Good, better, best budgets for room treatment
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Wow. Even as a woodworker I cringe at the thought of building diffusers. My hat is off to you.
You a woodworker?? Thought you was a computer/software nerd!!
Can I blow my own trumpet slightly?? Now I think of it, I did not mention this in this thread at all.
these are rather unique PRDs. Firstly, you will notice the well dividers between the wells. The maths only really works as predicted with the dividers in place. I think the use of no dividers really came about from the BBC document, their main emphasis was to produce them easily and cheaply, so not only did they remove the dividers they also only had four or so levels of depth. Additionally, there use was only to stop the vertical slap between the floor and ceiling, and their crude version worked well enough in that application.
Those you saw were prime 157, so 156 wells. The proper number of levels is 156, ie no two wells having the same depth.
Even the ones you buy from RPG have only (as far as I can work out) about 17 differing levels, and of course no well dividers.
The ones in my pic do have 156 differing depths there, and well dividers. So, in the world of PRDs it is unique in those regards anyway, at least I have yet to see any other PRD with wells, and have yet to see any build that had full quantisation of depths like this one.
It is really weird talking in front of them, you can hear the space around you open up (when compared to talking to a flat panel of the same size that is) so I am excited and hopeful of the results they may bring.
Now, this is where I am quite proud and where I did get clever. This, again, has never been done before.
What you saw was the FRONT of the PRD, I have also utilised the space behind that and have an INVERSE PRD that is fully operational.
Not only is that clever in itself (even tho I say that myself, but it is clever I think) it makes it very easy, quick and light to build!!
Why have an inverse behind it?? My room is very large, with a lot of space behind my chair and to the side. My plan is to set these up at the correct distance for their depth from the chair, but have a series of them set apart from each other...ie gaps and spaces between the diffusors.
Kind of in a horseshoe pattern ringing the seat if that makes sense.
So the incident sound will diffuse from them across the LP, and the (biggish) gaps between them allow some sound thru to hit back and side walls, reflect back and hit the back of the diffusors to be diffused back to the walls, reflected again and on the cycle goes. Some of the reflected sound passes thru the gaps each time to hit the LP, conceivably some of the sound that hits the seat has been reflected and diffused many many times before reaching my ears.
A bit hard to explain in words, when it is done I will certainly show pics, it will become clearer then.
Anyway, for those more interested in the how and why etc, and the simple way to build these accurately, here is the thread.
http://www.gearslutz.com/board/bass...ilds-new-technique-interesting-variation.html
Some pics in that thread show the PRD from the front as well as the back, you can then see the two diffusing surfaces.
Every nerd needs to do something primitive to feel like a real personYou a woodworker?? Thought you was a computer/software nerd!!
. For me, that is woodworking and smoking meats. OK, clearing my field and gardening falls in there too . My woodworking gear rivals my small theater in cost btw with swiss made table saw and such .
A strange and small world... I have a collection of woodworking tools in storage (lost my work room when we redid the basement, but gained a media room). But, I resist the term "nerd" -- "geek" maybe, but I'm not a nerd! I used to ride in rodeos; nerds don't do that, but a geek, well...
I had in mind much simpler diffusors, but now terryj (durn you!) has me thinking bigger... Those would really help my room. Hmmm...
I used to ride in rodeos; nerds don't do that, but a geek, well... I had in mind much simpler diffusors, but now terryj (durn you!) has me thinking bigger... Those would really help my room. Hmmm...
A strange and small world... I have a collection of woodworking tools in storage (lost my work room when we redid the basement, but gained a media room). But, I resist the term "nerd" -- "geek" maybe, but I'm not a nerd!
I had in mind much simpler diffusors, but now terryj (durn you!) has me thinking bigger... Those would really help my room. Hmmm...
Glad to be of service!! hahaha (fiendish laugh)
I presume you looked at how it was done? If so, and you have further questions, then shoot. I have not updated it yet (still playing with systems changes at the moment) and there are a few things that you'd need to know.
But, you also could very well be up to it if you have the woodworking skills.
Most people would never have the need for the two sided nature, ie they would place them on/against the wall as normal. Even in that case, that method of building still has it's advantages, namely very light weight.
