# Room acoustics talk



## Dan Mott (Oct 26, 2011)

So I'm trying to get my room in oder here. Taking a break from doing music and trying to get the best sounding room I can.

I'm in a 12 by 11 foot room. I'd say that's medium..ish.


Now. I have rencently changed spots in the room and I really want to sit in this certain spot because of the layout. I have noticed that I have standing waves at about 310Hz and it's very unpleasing. I listened to a track I knew well and that frequency resonated so bad that it drowned all the other instruments out. I have no idea what the cause of this is. I tried moving around the room and touching things to see if the frequency was resonated on to something and I couldn't find the issue. Back in my normal spot I didn't have this problem. I have other issues going on, but no where near as bad from 100Hz to about 600Hz or so, but this is normal because my room isn't treated yet.

The reason I moved spots is that if I stayed in my oringinal spot, I then couldn't treat my first reflections from the side walls. On the right of me I had a window with I blind I pull down and on the left and had a wardrobe with little areas for clothes, therefore I couldn't treat them because there's no way of putting panels up on the areas. So I moved to a new spot which is on the longest wall in the room and both sides of me have walls that I can perfectly treat. In my original spot I had a plain wall behind me, but now In my new spot I have the wardrobe behind me and the window infront with the blind down.

I have read about treatment in rooms such as mine and there are some things you just can't get passed in a bedroom, but treating first reflections is most important. I suppose the ceiling would be next, treating the cloud above you, then finally the back or front wall. So now I'm able to treat the first reflections but I have no idea if they would stop that big 300Hz resonance. Now I'm not going to make any panels my self, I don't know how and I'm really not handy at all, but I will invest in some custom made broadband panels here in AUS so that's no issue. I will be needed some bass traps which I have found some great custom made ones too. 

I did a pink noise test and looked in a freq analyser to see what was going on. Then I just had a blind listen and cut the problem freq and made it even. 300 was a big stand out.

I just want to get down to the bottom of this 300Hz thing, it made me not enjoy one of my fav songs!!

Should I move to my original spot I cannot treat? 

Any adivce here? I'm passionate about good sound.


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## dannthr (Oct 26, 2011)

The speed of sound is 1125 feet per second, with variances made for air pressure density/temperature.

With that in mind the wave-length of a frequency is 1125/frequency.

So 1125/310=3.6 feet

My guess is that you're probably located 1/3 way down the 11 foot width.

Your biggest problem is going to be having waves that bounce off of your walls and build upon themselves.

Go here.
http://www.marktaw.com/recording/Acoustics/RoomModeStandingWaveCalcu.html (http://www.marktaw.com/recording/Acoust ... Calcu.html)

Ideally, you will need to change how waves reflect into your listening spot.


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## bryla (Oct 26, 2011)

The optimal position is to sit 38% from the wall in front of you.

The problem you're experiencing is called a room mode. As Dan points out, the frequency that is resonating, is resonating because it doubles in amplitude on the return from the reflectinal wall. Similarly you'll have frequencies that dips in amplitude.


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## Mike Greene (Oct 26, 2011)

The easiest solution is to just move to a position where things sound good. There's no rocket science in that, just experiment. The room is flawed (since it has a heavy resonance at 310hz,) so any textbook theory about optimal positions gets thrown out the window.

To actually fix the room (which is what I would recommend,) you need to install resonators. Resonators are basically the same idea as regular sound absorption panels, except they can be "tuned" for specific frequencies.

Google "Helmholtz resonator" to find how to build them. If you have basic carpentry skills, it's a pretty easy project. They're basically boxes (say 2' by 4' by 6") stuffed with fiberglass and with holes drilled into the face panel. This face panel is usually "hardboard," which is that thin stuff they make pegboard out of. The size and quantity of the holes is what determines the frequency the resonator works at. Pegboard has way too many holes, so get hardboard and drill them yourself. (Hint - if you're making more than one - and you should - then stack the hardboard sheets and drill several at once.) Cover them with cloth so they're not so ugly. The kind of cloth matters very little so long as it's not some thick stuff, so just get something cheap that looks good.

It sounds like voodoo, but it really works. In my second studio (the one before this one,) I had just finished construction. I hadn't started any of the acoustic treatment or decorating, but I was anxious to see how the room sounded, so I brought in my mixer, speakers and a drum machine and a couple synths. I played a snappy kick drum and . . . it rang for about two seconds, as if it was an 808 boom kick! It was so bad that it didn't even sound like reverb, it sounded like it was actually coming out of the speakers that way. I checked and checked and ckecked that my drum machine wasn't malfunctioning and playing hip hop kicks. (I used to do lots of rap.)

I brought in a synth so that I could identify what frequency was the problem and determined that I had a serious node (not mode) at 98hz. I built two 4' by 8' by 5.5" Helmholtz resonators. (Standard plywood/hardboard sizes with 1"x6" framing.) Completely solved the problem. It was freakin' magic how well it worked, because before the fix, that node was beyond bad.

By the way, one reason I tested the room before doing the acoustical treatment is because then you can spot nodes much more easily. As furniture goes in and acoustic panels (real ones, not foam) go on the walls, then problems start to get masked. That node at 98hz would have been harder to pinpoint, since the rest of the acoustical treatment would have made it less severe. That doesn't really apply in your situation, but it's worth noting.


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## wst3 (Oct 26, 2011)

A few more thoughts on acoustical treatments for small critical listening spaces...

1) left/right symmetry is critical

2) reflections are bad... but some reflections are worse than others

3) room modes exist in every space, but they do not have to cause problems. As room size decreases the potential for problem modes increases.

4) small spaces are not reverberant.

5) you will solve more problems more completely with geometry than ANY other solution. Proper geometry resolves low frequency modes and bad reflections. Proper geometry includes the boundaries and EVERYTHING in the room... yes, including you.

6) placement of loudspeakers and listener is very nearly as important as room geometry.

7) loudspeaker placement is dependent on the loudspeakers first, and the room second. Once you optimize loudspeaker placement it is easier to optimize listener position. 

8) eventually you'll need to add room treatment, there are three flavors, reflection, absorption, and diffusion, and you probably need all three.

9) start with broadband treatments, tuned treatments can cause more problems than they solve, and usually do.

10) small space acoustics is fun, and it isn't rocket science. BUT, if your goal is make music you may want to get help from a trained professional. It might be less expensive, and it will probably be quicker.

And that's just the acoustics<G>... other topics you may or may not need to look into include isolation (keeping sound in or out), power and grounding, interconnections, lighting, HVAC, and ergonomics.

I know that's all pretty general, but it can serve as a jumping off point if you want to DIY (which I highly encourage!) The problem with specific answers is I'd need a LOT more specific information.

I can share my own process for an existing space, fwiw, ymmv, etc.

A) choose your loudspeakers, and I gather you already have. Determine how they want to be placed, against a boundary, against a couple boundaries, free standing, or baffled.

B) let's assume (see, this is where I don't have enough information) that your loudspeakers want to be mounted away from any boundary. Place them on stands, and put them 2 - 3 feet from the front wall and 2 - 3 feet from the side walls. This is just a starting point! Place your chair at the point that forms an equilateral triangle with the loudspeakers and listen. Then move the either the loudspeakers or the chair (but not both) closer to the walls, then further away from the walls. With each new loudspeaker placement try different listening positions as well. Take notes for each configuration, including exact locations and your subjective impressions.

