Nousaine wrote:

the axial mode needs two parallel surfaces, (you dont see that in my
example do you?)

that's right you keep confusing an interference pattern with a standing wave.

An interferance pattern IS EXACTLY what a standing wave is!!

Eddie Runner

Eddie Runner wrote:



Nousaine wrote:

the axial mode needs two parallel surfaces, (you dont see that in my
example do you?)

that's right you keep confusing an interference pattern with a standing
wave.

An interferance pattern IS EXACTLY what a standing wave is!!

Eddie Runner

No it isn't. It's a normal function of sound pressure distribution in enclosed
spaces. Further standing waves don't just occur at low frequencies. Play a 1000
Hz tone, with a wavelength of about a foot, in a room (or car) and you'll hear
the sound pressure vary as you move your head a few inches. That's the standing
wave pressure distribution.

However that will occur in the same way no matter where you are in the room or
car except when you're within a foot of a surface. So uneven pressure
distribution isn't an issue in the space because the wavelength fits completely
in the room.

At lower frequencies, with longer wavelengths distribution may vary widely by
position. But below the lowest axial mode (coresponds to the length dimension
pf the space) which will be about 60 Hz in a compact cart or 26 Hz in a 22-foot
long room) the space is directly pressurized by the speaker displacment and we
get low frequency reinforcement.

Above this frequency there exists what is called the standing wave region where
wavelengths are long enough that there can be pressure distribution problems.

This is not the same thing as a reflection interference issue froma single
boundary as Eddie would have you believe.

That problem exists at lower midrange frequencies. The most common one seen in
audio is the floor bounce problem with tower speakers where the floor
reflection from woofers output combines with with the direct sound slightly out
of phase and causes a 150-300 Hz notch in response at a given
listening/microphone position depending on the distance of the woofer from the
floor.

In typical 2-channel stereo systems there may be such effects with side-wall
and celing reflections as well as interference with the OTHER woofer when they
are getting an identical signal. This whole deal is known as the Allison Effect
after Roy Allison who first described it.

It is not a standing wave problem and it doesn't occur at 60 Hz in a car or
room. And its not the reason that facing a woofer away from the listeners ears
is a good idea in a system, especially one without a low pass filter.

Nousaine wrote:

An interferance pattern IS EXACTLY what a standing wave is!!
No it isn't.

Yes it is!!
According to one definition I have
here from Professor C. Kletzing & R. Williams
which says
***
When a wave reflects off of something, it can interefere with its own
reflection. The interference is alternately constructive or destructive
as the two waves move past each other. This creates a standing wave.
***

Doesnt this say YOUR WRONG????


Eddie Runner

Nousaine wrote:

Further standing waves don't just occur at low frequencies.

Of course not, in fact they happen MORE at high frequencies!

Play a 1000
Hz tone, with a wavelength of about a foot, in a room (or car) and you'll hear
the sound pressure vary as you move your head a few inches. That's the standing
wave pressure distribution.

More precisely thats usually a COMB EFFECT from reflections and or
multiple drivers.....!!

Im sure they probably cover Comb effects in your ONLY book..... ha ha

Ya know you might be able to find some decent sound books on Ebay Tom..
The good ones are hard to find in the bookstores....

At lower frequencies, with longer wavelengths distribution may vary widely by
position.

Comb effcts change quite a bit by changing frequency, or changing location in
the car... I have done some pretty extensive study on this matter....

* For the kiddies, a comb affect is when two or more speaker or reflections
cross over one another... You can imagine it like dropping two pebbles
into a pool of water, the two seperate circles of ripples the stones create
overlap one another and you can see HIGH and LOW spots on the ripples,
these are areas where the high waves combine to make higher waves and
low waves combine to make low spots that may seem to stand still... ***


Eddie Runner
http://www.installer.com/tech/

Eddie Runner wrote:




Nousaine wrote:

An interferance pattern IS EXACTLY what a standing wave is!!
No it isn't.