The '''normal''' method of building without fins forces you to use solid lengths of wood to get the varying heights. As you can imagine, that makes it very heavy indeed. AND, you have no fins (tho if you wished you could still have 156 discrete depths via that method, depends on your level of patience).
So, even if you want it against the wall this method makes it lighter and almost as quick, with the added performance benefit of the fins.
The only other advice would be how to design it. Either browse the forum there in the room treatment section or shoot a question here. I can then give all the links and tools, plus a design procedure for you and others.
The lighter weight is very appealing, although the build time is probably much longer (judging from your other "blog" and guessing at the work to glue all those fins and baffles in place). I already have about 20 steel-framed panels in my room, and am a bit worried about all that weight on my suspended (isolated by Kinetics IsoClips) walls and ceiling. I have built diffusers in the past from wood and various other materials (including using light weight plastic "bricks" from a toy store, building a "shoebox" frame much like yours and then adjusting how far the "bricks" go in), to save weight. Hadn't thought too much about them, but after seeing the prices on decent new ones I am thinking of building again. My room is a little too dead right now, though the resulting image is amazingly stable and the sound is very clean.
I was thinking of using some sort of slots cut into the frame and "end" pieces so they would interlock. Easy to cut but probably doesn't really help much except save some assembly time (offset by the time to saw the slots).
The most important thing you've done for me, and perhaps others, is to demonstrate an interesting approach and get me thinking on how I might add a bit of "air" to my room, for which I thank you! - Don
I was thinking of using some sort of slots cut into the frame and "end" pieces so they would interlock. Easy to cut but probably doesn't really help much except save some assembly time (offset by the time to saw the slots).
The most important thing you've done for me, and perhaps others, is to demonstrate an interesting approach and get me thinking on how I might add a bit of "air" to my room, for which I thank you! - Don
go to woah I'd estimate about six hours to build mine?? anyway, that may help decide if that is too long.
Re the weight, there is nothing to stop you using polystrene, prob you can get that from hardware stores? Most guys who use polystyrene use the dense stuff (often blue) rather than the normal white. That is because with a diffusor it needs to be reflective, so denser is better.
However, I'd still use the white stuff. I have experimented a bit with that. What I did was paint it with concrete glue, that has paint tint in it! The concrete glue is water soluble, so you need the correct tint type.
Use a roller to do it. You get the colour you want, AND glue them together at the same time.
To get back the denseness needed for the diffusion, and to have a nice look, I'd then simply glue square pieces of ply, mdf painted, whatever it is you want as the final finish on top of each 'skyscraper' piece of foam.
Nice hard finish to the top, easily cut foam on the panel saw you use (use exactly the same setting for the wood pieces as you did to cut the foam, then a drop saw to cut the squares...will be exact then) and easily glued together whilst colouring the foam to suit.
You know which calculators etc to use??
Ha! Maybe we should have this transferred to the DIY section
Re the weight, there is nothing to stop you using polystrene, prob you can get that from hardware stores? Most guys who use polystyrene use the dense stuff (often blue) rather than the normal white. That is because with a diffusor it needs to be reflective, so denser is better.
However, I'd still use the white stuff. I have experimented a bit with that. What I did was paint it with concrete glue, that has paint tint in it! The concrete glue is water soluble, so you need the correct tint type.
Use a roller to do it. You get the colour you want, AND glue them together at the same time.
To get back the denseness needed for the diffusion, and to have a nice look, I'd then simply glue square pieces of ply, mdf painted, whatever it is you want as the final finish on top of each 'skyscraper' piece of foam.
Nice hard finish to the top, easily cut foam on the panel saw you use (use exactly the same setting for the wood pieces as you did to cut the foam, then a drop saw to cut the squares...will be exact then) and easily glued together whilst colouring the foam to suit.
You know which calculators etc to use??
Ha! Maybe we should have this transferred to the DIY section
Hmmm... I have a vague memory of using the blue stuff in the past, don't recall the paint. As for the calculator, if you have some good links or references you'd care to share that'd be great. What I have are equations/alogorithms in various texts (I think, have not looked recently) and pretty good calculation tools (Matlab, Mathcad). What I don't have (despite appearances) is a lot of extra time. However, 6 hours is not bad -- a one-day build.