C) after three or four tries you will find locations for the loudspeakers and your tuckus that work better. You can continue to tweak, but don't go overboard, there is a law of diminishing returns!

D) Now it is time to find the bad reflections. There are lots of ways to do this, some people use a mirror, some use a laser pointer, some use CAD software... doesn't matter how, but find them and stick something absorptive there. If you've done everything right thus far all side wall reflection points should appear on both walls, so treat them both. 

You can treat them with absorption (foam, spun glass, etc) or believe it or not, reflection. I've seen studios with little plywood panels placed on the walls to re-direct the energy away from the listening positions, and they've worked really well!

Aside - I am not Russ Berger, or any other internationally renowned acoustician, I've designed a handful of rooms over the years, some have turned out better than others. It is my belief that the early reflections do far more to skew your perception of your mix than all but the worst low end modes. And, those modes can be linked to reflections, so I choose to go after reflections first when working with an existing space. If I am fortunate enough to start with a clean slate then I address low frequency problems and reflections at the same time through geometry.

E) the distance from the front wall to the rear wall is not long enough to support conventional diffusors, they might do some good, but it's a big expense, and it doesn't look promising in this case, so lets skip over that for now.

F) which brings us to absorbers, mostly to smooth out the low end frequency response aberrations caused by the room dimensions. Once again I'd strongly suggest broadband traps as my starter solution. And I'd suggest placing them in corners first. I'll also mention that it is possible to add too much absorption.

G) if you reach a point where additional broadband absorbers aren't helping then it's time to bring out the big guns - and Helmholtz resonators are one solution, and a good one at that. 

Here's a neat trick, as it will provide tuned absorption, broadband absorption, and even some diffusion - build two or three "polycylindrical diffusors and place them on the rear wall. Exact placement will take some experimentation, but a foot or less from each rear corner and then dead center is a good starting point. These are very easy to build, and you can combine broadband and tuned absorption into the poly. Also note that orientation may be important, so try both vertical and horizontal placements.

A quick word about measurement tools and prediction tools... they are cool! Really cool! But, interpreting the results is tricky, and if you don't have a mentor to help you figure out what your measurements mean you can end up wandering down dark alleys spending all kinds of money on problems that did not need to be solved!

Put another way... you are a musician, trust your ears!

To that end, these subjective tests take time. Listen to lots of different 'reference' music, but not all at once. Ear fatigue is every bit as much a danger when evaluating your room as it is when you are mixing!

That's the five cent version, I hope it helps.


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## mpalenik (Oct 26, 2011)

dannthr @ Wed Oct 26 said:


> The speed of sound is 1125 feet per second, with variances made for air pressure density/temperature.
> 
> With that in mind the wave-length of a frequency is 1125/frequency.
> 
> ...



If he were sitting 3.6 feet from a wall, that would actually be at a node and he wouldn't hear the 310 Hz sound (or at least, it would be minimized). The sound would be maximized at distances of (1/4 + n/2)3.6, where n is an integer, so, for example, 0.9 ft, 2.7 ft, 4.5 ft, etc.

Of course, at that frequency, the wavelength is pretty short, and given the size of your head/ears and how much people tend to move around, it would probably sound almost equally loud wherever he put his chair.


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## Dan Mott (Oct 26, 2011)

Wow!

Thanks for all the information guys.

I have to say I'm a little over whelmed. I guess I really should take it step by step.

First thing I need to do is put some broadband panels up on the side walls for my first reflections and also get in the best spot in the room. The only thing is, my best listening spot cannot be be treated, other than the back wall and ceiling. There are no side walls in my original spot. So I'm in a pickle.

I do have my speakers in a perfect triangle, so the speakers are the same distance apart from where I'm sitting. I'm a terrible at making stuff like panels, so I think I might just buy some broadband panels. 

In my original spot, the room was longer in length, but in my new spot it's shorter, so I don't know if that means anything. I will need bass traps for sure and diffusers on the back wall and maybe some panels behind the speakers.

From all the great info, I just don't know where to start and my mind is spinning. It's really confusing. So if I could just get a good starting point going then that would be awesome.

I'd really like a starting point guide. The info I read on here made my head spin and I should look at it all as a go step by step instead of stressing. 

Any suggestions would be awesome, but I think I know what I have to do, but I'm just not sure how yet.

Thanks so much!


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## dedersen (Oct 26, 2011)

You should seriously consider getting "Mixing Secrets for the small studio" by Mike Senior,

http://www.amazon.com/Mixing-Secrets-small-studio-Senior/dp/0240815807/ref=sr_1_1?ie=UTF8&qid=1319697473&sr=8-1 (http://www.amazon.com/Mixing-Secrets-sm ... 473&amp;sr=8-1)

The whole first part of the book is devoted to setting up a proper listening environment. It's precise, to the point and full of excellent tips and guides to getting the most out of whatever room you find yourself stuck in.

Also, the rest of the book is a gem. The title is really a bit misleading as it sounds like one of those "here's a single solution for all your mixing problems", but it is really more like a long tutorial on how to approach mixing.

I'd recommend it for anyone looking to get a good, basic understanding of the skills involved in mixing.


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## dannthr (Oct 27, 2011)

mpalenik @ Wed Oct 26 said:


> dannthr @ Wed Oct 26 said:
> 
> 
> > The speed of sound is 1125 feet per second, with variances made for air pressure density/temperature.
> ...



Yes, you're absolutely correct!


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## John Rodd (Nov 20, 2011)

The short answer is that 

as your room is 12' x 11' (I don't think you mentioned the height, did you?)

it will never be good.... it is too small, and in 2 dimensions.... SQUARE.

:shock: 

I recommend you:

put the speakers as close to one wall as possible..... possibly with a GIK 244 panel (or similar) behind each speaker on the wall

and

buy as many GIK 244 panels (or similar) as you can fit into your room, and put them in the CORNERS as bass builds up in corners. (wall/wall corners, wall/ceiling corners..... straddling them all)

also put one at each 1st reflection point on the side walls, but spaced out from the wall about 6" or so, if possible

and if you can, also deaden either the floor with a carpet, or put a few GIK panels over your head. (or both)

that is the very short answer to help somewhat solve bass problems.

but in a room that small, and that square... it will always have big bass problems. One needs a room 20' long, or more, to have a shot at having somewhat flat bass....

anyway - the good news is - when you move next, just take the GIK panels with you.


:mrgreen:

and...

sorry for the bad news.....

John


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## Nick Batzdorf (Nov 20, 2011)

> 2) reflections are bad... but some reflections are worse than others



Lots of great stuff in Bill's posts as always, but as I've posted too many times, I actually disagree with that.

Reflections from the sides are not bad. Reflections from the same angle as the speakers - the front - are bad, because they are the ones that "comb filter" with the sound coming directly from the speakers (which by the way is not the same thing psychoacoustically as the direct sound from an instrument).

And while I don't claim to be a real engineer like John, the same applies to muffling the sides: I have to disagree with that as a tactic, because all it does it put a lowpass filter in the way. That reflection - which again is not heard as the first reflection - actually helps the imaging. I'm unable to set my room up quite that way for practical reasons, but I've done some experimenting with this, and it really works.

