masterxela
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Posts posted by masterxela
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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
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There are pretty strict formulas on how tall the entire box is, and how far the driver is from the top. Ends up, driver height off the floor is directly related to the drivers Fs. Length of the expansion "horn" = (13560/2/Fs). So total height is half that. Distance of the driver from the top is L*.217. (From the zillaspeak site)
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I think I'm going with the fostex fe126e's, the 4.5". Expecting the need for a sub, but hoping to get by without a supertweeter. I won't have a room to put them in until August, so maybe I should hold off........
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A better challenge might be: who has spent the largest percent of their annual income on audio gear. In 2007, I made $5500 (just did my taxes). My purchases in 2007 included:
kg1
kv-3
heresy
rf-7
rb-75
denon avr-1906 (XXX-lightning)
denon avr-1907
crown xti2000
diy sub
=>$3000, so I'm at 60%.........
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Yea, there is a lot of disagreement over which size drivers are the best, foxtex's in particular. I'm looking at the 4.5 or the 6, the 8's fs is too low, I don't want a 7ft thing in my room.
Is the .3mm xmax not a problem with the fostex's? That's why I mentioned the tang band and jordan, they have 10x the xmax, and just as nice fr, for the same price.
How did you go about tuning the enclosure with stuffing? Seems like it will be very hard to get to most of the enclosure after its up and running and I have a chance to listen.
What type of amplification did you use with the 168's? How loud could they play full range music without sounding stressed?
Thanks for the replies,
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I'm going to build one, and can't decide on the driver.
Fostex fe126e, fe166e
Jordan JX92s
Tang Band w4-1320sd, w4-1337sa
Some reading if you're interested:
http://www.zillaspeak.com/bib-pics.asp
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EASE was the only other one they mentioned, and didn't stop saying how much faster theirs was at the same thing.
The problem with a demo was that the chin rest is not easily handed around a table, so one guy got a demo, and i heard from across the table. We heard a HS auditorium with and without ceiling treatment. I got what I expected, the sound reverberated longer, and the person on the chinrest said, "It sounds ringy".
As far as the engineers said, ALL PROFITS are pumped back into R&D, after salaries etc. Last year, bose did 2-3 Billion in sales.
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The presentation was from guys who work on the professional side of bose, selling/designing systems for churches, auditoriums, stadiums, etc.
They demonstrated a software called "Modeler" that was pretty slick. A user can "build" a 3d room, much like AutoCad, letting the computer know what material each surface is, where people are, how hot it is, etc. Then you place any number of bose loudspeakers anywhere you want, and the program will generate several gradient style maps depending on what you want to analyze: speech intelligibility (apparantly a standardized quantitative thing now), soundpressure, etc, at any listening position.
They use it as a sales/presenation tool to owners of venues. They can show up, show an owner what speaker system A or B will sound like, or recommend acoustic treatment, and show how it will affect the sound.
The program has a database of bose's speakers with pre-measured parameters, which it uses in the "mapping" portion: vertical and horizontal dispersion, sensitivity, max power handling, freq response, etc.
They do NOT have any other manufacturer's loudspeakers built in, available to place in the room to compare to their systems. The engineers said that was the only reason a competing program has more users.
The only portion I raised my eyebrows at was a portable "boombox" looking thing with a chinrest between the speakers, where a owner could listen to what the room would sound like in each scenario..... Yes, it had the cubes. How it could possibly recreate a church in the 3rd row with professional speakers, and then compare the sound to the same church with acoustic ceiling tiles and different speakers, I have no idea. They claimed it did, actually guaranteed it did.
If you guys have any questions, I might be able to answer. By the way, I'm listening to Racer X on my Sennheiser HD 280 Pro's right now, and they are amazing. I should listen to klipsch's new offerings sometime.
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Sorry, no April Fools. I've been asked to do a presentation as a summary of his presentation to our Society of Physics Students club... blah
I wish I had a PWK shirt or something
I guess I'll let you know how it went later tonight
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My invite through the physics department here at MSU:
01Apr08 is the next meeting of the IEEE SW MO Subsection. We will host Tom Tyson,
Chief Field Engineer, and Stephen Payton, Field Engineer, both of the Bose
Corporation. They will present the Bose® Modeler® Design Software and Auditioner®
Technology:
Have you ever wondered what goes into designing loudspeaker systems for public
spaces? Come see how state-of-the-art Bose® tools remove the guesswork. Modeler®
Design Software analyzes performance of loudspeakers and anechoic speech in threedimensionally
modeled acoustic environments. Auditioner® Technology allows you to
listen to a system's performance in real-time with calibrated sound pressure level
playback devices.
