jmatheus,
sorry but I'm not enough familiar with american/english, so, if your question is "what is an acoustic diode", it's a shape allowing to propagate the wave in one direction and avoid it to return to the source, quite the same work than an electrical diode.
The network of several diodes allows the waves to be breaked inside each by some rebounds on their walls, so dampening is get without stuffing.
If your question was not this one, please ask with other words than "what the heck is an acoustic diode?"
Thanks
sorry but I'm not enough familiar with american/english, so, if your question is "what is an acoustic diode", it's a shape allowing to propagate the wave in one direction and avoid it to return to the source, quite the same work than an electrical diode.
The network of several diodes allows the waves to be breaked inside each by some rebounds on their walls, so dampening is get without stuffing.
If your question was not this one, please ask with other words than "what the heck is an acoustic diode?"
Thanks
I'm not sure that I see much advantage here, while any structure inside the enclosure will provide damping to some degree, from the quick google reasearch I've done, acoustic diodes appear to be heavily focused on a narrow frequency band and not provide broard band damping like typical fill.
I feel that the effort in reasearching,testing and building these things would be better used in the overall enclosure design, or rather, avoiding the enclosure designs that would cause the problems that you would use acoustic diodes to fix.
I feel that the effort in reasearching,testing and building these things would be better used in the overall enclosure design, or rather, avoiding the enclosure designs that would cause the problems that you would use acoustic diodes to fix.
Member
Joined 2004
Excuse my ignorance about the acoustic diodes but I've never
heard of such term. I've beeen an avid speaker builder in the past
and I was never aquainted with the subject.
And apparently I'm not alone......
However I'm open minded enough to learn something each
time I don't know, it would be good to have a sketch or pic
to ilustrate that principle.....
Thanks beforehand.
heard of such term. I've beeen an avid speaker builder in the past
and I was never aquainted with the subject.
And apparently I'm not alone......
However I'm open minded enough to learn something each
time I don't know, it would be good to have a sketch or pic
to ilustrate that principle.....
Thanks beforehand.
crazyhub said:
ShinOBIWAN said:
Hmm.....
Its not obvious at all.......
Rectifying acoustic sine waves is a very bad idea.
Distortion levels would be horrendous.
Acoustic diodes would not achieve any of the goals stated.
If you enclosed the back of a bass unit with one the cone would
either settle on its backstops or pump the cone out until it would
literally explode !
The device that will let sound waves travel in one direction
and not come back is commonly known as a transmission line.
/sreten.
Re: Re: Acoustic diodes in sealed enclosure
It is though
You don't want the rear wave reflected back into and through the cone.
Perhaps your taking it as a literal extreme in that soundwaves and hence air can only move in a single direction. Its quite obvious that this is infact impossible to implement and undesired. But what we would like is to prevent the reflection of the acoustic rear wave for midrange and treble since its here where it matters the most.
BTW: I agree with everything you've said, its just that when someone mentions an acoustic diode, I think in terms of pratical application rather than the theoretically perfect method you've pulled to bits
sreten said:
It is though
You don't want the rear wave reflected back into and through the cone.
Perhaps your taking it as a literal extreme in that soundwaves and hence air can only move in a single direction. Its quite obvious
that this is infact impossible to implement and undesired. But what we would like is to prevent the reflection of the acoustic rear wave for midrange and treble since its here where it matters the most.BTW: I agree with everything you've said, its just that when someone mentions an acoustic diode, I think in terms of pratical application rather than the theoretically perfect method you've pulled to bits
Re: Re: Re: Acoustic diodes in sealed enclosure
Whats perfectly obvious to me is the original posters
misunderstanding of diodes, and you stating an acoustic
diode is the same as an electrical diode did not help matters.
So I pulled it to bits
/sreten.
ShinOBIWAN said:
It is though
BTW: I agree with everything you've said, its just that when someone mentions an acoustic diode, I think in terms of pratical application rather than the theoretically perfect method you've pulled to bits
Whats perfectly obvious to me is the original posters
misunderstanding of diodes, and you stating an acoustic
diode is the same as an electrical diode did not help matters.
So I pulled it to bits
/sreten.
I do believe Crazyhub was also referring to a principle like the Acoustic Matrix by B&W, which is designed to suppress higher frequencies from the back wave by these frequencies repeatedly being bounced around the complex series of pipes in the internal volume. It is not just the bass frequencies he was concerned with.
kelticwizard said:
Hi,
the B&W matrix technologies fundamental concept is a cabinet wall
with wall to wall bracing at the point it is braced cannot move, so
make your bracing 3D with small distances between braces and
Voila ! an inert cabinet.
(Think there is a white paper on the B&W site)
The acoustic effect of the matrix is a side issue, and the acoustic effect
of the matrix is fairly minimal if the matrix has light stuffing compared
to a plain box with light stuffing. Unstuffed is a different issue.
/sreten.So guys, lets go:
The almost only common existing inner special shapes are for the moment helmoltz resonators (commonly one or two per enclosure) or the tapered sphere from B&W. I want to try something more related to waves propagation than resonators. The TL line don't enhance propagation, don't act on the return of the waves towards the cone and do only lengthen their way to avoid the out of phase. Same with Helmoltz about the return of waves. Tapered sphere/tube would be too large for bass range.