This is a link to an interview I did with my friend Dave Moulton in the mid-'90s on the subject:

http://www.moultonlabs.com/more/nick_ba ... interview/


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## Nick Batzdorf (Nov 20, 2011)

By the way, what John said in another thread a couple of months ago - not having any parallel walls - is another tactic that works. But you're unlikely to call in architects for the kinds of rooms most of us work in. Nor do you really need to.


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## Kralc (Nov 21, 2011)

Dan-Jay: interested in knowing what the custom panels and traps you're looking at in Aus?


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## Dan Mott (Nov 21, 2011)

Not sure if you are in Melbourne, but this is more than enough to get a well treated room going.

http://www.acousticvision.com.au/

Have a look around. I'd have to say that this is pretty professional if you ask me. I have seen sites like this that I haven't bothered with because it's not really for a regular consumer IMO. This is serious shit :D and most likely expensive.

I'm going for the 104mm thick RPG BAD panels which absorb pretty much the whole range I'm having problems in, aswell as it also diffuses from 1K and above. Pretty cool panel, used in quite a few known professional studios here in AUS. All fibreglass insulation too. One RPG PANEL is like 360 bucks....... not cheap, but you get what you pay for.

Then I'm also going to get some free standing panels because there's a window right behind my speakers that I cannot treat with panels.

It's not exactly cheap, but I'd rather spend my money on a product that will actually do what I want, rather than foam products, which can be very good, but I'm looking to go beyond that. Also, it would save time and headaches when trying to make a panel my self which I would not be able to do, not to mention I'd have to seek help. (lazy)

I have found a few places and have asked a billion questions and I actually found this off a guy from another acoustic place. He suggested this place because his panels weren't right for what I was trying to do.

If you want to know the much cheaper place, just let me know.


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## Dan Mott (Nov 21, 2011)

John Rodd @ Mon Nov 21 said:


> The short answer is that
> 
> as your room is 12' x 11' (I don't think you mentioned the height, did you?)
> 
> ...



Sorry. I never read this :D

Thanks so much for the info. Can I have a link to those GIK panels?


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## Kralc (Nov 21, 2011)

Thanks alot, I have really no idea about anything in this kind of department, this is all new to me. Lot of good info in this thread though.

Those products look great, shame I don't live in Melbourne, I can't find anything like that where I am. But I doubt I really need anything that high-end, especially in my bedroom/"studio". :oops: 

here's the link to the GIK site, http://www.gikacoustics.com/


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## Dan Mott (Nov 21, 2011)

Thanks for the GIK link man. I'm sure that if I ordered panels from the US, the price would be off the rails :0

And Nick, thanks for your input. I'm now gong to read that interview


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## Dan Mott (Nov 21, 2011)

Nick. That was an interesting read.

It seems odd that he is so keen on not having much absorption on the side walls. He also says that you want to hear sounds from a speaker, just like we hear instruments, but wouldn't that be bad because we are hearing sounds that have already been recorded in a space, plus the space of our rooms? We would be getting a double up on 2 different spaces, therefore not hearing the original space properly which can lead to inaccurate mixing decisions that deal with space and depth... No?

But basically, it sounds like the best thing to do would be to treat the bass and mid freq range of a room to the best of ability, then pretty much use diffusion for the highs to prevent the room from being dead and also prevent the whole lowpass filter affect when putting panels up where your first reflections are?

Interesting


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## Nick Batzdorf (Nov 21, 2011)

Dan-Jay, he's keen on having NO absorption on the side - the idea is to have hard, flat surfaces and not stick lowpass filters in the reflections coming off them. And it's not that you're treating the mid and low frequencies, you're simply soaking up excess reverb at the front of the room with broadband absorption (including bass trapping).

As to your question about the space of the room conflicting with the recorded sound, the simple answer is that it works the other way around: you need the monitoring room to hear the information in the recording properly, and that includes the spatial information. We could mix outdoors if we didn't want any reflections from the room.

Of course, this idea is considered worse than heresy in some circles. Dave presented a paper on some of this at an AES Convention a few - quite a few - years ago, and several experts were really annoyed. How could this professor pee all over their long-held beliefs?! But there were also a few people there who either knew or agreed - including Floyd Toole, who at the time was the head of the AES.


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## Daryl (Nov 21, 2011)

Dan-Jay @ Mon Nov 21 said:


> Thanks for the GIK link man. I'm sure that if I ordered panels from the US, the price would be off the rails :0
> 
> And Nick, thanks for your input. I'm now gong to read that interview


I have a coupe of GIK bass traps. Not great, IMO. They didn't do the job they were supposed to do, so I removed them and got some from Real Traps. These were not only far superior, but also made much better. The GIKs look and feel a bit cheap, which, to be fair, compared with Real Traps, they are.

D


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## germancomponist (Nov 21, 2011)

Always an interesting theme.

Has anyone tried this VPR absorbers out? http://www.renz-akustik.de/page/index.php?id=46

http://www.pia-alfa.de/de/dat_vprbka.htm

Sorry, these are links to german websites, but I think one can see how these absorbers work: With a big steel - plate........ .


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## Dan Mott (Nov 21, 2011)

Nick Batzdorf @ Tue Nov 22 said:


> Dan-Jay, he's keen on having NO absorption on the side - the idea is to have hard, flat surfaces and not stick lowpass filters in the reflections coming off them. And it's not that you're treating the mid and low frequencies, you're simply soaking up excess reverb at the front of the room with broadband absorption (including bass trapping).
> 
> As to your question about the space of the room conflicting with the recorded sound, the simple answer is that it works the other way around: you need the monitoring room to hear the information in the recording properly, and that includes the spatial information. We could mix outdoors if we didn't want any reflections from the room.
> 
> Of course, this idea is considered worse than heresy in some circles. Dave presented a paper on some of this at an AES Convention a few - quite a few - years ago, and several experts were really annoyed. How could this professor pee all over their long-held beliefs?! But there were also a few people there who either knew or agreed - including Floyd Toole, who at the time was the head of the AES.



I see, but what if you have problems in your room then? What are you supposed to do if you aren't going to control, NOT kill?

I recently demoed some PMC TB2S-AIIs in my room and they sounded terrible, but I know they don't really sound like that because I work in radio and I've been using them in well treated broadcast studios. I then put them in my room and my reaction straight away was OOWWWW.. what the!!? I played a song I knew very well and I have listened to it on as many systems you could think of and it sounds great, though it sounded terrble in my room. The 125Hz to 400Hz range was brought up and put a huge cloud over anything else. Now I do not believe this is the speakers fault because I know they sound amazing. It was simply because those speakers aren't right for my room. 

So I guess if you are not going to treat the room, you pretty much need to demo as many speakers as you can in your space to see which one sounds the best, instead of treating your problem frequencies and choosing a speaker you really like and still like when brought into your space. Basically I'm not choosing a speaker I like, but choosing a speaker for the room ;s. If I don't treat my room, then how can I ever have the speakers I want in my space?

Nick. Do you agree with everything that guy said in the interview, or just some things? Have you done any experiments?


