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  • Driver-Baffle Isolation

    Has anyone tried isolating the driver from the baffle? I was thinking (2) boards, maybe in a "constrained layer" sitaution, with the driver's frame clamped between the 2 baffle boards with some sort of isolating material, silicone sheet, maybe, between the driver frame and the wood.

    Something like this where the black is the wood, red is the isolating material, blue is constrained-layer material, and gray is the driver frame.

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    Furthermore, what benefits would there be to a design like this?

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  • #2
    Re: Driver-Baffle Isolation

    One of the meanings of a baffle would be something that would obscure (in this instance) the sound, rather than just a place to mount the driver. I could see benefits regarding diffraction, even minimizing any sonic output from the cabinet. SL or someone had a mounting system where the rear of the driver is mounted to a brace and the driver face was gasketed with a foam gasket but not hard mounted to the baflle at all. On the 3 ways I am doing I had considered mounting the cosmetic baffle on a layer of that waffle foam material used for refrigerator bins, but ended up hard mounting that board and setting the drivers in a heavy roll of speaker caulk and the fasteners all have rubber gaskets on either side of the washers on the screws mounting the drivers, but I like your method - it would be great to try and get a waterfall from a hard mounted and also one from a true baffle system.
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    • #3
      Re: Driver-Baffle Isolation

      I see what your getting at but the way your going about it still has the driver mounted to to baffle. Even though its not technically "screwed" to the baffle, its still inserted and supported by it. That may offer some isolation, but you'd have to go the route like the Linkwitz Orions where the driver is supported from behind and just mearly "floating" in front of the baffle to gain true baffle isolation, which is basically trying not to resonate the baffle or enclosure. This is in effect trying not to color the sound by vibrating the surrounding material that would radiate its own sound or sonic signature.
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      • #4
        Re: vivienne westwood melissa wedding shoes www.louislvuitton.com geographic

        The spammers are waging war tonight!

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        • #5
          Re: vivienne westwood melissa wedding shoes www.louislvuitton.com geographic

          Grey,
          I see your reasoning behind thinking about driver isolation, but I cannot see how it would much affect towards what you are working for.
          We know that we have to fight panel resonation, but we also know that comes from the pressure of the soundwaves in the enclosure...so this idea wouldnt help much.
          Also, you may be trying to effectively remove vibrations from the baffle, but I would think that any decent driver frame would do just the same for stiffening the area around it, in relation to having no driver there at all.
          Perhaps this attachment method could cut down on distortion from the driver itself, if the typical enclosure is a cause for driver distortion in the first place, this I am not sure of. Does anybody know if a driver's distortion measurements generally get better, or worse, when put into a properly built enclosure?

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          • #6
            Driver Baffle Isolation

            What you're describing is exactly what we did in the MiniByzy The woofer has a rubber layer on front and back, and we pinched it into place between an inner and outer baffle, no hardware holding it in place.

            There's a slight reduction in transmitted vibration as opposed to hardware directly connected to the frame and baffle. I doubt that it's an audible difference, but it sure makes mounting the woofer attractive and easy.



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            • #7
              Re: Driver-Baffle Isolation

              Alright, well, maybe I'll try it out and run some HD sweeps, and see what happens. I'm really kind of interested in making the baffle the way you guys did with the Byzantium and MiniByzy, the 1/8" Hardboard and Epoxy, I'm just not sure how I'm going to do it, haha. Thanks for the thoughts and concerns guys.

              So now I'll ask, if you were going to do this, say with a pair of ND140s open baffle, what meterial(s) would you use for panel and driver damping?

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              • #8
                Re: Driver-Baffle Isolation

                i have thought about this also. not so much for the mids and bass drivers, but for the tweeter. if you think about how small the distance a tweeter dome move when reproducing a higher freq, it seems like any amount of vibration at all would have to smear the sound. i sometimes wonder if mounting the tweeter on a seperate stand or frame would not be the answer ??? would be intersting to see some graphed info on a tweeter mounted in a 2 or 3 way system vs. one mounted seperate to see if it does effect the top end. vibration in a speaker is not your friend.
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                • #9
                  Re: Driver-Baffle Isolation

                  This is what I do because I can. Is it effective? who knows.

                  My signature is the black oval supra-baffle:

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                  I have applied that piece with silicon seal in the past. Currently, I am using 3M high adhesion foam tape. Ordinary foam tape should be adequate for smaller drivers and has the advantage that is is removable if you ever need to take the oval off.