An acoustic diode is a shape allowing the entering incident waves to lose energy by inside reflections before the resulting waves to be forced to escape by an exit different from the entrance. This can be made by slanted walls...and a good knowledge of propagation principle. Obviously, because the environment is only air (and not 2 different materials i.e.), we can only act on the shape characteristics and not with different impedances; so efficiency will be less than playing with another environment; but having one impedance enhances the transfer from one diode to another..and unfortunately reduces the efficiency of the diode principle. Thus, to get a good efficiency, we have to make several bridged diodes, at least 6 or 7 from previous experiences.
The other problem is that we have to act on the complete surround of the driver, so the diodes have to be builded in a network made of multiple "lines". The total section of the entrances of all the lines of the network must have at least the section of the driver cone, otherwise part of the incident wave will be reflected towards the cone.
The last issue is about the "resonator" effect because in fact each diode is a box, even with 2 or more holes, so not acting really as an Helmoltz one but...So we must obligatory change the volume of each diode vs each other and their relative holes sections. In this way we get a smoothed resonance range.
Why do I want to build such an enclosure? Because I am sure that the bad issue with stuffing is its unlinear working: when you increase the amount of stuffing, what happens is that inner resonances are killed but micro details too because the amount of waves returning toward the cone and then escaping from it is very different with frequencies. On the contrary, reducing stuffing do not kill inner resonances, so the amount of returning waves interfers with the cone work and also reduces its Qms unlinearly.
That's why, for example, a real infinite baffle gives real transparency, even if the cone isn't well controled near its foundamental resonance.
So, because proof is in listening, I will try this thing. At least, it's a relatively new idea and I enjoy this...idea. Isn't it?
The almost only common existing inner special shapes are for the moment helmoltz resonators (commonly one or two per enclosure) or the tapered sphere from B&W. I want to try something more related to waves propagation than resonators. The TL line don't enhance propagation, don't act on the return of the waves towards the cone and do only lengthen their way to avoid the out of phase. Same with Helmoltz about the return of waves. Tapered sphere/tube would be too large for bass range.
An acoustic diode is a shape allowing the entering incident waves to lose energy by inside reflections before the resulting waves to be forced to escape by an exit different from the entrance. This can be made by slanted walls...and a good knowledge of propagation principle. Obviously, because the environment is only air (and not 2 different materials i.e.), we can only act on the shape characteristics and not with different impedances; so efficiency will be less than playing with another environment; but having one impedance enhances the transfer from one diode to another..and unfortunately reduces the efficiency of the diode principle. Thus, to get a good efficiency, we have to make several bridged diodes, at least 6 or 7 from previous experiences.
The other problem is that we have to act on the complete surround of the driver, so the diodes have to be builded in a network made of multiple "lines". The total section of the entrances of all the lines of the network must have at least the section of the driver cone, otherwise part of the incident wave will be reflected towards the cone.
The last issue is about the "resonator" effect because in fact each diode is a box, even with 2 or more holes, so not acting really as an Helmoltz one but...So we must obligatory change the volume of each diode vs each other and their relative holes sections. In this way we get a smoothed resonance range.
Why do I want to build such an enclosure? Because I am sure that the bad issue with stuffing is its unlinear working: when you increase the amount of stuffing, what happens is that inner resonances are killed but micro details too because the amount of waves returning toward the cone and then escaping from it is very different with frequencies. On the contrary, reducing stuffing do not kill inner resonances, so the amount of returning waves interfers with the cone work and also reduces its Qms unlinearly.
That's why, for example, a real infinite baffle gives real transparency, even if the cone isn't well controled near its foundamental resonance.
So, because proof is in listening, I will try this thing. At least, it's a relatively new idea and I enjoy this...idea. Isn't it?
sreten said:
Hi,
the B&W matrix technologies fundamental concept is a cabinet wall
with wall to wall bracing at the point it is braced cannot move, so
make your bracing 3D with small distances between braces and
Voila ! an inert cabinet.
(Think there is a white paper on the B&W site)
The acoustic effect of the matrix is a side issue, and the acoustic effect
of the matrix is fairly minimal if the matrix has light stuffing compared
to a plain box with light stuffing. Unstuffed is a different issue.
I would have thought that B&W's tapered tubes were of more significance to this discussion than matrix bracing. Or was that what Kelticwizard meant?
No, I thought Crazyhub meant the Acoustic Matrix. Erroneously, as it turns out.
When the 801's first came out, I read that the Matrix's purpose was to make the walls inert. However, a couple of years ago, someone started a thread about the Matrix being used to break up back waves, and apparently produced a white paper or quote from B&W to the effect that was also part of the reason for the Matrix. That was what I was referring to.
Until now, I was unfamiliar with the B&W Tapered Tube, which is what Crazyhub was actually referring to.
When the 801's first came out, I read that the Matrix's purpose was to make the walls inert. However, a couple of years ago, someone started a thread about the Matrix being used to break up back waves, and apparently produced a white paper or quote from B&W to the effect that was also part of the reason for the Matrix. That was what I was referring to.
Until now, I was unfamiliar with the B&W Tapered Tube, which is what Crazyhub was actually referring to.
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