Gentlemen:
I rarely post here because I prefer to let you perform your own experiments and make your own evaluations from hard data, not my opinions. You don't need me acting like some know-it-all just because my name is on a patent as co-inventor. I greatly enjoy the contributions from all here, including skeptics because they help us avoid groupthink.
I think the results posted by gmad and others speak for themselves. The plots validate much of my experience with these speakers, as do the subjective reports I am hearing. However, since I am hearing questions about thick vs thin materials etc., I thought I should comment.
From the beginning there were two schools of thought about enclosure thickness and rigidity with this design.
One view held that absolute rigidity would be best, because allowing the cabinet walls to move makes the boundary defined by them *variable*. In that view, the wave mechanics inside the enclosure is more clearly defined with boundaries that do not change their shape or position over time. Also, resonance is usually considered undesirable in a loudspeaker, since it might color the spectrum of the sound being reproduced.
Another view was that resonance is *desirable* in this particular design (although not in most) because of the omnidirectional emanation that greatly enhances the speaker's acoustic "presence" and simplifies its positioning. Violins and acoustic guitars demonstrate that resonance is not necessarily a bad thing.
After many years there is still no final resolution of this debate. It appears that the distortion reduction obtained does not depend on rigidity as much as one might think...but that there *is* a danger of excessive coloration if the sides are not tight enough. This is still more of an art than a science, however, given the range of drivers and materials and adhesives available. As materials and construction techniques evolve, I imagine that the picture will clarify over time. My experience has been that more rigid enclosures of this shape are a bit muted omnidirectionally. Obviously there will be individual preferences in this regard.
I have always believed that the best results would come when more people learn of this design and try it for themselves, adding to the body of knowledge about it as they do so. We are all still learning. Experience shared is knowledge multiplied. Thank you all for your contributions to this ongoing research!
I rarely post here because I prefer to let you perform your own experiments and make your own evaluations from hard data, not my opinions. You don't need me acting like some know-it-all just because my name is on a patent as co-inventor. I greatly enjoy the contributions from all here, including skeptics because they help us avoid groupthink.
I think the results posted by gmad and others speak for themselves. The plots validate much of my experience with these speakers, as do the subjective reports I am hearing. However, since I am hearing questions about thick vs thin materials etc., I thought I should comment.
From the beginning there were two schools of thought about enclosure thickness and rigidity with this design.
One view held that absolute rigidity would be best, because allowing the cabinet walls to move makes the boundary defined by them *variable*. In that view, the wave mechanics inside the enclosure is more clearly defined with boundaries that do not change their shape or position over time. Also, resonance is usually considered undesirable in a loudspeaker, since it might color the spectrum of the sound being reproduced.
Another view was that resonance is *desirable* in this particular design (although not in most) because of the omnidirectional emanation that greatly enhances the speaker's acoustic "presence" and simplifies its positioning. Violins and acoustic guitars demonstrate that resonance is not necessarily a bad thing.
After many years there is still no final resolution of this debate. It appears that the distortion reduction obtained does not depend on rigidity as much as one might think...but that there *is* a danger of excessive coloration if the sides are not tight enough. This is still more of an art than a science, however, given the range of drivers and materials and adhesives available. As materials and construction techniques evolve, I imagine that the picture will clarify over time. My experience has been that more rigid enclosures of this shape are a bit muted omnidirectionally. Obviously there will be individual preferences in this regard.
I have always believed that the best results would come when more people learn of this design and try it for themselves, adding to the body of knowledge about it as they do so. We are all still learning. Experience shared is knowledge multiplied. Thank you all for your contributions to this ongoing research!
Hmm, the ideal loudspeaker would be omni and fit on the head of a pin, so short of that the box in [one] theory should 'ring' at the mean of whatever BW it's designed for same as a compression horn and let the individual damp to 'taste', i.e. how much 'BBC dip' one desires.
I take it that designing in the right amount of box tuning [resonance] is yet to reveal itself?
GM
I take it that designing in the right amount of box tuning [resonance] is yet to reveal itself?