                  Bob

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                  • #10
                    Re: Driver-Baffle Isolation

                    IMO driver isolation makes sense until you really start thinking about it. To be truly isolated you'd have to use something like a rubber coupling between the driver and baffle, glued in place, since as soon as you use bolts or screws through the driver frame you're coupling it again. Now consider what happens with the rubber coupler: if it's effective in damping vibration it would have to be soft enough to flex, and that would allow the driver to move back and forth. If stiff enough so that the driver can't move it won't damp vibrations.
                    Since the idea behind driver isolation is to prevent vibration transfer between the baffle and driver just brace the baffle sufficiently so that it can't vibrate.
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                    • #11
                      Re: Driver-Baffle Isolation

                      I feel that hard-mounting is probably -better- for the sound, and here's why.
                      Note: this is only my theory.
                      With the whole newton's law mantra, every action has equal and opposite reaction, it makes me think that if the cone of a speaker is moving, it makes the basket/motor assembly also want to move. If the motor assembly has the freedom of motion, it will move slightly, changing the net x-axis motion of the cone of the speaker from a hard-mounted to soft-mounted situation. I feel that this difference in x-axis motion and associated air displacement will color the sound more than the cabinet vibrations of a well-dampened cabinet.

                      Just my thought on the matter, I've never done any testing on it. You should do a test on a test baffle w/ the same driver, soft mounted in one test hard mounted in the other, see if there are any measurable or audible differences on an a/b test.

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                      • #12
                        Re: Driver-Baffle Isolation

                        The real answer: Float your drivers in the air with magnets! It's genius! It won't interact with the drivers I swear! :p
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                        • #13
                          Re: Driver-Baffle Isolation

                          Originally posted by Adam_G View Post
                          I feel that hard-mounting is probably -better- for the sound, and here's why.
                          Note: this is only my theory.
                          With the whole newton's law mantra, every action has equal and opposite reaction, it makes me think that if the cone of a speaker is moving, it makes the basket/motor assembly also want to move. If the motor assembly has the freedom of motion, it will move slightly, changing the net x-axis motion of the cone of the speaker from a hard-mounted to soft-mounted situation.
                          My opinions agree with this and are based on the same logic. In my mnd it's why the imaging, clarity and "impact" in my speakers snapped to a higher degree when instead of resting the tall cabinets on the padded carpet I switched to spikes which rigidly supported the cabinet to the floor and prevented them from rocking. Later I filled their hollow bases with sand and noted another slight impovement. I am not certain if the sand damped cabinet vibrations or merely added more mass and therefore held the driver frames more rigidly in space but I suspect the larger change was from the latter given what I noticed with the spikes.

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                          • #14
                            Re: Driver-Baffle Isolation

                            Originally posted by greywarden View Post
                            Has anyone tried isolating the driver from the baffle? ...
                            Yes!
                            What you're describing is exactly what we did in the MiniByzy The woofer has a rubber layer on front and back, and we pinched it into place between an inner and outer baffle, no hardware holding it in place.

                            There's a slight reduction in transmitted vibration...
                            Pete, if I understand you correctly, the pinch ring in the back is bolted to the baffle, sandwiching the driver frame in rubber? If this is the case, you've isolated the driver on the baffle, but you have not isolated the baffle, as the baffle still supports the mass of the driver. I tried to do both.

                            My design goal was to minimize radiation from sources other than the drivers' driven surfaces (cone and dome). My approach was to limit paths for vibration to leak from the box (limit transmission) while absorbing the heck out of energy inside the box (reflect and absorb). I substantially accomplished this by use of a sub-baffle, closed cell foam and internal CLD treatment. When playing loud (90dB?), the baffle is not vibrating to the touch, nor is the rest of the box.

                            Continuum are a rear-mount design, so it was ammenable to this approach. In cross section, they have baffle - foam - inner baffle - brace - CLD rear panel. The inner baffle is fully isolated on 5 sides by closed cell foam, and the driver mounted to the front side. CLD treatment on 5 inner sides is in the form of cermic tiles with a layer of roofing compound, with full XZ braces, not just Y direction from the inner baffle.

                            The only issue I've had is getting the brace length right, so it pushes the driver to the right position, but not so the frame touches the baffle or it transmits energy. My fingertips have no problem sensing vibration when the frame touches, but there's nothing there when it doesn't. The tweeter is not isolated.

                            BTW, these are mounted on the lightest stiff stands I could make, and the absence of a massive support does nothing but improve the sound. Continuum have very pleasing room interactions that I wanted to maximize. To Adam's point about Newton's laws, this uses the AC-130 F1 driver, which has a moving mass (Mms) of 9.7g. With CLD treatment, the finished speaker weighs ~21lb, or about 9.7kg. Per Conservation of momentum..
                            m1 v1 = m2 v2
                            If m1 v1 is the cone, then the box reaction to come motion, v2, is m1/m2 v1.
                            m1 = 9.7g, m2 = 9000g, therefore box velocity v2 is 0.001 v1.

                            Now let's convert this to energy, which is related to the square of velocity. What was a 1000:1 speed ratio becomes a 1,000,000:1 energy ratio, or -120dB. Swinging like a pendulum, that box isn't radiating due to Newtonian reaction to driver motion, per se, but rather from the sonic energy tapped inside, and that only comes out the cone.

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                            • #15
                              Re: Driver-Baffle Isolation

                              Awesome! Do you have any pics or diagrams that show what you did? I don't quite think I'm grasping it.

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