It's been my experience that the effect is serious on an enclosure-type speaker... when I build new speakers and re-torque the drivers after they've played for awhile, I can usually hear a noticeable improvement in the speaker's sound - especially in the bass response - after tightening the driver's mounting screws up. Don't know if that would show up on frequency response graph, but it shows up to my ears, and I would think that purposely decoupling a driver would have the same dynamics robbing effect.
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planet10,
Maybe we are thinking of two different ideas here...but it looks as if the driver you posted up has a connecting rod that would create a push pull design. I don't think this would accomplish what you want. To cancel resonance the drivers would have to be moving in phase pointing in opposite directions. Your driver(s) are working out of phase. My line of thinking is you want to create a tug o war that nobody wins. That would be idea for canceling modes.
Maybe we are thinking of two different ideas here...but it looks as if the driver you posted up has a connecting rod that would create a push pull design. I don't think this would accomplish what you want. To cancel resonance the drivers would have to be moving in phase pointing in opposite directions. Your driver(s) are working out of phase. My line of thinking is you want to create a tug o war that nobody wins. That would be idea for canceling modes.
This configuaration is exactly what i want. The connecting rod is immaterial to the concept -- it just ties the fixed portion of the woofers together. The drivers could be wired in acoustic phase or not, but it only makes sense to wire them in acoustic phase. That way they compress and rarefract the air in phase, but the mechanical direction they move is in opposition.
dave
Here is more on the woofer in the diagram,
I would of course be considering the 4 sides that are not coupled by bolting the woofers together. I agree wholeheartedly with your diagram and explanation of the two that are. No argument as I see it.
Cal,
You know i'd have the box "well-connected" with braces. You could thou, mount up 6 woofers and support the cube by its corner.
dave
You know i'd have the box "well-connected" with braces. You could thou, mount up 6 woofers and support the cube by its corner.
dave
OK, now I'm confused. I thought we were discussing the difference as seen by the box between a single woofer and two in a push push. Two woofers (twice the displacement) are causing twice the box flex as one on the unbraced sides. Of course you would have it well braced, we expect nothing less. 🙂
I've experienced this as well..
Using cement or thick steel plate for a baffle makes the effect more "pronounced".
So - "magic" or not - others do hear this (..and not simply when "prompted" to hear it).
I tried to make it clear that to compare 2 drivers push-push you'd have to add a 2nd driver to the other box as well (and double its volume) so that you could isolate only the effect of push-push.
dave
For the same volume, why would air displacement double?
Edit: Volume = sound o/p, not cubic type liters.😉
Edit: Volume = sound o/p, not cubic type liters.😉
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This still seems to me to be amplitude related. Twice the air displacement caused by cone movement. Am I misreading? (It is past my bedtime...)
Don't know why you feel the need to denigrate me, but you have a long history of rude and inappropriate behavior here on the site, so I guess I'm in good company. 🙄
To further clarify, my statement in regard to before/after driver re-torquing sound differences not showing up on a frequency response graph was not meant to imply that it isn't measurable, it was meant to imply that the noticeable and important (to me) differences that I hear before/after might not show up as large differences on the graph.
So much for your audio "magic".
I'm sorry that you feel that way. But when one thinks that they sense something that science cannot detect, then, simply put, it is "magic".
If it " does "not show up on a frequency response graph" then how is it measured?
I have a history of being blunt and demanding more than simply someones impression of what they hear. If this is "demeaning" then so be it! If you cannot support what you believe with data then you should expect it to be questioned. If this "demeans" you then maybe science is not you 'cup of tea", because that is what the scientific method requires.
If it " does "not show up on a frequency response graph" then how is it measured?
I have a history of being blunt and demanding more than simply someones impression of what they hear. If this is "demeaning" then so be it! If you cannot support what you believe with data then you should expect it to be questioned. If this "demeans" you then maybe science is not you 'cup of tea", because that is what the scientific method requires.
..who said that science cannot detect it?
Such an assumption has a gap in logic wide enough to drive a semi through it.