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## wst3 (Nov 21, 2011)

wish I had time to post in more detail, I will if anyone so desires, later.

The plain fact is that there is NOTHING wrong with LEDE, or RFZ, or the Non-Environment approach. They can all work, and they can all be unmitigated disasters.

If you are going to play at the level where you are worrying about the room design at this level you need to consider a bunch of other factors first. The most important is how you wish to work. Do you want to hear the control room, the recording space, the loudspeakers, or some combination of the above? How can you work most efficiently and effectively.

Dave Moulton is not the only well known engineer that supports the non-environment idea, in fact I'm not even certain it is still called that<G>. Philip Newell is also a big proponent. In fact if you go way back to some of the pre- LEDE literature you'll find the seeds.

Me? Given my space limits I've decided that a modified LEDE approach is going to work best for my next space. If I had the resources I'd LOVE to build a fully non-environment space. Mostly out of curiosity.

more later...


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## Dan Mott (Nov 21, 2011)

I'd want both. As I said, to control and NOT kill.

I'm not an expert and I am new to acoustic treatment, but from what I've read, rooms can be out of control and need to be treated. I respect if the no treatment approach works for some, but maybe they just have the right room layout to do so. I have no idea :s


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## John Rodd (Nov 21, 2011)

Daryl @ Mon Nov 21 said:


> Dan-Jay @ Mon Nov 21 said:
> 
> 
> > Thanks for the GIK link man. I'm sure that if I ordered panels from the US, the price would be off the rails :0
> ...



"a couple" of bass traps will NEVER do hardly anything in any room.... you need as many as possible (6? 8? 10? 12?) to make a noticeable difference.....

I meant to also mention Real Traps... yes they also have a good product. However 'till recently they were about 2.5 times the price of GIK traps.

However now Real Traps have a trap for about $100 and that might be a good option, generally speaking.

However.... for Australia I would try to source bass traps made locally, for obvious reasons.

:wink: 

cheers

John


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## Daryl (Nov 22, 2011)

John Rodd @ Tue Nov 22 said:


> Daryl @ Mon Nov 21 said:
> 
> 
> > Dan-Jay @ Mon Nov 21 said:
> ...


That's not totally accurate. If you are sweeping, you can easily see what even just one panel will do by moving it around the studio and re-sweeping. Obviously it doesn't make a good mixing environment with just one or two panels, but you can certainly see how they affect the room modes. GIK's product did affect the sweep, but there was no position to put it in that tamed the bass at all. Real Traps worked, and even if I only put one panel in, I could move it around the studio and see what it was doing on the sweep really clearly. Maybe if I'd bought 8 bass traps from GIK it would have made more of a difference. but based on the two that I bought to try out, they were pretty much useless, when compared with Real Traps products.

D


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## Daryl (Nov 22, 2011)

Dan-Jay @ Tue Nov 22 said:


> I'd want both. As I said, to control and NOT kill.
> 
> I'm not an expert and I am new to acoustic treatment, but from what I've read, rooms can be out of control and need to be treated. I respect if the no treatment approach works for some, but maybe they just have the right room layout to do so. I have no idea :s


If you have a room that has a huge gap between peak and trough in the bass area, you need to do something to tame that. In my studio I could even tell you which notes were affected by the room modes, so didn't really need to do a sweep. However, the sweep confirmed what I was hearing.

D


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## Nick Batzdorf (Nov 22, 2011)

Bill, I've never heard the term "non-environmental." Actually Moulton's concept is the opposite - in fact that's the point: making a regular room workable. LEDE is part of that but not the whole idea...it's more just DE with flat, reflective hard sides.

And not only do I agree that there are different approaches to room design that all work yet sound different from one another, I said as much in this thread. But how many of us are going to create a ground-up control room that costs thousands of dollars - even if we want a more controlled sound?


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## John Rodd (Nov 22, 2011)

Daryl @ Tue Nov 22 said:


> John Rodd @ Tue Nov 22 said:
> 
> 
> > Daryl @ Mon Nov 21 said:
> ...



I’ll clarify what I meant. Sorry to not be clear.

I think we are into semantics.... :idea: but I will try to clarify my point.

I would maintain that the sound of a room (or speakers, or microphones, or gear) will have qualities and characteristics of sound that can not be quantified by frequency plots & measurements alone.

Thus putting 2 GIK 244 traps into a room would make SOME audible difference (as they are bass traps, and they are also partially absorptive at mid & high frequencies - just as most bass traps would be)

I am surprised that you could not see ANY difference in measuring the frequency measurements.

My point was that any 2 bass traps would not be enough to make a significant audible difference in an average room. Most untreated rooms in a house that people use may well have peaks and troughs that could be +/- 20 db or more. In my experience two 2‘x 4’ bass traps of any kind would not begin to significantly address problems such as those.

I generally recommend GIK 244 traps as they are one of the cheapest solutions, ($70 each) and are easy to hang, so they are a good ‘bang-for-the-buck’ however I now remember that Real Traps now make a ‘budget’ trap called the Bare Trap..... for $125/each.

http://www.realtraps.com/p_baretraps.htm

I always suggest to people that they put as many bass traps as possible into a room..... and budget is a concern for many people..... thus I suggest GIK 244 traps first. But yes Real Traps do make a good product. 8)


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## germancomponist (Nov 22, 2011)

John Rodd @ Tue Nov 22 said:


> I always suggest to people that they put as many bass traps as possible into a room.....



+1

I underline this!


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## Hannes_F (Nov 23, 2011)

FWIW to help both my friends out here: the RealTraps "bass traps" have a limp membrane in front of the absorber which changes the acoustical effect compared to traps that work as a pure absorber like the GIK "bass traps" - at least to a certain amount.

Doesn't necessarily mean better or worse - that will depend on the conditions - but definetely slightly different.


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## Aaron Sapp (Nov 23, 2011)

I contacted John via email about purchasing six GIK traps for my 10x12 room. He pretty much said the same thing he is saying here. So I thought "hmmph, I'll make my room sound good and build my own".  So I built 18 4x2 4" thick bass traps. 

Guess what? He was right. I hung them on every wall/wall ceiling/wall corner I could (as well as first reflection points, save for the ceiling). While it did help lessen the room problems a great deal, it definitely did not alleviate all the problems. At the very least, the problems were reduced enough that I don't suffer from ear fatigue with those super resonate frequencies. But now I know there really isn't anything you can do to completely flatten a small room. If 18 bass traps don't do it... 

I would definitely recommend you just build these on your own - you would save a lot more money and they are super easy to build. Given the incentive, I could now probably build 20 of these in a day. It's that easy. Here's the tutorial I used (I would forgo the corner brackets and wood glue - just use two screws each time you attach another piece of wood): http://www.youtube.com/watch?v=iyYUpkpL0gw

It also occurred to me that once you've really deadened your room, you might invest in one of those monitor tuning systems to help the room problems even further. I'm sure most engineers scoff at that idea, but we gotta work with what we got...

http://ikmultimedia.com/arc/features/


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## John Rodd (Nov 23, 2011)

Aaron Sapp @ Wed Nov 23 said:


> I contacted John via email about purchasing six GIK traps for my 10x12 room. He pretty much said the same thing he is saying here. So I thought "hmmph, I'll make my room sound good and build my own".  So I built 18 4x2 4" thick bass traps.
> 
> Guess what? He was right. I hung them on every wall/wall ceiling/wall corner I could (as well as first reflection points, save for the ceiling). While it did help lessen the room problems a great deal, it definitely did not alleviate all the problems. At the very least, the problems were reduced enough that I don't suffer from ear fatigue with those super resonate frequencies. But now I know there really isn't anything you can do to completely flatten a small room. If 18 bass traps don't do it...
> 
> ...



