Helmholtz resonator physics project

[masterxela]

Hey guys,

I have a "project" due for school (engineering physics major), and I'm considering trying to design a helmholtz resonator with variable attenuation, resonant frequency, and bandwidth; a one size fits all kind of thing.

Would the audio world buy such a thing?

It seems like anyone with a dedicated room would be interested, depending on the price/performance. Virtually every room has gain worth addressing in the 30-100hz range. Why have a stereo worth a few thousand, with big annoying peaks down low? (my previous basement was awful. 10db peaks at 40 and 80hz)

As far as I can tell, there isn't a company really advertising one, if one is commercially available.

If you have any ideas about what the community would be looking for, shout 'em out. (price, attenuation down to 12hz, size, etc)

If anyone has a helmholtz resonator and has taken any measurements, those would be awesome.

Thanks,

Alex

[fenderbender]

I don't know about your resonator, But if you could whip up a Holtzman Generator, I could get my hands on some melange and we could Fold Space to our hearts content.....Where you want to go first??? []

[jtnfoley]

I don't know about your resonator, But if you could whip up a Holtzman Generator, I could get my hands on some melange and we could Fold Space to our hearts content.....Where you want to go first???

Dam -n-... I thought I'd be the first to think of the uber-nerd response. Don't let Zufa Cenva hear you talkin that way!

[pmsummer]

Ask Dave Mallette.

[Mallette]

I have a house full of of them and only Klipsch makes anything with similar cost performance and efficiency. I've said for years that the current Frazier owners would starve to death in a grocery store as these designs would sell very well indeed, even in the ignorant consumer world, due to their cost peformance and top of the line sound quality.

See if you can grab these cheap: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=150320982410&ssPageName=ADME:B:SS:US:1123

Jack Frazier called his designs "Modified Helmholtz Resonators." I don't have any of his engineering papers, but Todd Crane (see the F.U.G. thread) could perhaps define.

Dave

[fenderbender]

Ah I knew somebody besides GLA51 would get the reference....Nerds in arms....

You know I have had a copy of "the Machine Crusade" sitting on my shelf for the longest time and haven't gotten around to reading it yet.....Guess I'd better to see what happens to Tio and Norma

[sheltie dave]

Are you Springfield IL, MO, OH, or some other state?

[masterxela]

Springfield, MO during the school year. St. Louis in the summer and winter

And to clarify, I'm not wanting to build a speaker enclosure that acts as a helmholtz resonator: all ported subs. Ported loudspeakers are aswell, but the math and theory gets more involved i believe once the the wavelengths in question are relatively close to or smaller than the dimensions of the resonator

I'm interested in an enclosure to place in a room to modify the frequency response characteristics of the space.

Kind of like normal bass traps, but focusable on a trouble spot, and hopefully able to "suck out" a lot, without being 1000L

[DrWho]

Just some things that come to mind...

First, the problem needs to be identified. Helmholtz Resonators won't fix all low frequency acoustical concerns in a small room. So I would try to do some research on what problems can be adderessed by HRs that way you can actually seeing it work.

If you want it to be commercially viable, then I think one of the biggest concerns is making something that is easy to use....or something that automatically configures itself for the application. That might be beyond the scope of a single semester though....just getting something to measure acoustics was a solid semester of work for me when I was in college (all of one year ago). Maybe you could make it semi-automatic where the user just tells it what frequency and bandwidth is required.

As far as size, I would recommend ignoring that for a college project and just let the physics dictate what the size should be. I think making something small or aesthetically acceptable comes after the proof of concept and requires a much deeper understanding of everything since it will involve choosing compromises. Although I wouldn't overlook things like suspended panels with a certain mass and compliance of the "suspension"....that could make it a lot smaller.

This sounds like an interesting project - hopefully you'll keep everyon informed as to how it turns out.

[laager]

I don't know about your resonator, But if you could whip up a Holtzman Generator, I could get my hands on some melange and we could Fold Space to our hearts content.....Where you want to go first???

Classic. Absolutely classic.

[masterxela]

Thanks for the reply,

I actually have 2 semesters.
This semeser is supposed to be used to write up a proposal to the
department about what I'm going to do, how I'm going to do it, who's
help I'll need, how much space, and money I'll need etc.

Next semester I "do" it, and present my findings.

Traditionally,
students don't really pick their topics. They team up with a professor
and tag along with his current research.

So I can do that, or try
to persuade them that a random acoustics topic is worthy, or convince
them that the research I'm already doing at work for 20hrs a week is
worthy: Internship with a company that is developing highly
semi-conductive carbon nanotubes for applications in thin film coatings
for micro-electronics. lol. (I'm a glorified test tube cleaner)

I'll update this thread with anything new along the way.

BTW,
I just read over the math for port end correction, and its pretty
sweet. Anyone who's made a diy ported sub has seen the numbers, but the
derivation is rather advanced.

Also,
the community's wishes would just be a part of the presentation, like a
"what's next" section, not dictating my design really.