GM
It might be when you're trying to reproduce the sound of a flute
.As long as people are having fun with whatever they are doing and enjoy their results there should be room enough for all of us to enjoy this hobby.
It might be when you're trying to reproduce the sound of a flute
As long as people are having fun with whatever they are doing and enjoy their results there should be room enough for all of us to enjoy this hobby.
Yep, think of the list of things that were supposedly "unwanted" and are pretty much desirable now... (distortion for the guitar instrument stands like a giant) Or things intended for one purpose at which they totally failed, but were great for something else, etc. (a lot of medicine sold for something today is an "unexpected side effect" of medicine intended for something else).
Just one out of a lot of examples: the baby bass by Ampeg, the inventor wanted it to replace double basses in orchestras, by an instrument more portable and easy to amplify. It totally failed at that. But it became the iconic salsa bass. It sounds dull, the band of frequencies is very limited, but for one specialty kind of music, it's the perfect instrument.
Also, leave it to humans to completely change around the majoritarian view on anything...
Yes to the resonance raised (which is normal for a sealed box) and no to the 3rd harmonic, IMO. It's not easy to see in the graph, but the glitch is already in the driver and is only accentuated in the box (and also raised a bit in frequency).
What is to be said of the lower impedance in the box? I did not add any offset.
Probably it indicate a tighter spring now, try add dampening material and it probably raise up a bit above the free air reference.
Theoretical Q should be relative high for B200/17,7 liters combination but not shure at those frq it will show up other than in few milimeters nearfield measurement.
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"Hypercube" thin walls are flexing, soaking the energy and emitting it in to the room - which is not good. "Hypercube" is difficult to build (cutting board to exact angles) with traditional MDF or plywood. It is lot easier to build "hypercube" with (flexing) foam-board panels, as xrk971 demonstrated with his wizardry earlier. Or, abandon "hypercube" and build conventional or multifaceted box. "Hupercube" is not better than any other multifaceted box with the same volume. Or, to put it bluntly, "hypercube" is a hyper-snake-oil.
FWIW, I have made both stiff (4.25"-4.75" baffle with 6mm material/6.25" baffle using 1/2" material) and not-so-stiff (6.75" baffle using 5mm material) enclosures.
The stiffer enclosures resonated in the ~1.5kHz range and a small amount of stuffing or adhesive damping sheet killed the ringing. I think this is a great option for hifi/mixing/mastering in a quiet room when the most accurate response is desired.
The panel resonance of the not-so-stiff enclosure dropped to a lower freq where it would not be as easy to damp it (I think it may have been more "broad" though). I only really noticed it while listening to familiar instruments from behind the enclosure (and even less so after EQing). These speakers went to a friend, so I did not listen to them long term, but I thought (in normal use at least) they were subjectively as good or maybe even better in some ways than the others (apples to oranges though).
For musical instrument applications (like what White Fang is planning) where the speaker is part of the "tone recipe", I think it's a natural choice to increase the resonance of the enclosure and use a "tone wood".
Of course the enclosure resonance (short of possibly finding some magical combination of size/material/thickness/damping etc...) won't match the driver's motion exactly, but I think it's pretty surprising how euphonic/non-detrimental that resonance seems to be.
On another note, I have some quasi-free field measurements (unlike the quasi-infinite baffle ones I previously showed) of 3 different speakers that I'll try to share when I get a chance.
The stiffer enclosures resonated in the ~1.5kHz range and a small amount of stuffing or adhesive damping sheet killed the ringing. I think this is a great option for hifi/mixing/mastering in a quiet room when the most accurate response is desired.
The panel resonance of the not-so-stiff enclosure dropped to a lower freq where it would not be as easy to damp it (I think it may have been more "broad" though). I only really noticed it while listening to familiar instruments from behind the enclosure (and even less so after EQing). These speakers went to a friend, so I did not listen to them long term, but I thought (in normal use at least) they were subjectively as good or maybe even better in some ways than the others (apples to oranges though).
For musical instrument applications (like what White Fang is planning) where the speaker is part of the "tone recipe", I think it's a natural choice to increase the resonance of the enclosure and use a "tone wood".