Yes it is!!
According to one definition I have
here from Professor C. Kletzing & R. Williams
which says
***
When a wave reflects off of something, it can interefere with its own
reflection. The interference is alternately constructive or destructive
as the two waves move past each other. This creates a standing wave.
***

Doesnt this say YOUR WRONG????


Eddie Runner

But in your case you're simply describing an interference pattern and not a
standing wave in an enclosed space. But, even so, standing wave or not, the
effect you describe doesn't happen at 60 Hz with a 60 Hz source @ 3 feet. It's
more than an octave above that.

Eddie Runner

Nousaine wrote:

Further standing waves don't just occur at low frequencies.

Of course not, in fact they happen MORE at high frequencies!

Play a 1000
Hz tone, with a wavelength of about a foot, in a room (or car) and you'll
hear
the sound pressure vary as you move your head a few inches. That's the
standing
wave pressure distribution.

More precisely thats usually a COMB EFFECT from reflections and or
multiple drivers.....!!

Stick to the case here and use a single driver well away from walls in a larger
room. You will hear the standing wave effect with the same pressure variation
everywhere in the space. Comb effects are, of course, a different acoustic
phenomenon and folks like Eddie just love to muddy the conversation when he
gets out-gunned intellectually.

Nousaine wrote:


According to one definition I have
here from Professor C. Kletzing & R. Williams
which says
***
When a wave reflects off of something, it can interefere with its own
reflection. The interference is alternately constructive or destructive
as the two waves move past each other. This creates a standing wave.
***


But in your case you're simply describing an interference pattern and not a
standing wave in an enclosed space. But, even so, standing wave or not, the
effect you describe doesn't happen at 60 Hz with a 60 Hz source @ 3 feet. It's
more than an octave above that.

A standing wave IS an interferance pattern Tom!
thats EXACTLY what that quote above says!!

And whats with you and 60Hz??????

A standing wave can exist at ANY FREQUENCY!!!!!!!!!!!!!!!!!!!!!!!
(if there is enough space for at least 1/4 wave between reflectors....)

a 1/4 wave of 60Hz is only about 4 1/2 ft.....!!!

WHAT IS IT ABOUT 60Hz that you find so hard to believe???????

ANSWER ME!

Eddie Runner

Nousaine wrote:

More precisely thats usually a COMB EFFECT from reflections and or
multiple drivers.....!!

Stick to the case here and use a single driver well away from walls in a larger
room. You will hear the standing wave effect with the same pressure variation
everywhere in the space. Comb effects are, of course, a different acoustic
phenomenon and folks like Eddie just love to muddy the conversation when he
gets out-gunned intellectually.

Tom...

Comb effects are NO DIFFERENT (fundamentaly)...

When two (or more) sound waves pass each other, standing waves
can form....

The standing waves at mid and high freqency from two
sources (or reflections) have the RISE and FALL of the
reinforcments and cancelations (BTW, they are calles nodes and antinodes)
so close together (because they are high frequency) that they
resemble a comb (up, down,up,down,up,down) as they are moved
through with a microphone....

Comb effects ARE standing waves also...

Get with the program Tom...!

Eddie Runner
http://www.installer.com/tech/

Seriously, the two of you should get a room.

On Fri, 18 Jul 2003 02:59:56 GMT, Eddie Runner
wrote:

Nousaine wrote:

More precisely thats usually a COMB EFFECT from reflections and or
multiple drivers.....!!

Stick to the case here and use a single driver well away from walls in a larger
room. You will hear the standing wave effect with the same pressure variation
everywhere in the space. Comb effects are, of course, a different acoustic
phenomenon and folks like Eddie just love to muddy the conversation when he
gets out-gunned intellectually.

Tom...

Comb effects are NO DIFFERENT (fundamentaly)...

When two (or more) sound waves pass each other, standing waves
can form....

The standing waves at mid and high freqency from two
sources (or reflections) have the RISE and FALL of the
reinforcments and cancelations (BTW, they are calles nodes and antinodes)
so close together (because they are high frequency) that they
resemble a comb (up, down,up,down,up,down) as they are moved
through with a microphone....

