Acoustical Treatments Master Thread - Page 264

"other mathematical techniques". hmm. sounds like marketing.

do they provide: polar responses, absorption coefficients, scattering coefficients, normalized diffusion coefficients, etc?


not sure how they are claiming 800hz "diffusion" with only 3" well depth. do they have a polar response @ 800hz?

have you toyed around with QRDude? if you are capable of some wood-work you would be much better off with constructing some schroeder QRD or PRDs. you can fine tune the design to your requirements (physical size, design freq, HF cut-off, etc)...and their performance is proven (and can be modeled with AMFG Reflex).

Auralex used to publish test data. It disappeared from their own web site a couple years ago, and from re-seller web sites some time in the past year.

right on.

if someone you know owns that product, ask if they could take measurements of it - and we could quickly model it into AMFG Reflex to gather an idea of the performance.

QRD/PRDs are tried and true. and the performance speaks for itself. you can also fine tune the design based on your requirements (design freq, period size, etc). if you're up for a challenge and have some work-working skills, maybe constructing your own would be something to look into

I like the DIY idea, though I admit: I'm better at rough carpentry (framing a wall) than fine finishing (I outsourced the mudding after I hung my own drywall).

I certainly meant nothing malicious by doing so. I merely wanted to reiterate that there are individuals that are adamant about taming 'early reflections'.

Since DE and I first disagreed wrt early mirror point energy (I suggested it be attenuated, he claimed not necessarily), I've continued extended subjective experimentations with all my treatments down in order to gain as much perspective as possible in the only room that matters to me. I've got Toole's Sound Reproduction, Everest's Handbook, I've read a great deal on Gearslutz and elsewhere,... I'm experimenting with several different mains, and mains optimization techniques. I like envelopment, spaciousness, however I value clarity and image specificity as well.

I've found localhost's posts very solid and quite enlightening wrt small room acoustics. Just as localhost's post have been very helpful to many, so has several other contributors here, and for that I'm grateful. Now retired, I've entered into this deep foray back into home audio because I decided to re-vamp the modest family AV room from bottom to top. I've always had small dedicated mixing/editing/mastering rig and the primary family system has been quite mid-fi in quality. For the family room, a new big IB, new mains, surrounds, front end source and pre/pro, and ultimately,..strong acoustic properties are all immediate priorities. This, in a non dedicated space has proved to be quite a challenge.

Anyway, I changed the quote to suit my point I wanted to make, that's all. I certainly didn't want to piss anyone off, as I'll likely be in need of more specific advice, from many of you, when the time comes

Thanks

^^^

FOH, you'll like your IB sub, some guys here have dual line array 4 x 18FI (penngray is one in my memory). My modest 4x15 single line array never ceases to amaze me.

I've very much enjoyed reading about your room in general, and more specifically your IB and various acoustical treatments. I do have a question for you or anyone; I've seen different acoustical cotton products and I really like the idea of trying them in a couple applications. I've got a great source for rigid fiberglass, however I looking for a good source for acoustical cotton,..any help in this regard?

Thanks

... bookmarked yet another of your posts!

Jeff

I've used this as a source for acoustical cotton, http://www.acoustimac.com/index.php/...oinsul422.html

From another post I made

+1, +2, +3, ....:d

Thank you sir.

Is there a reason you want acoustical cotton over rigid fiberglass? If because of the air quality or "itchy stuff" stuff then check out Knauf rigid fiberglass.

Cool, I'm down the road from the Knauf plant

dirt cheap deep pink fluffy corner traps (although they need to be fluffed out a bit better). and the plastic will reflect some highs back into the room.

Nice localhost!

Makes me wonder about the performance of the above mentioned big rolls of insulation, merely set into a room corners etc. Anyone familiar with such a temporary approach? It'd be interesting to know how well they perform. I realize they are bound a bit too tight, however I'd think they'd work to some degree.

You know how one brings a bottle of wine as one visits an acquaintance? Well, during these multi-sub, multi enthusiast subwoofer shootouts that are hosted on occasion, instead of wine, each attendee should bring a huge roll of insulation as a party favor. Strategically place them around the room, then upon completion of the GTG, the host gets to increase their attic insulation significantly

Rolls of fiberglass work. Kind of hard to make look nice though. Here is a room I found on you tube
http://www.youtube.com/watch?v=DsJVHcb9k4c

such a waste when compressed. i made those 6 pillows with a little over 1roll of the smaller rolls of insulation (!). the point of compressed is to make the traps very thick of low GFR - and to cover as much sq area as possible. leaving them compressed somewhat defeats all of those purposes. it looks like that guy is using the larger (standard) rolls of r30 insulation. i bet he could cover all corners with 48" faced (16"+ thick) fluffy traps in plastic wrapping with about 1/3rd of the rolls he has in that room stacked.

