Cabinet resonances
I redid some new cabinets over the winter. They have a sound absorbing "burrito" that sits in the center between the braces.
My opinion on the whole "musical cabinet" thing has changed. Ideally the cabinet should be resonance free and an acoustic black hole, meaning it gets rid of the back wave. It should also be stiff so that the only thing moving is the cone.
However I would say that if one is going to live with resonances then they should be as harmonic and balanced as possible. In some instances cabinet resonance can help offset other kinds of resonances and be useful.
I redid some new cabinets over the winter. They have a sound absorbing "burrito" that sits in the center between the braces.
My opinion on the whole "musical cabinet" thing has changed. Ideally the cabinet should be resonance free and an acoustic black hole, meaning it gets rid of the back wave. It should also be stiff so that the only thing moving is the cone.
However I would say that if one is going to live with resonances then they should be as harmonic and balanced as possible. In some instances cabinet resonance can help offset other kinds of resonances and be useful.
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The resonances are harmonic for a 1-dimensional space, like a string. But that is only true to the extent that the string has no stiffness, otherwise the resonances drift away from harmonic just as the strings on a piano do.
But in 3-dimensions the resonances will only be harmonic if the dimensions are all integral products of each other. But then this puts the resonances on top of one another, making them much worse.
Given that the idea is to spread the resonances as smoothly as possible it is inevitable that they won;t be harmonically related. The dimension that best distribute the modes are know as the Louden Room.
I read this and drew a total blank....how does one separate a high q from a narrow q? High q represents a number...on the “high” side...as the q number increases, the width of curve narrows...so what’s going on here that I do not understand.
Input Magnitude for these types of comparisons would be equal....the magnitude that a panel would resonate outside of curve around the resonant (q) would be expressed in some other unit other than Q, would it not? I’d think (panel) sensitivity would be a nice place to start...
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Hi Earl. Yes, I shouldn't have called it "harmonic". If one wants to spread out the resonances as much as possible then they aren't harmonic.
So a more "musical" cabinet (as I envision it) would not have conspicuous resonances at all. It would essentially reradiate the sound energy. Whereas a dead cabinet would absorb more of it.
My experience with the sound absorbing burrito is that properly done sound absorption can be very clean. But simply "stuffing" a cabinet will end up creating an impedance difference to the backwave and also have very uneven absorption of the sound which is bad.
As far as a musical cabinet the effect is to smear the sound. This might work better when one needs to offset some other kind of problem. For example masking some hard cone break up. Or in a small room when there is too much direct sound.
But if one has a proper room and proper source then an ideal cabinet that is dead will give the best imaging and reproduction of the sound. Again my experience.
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So is "audiophile" meaningless. But then obviously cabinets contribute hugely to the overall sound of a speaker. Cabinets also happen to be the most laborious and complex part of a speaker. So its not surprising that many switch to the "open" sound of open baffles.
But I can say its definitely possible to build or buy very well made and effective closed box cabinets. At least adequate for my tastes.
Some conjecture. I wonder if reducing directivity is your goal, why not build an omni speaker? For that matter why have four woofers vertically in a large cabinet? They could reduce internal vertical involvement, and externally their increased directivity will likely reduce floor and ceiling interaction.
The cabinet in the picture is a redesigned cabinet for the quad 4 fusion speaker I built years ago. Quite frankly the original design had some flaws, but it also has a certain special quality. I think the narrowed vertical directivity is part of why I like it. I still haven't heard a speaker with as much emotional content. Its a horn tweeter and I definitely prefer to sit a good 5m from it. The new cabinet isn't meant to be musical.
If you want to talk 'special qualities' I might agree that a colourful cabinet could sound better than the underlying distortions it may be covering, but reducing all distortions is much better still.
Further, while I can do this with a speaker I'm less confident that when I hear and identify (some) problems, to be able to determine what is causing it without tracking down some supporting evidence.
Further, while I can do this with a speaker I'm less confident that when I hear and identify (some) problems, to be able to determine what is causing it without tracking down some supporting evidence.
Maybe my initial post was misleading. The cabinet in the picture is meant to be dead (though not perfect of course). Its built like a tank with a sound absorbing "burrito" in the middle. The main issue with mmtmm designs is that there is an inherent 6 db hump in the response when all 4 drivers are within a 1/4 wave distance. But I don't want to drift off topic.
But yeah the concept of a lively cabinet or using colorations to offset other issues is not ideal, but i wouldn't say its wrong either.
Fwiw the speaker in this video sounds like a "musical cabinet" to my ear: YouTube
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I would agree with you here - damping is the key, not where the resonances are. With enough damping the box becomes "musical" because it does not add to or take away from what is being reproduced. The speakers are not creating the music, they are reproducing it.
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