Comb effects ARE standing waves also...

Get with the program Tom...!

Eddie Runner
http://www.installer.com/tech/

Eddie Runner

Hppelessly flails away.

Nousaine wrote:

Haven't you been reading these posts? You example is supposed tobe 60 Hz.
If
that's true than the 'effect' you are trying to illustrate will occur an
octave
or two above 60 Hz.

BULL****!

How on Gods green earth can a standing wave occur an octave or two
ABOVE 60Hz if the only sound in the car is coming from my 60Hz
sine wave generator????????????????????

OK then there will be no effect, I agree.


If I put 60Hz tone into my car, my analyzer will show 60Hz!

But it won't show a cancellation at 60 Hz? As you claim that can only happen at
1/4 wavelength which is 240 Hz.


it wont show ANYTHING an octave above at 120Hz
and it wont show ANYTHING another octave up at 240Hz....


And it won't show a cancellation at 60 Hz. By the way exactly what is the level
of your supposed cancellation? How much is the 60 Hz supposedly reduced by this
effect?


what yoru saying is ABSOLUTE BULL****!


The Allison Effect (interference with a single or multiple
boundary or other source) does happen it just doesn't happen at 60 Hz or
any
other bass frequency.

Yes it does, it happens AT ALL FREQUENCIES at 1/4 wavelength from
any reflector!

more bull****

Eddie Runner
http://www.installer.com/tech/

Why doesn't it occur as you claim in my car at 60 Hz? Or some bass frequency?
The face/center of the woofer is 2.5 feet from the rear of the interior, 2 feet
from either side wall and 5 feet from the dash; yet the only visible
cancellation effect occurs at 188 Hz and then ONLY when the woofer is facing
the rear of the car.

Nousaine wrote:

How on Gods green earth can a standing wave occur an octave or two
ABOVE 60Hz if the only sound in the car is coming from my 60Hz
sine wave generator????????????????????

OK then there will be no effect, I agree.

No affect at 120 or 240Hz
but there certainly could be a standing wave at 60Hz!!!

Is there some reason you think standing waves cant occur
at 60Hz????

STANDING WAVES can occur at ANY FREQUNCY ya moron!!

If I put 60Hz tone into my car, my analyzer will show 60Hz!

But it won't show a cancellation at 60 Hz?

sure will!!!!!!!!!!!!!!
As I move my mic around in there car it will be quite easy to
find NODES and ANTINODES....

Simple as pie! Try it TOM! Try it!!

As you claim that can only happen at
1/4 wavelength which is 240 Hz.

I NEVER SAID THAT!
Now your lieing through your teeth again!

Show me ANYWHERE where I say it only happens
at 240Hz!!!!!!!!!!

Cant do any research for yourself so you cut loose with LIES instead.

I guess MAGAZINE WRITERS are the scum of the earth
when it comes to INTEGRITY....

Why doesn't it occur as you claim in my car at 60 Hz?

maybe because your CORVETTE is a little tiny cheap piece of CRAP!
maybe it does but you just dont now it....

Eddie Runner

Eddie Runner wrote:

Nousaine wrote:

How on Gods green earth can a standing wave occur an octave or two
ABOVE 60Hz if the only sound in the car is coming from my 60Hz
sine wave generator????????????????????

OK then there will be no effect, I agree.

No affect at 120 or 240Hz
but there certainly could be a standing wave at 60Hz!!!

But no cancellation then either. So your 60 Hz tone will sound the same no
matter whihc way the cabinet faces.


Is there some reason you think standing waves cant occur
at 60Hz????

STANDING WAVES can occur at ANY FREQUNCY ya moron!!

Yes they can. I consider your naive nattering something like a standing wave.
You just keep chanting this stuff even when the data clearly shows you're
wrong.


If I put 60Hz tone into my car, my analyzer will show 60Hz!

But it won't show a cancellation at 60 Hz?

sure will!!!!!!!!!!!!!!
As I move my mic around in there car it will be quite easy to
find NODES and ANTINODES....

