Are helmholtz resonators and diffusers all we need? - Page 2 - Home Theater Forum and Systems - HomeTheaterShack.com

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post #11 of 30 Old 10-27-08, 03:50 AM
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Re: Are helmholtz resonators and diffusers all we need?

So, I have a huge room node at 33,4Hz (measured). How will a helmholzt work vs EQ? I have basstraps (Rockwool absorbers) that do a great job down to 60-70Hz, but nothing below that.

The timedomain issues with helmholzt is news to me. What are the issues vs EQ?

sorry ro hijack the thread, Omholt, I feel it's relevant, though.


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post #12 of 30 Old 10-27-08, 05:18 AM
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Re: Are helmholtz resonators and diffusers all we need?

A Helmholz could be a good solution for you.

Just to be clear, there's no time domain problem specific to a Helmholz. My point was that if you only treat a small, narrow band, then that's the only place where you're getting some decay time reduction and you're leaving the rest unaddressed. If you already have some broadband in the room, that shouldn't be an issue.

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post #13 of 30 Old 10-27-08, 08:51 AM
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Re: Are helmholtz resonators and diffusers all we need?

So how do one know how much/many H-boxes to build? Does it go by surface area liek broadband absorbers or by volume or what? In my case it's obviously a front/backwall resonance, and I have lots of room against my back wall. Are Hellmholzt more effective on the velocity or pressure zones? Do I go with one big one or several smaller ones?


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post #14 of 30 Old 10-27-08, 08:55 AM
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Re: Are helmholtz resonators and diffusers all we need?

You'd need several of them. Size is going to be determined by the frequency it needs to be tuned to.

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post #15 of 30 Old 10-27-08, 09:40 AM Thread Starter
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Re: Are helmholtz resonators and diffusers all we need?

Bryan,

I think you guys at GIK really should start producing Helmholtz resonators at different sizes that can be tuned. That would really complete your product line. Right now, you don't have anything that treats the lowest bass.
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post #16 of 30 Old 10-27-08, 09:53 AM
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Re: Are helmholtz resonators and diffusers all we need?

The Monsters and Tri Traps do pretty well down into the 50's. Below that, it's pretty tough to deal with.

Doing Helmholz Resonators would be interesting for sure - It's just such a narrow tuning that they'd almost need to be custom built for each application which makes it a tough product to market. That's why nobody else has them either.

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post #17 of 30 Old 10-27-08, 10:50 AM Thread Starter
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Re: Are helmholtz resonators and diffusers all we need?

This swedish company sells some:
http://www.diffusor.com/Basabsorbenter.htm

The first one can be tuned in the 60-100Hz area and the second between 25-60Hz. They also have one that goes even deeper, but it's not on the site. So, is possible to make Helmholtz' that are tunable in a certain range. Not 100% sure how it works, but I think the tuning works by simply how much you open the "door".
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post #18 of 30 Old 10-27-08, 11:17 AM
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Re: Are helmholtz resonators and diffusers all we need?

Those certainly look interesting. I'd agree on the slot size changing doing the tuning. I wish they had specs for those 2 products like they do for the others on the site.

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post #19 of 30 Old 10-27-08, 02:33 PM
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Re: Are helmholtz resonators and diffusers all we need?

Should be real easy to make, though. It's basically a box, they have the measurements in the specs. Make a slot, make some sliding arrangements for the port, and Bob's your uncle. Do these things need any damping inside or will that throw the tuning off?

Also, do you have any info on placement? DO they go in the pressure zone or the velocity zone of the node?


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post #20 of 30 Old 10-27-08, 02:42 PM
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Re: Are helmholtz resonators and diffusers all we need?

Quote:
omholt wrote: View Post
This swedish company sells some:
http://www.diffusor.com/Basabsorbenter.htm
I'm sure that the pictures the company has on their site are to help market their products...but get a load of this room (below). Pretty futuristic looking. Their Golden Horn product looks neat too. I've always wondered how to make something like those. There are formulas for the Skyline type but I can't find any for the RPG Hemifusor type.

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