I have killed the front wall (behind my bipolar speakers) and early reflections (walls and ceiling), plus have a couple of thicker (6") panels on the back wall and ceiling to handle the rear surrounds (my surrounds are behind me; combination of room issues and using Magnepans -- can't put surrounds on the sides of the couch due to door/window issues, and Magnepan suggest putting them on a rear wall, which works well for my room). What I have left are a couple of room modes at 40 and 50 Hz ('ish) that are putting a big notch in the response, and a room just a little deader than I'd like. I am planning to tackle the notch first, if I can, then add some diffusion to liven it up just a bit.
I have all these great tools and references, a lot of prior experience (very old, unfortunately, since I have not done this for a decade or two), and the lingering thought that my calculating little pea brain is outstripping my reason... I might ping Ethan's company again with my pix and drawings to get some feedback, or contact a local acoustician with more toys, oops, I mean "tools"! I don't mind paying a little for expertise and experience; it's what I get paid for, after all. - Don
I have killed the front wall (behind my bipolar speakers) and early reflections (walls and ceiling), plus have a couple of thicker (6") panels on the back wall and ceiling to handle the rear surrounds (my surrounds are behind me; combination of room issues and using Magnepans -- can't put surrounds on the sides of the couch due to door/window issues, and Magnepan suggest putting them on a rear wall, which works well for my room). What I have left are a couple of room modes at 40 and 50 Hz ('ish) that are putting a big notch in the response, and a room just a little deader than I'd like. I am planning to tackle the notch first, if I can, then add some diffusion to liven it up just a bit.
I have all these great tools and references, a lot of prior experience (very old, unfortunately, since I have not done this for a decade or two), and the lingering thought that my calculating little pea brain is outstripping my reason...
I might ping Ethan's company again with my pix and drawings to get some feedback, or contact a local acoustician with more toys, oops, I mean "tools"! I don't mind paying a little for expertise and experience; it's what I get paid for, after all. - Don
We're very good with email, so if you or anyone emails and doesn't get a reply, it must be an email problem with either our or your email being flagged as spam. In that case please just call us on the phone!
I just checked Jim's email account settings and he has no spam filtering in place, meaning he gets everything sent to him even if it's deemed "highly likely" to be spam. But this is a new system put into place only a few months ago, so I can't say what might have happened before that. We get customer inquiries from all over the world, including Russia and China and other common spam sources. So we're very conservative about spam settings to not lose anything legit.
--Ethan
Pretty much right. You can control them to some degree with room treatment, but for fundamental LF modes it takes a LOT of treatment, more than most if us can or are willing to do. I think Ethan would say the same.
In my case, my listening position is about in the center of the room and I think where one of the modes has a null. I am thinking by adding some treatment right around the couch I can reduce the impact somewhat. I damped the early reflections and front and rear walls, but not right at the listening position (didn't think it needed it). I have some extra panels (not covered) so plan to prop them up, measure, and see if it helps. Part of the problem is that LF modes often require big bass traps in the corners, and there's no room in my rear corners (window and door too close).
Ethan, it was a couple of months ago (maybe three), and best I recall there were some glitches in your website when I tried to upload so I tried email. I have had issues now and then and have little doubt it was on my end. Yours was one of two "commercial" companies I was advised to contact, and I had no personal experience with either (I have worked with Mason, Kinetics, and some other professional "industrial" suppliers). I should have tried harder. I thought I had time to go back and forth, then got swamped with work stuff and went with another firm after some correspondence. No reflection on you or Real Traps. I did get good service from Ready Acoustics and am happy with the end result.
As I think on it now (in hindsight) I should have left that comment off -- I put it in to flag that your price might have been higher because I did not get any sort of consultation that might have directed me to a different scheme that might have saved money (or cost more, who knows?) Not to highlight a contact problem that was probably my own. I was going to go back and delete or modify it, but since we now have a couple of posts it's probably best left alone (?)
My apologies - Don
As I think on it now (in hindsight) I should have left that comment off -- I put it in to flag that your price might have been higher because I did not get any sort of consultation that might have directed me to a different scheme that might have saved money (or cost more, who knows?) Not to highlight a contact problem that was probably my own. I was going to go back and delete or modify it, but since we now have a couple of posts it's probably best left alone (?)