Well you can do that with a traveling wave too; as you MOVE the microphone with
any wave, standing or not.


Simple as pie! Try it TOM! Try it!!

As you claim that can only happen at
1/4 wavelength which is 240 Hz.

I NEVER SAID THAT!
Now your lieing through your teeth again!

Show me ANYWHERE where I say it only happens
at 240Hz!!!!!!!!!!

The condition you specified, an interference pattern with a single wall
reflection, only happnes at some multiple of the original.

That's why when I put a full band noise signal in my car there is a
cancellation notch at 188 Hz when the enclosure is facing the rear of the car.
But not when ots facing forward. And there is less than a dB difference below
60 Hz at any frequency under static conditions or with individual 1/3 octave
preferred frequency signals.

Your theory just doesn't stand up under analysis with real speakers in a real
car.



Cant do any research for yourself so you cut loose with LIES instead.

I guess MAGAZINE WRITERS are the scum of the earth
when it comes to INTEGRITY....

Why doesn't it occur as you claim in my car at 60 Hz?

maybe because your CORVETTE is a little tiny cheap piece of CRAP!
maybe it does but you just dont now it....

Eddie Runner

Eddie Runner wrote:



Nousaine wrote:

STANDING WAVES can occur at ANY FREQUNCY ya moron!!

Yes they can. I consider your naive nattering something like a standing
wave.

Thank you Tom, I am pretty relentless arent I.... ha ha

Show me ANYWHERE where I say it only happens
at 240Hz!!!!!!!!!!

The condition you specified, an interference pattern with a single wall
reflection, only happnes at some multiple of the original.

Bull**** again Tom...
If you have a 60Hz tone, there IS NO STANDING WAVES at multiples
of the frequency because there is no sound at the multiples of the frequency!
(IE 120 and 240Hz)

Your so far out of it on this one your gonna hurt yourself...

with a 60Hz tone YOU CAN have standing waves at 60Hz, you dont have
to look elsewhere like 120Hz or 240Hz to find it....(specially if my sine
wave
is 60Hz, there will be no sound at 120Hz or 240Hz)... ya Moron!

Well then how can there be a cancellation at the fundamental of 60 Hz? If that
were true then a 60 Hz tone would produce no sound if the enclosure were
positioned incorrectly.

So exactly how much cancellation is going on? If your circumstance were true
you should be able to tell me exactly how much signal is cancelled with
position reversal.

How much is that?

Your theory just doesn't stand up under analysis with real speakers in a
real
car.

Ha ha ha
Your Pansy assed Corvette ISNT A REAL CAR!

ha ha ha

An insult is always the final retort of a true loser.

Eddie Runner wrote:

Nousaine wrote:

Well then how can there be a cancellation at the fundamental of 60 Hz? If
that
were true then a 60 Hz tone would produce no sound if the enclosure were
positioned incorrectly.

Cancellation occurs when one wave meets another wave and is near 180degrees
out of phase... it can happen at ANY frequency Tom... I dont know why you
wanna say it cant happen at 60Hz....

Sure, but It doesn't occur at 60 Hz with normal audio equipment not in your
house or in your car.


So exactly how much cancellation is going on?

If you read my CARTOON article Tom, it refers to the BASS getting better
when the trunk is open.... Exactly how much cancelation in % when the
trunk is closed would vary by car, and woofer location... Your question
cant be answered without these variables defined first... (unless you just
just wanna make something up off the top of your head like you do in your
magazine articles) (But I wont do that)....

So why does the maximum SPL @ 10% distortion limit in the drivers seat fall by
10 dB when I open my hatch?

Your Pansy assed Corvette ISNT A REAL CAR!
ha ha ha

An insult is always the final retort of a true loser.

Oh!
Im sorry, did I hurt your feelings..??

1) its not my final anything...
2) im not the looser here, you are... Everyone beleives me..
3) I didnt say that as an insult I said it as FACT! ha ha ha

Eddie Runner

Another splendid sign-off from Eddie. People without evidence are always
reduced to shouting.