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there's an 80% chance that you've already experimented with placement, but
try listening to your sub behind your right main where that lamp is first. or any other corner for that matter. Placement is everything
Or, instead of spending $500 on a sub that covers 50hz of material out of 20,000... you could buy my dean g'd rf-7's and rock out.
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I'd sell one pair and buy something else.
Probably doors for my car.
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get your speakers out into the room with you.
If that is not possible, I would not invest in processing and expect to solve the problem.
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Rf-7's are great speakers, and your amplification isn't shabby either. I can relate to not being completely satisfied with their sound under 90db or so. Have you played around with room placement or room treatment?
With my rf-7's, without changing source material or processing, I experienced 3 completely different "sounds" depending on what room I had them in.
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the 75's have the same top end as the 7's, and the 81's have the same top end as the 82's if my memory is correct.
75's are front ported so you can put them on stands against a wall, in a cabinet, on a wall etc.. I loved mine.
were not as good as my rf-7's, but, that would be impossible, 1 8 outperforming 2 10's
good luck finding 75's if that is the path you choose, they have become quite rare
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buy him my dean g'd rf-7's
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My denon avr-1907 is awesome. Got it for $400 brand new from BB. Hint: go buy it, return it, and then buy the open box one (yours). Save a lot of money. Repeat for tv's, etc...
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bad news, emotiva won't ship the mps-2 with only 2 modules, and mps-1 is out of stock.
good news, I might buy this on Saturday. (someone needs to buy my rf-7's........)
(and yes, the tires are 39" tall, estimated gas mileage=4)
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I'm only looking at 2-channel for now, and I don't know what they'll be driving yet. It'll be Dean g'd rf-7's for awhile, but they're for sale- Need to downsize till I get a house; thinking about auditioning the speakers available by manufactures with 60 day return warranty deals.
Outlaw 2200, 2@ $325= 624 (free shipping when you get 2)
http://outlawaudio.com/products/2200.html
emotiva mps-1/2 chassis + 2 epm300 modules=$600 something i think, (expandable up to 7 channels, which is sweet)
anything else to consider? (no pro stuff, didn't care for crown xti2000)
Thoughts on the outlaw or emotiva?
Thanks in advance
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I noticed a much bigger difference between running rf-7's off an entry level sony reciever and an entry level denon receiver, than from denon to crown xti 2000. Actually, I prefered the denon.
At extreme volumes yes, you can tell the power supply wants more; the inner detail fades and everything starts to sound a little compressed. Still unbelievable what that $250 receiver can do (avr-1907).
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i think soundsplinter was making some cool drivers when i was designing mine - could look at them.
i'd stay away from plate amps in general too, pro amps are just more versatile, should you ever dismantle this project.
have fun
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Anybody know anything about these? I can't find any literature, reviews, manual, etc
Thanks,
Alex
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December 22, 2007
Subwoofer Tests Round 5, 6th of October 2007, Test Summary ***READ ME*** Fall 2007 Subwoofer Tests Discussion Thread Anthony Gallo TR-1 Audio Pro Level 110 BK XLS300/PR DIY CSS 2xSDX15 sealed 140L DIY CSS SDX15 sealed 100L DIY Servo v2 DIY TC Sounds LMS-5400 18" + 2x18" PR 200L DIY TC Sounds LMS-5400 18" sealed 100L DIY TC Sounds LMS-5400 18" sealed 100L LT Gradient Evidence MK2 JL Audio Fathom f113 SVS PB12-NSD SVS PB13-Ultra 20 Hz tune SVS PB13-Ultra 15 Hz tune SVS PB13-Ultra 10 Hz tune SVS PB13-Ultra sealed Velodyne SPL-1200 MK2 Yamaha YST-SW1500
The latest Subwoofer Tests - Round 5 results from Ilkka Rissanen are posted.
Summary, svs pb-13 ultra, tuned to 20hz, was the best (loudest) commercial sub in every category. No klipsch subs tested though -
Why does your tv say denon on it?
Helmholtz resonator physics project
in 2-Channel Home Audio
Posted
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