My apologies - Don
Don, if you're in a standing wave null moving the couch a couple feet is likely the least painful solution. They're different than reflections or standing wave peaks. You can't absorb them, diffuse them or knock them down with EQ. Going after a null with EQ is like trying to fill a black hole.
Uh, I agree, I think that's what I said; it's certainly what I meant. <pause to read what I wrote> Yeah, OK, I see now -- fingers typed babble that brain did not mean, sorry. I wish I had the excuse I did not understand acoustics, but my grad text is on the shelf behind me, laughing, along with all those years spent in the field, and I really do know better... This is my third stoopid mistake in a post on various forums today; think I need more sleep (less work, something!)
I have been able to make minor corrections with various panels (not absorbers) that serve to physically move the null a bit, but the impact is very minor and only helps in a room big enough that you can effectively change the physical dimensions without intruding into the listening space (think large auditoriums, churches, concert halls, etc.) Doing something like that in a relatively small room (which describes almost any room in a house) is an exercise in futility -- not enough room to do what needs doing, and you'll just create some other problem (push in on a balloon, the other side pushes out). I agree EQ is worthless -- the null is a null, and remains a null no matter what amplitude you try to throw at it. (For those who aren't aware, the null is due to wave cancellations in the room, bouncing off the walls/floor/ceiling and combining destructively, and there's really nothing you can do about them -- cranking up the gain does not matter because it all gets canceled in the room. The black hole analogy is very apt.) Massive damping can help some by de-Q'ing the null slightly, which tends to spread it just a little and make it hair shallower, but you're really just pissing in the wind (farm boy expression).
Moving the couch is the best solution but not real practical in my room -- space constrained. I may rethink things a bit. My original plans called for prime dimensions, but the room shrank to accommodate an additional bedroom for my younger son and a bit larger game room when we finished the basement a couple of years ago, with the result that two dimensions doubled up and now I am paying the price. What I need to do is perform a few more calculations and some measurements to see how far I can move the couch and what the impact will be. At least nulls tend to be fairly narrow.
The good news is that the room is within about +/- 6 dB (on a 1/3-octave smoothed plot) from 10 Hz to 20 kHz after treatment and some fiddling with the speakers and AVR's EQ settings, and less than +/- 3 dB if you discount that null and the tweaking I did to increase the frequencies on either side of it (I shelved the bass a little hotter). And, by floating the walls and ceiling as best I could and insulating well, there is almost no sound transmission to/from the room except for very heavy footfalls on the room above (could not completely float the ceiling; will next time!) I can crank it at midnight and my son can barely hear it in his room (the one next door that took away my prime-ness!) with his fan off.
Ah well, at least I should have tomorrow off! Thanks for the correction and gentle reminder to think more before I post. - Don
I have been able to make minor corrections with various panels (not absorbers) that serve to physically move the null a bit, but the impact is very minor and only helps in a room big enough that you can effectively change the physical dimensions without intruding into the listening space (think large auditoriums, churches, concert halls, etc.) Doing something like that in a relatively small room (which describes almost any room in a house) is an exercise in futility -- not enough room to do what needs doing, and you'll just create some other problem (push in on a balloon, the other side pushes out). I agree EQ is worthless -- the null is a null, and remains a null no matter what amplitude you try to throw at it. (For those who aren't aware, the null is due to wave cancellations in the room, bouncing off the walls/floor/ceiling and combining destructively, and there's really nothing you can do about them -- cranking up the gain does not matter because it all gets canceled in the room. The black hole analogy is very apt.) Massive damping can help some by de-Q'ing the null slightly, which tends to spread it just a little and make it hair shallower, but you're really just pissing in the wind (farm boy expression).
Moving the couch is the best solution but not real practical in my room -- space constrained. I may rethink things a bit. My original plans called for prime dimensions, but the room shrank to accommodate an additional bedroom for my younger son and a bit larger game room when we finished the basement a couple of years ago, with the result that two dimensions doubled up and now I am paying the price. What I need to do is perform a few more calculations and some measurements to see how far I can move the couch and what the impact will be. At least nulls tend to be fairly narrow.