Hey Aaron.... cool you built your own, and glad they made a difference! 8) 

But as I said before... a room that is almost square (10' x 12') and is that short in the long dimension will NEVER be anywhere near flat. You need the longest distance (that the speakers are firing down) to be about 20 feet or more to have a shot at getting anywhere near flat... simply as bass frequencies are so long, and have so much energy...

You mentioned putting EQ across the monitors (IE self calibrating speakers, or a hardware box).... maybe the reason that most engineers would scoff at the idea is that it is a BAD IDEA..... ? :wink: 

I got bad news for you...... you can't beat physics. I am VERY skeptical of  "self-calibration" speakers and room analysis software. It is like what everybody did in the 80's by EQ-ing the monitor path. Finally, everyone realized... it just doesnt work.

You have to acoustically fix the room. Maybe the auto-correcting speakers (or and room analysis software) can tweak for one listening position, but what happens when you move your head 6" back? Yer screwed. What about the client who is sitting 4 feet (or more) behind you? Wow - he is super screwed. Peaks and nulls will add and subtract even more with all the EQ that the 'correcting' speakers are pumping in... plus the problems are not just frequency based... but they are also TIME (reflection) based... and you can't mess with time. (physics)

Plus the EQ in the monitor path just sounds bad. Plain and simple.

The reason the feature is there is that DSP is now cheap, as are built in d-a converters (another bad idea in a powered speaker, in my opinion) and with a bunch of advertising, they can sell more speakers. 

I'm a purist, generally speaking... and it has always served me well.

example - Dynaudio 'Air' powered speakers with built in DSP processing... I prefer the sound of the Dynaudio models without it, by a long shot.

This is why I'm spending a TON of money on a studio for myself (with tons of amazing acoustic treatment built right into it)... you can't beat physics.

john


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## rgames (Nov 23, 2011)

I treated my room a while back and described it here:

http://www.rgamesmusic.com/acoustics/index.html

I checked the response as I added each piece of the treatment so you can see how each one affects the overall response.

If you can find the materials, it is extremely easy (and cheap) to build your own traps. Each one takes about 20 minutes to put together.

rgames


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## Aaron Sapp (Nov 23, 2011)

Hey John,

I do agree with you, but what suggestion would you have for someone who has little choice but to work in the environment they have? I think I've pretty much maxed out my room with traps, but some problems still exist. Short of moving to a bigger space, it seems the only two choices left are: acquaint yourself with your room problems and compensate accordingly, or speaker calibration to help feather down the remaining problems?


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## John Rodd (Nov 23, 2011)

Aaron Sapp @ Wed Nov 23 said:


> Hey John,
> 
> I do agree with you, but what suggestion would you have for someone who has little choice but to work in the environment they have? I think I've pretty much maxed out my room with traps, but some problems still exist. Short of moving to a bigger space, it seems the only two choices left are: acquaint yourself with your room problems and compensate accordingly, or speaker calibration to help feather down the remaining problems?



Hey Aaron

I want to stress.... in my experience self calibrating speakers (& hardware) tend to sound terrible, and don't work well at all.

The solutions are:

- listen to the mix in a different room, on a different set of good speakers (like your living room... that can tell volumes about a mix)

- listen to a commercially mastered CD and compare your work to a score you know sounds good... in the same genre. If your score has way more or way less bass, then you know you're off the mark.

- listen very quietly to check

- listen on an alternate set of speakers... maybe a tiny crappy computer size set... if there is tons of bass there and the speakers are blowing up... that is a clue

- listen on good headphones..... closed - the Shure SRH 840 would be a good bet - $150-ish - and again compare to a commercially mastered CD.

http://www.amazon.com/Shure-SRH840-Professional-Monitoring-Earphones/dp/B002DP8IEK/ref=sr_1_1?ie=UTF8&qid=1322068991&sr=8-1 (http://www.amazon.com/Shure-SRH840-Prof ... 991&amp;sr=8-1)

There are more... but those are my top tips for right now.... :mrgreen: 

John


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## Frederick Russ (Nov 23, 2011)

Aaron Sapp @ Wed Nov 23 said:


> Hey John,
> 
> I do agree with you, but what suggestion would you have for someone who has little choice but to work in the environment they have? I think I've pretty much maxed out my room with traps, but some problems still exist. Short of moving to a bigger space, it seems the only two choices left are: acquaint yourself with your room problems and compensate accordingly, or speaker calibration to help feather down the remaining problems?



Exactly. Cannot improve on what you just said here. I think JBL does come out with a universal room calibration tool for any speaker monitors to help isolate problem frequencies and make adjustments to improve performance. Its not going to be like having an acoustic engineer design your music authoring space but it does help some.


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## Aaron Sapp (Nov 23, 2011)

DOUBLE POST.


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## John Rodd (Nov 23, 2011)

Frederick Russ @ Wed Nov 23 said:


> Aaron Sapp @ Wed Nov 23 said:
> 
> 
> > Hey John,
> ...



No. Read my post above. I strongly believe that Eq-ing monitors does NOT help acoustic problems. My suggestions will lead to a better mix, at far less expense.


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## germancomponist (Nov 23, 2011)

As I mentioned before, there is a very interesting thing, called VPR absorbers, built with a steel plate and foam.... .

http://www.pia-alfa.de/en/dat_vprbka.htm

This absorber type works very good from 63 to 500 hz. Much better than an only absorber type, built with rockwool e.t.c. . 

An interesting thread about this absorber startet some days ago on gearslutz: http://www.gearslutz.com/board/stud...67929-my-experiment-metal-panel-absorber.html


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## Aaron Sapp (Nov 23, 2011)

All good tips, John. A/B'ing has definitely helped and I'm constantly listening to my mixes on my headphones, crappy ipod/iphone dock radio, living room stereo and car. They all are enlightening when assessing the various shortcomings in my mixes. 

I already had an appreciation for great engineers, but having since delved into mixing a bit more, I find myself often saying "how the hell did he do that?"


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## Nick Batzdorf (Nov 23, 2011)

The glass French door at the back and to a lesser extent the windows at the front help "trap" bass in my room.


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## John Rodd (Nov 23, 2011)

Nick Batzdorf @ Wed Nov 23 said:


> The glass French door at the back and to a lesser extent the windows at the front help "trap" bass in my room.



You're kidding, right?

Glass does nothing to help tame bass frequencies. ~o) 

john


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## germancomponist (Nov 23, 2011)

John, 

did you have had a look to the Fraunhofer / Renz VPR`s? It looks interesting, but I never have heared or seen these kind of resonators 7 absorbers. They say, with 2,5 mm steel it will absorb 40 hz frequencies very well in a small room...... . ?!


