Nousaine wrote:
The fact is one trace is significanly lower SPL than the
other trace... I know you want them to be more SPIKED
so that my theory about standing waves would be realized.
If they were standing waves, tied to wavelength/distance then they would HAVE
to be frequency related and would NOT be evenly distributed.
You keep saying that over and over and over....
Your saying that to prove my graphs are wrong!
But Tom, my graphs are real and undoctored...
I have an explanation for whats happening....
http://www.installer.com/tech/aiming.html
http://www.installer.com/tech/aiming2.html
You on the other hand claim
1) my graphs are wrong, maybe I just made them with photoshop!
2) my explanation is wrong because it CANT HAPPEN!
OK, I think it can, and I have submitted evedence ....
YOU think it cannot happen but you havent done any
sweeps to show your side of the story...
We are at an IMPASSE....
I understand your arguements, but they just dont match up to my
experements... Are your arguements just a part of your perception
of how you interperate the physics involved or can you show us some
actuall data to back up your position?
You say READ BARANEK but you dont mention the page number
or chapter and how it pertains to your point!
But fact remains that one trace is still lower even though there
are no spikes... That lower difference can only be cancalation!!
No; they CANNOT be 'cancellations' or they would be unevenly distributed. The
only other acoustical sound pressure losses are distance (the closer enclosure
would be louder) and absorption (how would the vehicle absorb more low
frequency energy at any given frequency in the omnidirectional range with any
given orientation?)
There is not enough distance for distance to be the factor.
Besides its Further and Louder so distance could nto be it.
it has to be REFLECTIONS!!
I cant think of anything else that could be it.
Same thing when the bass gets louder as you open the trunk
(sometimes on some cars)
You claim it DOESNT HAPPEN but many folks know it
does happen....
HOW CAN IT? Were lettting sound get away!!
Well, the fact is the sound going away was sound that reflected back
into the cabin out of phase with some other sounds so it CAUSED
cancelation, when we open a trunk we lessen the cancellations....
Just like turning the box around
I CAN HEAR THE DIFFERENCE!!!
I CAN MEASURE THE DIFFERENCE!!!
For you just to say it doesnt happen at all is not really helping us out...
Those exhaust the physical/acoustical possibilities.
What's left ....??? You tellme.
I have told you
http://www.installer.com/tech/aiming.html
If you dont like my explanation then YOU TELL US!!!!!
I mean real data not just generalities like when you say to
READ BANECHEKS BOOK or whatever.. (I misspelled that
on purpose BTW, remember Banachek TV show? (Just trying
to give your sense of humor a little boost))...
One thing for sure it isn't "cancellations". If you don't want to accept that
study Baranek some more.
Can you explain why you believe it cant be cancellations???
Or do we just have to take your word for it??
I dont see where Baranek supports your side...
Baranek does get into the resonant MODES in enclosed spaces but
I dont think you really understand the uderlying causes of the
resonances.
Resonances are not the same as standing waves by the way!
Resonances are identified by MODES
Standing waves are identified by NODES and ANTINODES.
Since the box output is the same and the only difference is the
speaker location... It can ONLY BE cancellation, the NODE
(standing wave) is more pronounced in the listening area!
But it CAN'T be, at these frequencies, where sound is being radiated equally in
all directions. If it WERE a standing wave it would have to be
wavelength/frequency related.
And it is!
since sound comes out of the box in all directions, some of the sound goes
directly to the listening area and some goes to the back of the vehicle, the
sound going to the back of the vehicle has some of it reflected forward to
the listeing area, that sound that bounced off the back of the car is out of
phase by the extra distance that it traveled when compared to the wave that
went (and is still coming from the speaker) directly up to the listing area..
A distance to the reflector and back could be 2 or 3 feet or more each
way, so thats about 4 to 6ft in many cars.... for the reflected wave to be
180degrees out of phase with the direct wave the frequency would be about
120 to 90 Hz.....
But, lets take the 90Hz example...... at that distance where it is out of phase
180degrees at 90 Hz, how much (degrees) out pf phase would it be at 80Hz?
70Hz, 60Hz, 50Hz, 40Hz?????
At 40 Hz, it would still be close to 90 degrees out of phase!!!!
Would that cause cancelation at 45Hz????
It would nt cause complete cancelation but would STILL drag down the
original sound to a slightly lesser SPL....!!!
Think about this Tom..... What happens if we have 100dB of SPL
on one sine wave and we introduce a like Sine wave 90Degrees out
of phase with the first????
In my graphs, cancellation occured like I predicted at slightly below
100Hz.... But it happened also below 100Hz because there is still
some interactions that are not completely in phase with each other!
But it will tell you if there's a related effect regarding system tuning. Of
course, there's not but you haven't exhausted up-stream possible causes. We
already know it's not an acoustical effect.
You mean we already know IT IS AN Accoustical effect!
CANCELLATION !!!
my sweeps show otherwise!
And you'll say that the other laws of physical acoustics still work their
normal way? But, in this case you've superceded them?
No, you just dont seem to understand the physics involved... To say its
a law doesnt have any meaning unlesss it actually is...
Alof of folks think they are going to jail if they tear the tags off thier
mattresses but YOU WONT!!! Alot of folks missunderstand that law
and I think you misunderstand the laws of accoustics and cancelations.
The Barencheck book might not be the best book for you to
use to read more about cancelations.... Is it the only book you
have???
I have a huge library of physics and accoustics books, its fairly common
to see more than one take on a phenomonon from one book to another,
most of them only briefly skim the cancelations and standing wave theory.
For one book to different than another doesnt mean one of them
breaks the laws of physics! Some books on standing waves for instance
talk about particle velocity instead of SPL which is NOT the same!
Someone trying to inteperet the particle velocity as SPL could make
some errors...... Alot of books are not real plain on this for the average
reader and I have seen folks with the missinterpretation to make errors..
Are you making these types of errors in your theory? I dont know !
I suspect so, but I dont know for sure.... If you had some actual
experementation to look at to back up your theory it might be a more
fruitfull engagement....
(WHAT ELSE COULD IT BE???????)
It's not standing wave activity. You tell me? I have a good idea but apparently
you don't.
I am telling you!
http://www.installer.com/tech/aiming.html
you keep saying, THATS WRONG!
Then you ask me to TELL YOU AGAIN!!
Whats wrong with you???
Not source DIRECTION but instead SOURCE LOCATION!!
Same thing at these frequencies.
is 90 to 180 degrees out of phase the same thing????
NO IT IS NOT!!
Do me a favor, read what I typed here at least twice and
think about it Tom before you reply!
Eddie Runner
tryin to be nice