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Author Topic: ABS cabinet damping.  (Read 2052 times)

Jim McKeveny

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ABS cabinet damping.
« on: March 24, 2017, 09:19:30 AM »

Would strategic internal application of an adhesive butyl dampener (e.g. Dynamat) enhance the performance of K-Series boxes (and similar)? At higher SPL there seems to be a lot of radiation from the box itself.

It seems to be a low-buck, low weight improvement vs. KW112.
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Gordon Brinton

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Re: ABS cabinet damping.
« Reply #1 on: March 24, 2017, 11:12:42 AM »

Well, I doubt it. I don't know what frequencies you are referring to, but regardless...

The box itself (size, shape, and damping,) only affects the lower end of the frequency spectrum, say, below 500 Hz. However, the wavelength of frequencies that low is measured in feet, not inches. Thus, a thin layer of damping material will do very little to reduce internal reflections. Even 4 inches of dense damping material would only contribute minor improvements.

If you are talking about subs, every box exhibits some degree of one-note-bass due to box vibration and resonant frequency. Adding solid mass to the box walls would probably only lower the resonant frequency which would serve to change the tuning. The box walls will still be vibrating surfaces that radiate sound. They will just "come alive" at a lower frequency. If you can lower that frequency to below the usable range of the sub, it may be productive, but would also make the boxes much heavier.

Perhaps a better way to manipulate vibration might be to add strategically placed internal bracing. IDK.

Good luck.
« Last Edit: March 24, 2017, 11:37:48 AM by Gordon Brinton »
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Stephen Kirby

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Re: ABS cabinet damping.
« Reply #2 on: March 24, 2017, 01:53:29 PM »

While I've noted the cabinet vibrating, I think it's fairly neutral or broad enough in the lower midrange that it doesn't adversely affect the sound.  May even contribute to the "warm" sound.  When building guitar cabinets I've aimed for a broad lower midrange (~200-500) resonance to accentuate the fundamentals of the notes and provide "carry" instead of everything in overtones.

My issues with the K's I have is more with lack of HF dispersion and whatever it is about the HF that seems to give up when pushed.
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George Friedman-Jimenez

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Re: ABS cabinet damping.
« Reply #3 on: March 27, 2017, 08:50:42 PM »

The box resonance is not the issue, so internal reflections are not the problem and thickness of absorber inside is not relevant. The vibration of the box walls and radiation of its resonances is the issue. I tried damping the inside of a well built ABS cabinet and couldn't hear a difference, but I didn't experiment around very much. You could try it first on the outside (shouldn't matter) and see if you hear a difference, then put the damping materials inside if you do. You could even us an RTA to look for harmonic resonances as you push the SPL and see if you can damp them effectively. Let us know what you find.
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Stephen Kirby

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Re: ABS cabinet damping.
« Reply #4 on: March 27, 2017, 08:54:44 PM »

Understood.  I was referring to radiation of the cabinet because of resonances.  In a guitar cabinet that's a large part of it's sound, and a reason why close micing doesn't sound the same.  What I hear off the sidewalls of my K10s is fairly broadband lower midrange.  If it had a pronounced peak somewhere then damping may "help".  As it is, more damping might reduce the warmth and cut more, but probably not make a major change.
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ProSoundWeb Community

Re: ABS cabinet damping.
« Reply #4 on: March 27, 2017, 08:54:44 PM »


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