The good news is that the room is within about +/- 6 dB (on a 1/3-octave smoothed plot) from 10 Hz to 20 kHz after treatment and some fiddling with the speakers and AVR's EQ settings, and less than +/- 3 dB if you discount that null and the tweaking I did to increase the frequencies on either side of it (I shelved the bass a little hotter). And, by floating the walls and ceiling as best I could and insulating well, there is almost no sound transmission to/from the room except for very heavy footfalls on the room above (could not completely float the ceiling; will next time!) I can crank it at midnight and my son can barely hear it in his room (the one next door that took away my prime-ness!) with his fan off.
Ah well, at least I should have tomorrow off! Thanks for the correction and gentle reminder to think more before I post. - Don
Every nerd needs to do something primitive to feel like a real person
There is nothing as therapeutic as playing in the dirt.
Intelligent <> smart, or Stoopid is as Stoopid does...
Maybe this should go in the "embarrassing moments" thread, but I started here so I'll finish it here.
After my exchange with LesAuber, I had couch position in my mind when I went down to my media room this afternoon, first time I've had any real time there in the past couple of weeks. I have spent quite a bit of time off and on, tweaking it in originally, then again after installing room treatment a couple of months ago -- including hours of measurements and adjusting speaker positions and AVR settings. The last thing I did was to manually tweak the AVR's EQ/PEQ settings to optimize (flatten as best I could) the measured response, while adjusting for best listening (image and such), and I was happy with the results, mostly.
The one thing I noticed was a big dip in the response from about 40 to 50+ Hz, corresponding to a couple of room modes that happen to double up due to room dimensions. An annoying place; a low bass guitar string is at 42 Hz, and a lot of music puts plenty of information in the 40 - 60 Hz region as many speakers roll off below that, and that band will give the "feeling" of bass to most people without having truly deep bass (recording engineer trick).
Now, I knew of this null, and had previously performed calculations followed by tweaking the listening position (couch) to reduce the impact. After adding room treatment, the null seemed worse than before, but since there was a peak at 60'ish Hz I assumed it was because I had flattened the upper bass so the null just seemed worse. I spent many hours measuring and tweaking to get everything as close as possible, but somehow the sound never seemed quite as good down there as I remembered from before treatment, a very frustrating experience. Everything was great but that hole, right where I didn't want it, and right where I had spent so much effort minimizing it. Why would adding room treatment make it worse? At worst, there should have been no change; at best, all the treatment should have reduced it very slightly and spread it a hair by dropping the Q... So what happened?
I moved the couch.
Yup, when I was installing the room treatment I moved the couch back and pulled the equipment console out to provide access behind to mount the panels on the front wall, then left it as I was installing a new AVR and amp in a week or two. Got the new toys in, moved the console back and dialed everything in, forgetting after all that time that the couch was about 18" further back than it had been.
Moved it back today, and got my sound back! At least it sounds better; I'll have to wait another couple of weeks (work etc.) before re-running my measurements and tweaking everything in. Again. But, this is where I had the couch before to escape the worst of the null, so I am confident things will be even better after hauling out all my gear and dialing it in again.
"Never underestimate the power of human stupidity." - Heinlein
Or forgetfulness! - Don
Maybe this should go in the "embarrassing moments" thread, but I started here so I'll finish it here.
After my exchange with LesAuber, I had couch position in my mind when I went down to my media room this afternoon, first time I've had any real time there in the past couple of weeks. I have spent quite a bit of time off and on, tweaking it in originally, then again after installing room treatment a couple of months ago -- including hours of measurements and adjusting speaker positions and AVR settings. The last thing I did was to manually tweak the AVR's EQ/PEQ settings to optimize (flatten as best I could) the measured response, while adjusting for best listening (image and such), and I was happy with the results, mostly.
The one thing I noticed was a big dip in the response from about 40 to 50+ Hz, corresponding to a couple of room modes that happen to double up due to room dimensions. An annoying place; a low bass guitar string is at 42 Hz, and a lot of music puts plenty of information in the 40 - 60 Hz region as many speakers roll off below that, and that band will give the "feeling" of bass to most people without having truly deep bass (recording engineer trick).