I think you guys might really enjoy this video done by Zalan Schuster. I appreciate not everyone can speak Slovakian but it has some audio demonstrations starting around 3:35. Before hand he has some nice before and after test graphs of the room.

Is that a ... railroad car???

ive read some say that maintaining early reflections (in small acoustical spaces) offers more "spaciousness" or other characteristics. my question is, do large rooms not offer such "spaciousness"? large rooms do not have early-reflections, so why is it that in larger rooms we do not see an effort to induce early reflections towards the listening position - if they are indeed so critical to spaciousness?

something fundamental that i think is constantly missed regarding attenuating early reflections is that you are changing the brain's perception of how large the room is. the longer the distance between the original signal and the first loud specular reflection, the larger the perceived room size. one can essentially "cheat" by artificially delaying this first specular reflection (in the time-domain) to make the room sound larger. this logic is taken to the extreme with anechoic spaces - where the first loud specular reflection after the original source is an infinite time away - making the room sound infinitely large. of course, our brains do not prefer this - but the brain has never been put in such a situation in the real world, anyways...as such an event (no reflections from any boundaries) does not exist in the real world that we would be constantly subjected to.

also perhaps what goes unnoticed is that in music, the `room' that the music was recorded in is already present on the recording. early reflections in your listening space mask the sound of the room that the music was originally recorded in. you are hearing the reflections of your small acoustical space's boundaries earlier than the reflections from the room the music was recorded in - and therefore are 'hearing' your room instead of being mentally transported into the room of the recording.

this is why in a control room, the ISD-gap needs to be a few ms longer than the ISD of the room of which the music was recorded in. otherwise, the control room itself is masking the sound of the recording. the design for making the control room as neutral as possible can be directly related to critical listening rooms - if that is one's goal.


have you anything to report regarding your own personal experimentation, FOH?

Aren't large rooms already by definition spacious? They wouldn't need to simulate largeness - they already are large.

The difference lies in the delta between arrival times and the decay of the reflected sound over time/distance.

my question was, if we are attempting to create 'spaciousness' in a small acoustical space (emulating a 'larger room'), then why do we inhibit early-reflections which are not present in larger rooms (by definition).

im just trying to understand what the ideal specular response is when one induces (or maintains) early reflections in a small acoustical space - so i could recreate for my own personal testing.

can you elude any further to what the delta times should be?

i already have these answers for RFZ/LEDE room models, but for my own testing i'd need to know what the ideal specular response should look like when incorporating early-reflections, so i can verify that i am testing properly - for comparison. thank you,

In theory - I have however gotten great results with corner stacking of these Cellulose bundles ($8 each- home depot) - has greatly reduced low end energy /bass decay in that corner (concrete)
- don't mind the mess -back of room is currently experimental center
I am now trying out different combos of 4 bass traps (made from OFI-48)
I have great low-end response now in room (34L/12.5w/7.5h with large opening in back ) but always tweaking

if you have enough of those Cellulose bundles lying around, may i suggest an experiment? stack them floor to ceiling like you have now, but stack them 2 units wide (you'll have to bring them out from the corner a bit to be able to fit 2x bundles wide - and they'll be straddling the corner)...but bringing them further away from the boundary and making a wider trap could really increase effectiveness.

may be a fun experiment if you're interested

Yes - I found that as well as straddling my DYI bass Traps diagonally - floor to ceiling in that same corner all had very similiar results
I will probally end up doing corner chunks (fabric covered) and nicely made traps covering the back wall for nice compromise between performance and aesthetics

I Have Some Queries here in India.
My Room size is 25*15.5*9.5(height)(Sizes in feet).It's a basement room.It's
a corner part of basement i.e with no adjoining basement on 3 sides.My Room
is Bricked from all 4 sides.I have a lot of echo in my room.

I am getting Fibre Glass Sheets 2*3 feet
48kg/m3 in 2,3,4inch.
Q1 Which is preferred?
Q2 For Making Membreane Bass Traps, (as explained in Ethan Winers Page),Can I Use Laminate(For Decorative) on top of plywood?
Q3 Can sheetrock be used over fibreglass for more effectiveness?Can Someone Explain it's use? and How To Place it?
Q4 What Should Be Done to absorb all lower frequencies?
like changing Thickness of fibre glass, changing the air gap, placing the top plywood with some angle?

Q5 Should the plasterd bricked walls be first covered with plywood for placing glass wool or can be directly placed on the wall for medium and high frequencies absorbing?

Please Help Me With This and help me build my Theatre Room?

Thanks In advance