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2d qrd diffuser make


elusive4

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congrats! you seem like a prick.

 

edit: read the rest of the thread, confirming my hypothesis. there's a fine line between being helpful/educational and being a pretentious ass. you stomped all over that motherfucker. all over it.

 

let's go PM

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stand finished

 

was very worried regarding the design requirement to have the unit flush against my back wall (e.g. the back of the stands (feet) couldnt protrude back past the array very far) ... as my living quarters is quite small. i was mostly concerned about the unit being top-heavy and easily to flip over. built the fuck out of it and there isn't even the slightest bit of wobble. def surprised me

 

and the CoG was a fucking guesstimate from the start...but things work wonderfully on the first attempt on the feet (CoG).

 

the frame in the back will hold 4" of OC705 rigid fiberglass insulation for some added absorption on the freqs below the diffusor cutoff

 

 

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That's cool an' all but I don't know if you're going to get much of a response from it now. You seem to have pissed off most of the people who actually have something worthwhile to say.

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Guest disparaissant

congrats! you seem like a prick.

 

edit: read the rest of the thread, confirming my hypothesis. there's a fine line between being helpful/educational and being a pretentious ass. you stomped all over that motherfucker. all over it.

all the fuck over it, holy shit.

 

brb listening to analord on my 15 year old pc speakers out of spite.

 

(converting to 96kbps mp3 first, natch.)

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congrats! you seem like a prick.

 

edit: read the rest of the thread, confirming my hypothesis. there's a fine line between being helpful/educational and being a pretentious ass. you stomped all over that motherfucker. all over it.

all the fuck over it, holy shit.

 

brb listening to analord on my 15 year old pc speakers out of spite.

 

(converting to 96kbps mp3 first, natch.)

 

rattled

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Guest fiznuthian

Thats fucking cool man. I take back every insult to you and your lossless ways, you're clearly hardcore.

 

the room is the single biggest determining factor in how your music sounds (or how your recorded music sounds)

the information is out there, but it seems like this is the one topic where you literally have to fucking force people to understand it, because no one believes it right away. ive never encountered a topic where i literally had to CONVINCE people of high school physics....you would think once you read the material that it would be a 'eurika' moment on how obviously beneficial it is. but it's not the case with anything related to audio...

 

no matter how nice of speakers of gear you put in your room, you still have fundamental room issues that dictate how things sound. and the best thing is -- people seem to think room treatments are the 'final touches' for rich people's listening rooms or high end studios ... when the real deal is, room treatments should be done FIRST. the best thing is, they're surprisingly cheaper than you could ever imagine --- everything can be done do-it-yourself....and there is tons of information and people out there to assist. on the forums i frequent, the people who sell commercial room treatments are the ones who assist the most with people building their own - it's wonderful.

 

ive spent very little money on room treatments and have a world of difference in sound quality, stereo imaging, etc...i know every analord hiss in and out and once i absorbed all my early reflections - im hearing even more details (like the slightest-ever pans, reverb hits, etc) ... it's great. if i were to upgrade my speakers it would cost ridiculous sums of money, and it still wouldnt address fundamental room issues. garbage in garbage out. the room has final say on everything you hear.

 

and no, EQ does shit. eq is like putting a band-aid on a stab wound. it's a nice 'final touch' but it's certainly not what you start with. if you'd like to no more why eq is garbage, speak up and ill go on.

 

this is very fascinating. i wouldn't mind at all if you continued to ramble on about room treatments and audio.

in fact please do continue about EQ

 

jeez guys stop eating him up, he's talking some cool and interesting information here.. acoustics is very interesting.

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Guest fiznuthian
just take a moment and make the effort to think about it...your speakers point towards your back wall. the sound traverses past your head (you hear the original signal) and continue until they hit the back wall where, because it's a flat boundary, all of the acoustic energy will then be reflected directly back towards the listener and the speakers (original source). as this happens, you have the obvious room mode which will dictate standing waves which will then dictate a series of peaks and nulls where that frequency will either be louder than the source, or out of phase with the source which will cause cancellations and you will not hear that freq (or itll be like -20dB). you also have the rest of the frequencies converging and causing comb-filtering. you do know and understand what comb-filtering is?