(..and I wouldn't be at all surprised if it's quite a bit easier to detect than HOM's.)
How it's measured or not? - we leave that up to someone who is actually willing and able to do the work, because for the most part it's well past a hobby interest.
Also,
..not that I objected to the "magic" slight, but there is a difference between questioning, and demeaning. 😉
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Gedlee, this is true for you on everything except your own work. Then you quote how other people love it and how every single person that has heard it has ............
What we hear from our own perspective is just as important as what something measures like. The most sensitive instrument is still the human ear. One day science may supplant it, but it hasn't yet.
You loose credibility when you denigrade someone else's listening while at the same time expounding your own projects by the self same listening sessions.
Terry
Terry - this is patently false. I would prefer not to quote subjective responses at all and to just relly on the data, which you cannot deny is shown more completely for my products than for the vast majority of others. And you cannot deny that I support my designs with solid science - further I post this on my site as white papers. The subjective impressions are there because people expect them.
I suspect that there are very very few loudspeakers whose performance is as completely disclosed and its design as completly supported in science as mine are. There is no "magic".
Actually it isn't false (..patently or otherwise).
You might *prefer* to NOT quote subjective response, but you do it all the same. (..and not just quoting others, but you have personally done this - i.e. "They are hear" sound, subjective descriptions relating to your foam insert, etc..)
There are descriptions in those subjective responses that have NOT been sufficiently correlated with proper objective measurements. The "science" is still decidedly lacking, despite the white papers and measurements. (..and note that many other manufacturers have white papers (credible or not), measurements, and often INDEPENDENT measurements.)
IMO none of this is a "slight", it just *is*.
I can understand not *wanting* to provide subjective commentary, but I can also understand the *need* for it - and not simply for marketing, but basic social interaction.
It's called p-e-r-c-e-p-t-i-o-n.
Here, let me try it this way... we all perceive sounds differently, and we all place different importances on the sounds we hear out of our stereo systems. I might like a lot of bass while you might like a lot of treble, so if the bass is increased or decreased by a small amount in my system then I'm going to notice it more than if increased or decreased by that same small amount in your system, even though the small increase or decrease will show up exactly the same on a frequency response graph. So re-torquing the drivers in my speakers might show up as a small difference in a before/after frequency response graph, but to my perception that difference is a larger difference than the graph would seem to indicate.
So to apply that to the discussion that Keyser and I were having, Keyser cited a frequency response graph that showed only a small difference in the frequency response of a coupled/decoupled driver, and I weighed in with the observation that that small frequency response deviation might be to one's perception larger than what's showing up on the graph.
So please stop twisting my words to say that I'm denying the science of measurements and that I'm into some type of audio "magic". And by the way, it's been my observation that some of your own "science" methods are about as far from science as one can get, but that's a debate for another day.
No, you have a history of being rude and boorish here on the DIY site, and you've been called on it many times, and no matter how hard you try to spin it you were being rude and boorish in your response to my post. And I wouldn't be so quick to be proud of your self-proclaimed bluntness - I have a brother who's a racist and he's very blunt about it - does his bluntness make him an admirable person?
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Personally, I think we do not need to be so sensitive about some comments. I somebody posts “Audio "magic" at work again!” we could also answer something like: “could be, because I definitely here it, and it doesn’t show up in the frequency response I made. Any tips how I could measure this phenomenon?”
By posting like this we could actually learn something, and other readers wouldn’t have to read tons of personal attacks going in all direction.
My boss make remarks like this all day long, and the best way to cope with this is to laugh with it, and every now and them, outsmart him in public…
So in conclusion, lets prove Dr Geddes is wrong, then you can feel good also, and we have learned yet another thing!
By posting like this we could actually learn something, and other readers wouldn’t have to read tons of personal attacks going in all direction.
My boss make remarks like this all day long, and the best way to cope with this is to laugh with it, and every now and them, outsmart him in public…
So in conclusion, lets prove Dr Geddes is wrong, then you can feel good also, and we have learned yet another thing!
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