********

Carlos,

I'm just saying what you assumed

Okay, fair enough. I agree I deserved it this time. :-)

I still stand by my position that acoustic treatment will do far more to
flatten low end response than the most ideal speaker position. But I'm happy
to be proven wrong if you can show that to be the case. When you have your
results I'll post mine, which I'm now putting together in Figure form for an
upcoming article in EQ magazine.

If I had got all offended and stopped reading his posts

I'm constantly offended, but I read his posts anyway. Today's gem was
excellent and very detailed, about the sensitivity of multiple speakers in
an array. This is what Dick does best - he doesn't need to be so insulting.
Then again, his insults reflect much more badly on him than on me!

Thanks.

--Ethan

Carlos,

I'm just saying what you assumed

Okay, fair enough. I agree I deserved it this time. :-)

I still stand by my position that acoustic treatment will do far more to
flatten low end response than the most ideal speaker position. But I'm happy
to be proven wrong if you can show that to be the case. When you have your
results I'll post mine, which I'm now putting together in Figure form for an
upcoming article in EQ magazine.

If I had got all offended and stopped reading his posts

I'm constantly offended, but I read his posts anyway. Today's gem was
excellent and very detailed, about the sensitivity of multiple speakers in
an array. This is what Dick does best - he doesn't need to be so insulting.
Then again, his insults reflect much more badly on him than on me!

Thanks.

--Ethan

"Ethan Winer" ethanw at ethanwiner dot com wrote in message ...

There's no need to be insulting. I never insulted you. Maybe you should stop
reading Dick Pierce's posts because he seems to be having a bad influence on
you. :-)

Yes, he is. It's too bad one's cherished biews are disturbed by
an interfering miscreant like pierce marching in and introducing
facts into a nice tidy love-fest of a discussion.

Bummer, ain't it.

"Ethan Winer" ethanw at ethanwiner dot com wrote in message ...

There's no need to be insulting. I never insulted you. Maybe you should stop
reading Dick Pierce's posts because he seems to be having a bad influence on
you. :-)

Yes, he is. It's too bad one's cherished biews are disturbed by
an interfering miscreant like pierce marching in and introducing
facts into a nice tidy love-fest of a discussion.

Bummer, ain't it.