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## wst3 (Nov 23, 2011)

Nick Batzdorf @ Mon Nov 21 said:


> > 2) reflections are bad... but some reflections are worse than others
> 
> 
> 
> Lots of great stuff in Bill's posts as always, but as I've posted too many times, I actually disagree with that.



I'm used to that<G>!



Nick Batzdorf said:


> Reflections from the sides are not bad. Reflections from the same angle as the speakers - the front - are bad, because they are the ones that "comb filter" with the sound coming directly from the speakers (which by the way is not the same thing psychoacoustically as the direct sound from an instrument).



ANY reflection can combine destructively with the direct sound - it's a matter of geometry, angle and distance, and while the reflections from the front wall are usually the most troublesome, they don't have to be. Similarly reflections from the side walls are often less troublesome, but not always.



Nick Batzdorf said:


> And while I don't claim to be a real engineer like John, the same applies to muffling the sides: I have to disagree with that as a tactic, because all it does it put a lowpass filter in the way. That reflection - which again is not heard as the first reflection - actually helps the imaging. I'm unable to set my room up quite that way for practical reasons, but I've done some experimenting with this, and it really works.



First, if you use absorbers that form a low pass filter you got trouble! And sadly, most of the foam products, and some of the spun glass products are so top heavy in terms of absorption that you do end up with a low pass filter.

Second, in order for a reflection not to be heard as a reflection it must arrive in a very specific time window. Have messed up the previous post by attributing the Non-Environment design to Moulton instead of Hidley and Newell I'm going to have to go look up the specifics. Providing reflections at specific times does reinforce our positioning cues.



Nick Batzdorf said:


> This is a link to an interview I did with my friend Dave Moulton in the mid-'90s on the subject:
> 
> http://www.moultonlabs.com/more/nick_ba ... interview/



An excellent interview!

Mr. Moulton is brilliant! His ear training course is a must-do for anyone that doesn't have access to professional studios and experienced mentors - and it's not bad even if you have those resources.

His design approach works. But so too do the design ideas from Davis, Hidley, Newell, et. al. The keys are (a) knowing how you want to work, and (b) adapting to that approach once you've built it.

I've told the tale before, but I once mixed a demo tape for a friend in my office on a pair of Polk Model 5s. This is NOT a good monitoring environment, and I'm sure I could have done better in a better space, but he needed the CD quickly, and he's a really good friend, and I know his voice really well, and I knew those loudspeakers in that room really well. So it worked out. But I wouldn't be in a hurry to repeat that experience!

Bill


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## Nick Batzdorf (Nov 23, 2011)

> Glass does nothing to help tame bass frequencies



It allows sound to escape around the edges, and also it also resonates at a pretty low frequency. ~o) 

I'm not saying it's a substitute for bass traps, of course. My post was just to emphasize that you need to know what's going on before "treating" your room.


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## germancomponist (Nov 23, 2011)

It seems that noone here is interested to get special news about room treatment with the special Fraunhofer / Renz VPR`s.......?!

Is there a reason for this? 

Do you not like to get newest informations about this theme?


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## Nick Batzdorf (Nov 23, 2011)

> ANY reflection can combine destructively with the direct sound - it's a matter of geometry, angle and distance, and while the reflections from the front wall are usually the most troublesome, they don't have to be. Similarly reflections from the side walls are often less troublesome, but not always.



To a microphone, yes. But the ear isn't bothered by reflections from the sides - the brain can separate the sound coming from different angles (even when it's within the Hass integration zone - and unless I'm missing subtleties that means the room is smaller than about 50' lengthwise [and the freqs are below about 10k]). That's the reason to muffle at the front: the sound does come the same angle as the speakers. We in the art world refer to this as psychoacoustics.

I think Moulton talks about that in that interview, but he always uses the example of the worst possible environment - a gym - in which you can localize sounds precisely all day long.

Of course, he also uses the example of his speakers.  B&O since bought the patent, but he developed an acoustic lens that disperses sounds 180 degrees. The image is unlike anything else you've ever heard, and that wouldn't work if the underlying theory were wrong.



> His design approach works. But so too do the design ideas from Davis, Hidley, Newell, et. al. The keys are (a) knowing how you want to work, and (b) adapting to that approach once you've built it.



Absolutely.

The only thing I'm digging in my heels about is that Moulton's approach is the one to adopt if you're working in a real room and aren't inclined to spend a fortune "tuning" it. That's almost everyone here.


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## Nick Batzdorf (Nov 23, 2011)

> Is there a reason for this?



My reason is that I have no idea what VPRs are.


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## germancomponist (Nov 23, 2011)

So click the links I had posted and read, ad download the pdf`s . 

You will be amazed!


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## Andrew Christie (Nov 23, 2011)

John Rodd @ Thu Nov 24 said:


> Aaron Sapp @ Wed Nov 23 said:
> 
> 
> > Hey John,
> ...



Agree. I tried IK Multimedia's ARC to attempt to smooth out the acoustical problems in my space...DOES NOT WORK! The few times I mixed with it, after I'd bypass the plugin for bounce down, sounded horrible.


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## Dan Mott (Nov 23, 2011)

So guys.

This is a situation I'd like to get advice from.

I simply cannot put panels behind my speakers because there's a window with a blind. However in my other postion I can put panels behind my speakers, but then I'll have the window with the blind on my right side and a wardrobe without a door on my left (clothes hanging/different shevles/good diffusion), plus the room length would be shorter.

I could do several things from reading in this forum.

I could solve the whole front wall problem by buying some good free standing panels since I cannot stick the panels on the window. Or I could move into the other postion with the window on my side and put good panels on the front wall. I have no idea what I should do or what would be best.

So are you guys saying, for a small, typcial home studio environment like mine, that I don't put panels on my sides, but muffle only the front and put some bass traps in the corners?

My head is exploding. I think its been two weeks now that I have researched and read a billion articles and I still cannot decide. 

Cheers.


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## Dan Mott (Nov 23, 2011)

I also want to know what you guys think of this panel 

http://www.acousticvision.com.au/RPGDiffusers/RPGResidential/BADPanel/tabid/160/Default.aspx (http://www.acousticvision.com.au/RPGDif ... fault.aspx)

I'm currently looking at it. There's a PDF sheet down the bottom you can click on. Also I'd be getting the 4 inch thick version.

EDIT - This free standing panel too 

http://www.acousticvision.com.au/RPGDiffusers/RPGResidential/Variscreen/tabid/159/Default.aspx (http://www.acousticvision.com.au/RPGDif ... fault.aspx)

About building my own. I just don't think I can do this and I wouldn't do it properly knowing my self. I'm willing to pay to get it properly done.


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## rgames (Nov 23, 2011)

Dan-Jay @ Wed Nov 23 said:


> About building my own. I just don't think I can do this and I wouldn't do it properly knowing my self. I'm willing to pay to get it properly done.


Did you take a look at the panels in the link I posted? I'm sure you could do it - seriously easy. They take about 20 minutes to assemble and I spent about $150 for eight traps, mostly 8" thick and a few 4" thick.

The insulation panels already come in about the right size, so all you have to do is throw some cloth over them and hang them up (actually, cloth is optional but they look pretty ugly when uncovered). Stack a couple on top of each other for tall ones in the corners. It's about like putting sheets on a bed, so if you can make a bed, you can build yourself some panels.

