CM:
No worry, I have loved your input. After all, behind the seemingly unselfish sharing of the edge, what really drives me are the discussions that emerge, and the improvements that are made possible as a result from those and finally the understanding I gain myself. Positive callouts are heart-warmers, constructive critisism are developers. Other types of feedback (negative&destructive) has been completely absent in this forum, which I am very happy about. I like the nice tone here!
/Svante
No worry, I have loved your input. After all, behind the seemingly unselfish sharing of the edge, what really drives me are the discussions that emerge, and the improvements that are made possible as a result from those and finally the understanding I gain myself. Positive callouts are heart-warmers, constructive critisism are developers. Other types of feedback (negative&destructive) has been completely absent in this forum, which I am very happy about. I like the nice tone here!
/Svante
Isn't it just 3dB afterall?
Svante, I've thought of something else you could do to make The Edge more accurate. One important thing that has been neglected in the simulation and everybody's assumptions so far is the ground/floor/earth etc beneath the speaker. I think it's significant enough to make a 6dB difference at low frequencies and a 3dB difference at high frequencies, resulting in a baffle step of only 3dB. Why is this? Because at low frequencies the sound from the speaker radiates into only one hemisphere anyway, while at higher frequencies direct + indirect sound is summed to produce a gain of up to 3dB. Of course, when I say "3dB gain", I really mean an amplitude multiplier of anywhere between 0 and 2, averaging at 1.414.
CM
Svante, I've thought of something else you could do to make The Edge more accurate. One important thing that has been neglected in the simulation and everybody's assumptions so far is the ground/floor/earth etc beneath the speaker. I think it's significant enough to make a 6dB difference at low frequencies and a 3dB difference at high frequencies, resulting in a baffle step of only 3dB. Why is this? Because at low frequencies the sound from the speaker radiates into only one hemisphere anyway, while at higher frequencies direct + indirect sound is summed to produce a gain of up to 3dB. Of course, when I say "3dB gain", I really mean an amplitude multiplier of anywhere between 0 and 2, averaging at 1.414.
CM
Re: Isn't it just 3dB afterall?
I'm afraid not.
With a normal height for a bass / mid unit you can treat
the floor as an any other room boundary except its fixed.
The baffle step occurs at frequencies above the effective point
the floor begins to boost bass (and there is generally a mid
bass dip just above this point due to the floor reflection)
Trying to use boundary reinforcement for BSC is counterproductive
in a full range speaker, as free space mounting gives smoother
bass and lowers the point room gain begins to take effect.
For compact speakers lowering the room gain frequencies allows
you to use room gain to reinforce bass extension below 100Hz,
if you have a suitable bass alignment.
sreten.
CeramicMan said:
I'm afraid not.
With a normal height for a bass / mid unit you can treat
the floor as an any other room boundary except its fixed.
The baffle step occurs at frequencies above the effective point
the floor begins to boost bass (and there is generally a mid
bass dip just above this point due to the floor reflection)
Trying to use boundary reinforcement for BSC is counterproductive
in a full range speaker, as free space mounting gives smoother
bass and lowers the point room gain begins to take effect.
For compact speakers lowering the room gain frequencies allows
you to use room gain to reinforce bass extension below 100Hz,
if you have a suitable bass alignment.
sreten.
Re: Isn't it just 3dB afterall?
As Sreten said, room gain starts at lower frequencies, and not just the floor, but also the walls and ceiling affects the response.
The reason for this difference in frequencies is that the baffle usually is smaller than the distances to these surfaces.
One theoretically interesting way of getting rid of the BS is to integrate the baffle with the wall, which leads to a case more like the infinite baffle. In practice, most people, but not all, hesitate to cut holes in the wall.
CeramicMan said:
As Sreten said, room gain starts at lower frequencies, and not just the floor, but also the walls and ceiling affects the response.
The reason for this difference in frequencies is that the baffle usually is smaller than the distances to these surfaces.
One theoretically interesting way of getting rid of the BS is to integrate the baffle with the wall, which leads to a case more like the infinite baffle. In practice, most people, but not all, hesitate to cut holes in the wall.
The thing about floors is that they're unavoidable, every speaker has to be placed on or slightly above one unless we're talking about PA speakers mounted way up in the air somewhere. As an example, let's say a speaker's midbass is 50cm above the ground, and the listener is horizontally 3m away and listening at a height of 1.2m. The reflection from the floor will be delayed by about 37cm after the direct sound from the speaker, resulting in constructive interference at 930Hz (360 degrees), a null centred at 465Hz (180 degrees), and constructive interference everywhere below 232Hz (<90 degrees) that smoothly approaches +4dB. These frequencies will be higher and amplitude gain will be greater if:
a)the speaker is closer to the floor, which often happens with subwoofers etc.
b)the listener is further away, also possible.
c)the person is listening at a smaller height above the floor.
In the above example, if the midwoofer is actually a theoretical full-range speaker, then the gain from the floor reflection at high frequencies will be 2dB. This results in a combined step function of only 4dB and a null in the low midrange. People often sometimes have subwoofers with a 6dB boost for BSC, when I've just shown that it may not even be necessary at low frequencies.
CM
a)the speaker is closer to the floor, which often happens with subwoofers etc.
b)the listener is further away, also possible.
c)the person is listening at a smaller height above the floor.
In the above example, if the midwoofer is actually a theoretical full-range speaker, then the gain from the floor reflection at high frequencies will be 2dB. This results in a combined step function of only 4dB and a null in the low midrange. People often sometimes have subwoofers with a 6dB boost for BSC, when I've just shown that it may not even be necessary at low frequencies.
CM
Hello Svante, your program worked great. I built a baffle step compensation network for my MTM's and that made a world of difference. I'm running them through an active crossover with 250 watts per channel of power, the circuit connects between the output of the crossover and power amp (midbass).
Thanks for your program, I've run it on several platforms and it is as stable as a rock. I guess I owe you a
Take care Svante and keep up the good work!
BTW, my avatar you can see at this link, it is a 500,000 volt switch opening up when the arc suppressor fails. It shoots an arc 50 feet in the air! They have to open an oil circuit breaker upstream to kill the arc.
http://205.243.100.155/frames/mpg/500kV_Switch.mpg
Thanks for your program, I've run it on several platforms and it is as stable as a rock. I guess I owe you a
Take care Svante and keep up the good work!
BTW, my avatar you can see at this link, it is a 500,000 volt switch opening up when the arc suppressor fails. It shoots an arc 50 feet in the air! They have to open an oil circuit breaker upstream to kill the arc.
http://205.243.100.155/frames/mpg/500kV_Switch.mpg
Rimband said:Hello Svante, your program worked great. I built a baffle step compensation network for my MTM's and that made a world of difference. I'm running them through an active crossover with 250 watts per channel of power, the circuit connects between the output of the crossover and power amp (midbass).
Thanks for your program, I've run it on several platforms and it is as stable as a rock. I guess I owe you a
Take care Svante and keep up the good work!
BTW, my avatar you can see at this link, it is a 500,000 volt switch opening up when the arc suppressor fails. It shoots an arc 50 feet in the air! They have to open an oil circuit breaker upstream to kill the arc.
http://205.243.100.155/frames/mpg/500kV_Switch.mpg
Thank you for those kind words! I could not see the movie, but are you possibly working on a ionophone woofer?
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