Of course the enclosure resonance (short of possibly finding some magical combination of size/material/thickness/damping etc...) won't match the driver's motion exactly, but I think it's pretty surprising how euphonic/non-detrimental that resonance seems to be.
On another note, I have some quasi-free field measurements (unlike the quasi-infinite baffle ones I previously showed) of 3 different speakers that I'll try to share when I get a chance.
As to be expected in a way too small sealed box. Given B200 Q it needs to be in a biggish (100 litre +) leaky box (ie aperiodic-like)
dave
My conclusion is related to your measurements from post #606, obvious difficulties in cutting the board for building the enclosure, nonsense in the thin-wall-enclosure-with-good(?)-resonances approach and especially to the laughable ridiculous claims in the "hypercube" patent.
Not wrong, something 'ideal' doesn't mean that it can be realized with current technology, merely a theoretical frame of reference for the rest of what I posted.
GM
Hi, Gmad.
I am about to start building 3 of these enclosures, this weekend, 2 to be used as guitar cabinets, and 1 that will be a marimbula (Marimbula - Wikipedia).
I have one question for you: I just have no idea how to use the speaker specs as a way to decide the volume, I have seen for this driver recommendations ranging from about 45 to 75 liters.
But then again I have here and elsewhere that the recommendation for this particular kind of enclosure is to build it as small as possible, and don't rely on the formulas. So I am kind of in a crossroads and I need to decide which way to go: use a higher volume, or the smallest possible where this speaker will fit the square face?
I attach the values, it is for the BG20. A 20 cm (8 ") diameter speaker. Here is a link:
VISATON BG 20 - 8 Ohm | Loudspeaker Database
Let me know what you think. At any rate for the marimbula I will be using a high volume, since the player uses the 'enclosure' to sit on. It will make things simpler if I could use the same patters for all 3. I was thinking something like rhombi with 29-30 cm to the side.
Cheers,
WF
Tried to upload a file that I compiled with data on the driver, but it didn't work, anyway, it's on the link (even if incomplete).
Since you have the chance anyway, why not build a speaker enclosure with smallest volume (square side = outer perimeter of chassis) and then in the Marimbula provide a possibility to mount the speaker driver as well. The Visaton full rangers do not mind large volumes.
My opinion is, though, that the smallest volume approach is correct and I have very good behaviour of the B200 in it.
FWIW, the impedance peak in the hypercube at 91Hz is fully in line with the simulation of a 17,7liters sealed box in the Visaton Boxsim software. So here we have no difference in behaviour.
Sonce's shot at the lower impedance in the box makes no sense to me. I compared with simulation software and did not find that impedance in a box is modeled to be lower. Also, flexing walls would mean higher impedance like without enclosure, IMO. I may be wrong.
So lower impedance would indicate special behaviour of the hypercube. As far as I remember, Tesserax had some measurements done, maybe he can chime in.
My opinion is, though, that the smallest volume approach is correct and I have very good behaviour of the B200 in it.
FWIW, the impedance peak in the hypercube at 91Hz is fully in line with the simulation of a 17,7liters sealed box in the Visaton Boxsim software. So here we have no difference in behaviour.
Sonce's shot at the lower impedance in the box makes no sense to me. I compared with simulation software and did not find that impedance in a box is modeled to be lower. Also, flexing walls would mean higher impedance like without enclosure, IMO. I may be wrong.
So lower impedance would indicate special behaviour of the hypercube. As far as I remember, Tesserax had some measurements done, maybe he can chime in.
A plasma speaker gets close as it is omni and a point source the size of a spark kernel.
So a mic caption from what is in front, the venue, would be spreaded all over in a room ? You know that walls exists and they reflect the waves.
The phisical world then dictates that, yes, a point source is optimal but it cannot be achieved with today's technology, a single and little FR speaker.
Which is not that bad since 3 way speakers are really lovably
The phisical world then dictates that, yes, a point source is optimal but it cannot be achieved with today's technology, a single and little FR speaker.
Which is not that bad since 3 way speakers are really lovably
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