yup.
It seems that alot of the fostex stuff benefits from being placed up against the back wall. When I look around alot of japanese sites, that is usually the way that I see things large and small actually implimented. I would credit this to the smaller rooms in most japanese homes, necessitating "space saving" systems. hence the folded horns and generally tall and slender fostex factory designs, etc.
as far as bass for classical goes, I do feel that it is most important to have it be "tuneful" bass rather than "hip hop" bass. of course, this does not take away from the stringent criterias of having immense slam when called for, immense anything really. acoustic instruments at realistic volumes are really hard to do well.
I did not understand that the driver would have a helper woofer. I would surely love to hear such a system some time.
however, I picked up this alarm clock radio from the thrift store today and happened to have a few drivers laying around....
I find that it serves extremely well for doing "background" classical music, which does not require alot of bass. the thing barely puts out .8 watts per channel before major distortion. Yes, y'all, I have decended into the realm of lower -fi. I think it sounds nice though when not distorting. and hey, I have to have SOMETHING to tote around campus to do my assigned listening on (I am a music major).
so I guess when I graduate, look for a Cain and Cain model alarm clock!
It seems that alot of the fostex stuff benefits from being placed up against the back wall. When I look around alot of japanese sites, that is usually the way that I see things large and small actually implimented. I would credit this to the smaller rooms in most japanese homes, necessitating "space saving" systems. hence the folded horns and generally tall and slender fostex factory designs, etc.
as far as bass for classical goes, I do feel that it is most important to have it be "tuneful" bass rather than "hip hop" bass. of course, this does not take away from the stringent criterias of having immense slam when called for, immense anything really. acoustic instruments at realistic volumes are really hard to do well.
I did not understand that the driver would have a helper woofer. I would surely love to hear such a system some time.
however, I picked up this alarm clock radio from the thrift store today and happened to have a few drivers laying around....
I find that it serves extremely well for doing "background" classical music, which does not require alot of bass. the thing barely puts out .8 watts per channel before major distortion. Yes, y'all, I have decended into the realm of lower -fi. I think it sounds nice though when not distorting. and hey, I have to have SOMETHING to tote around campus to do my assigned listening on (I am a music major).
so I guess when I graduate, look for a Cain and Cain model alarm clock!
Attachments
The rear wall reflection is a problem faced by all speakers. For an OB it is worse because an equal in magnitude, but 180 deg out of phase, signal is being reflected off the rear wall and can cause cancallation of the signal from the front at specific frequencies. This is what creates the irregularities in the combined SPL response.
In reality, the large baffle probably blocks or attenuates some of this signal from arriving at the listening position so that the peaks and nulls are most likely less than calculated. I debated how to include, or not include, this reflection in the worksheets and finally decided to include the rear wall since it can be removed by the user if the distance is increased to a large value.
I am open to suggestions on how to better model this effect as long as they represent solid physics and not fudges. I am still thinking about and working on the OB worksheets so hopefully slight improvements will be developed over time.
fudge...
perhaps it is the stored energy/acoustic impedance created by the small gap/long path with the wall (creating more of an independant action/reaction system with the front) (as well as closer gap giving higher frequency standing waves) that gives the back wave such an audible and modelable effect on the front wave with close to wall placement of open baffle?
owing to impedance and close dimentions, close to back wall placement seems closer to an ever growingly smaller volume sealed box, but not, being too "leaky" with the front and with extreme, yet undamped, rectagular dimensions giving unpredictable energy storage...giving the unevenness?
In listening tests, I have confirmed this "weird when close to wall OB effect." it can be quite profound.
its just fudge though. sorry. just using my imagination here.
I understand that I must sound like a dimwit here at times, using little theory to back up presuppositions. using as many conditionals as possible with technical explainations. (though they should be there anyways, no matter how certain a model). eventual graduate school in acoustics should remedy this. my current school offers nothing remotely acceptably in this realm of physics, other than the independant studies within which I am already enrolled.
delves into the realm of theory of complexity, like everything in acoustics, but promises to be more approximately modelable than say, the weather in walla walla.
Clark
perhaps it is the stored energy/acoustic impedance created by the small gap/long path with the wall (creating more of an independant action/reaction system with the front) (as well as closer gap giving higher frequency standing waves) that gives the back wave such an audible and modelable effect on the front wave with close to wall placement of open baffle?
owing to impedance and close dimentions, close to back wall placement seems closer to an ever growingly smaller volume sealed box, but not, being too "leaky" with the front and with extreme, yet undamped, rectagular dimensions giving unpredictable energy storage...giving the unevenness?
In listening tests, I have confirmed this "weird when close to wall OB effect." it can be quite profound.
its just fudge though. sorry. just using my imagination here.
I understand that I must sound like a dimwit here at times, using little theory to back up presuppositions. using as many conditionals as possible with technical explainations. (though they should be there anyways, no matter how certain a model). eventual graduate school in acoustics should remedy this. my current school offers nothing remotely acceptably in this realm of physics, other than the independant studies within which I am already enrolled.
delves into the realm of theory of complexity, like everything in acoustics, but promises to be more approximately modelable than say, the weather in walla walla.
Clark
Scottmoose said:
Time delay is phase delay. The rear reflection is NOT nominally 180 degrees out of phase with the front. This only holds true for frequencies where the baffle to rear wall distance is 1/2 wavelength or a multitude of that.
I can´t understand why people try to keep room effects out of their simulations when they have such big influence. The baffle-to-wall distance is perfectly suited to "taylor" the speaker response around 100 Hz and below. And it can be utilised to counterbalance the first floor bounce dip (which btw has magically disappeared from holdents diagram
)So I really appreciate that MJK has included these reflections in his worksheets. I already try to make up my mind whether the influence of the ceiling reflection should be included too.
Rudolf
here is one way to regain a bit of bass in OB.
be it 103e or whatever...
make your OB in decent size, at least
70cm x 80cm and then, after you angle it a bit
Place the Whole Darn thing
about 1-4 feet Away from an empty CORNER of room.
i presume you are not having thick towels , mattresses,
or carpets UNDER all this, or too nearby ?
experiment.
if you dont have subwoofer anxiety,
usually this is quite enuff good clean bass
from most CDs.
the rule of pi.
be good.
k
be it 103e or whatever...
make your OB in decent size, at least
70cm x 80cm and then, after you angle it a bit
Place the Whole Darn thing
about 1-4 feet Away from an empty CORNER of room.
i presume you are not having thick towels , mattresses,
or carpets UNDER all this, or too nearby ?
experiment.
if you dont have subwoofer anxiety,
usually this is quite enuff good clean bass
from most CDs.
the rule of pi.
be good.
k
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