Regarding your exploding head, welcome to the world of room acoustics  It's about 10% science and 90% religion.

rgames


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## Dan Mott (Nov 23, 2011)

Alright!

I'll give it some time and see what I can do. I did look at the link. I'm just teribble with my hands :(

Thanks!


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## Udo (Nov 23, 2011)

Aaron Sapp @ Thu Nov 24 said:


> .... what suggestion would you have for someone who has little choice but to work in the environment they have? ......


Simple, really (but it takes practice), ...... learn to understand/interpret/judge your mixes on headphones. Although useful, it can be done without the expensive Phonitor. There are other, more affordable ways, but ..... it takes practice and persistence (even with the Phonitor). 

Many "pros" (but not all) ridicule that approach, without seriously and persistently having tried to get the hang of it.

Of course, there's no substitute for a real, proper listening environment, but good results can be achieved using headphones and "helper" applications.


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## wst3 (Nov 24, 2011)

Nick Batzdorf @ Wed Nov 23 said:


> The only thing I'm digging in my heels about is that Moulton's approach is the one to adopt if you're working in a real room and aren't inclined to spend a fortune "tuning" it. That's almost everyone here.



That's a fair statement... in fact I think that except for the fact that the Earth would stop spinning, I'd agree.

I generally come at studio design from the perspective of a designer. I've designed studios for some really crappy spaces (the worst was a very nearly square basement with a seven foot ceiling.

In fact one of the best control rooms was designed by one of my mentors, again in a basement, needed a good sized recording room, so the control room was shoe-horned in. And yet the owner could get outstanding, and repeatable results every time. Part of it was his talent, part of it was that he KNEW the rooms inside and out, and part of it was my mentor knew where to make the trade-offs. He learned by designing studios in Europe for years, and if you think space is scarce in the US...

Anyway, it certainly colors my thinking, and if you are building out a space you do have options. But if you don't have that as your starting point then Moulton's approach makes a ton of sense.

At that point distances are generally short enough that the reflections from the side walls are manageable. And you can't dog-house (soffit) the loudspeakers.

HOWEVER... and Moulton supports this, before you apply any treatments you HAVE to optimize the loudspeaker and listener positions in such a room! That's how you get various reflections to work for you instead of against you!


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## wst3 (Nov 24, 2011)

John Rodd @ Wed Nov 23 said:


> I want to stress.... in my experience self calibrating speakers (& hardware) tend to sound terrible, and don't work well at all.



John provides a number of really good solutions, but the above is the most important part of the post... IMNSHO.

I'm really quite frightened that more than one reputable company is now selling DSP as a way to fix room problems.

Monitor problems fall into two categories:

1) errors in the electronic playback chain - these can be corrected electronically because they are the result of non-linearities in the electronics. If you can get an accurate definition of the transfer function you can compliment it and errors will cancel out.

2) errors in the space... these tend to be time-domain problems, even though they may masquerade as frequency domain problems. Put another way, the errors are not consistent over the entire space, they are position specific.

These CAN NOT be corrected electronically... at least not today. I won't go so far as to suggest that it is impossible - heck, when I was 18 I thought a sample library was impossible<G>! But neither the horsepower nor the algorithm exists today to do so from the same loudspeakers that are causing the problem. (If you are curious about what can be done with massive amounts of money and massive quantities of microphones and loudspeakers search for LARES)

Oddly enough, in some isolated cases, it is possible to make the monitoring system sound better. You haven't actually fixed the problems, but then that really isn't the point is it<G>! If you move your head or the loudspeakers then all bets are off and you have to re-do the whole thing, but you might mask some problems in a very limited fashion.

Please, before you spend your money on a loudspeaker correction system make absolutely certain you can return it if it does not work in your space.

Or, study the physics of small, critical listening spaces... aes.org is a great place to start.

Or, hire an acoustician to help you identify the trade-offs you can take, and the ones you should avoid. It is often a much more cost effective solution. If you are willing to spend $1K on a sample library it seems to me you might want to scratch together a couple hundred for some advice. It'll likely cost you more to implement the solution... but at least you'll be headed in the right direction. And you don't have to make all the changes at once!


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## wst3 (Nov 24, 2011)

John Rodd @ Wed Nov 23 said:


> Nick Batzdorf @ Wed Nov 23 said:
> 
> 
> > The glass French door at the back and to a lesser extent the windows at the front help "trap" bass in my room.
> ...



Oddly enough, a well designed room - in terms of isolation or sound-proofing - is the most difficult room to treat for listening.

If you have really good isolation then no energy comes in - which is good - and no energy leaves - which is very often not-so-good!

So the glass doors, which will not provide as much transmission loss at low frequencies, may appear to tame LF energy.

That's not really what's going on - but again, is that the point? Or is the point to reach a degree of confidence in what you are hearing?

Yeah - this is tricky stuff!!!


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## Mike Greene (Nov 24, 2011)

rgames @ Wed Nov 23 said:


> Did you take a look at the panels in the link I posted? I'm sure you could do it - seriously easy. They take about 20 minutes to assemble and I spent about $150 for eight traps, mostly 8" thick and a few 4" thick.


Richard's example is really good. Here's the relevant link for what he did:
http://www.briarwoodarts.com/music/acoustics/setup.html

The way he built his panels is really simple and he explains this stuff pretty well. (Nice looking studio, by the way.)

But if you're truly challenged at nailing four pieces of wood together, it's worth noting that you don't even have to build a wood frame for these panels. You can simply wrap them as is in cloth and you're good to go. Owens Corning 703 (or the equivalent from other companies) is pretty rigid, so it holds its shape pretty well.

I've never needed panels 8" thick, by the way. 4" has always been enough for me, and it's definitely enough for 300hz (which I think is where you said your resonance was.) Heck, lots of people even just go 2", which is still pretty darn good.


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## Hannes_F (Nov 24, 2011)

germancomponist @ Thu Nov 24 said:


> It seems that noone here is interested to get special news about room treatment with the special Fraunhofer / Renz VPR`s.......?!
> 
> Is there a reason for this?



The reason is that most people to consider themselves to be the most informed of everything, so anything else and unknown coming along is considered flapdoodle by default. That is the reason why I stopped participating in acoustics threads here and in gearslutz - it just makes no sense.

Truth is that VPR absorbers are THE gold standard for the top of the crop since nearly a decade, only second to custom built (and individually tuned) limp membrane absorbers*. The reason why these devices are rarely known is that they are usually hidden.

EDIT *: Actually this is nearly true but not fully and depends on the case, as usual.


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## Dan Mott (Nov 24, 2011)

Did I mention I have a 7ft ceiling. I just clapped my hands and I have a bit of flutter echo coming from the side walls.

I'm going to do a sweep today and send the wave file to an acoustican.

Does anyone know where I can get a 2 second sweep from 20Hz to 20KHz?


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## Dan Mott (Nov 24, 2011)

I also have pictures of each side of my room if that will help anyone?


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## Hannes_F (Nov 24, 2011)

Dan-Jay, you can yourself a big favour if you read these threads:

http://www.gearslutz.com/board/studio-b ... -here.html

+

http://www.gearslutz.com/board/studio-b ... 2-1-a.html

(Be sure not to read only the first of each posts).

