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PostPosted: October 15th, 2022, 10:55 am 
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Joined: February 28th, 2013, 3:31 pm
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The Occasional Podcast had an interesting discussion with speaker designer Andrew Jones on speaker enclosures. I especially appreciated his mention of eliminating panel resonances by choosing sizes that would resonate at frequencies that were not in the range being produced by the drivers used. I have used this in many of the speakers I have built with great success. I'm including a photo of the inside of my truncated pyramid bases for my current speakers showing how random placement of braces breaks the panels up into many different sized sections, none of which resonate at the frequencies produced by the woofers.

One question that I have had in the past was the wisdom of soft mounting drivers to lessen the vibration of the drivers to the enclosure. That will reduce resonances of a poorly designed box, but will also change the effective mass of the basket/box combination. I don't know how that will affect the linearity of the driver working against a less rigid mount. Probably better to design and build a better box.


https://theoccasionalpodcast.libsyn.com ... lacpioneer


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PostPosted: October 15th, 2022, 11:35 am 
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Tom,

That was a fascinating podcast, and very instructive of the options available to deal with cabinet resonances.

One thing I considered before building the Elsinore speaker project was to try a classic 3-way on Troels website, but construct a BBC style cabinet with lossy thin wall BB ply panels with bitumen damping like Harbeth instead of the heavily braced thicker wall BB ply cabinets as designed. However, I didn't realize that the BBC approach also modified the response in the crossover to compensate for the (tuned) cabinet resonance, as Andrew Jones mentioned in the podcast, so it would have been more difficult than I imagined. Still, given the high regard (and commensurate cost) of Harbeth speakers, it would have been an interesting experiment and against the grain of high mass and stiffness in many DIY designs to reduce resonance.

BTW, Joe Rasmussen (designer of the Elsinore speaker I built) put a lot of emphasis on a very thick and stiff front baffle to absorb the energy from the driver.

Of course, now that I have Charlie's excellent Nesterovics 5AS speakers, my speaker building days are likely over. However, podcasts like that one really is tempting...

David


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PostPosted: October 15th, 2022, 12:23 pm 
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The problem with trying to tune a crossover to offset a cabinet resonance is that you can achieve a "proper" frequency response but you can't get read of the transient smearing and time shifts caused by the energy stored in the enclosure. The best option is still to eliminate the resonances in the first place. Stored energy is the bane of good sound reproduction.


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