Now, I knew of this null, and had previously performed calculations followed by tweaking the listening position (couch) to reduce the impact. After adding room treatment, the null seemed worse than before, but since there was a peak at 60'ish Hz I assumed it was because I had flattened the upper bass so the null just seemed worse. I spent many hours measuring and tweaking to get everything as close as possible, but somehow the sound never seemed quite as good down there as I remembered from before treatment, a very frustrating experience. Everything was great but that hole, right where I didn't want it, and right where I had spent so much effort minimizing it. Why would adding room treatment make it worse? At worst, there should have been no change; at best, all the treatment should have reduced it very slightly and spread it a hair by dropping the Q... So what happened?
I moved the couch.
Yup, when I was installing the room treatment I moved the couch back and pulled the equipment console out to provide access behind to mount the panels on the front wall, then left it as I was installing a new AVR and amp in a week or two. Got the new toys in, moved the console back and dialed everything in, forgetting after all that time that the couch was about 18" further back than it had been.
Moved it back today, and got my sound back!
At least it sounds better; I'll have to wait another couple of weeks (work etc.) before re-running my measurements and tweaking everything in. Again. But, this is where I had the couch before to escape the worst of the null, so I am confident things will be even better after hauling out all my gear and dialing it in again."Never underestimate the power of human stupidity." - Heinlein
Or forgetfulness! - Don
steve williams
Site Founder, Site Owner, Administrator
i think cost depends on if you want aesthetics or not. buying basic traps and panels from GIK isn't costly at all. add RPG BAD panels for the ceiling and a QRD diffusor in the back and you have a pretty decent room---but it looks like a studio to me.
if i had gone the cheap route, i would have saved several thousand dollars---but i had carpenters make my ceiling tiles and polydiffusors (floor to ceiling). i also used a 3-span of art panels which costs about 3-4x what normal panels cost---but looks outstanding and is even on the GIK website. i learned a lot and would change a few details if i did it again- in particular, less costly polys behind the speakers. bass traps are ridiculously easy to make and are cheap---costs like 650/each and that was custom floor to ceiling that disappear into the room.
i used Rives, just a L1---i think it was money well spent. although next house i will find a particularly good room to start out with (dimensions) which will require less treatment. i can pretty much use everything from this build in the next one as well which is nice.---despite the custom treatment.
if i had gone the cheap route, i would have saved several thousand dollars---but i had carpenters make my ceiling tiles and polydiffusors (floor to ceiling). i also used a 3-span of art panels which costs about 3-4x what normal panels cost---but looks outstanding and is even on the GIK website. i learned a lot and would change a few details if i did it again- in particular, less costly polys behind the speakers. bass traps are ridiculously easy to make and are cheap---costs like 650/each and that was custom floor to ceiling that disappear into the room.
i used Rives, just a L1---i think it was money well spent. although next house i will find a particularly good room to start out with (dimensions) which will require less treatment. i can pretty much use everything from this build in the next one as well which is nice.---despite the custom treatment.
My theater room is a bit of an audiophile nightmare.... Washer, dryer, and furnace in a side closet space for noise (winter sucks with the furnace coming on a few times per hour), sliding glass door on the back wall and a picture window on the front, two doors on each side wall (one is metal), and a side-closet with a gun safe that mostly doesn't buzz or rattle. Oh, and I can't forget the wood cabinets on the opposite side from the safe closet with the loose fitting doors. Used a lot of felt stick on pads to make those stop buzzing. Also the whole room is full of stuff because the house is small. I think the easiest solution to all these problems is to get a new house. I've looked at accoustical treatments and they seem to be designed for rooms with less doors, windows, cabinets, bookshelves, laser disc and vinyl storage racks, cd cases, etc. I think the clutter is probably working to my advantage, but I don't even know where to begin with this room because I don't know how to identify what is a problems are and aren't. The metal door on the side wall just a few feet to the side and in front of my seat might be a good start, but how do I mount an accoustic panel to a 20 min steel fire door (door to garage)? Maybe I should just use headphones so my only problems really will be in my head and a good decongestant clears up everything but the voices.
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