There is a wealth of information that will consume some time but in the end it will save you lots of time.


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## Arbee (Nov 25, 2011)

I have a room the same size except that it has a sloping timber ceiling with exposed rough sawn beams. It is also carpeted. I had some serious layout constraints as I wanted room for a sofa bed to extend without dismantling the studio gear (the concession to my paternal guilt for "stealing" my daughter's bedroom once she left home  ). The room also had terrible flutter issues. 

After much web surfing I took the highly controversial diagonal approach. I stacked 4 bass traps into the corner behind the desk/monitors and put the sofa bed in the opposite corner. I then made my own timber framed panels from acoustisorb covered in cloth and spaced them out along both rear walls surrounding the sofa bed, placing them all a few centimetres out from the wall (in 3 different colours, looks great 8)) . I also strung up acoustisorb everywhere under the large corner desk I made myself (designed with a deep recess underneath for the acoustisorb). The desk has a gap at the back and doesn't go right to the corner where the bass traps are. Since the room isn't quite square I mapped out the "mirror" points from the speakers on a piece of paper before putting things on the walls.

The before and after sonic difference was stunning, it also looks great, accommodates the sofa bed nicely and was all done for very modest cost plus the bass traps. I've only just finished it so the proof is yet to be heard but the reference tracks I've put up sound very clean from top to bottom and left to right. There was a low end hump in the rear corner until I put the sofa bed in. I use Adam A7X (decided on front port speakers due to the layout), some Beyer headphones and a very cheap 2.1 system to keep an ear on the very low end.

With the constraints I had I'm extremely happy, limitations can be fun to work with....


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## Nick Batzdorf (Nov 25, 2011)

> I just clapped my hands and I have a bit of flutter echo coming from the side walls



Note that it's almost impossible for your speakers to excite that flutter echo, and even if they could it wouldn't be a problem if the echoes are really coming from the side walls (for a listening room - again, recording is a different matter).


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## Nick Batzdorf (Nov 25, 2011)

> Does anyone know where I can get a 2 second sweep from 20Hz to 20KHz?



Pro Tools and Logic have that built in. I don't remember whether other sequencers do.


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## germancomponist (Nov 25, 2011)

In Cubase this tool is available for 10 years ore more, I think... .


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## germancomponist (Nov 25, 2011)

Nick, have you informed yourself about the VPR resonator/absorber?

VPR`s are much better than all what I know, before I noticed these cool VPR`s! Especially in small rooms!


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## Synesthesia (Nov 25, 2011)

Hannes_F @ Thu Nov 24 said:


> germancomponist @ Thu Nov 24 said:
> 
> 
> > It seems that noone here is interested to get special news about room treatment with the special Fraunhofer / Renz VPR`s.......?!
> ...



Hi Hannes & Gunther,

Not entirely! I did visit the site to find out, but mein Deutsch ist nicht sehr gut, and so I left none the wiser!

http://www.renz-systeme.de/page/index.php?id=46

I do have seven limp membrane type panels in my work room but am moving soon so I'm very interested to find out more about these VPRs..

Are there any web resources in English for those of us who don't have the language skills of you chaps?!

Cheers,

Paul


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## EastWest Lurker (Nov 25, 2011)

An engineer friend of mine, Joshua Aaron, says these are pricey but in a league by themselves:
http://www.primacoustic.com/


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## Danny_Owen (Nov 25, 2011)

Paul: http://translate.google.com/translate?hl=en&sl=de&u=http://www.renz-systeme.de/page/index.php%3Fid%3D46&ei=OCzKStKCEYOgswP_9tWhBQ&sa=X&oi=translate&resnum=1&ct=result&prev=/search%3Fq%3D%2522vpr%2Babsorber%2522%26hl%3Den (http://translate.google.com/translate?h ... %26hl%3Den)

I use the primacoustics, love them, but couldn't really compare them to anything else as it's all I've had. I did a fair bit of research before buying them though, they've certainly had quite a lot of praise about them. They also look the business, don't discolour, and won't leave your wall a mess when you've taken them down.


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## germancomponist (Nov 25, 2011)

Synesthesia @ Fri Nov 25 said:


> Hannes_F @ Thu Nov 24 said:
> 
> 
> > germancomponist @ Thu Nov 24 said:
> ...



Paul, go here and look to the graphics: http://www.pia-alfa.de/en/dat_vprbka.htm

On the right site on your screen there are links to pdf`s, where you can see the results in diagramms. Awesome!

Also read this thread: http://www.gearslutz.com/board/stud...67929-my-experiment-metal-panel-absorber.html

Here you will find good informations in your language. 

Again: Sorry for my bad english/american..... .


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## Nick Batzdorf (Nov 25, 2011)

Gunther, I admit to being half-witted and not realizing that of course they're reflective too.

I was just thinking about the absorption. Duh.

Actually, what I find the most intriguing is that the little holes must function as tiny Helmholtz resonators.


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## germancomponist (Nov 25, 2011)

Huh......,

Nick, go to the links I had posted and read! 

You can combine these VPRs with absorbation, by using Basotect in front of the steel plate or these things with the little holes..... .

The most important thing here is the use of a steel plate, behind the little holes..... .

The steel plates are working in the lowest frequencies, and they do their job very well! Much better than all the other panels ever did!


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## Dan Mott (Dec 5, 2011)

Ok. Here's what I'm going to do.

First off, I'm going to take that advice on what Nick mentioned. I thought about it alot and it makes sense. I don't want to suck the life out of the room, just control my problems.

First off. I am going to create a reflection free zone behind and in between my speakers, therefore covering most of the front wall and making it pretty dead sounding. After that, I'm going to apply some good bass traps in the hots spots of the room. I have a massive peak a 44Hz. As far as the sides go, I have a little flutter echo, so I'm not going to do anything drastic. I might just apply some panels (4) on the side walls to tame that echo and make the room more warm welcoming to the sound. I think that's it really. I have gotten pretty nice mixes out of that room with nothing on the walls because I think I've adjusted to the room a bit. Aside from that, I feel that the room sounds cold and I'd like to warm it up a bit if you know what I mean.

Thanks!

PS - As far as panel choice goes. I'm still deciding whether to make my own, though I'm certian that I'd do a terrible job. I'm not at all handy in any way possible :D


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## Dan Mott (Dec 6, 2011)

Here's my room response if anybody is interested. The acoustic guy said it looks like there isn't much of a problem in the 300Hz range, but why can I hear such my res? I generally cut there all the time and in the 150Hz range. My 40Hz range is.... well... look!

I'm going to need bass traps that do a good job from 40Hz onwards.


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## RickD (Dec 19, 2011)

germancomponist @ Wed Nov 23 said:


> As I mentioned before, there is a very interesting thing, called VPR absorbers, built with a steel plate and foam.... .
> 
> http://www.pia-alfa.de/en/dat_vprbka.htm
> 
> ...



Hi, long time no see.

Looks like a nice product. the principles behind that technology have been around for over 20 years, they used to isolate air handling rooms with 4" 8# mineral wool and sheeted with perforated stainless steel about .035". I was shocked at how effective it was.


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