 

this paragraph just explained it all for me, and also explains why i never can find speakers that i like regardless of how much i spend on them.. i always end up moving my audio stuff to another room because some rooms make music sound awful. maybe i'm an audiophile just didn't know it

 

also i can understand being standoffish.. people mock audio enthusiasts often

there was a lot of that going on in the lossless debates on watmm..

its all pretty interesting shit anyway so who cares if someone obsesses over audio/listening quality

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its all pretty interesting shit anyway so who cares if someone obsesses over audio/listening quality

 

 

well, that's the problem

what one may consider 'obsessive', may be another man's 'normal work effort' into a project or hobby - and that drastically changes the attitude, doesnt it?

 

 

this paragraph just explained it all for me, and also explains why i never can find speakers that i like regardless of how much i spend on them.. i always end up moving my audio stuff to another room because some rooms make music sound awful. maybe i'm an audiophile just didn't know it

 

treating first reflection points and the back wall with heavy absorption has done more for me in regards to clarity of details, stereo imaging, etc than anything else i can think of.

the things that make the biggest differences are DIY and very inexpensive when compared to the costs of upgrading gear (and the upgraded gear still has the same fundamental problems because of the room).

 

you dont have to be an audiophile to comprehend high school physics

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Why don't you put some tube traps in the corners of your room? Standing waves and all that.

 

i use velocity based porous (broadband) absorption, vs that of tuned traps/helmholtz - but my place is small and as such my furniture dictates my living arrangement...so im not allowed to put a lot of this into practice just due to space constraints. maybe one day ill have a dedicated room.

 

the porous absorption (e.g. rigid fiberglass) is velocity based ... which means it is most effective spaced away 1/4 of the wavelength from the boundary --- in which particle velocity will be highest (and thus have that energy be converted into heat as it flows through the fiberglass, decreasing energy that will be reflected off boundary surfaces and interact with the source to form standing waves (peaks/nulls)). as a sound wave approaches a boundary (e.g. wall, ceiling), pressure increases as the wave slows down and is compressed before bouncing back...hence velocity based absorption right against the wall is ineffective as velocity of the wave particle approaches zero and makes your velocity based absorption ineffective. pressure is increased at the boundary which is why bass always sounds louder in corners/up against a wall. treating boundaries (multi-boundaries are even better, e.g. where 2 walls meet the ceiling or floor) is very effective, but you need to make sure you have an air gap for porous absorption to work effectively.

 

i use broadband absorption (4" thick OC703 insulation with an air-gap) at early/first reflection points. at higher/mid freqs, you dont need the panel spaced very far from the wall, but an air-gap is the closest thing you'll get to a free lunch. on the back wall i use 6" OC703 with a 2" air gap. this helps eliminate some nulls as well (based on where im sitting) and also eliminates comb-filtering from mid/high freqs bouncing off the rear wall and interacting with the original source.

 

people often only look at the frequency response but never take into account the time domain / decay times.

eq can't fix this

eq can fix/make your FR flatter at the listening position, but moving your head a few inches in either axis could result in a FR with a large delta/change. hence, it's more/less a band-aid for a very small listening sweet spot. it does help tame the lowest room modes tho, e.g. 40hz which is very difficult to tame with porous absorption. but it still does nothing for the time domain (decay times) once the waves egress the speaker and are in the room. eq is icing on the cake once the room is tamed.

 

what good is a flat freq response if you have a 500ms decay time at 80hz?

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  • 3 weeks later...

hey, found this video i thought i'd shart it

a lot of people hav difficulty understanding the temporal and spatial dispersion - but seeing it visually must be of some assistance on why it's beneficial

 

im building some 1D QRDs next, probably N13+4 model....dunno what i'll do with my 2D PRD (diffuser that this thread is about) .. my place isn't very big !

keep you posted on the builds

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my favourite listening environment is the bottom of a stairwell, music coming out of someone's cellphone and a few beers to go.

 

all this stuff is ridiculously subjective and our ears are very capable of adjusting to our environment. not saying your wood thingie doesn't look cool but reading your posts gives me a headache. no amount of bringing up comb filtering and math as an argument justifies a shitty-ass attitude.

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