GoodSoundClub - Romy the Cat's Audio Site

In the Forum: Horn-Loaded Speakers
In the Thread: Macondo’s Midbass Project – the grown up time.

Post Subject: I need absolutely no noticeable vibration on the listening floor.Posted by Romy the Cat on: 9/14/2010

Again, none of the pneumatic methods would work as any pneumatic leak air with time and it will be no access to it after the horns are installed and the walls are finished. Not mention that we have no high to play wit. We will be doing the following:

1) Places e the horns into the wholes in the wall
2) Before binding the bottom of the mouths to the attic joists (7 joists per mouth) we will shim the space between the joists and the bottom horn with shims. The shimming will assure that each of the joist (joists will have cut corners to accommodate the horn) care own portions of the horn load
3) The shims will be composite: a later of parallel wood (to keep the total shim angle under 12 degree), a layer of cork and a shim.
I think it all that we can do at this point from front side of the horn. Let hope that significant mass of the horn and the frame will do the trick and make the bone-transmitting vibration not detectable.

I kind of forgot about it as I did not have for years and years anything that vibrated. The bass towers that I had in my old room were absolutely free from any vibration and they were sitting on concrete slob. The last nigh I have a reminding that I might think about it in my new room.

I was visiting yesterday a local guy that made me to think about the structure vibration. He has an interesting arrangement – a pair of mono-strapped EV 30” woofers sitting in basement and fairing up into disabled air ducts in listening room floor. Since the ducts are relatively small and since he has a compression chamber before the ducts then it formed 4th order bandpass configuration. Regardless how good or pad the installation sound the vibration from 2 monster woofers was very much detectable across all floor. The give me almost panicky mode and made me to think how to make sure that my horn will not detectable on the listening room floor. Unfortunately it was a bit too late for me.

BTW, the idea that my local guy employed is still lucrative and I have some thoughts about it. I will share them when I finish my midbass channels and will deal with my next, the lowest octave, sub 40Hz channels. For now let pray that it will be no vibration on the listening floor.

The Cat

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