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Acoustic Room Treatment - help wanted

pocok

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#1
I have a rectangular shaped basement room I decided to make an audio listening room. Need some help how to treat the room so it can sound good. I'm debating to purchase ready treatments but that can be costly and not decided yet to DIY. I have 1 1/2 inch laminate with sub-floor and a heavy rug on it. Outside wall is treated with safe and sound from Rockwool. Insider wall unfortunately is empty.
 

SIY

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#2
I would search around for the excellent articles on DIY absorption and diffusion from Bill Waslo.
 

northrock

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#4
I illustrated my (relatively small, furnished, hard floor) room using https://www.gikacoustics.com/room-acoustics-visualizer/ then poked GIK for their free consultation service. Did a bunch more research and in room tests - then rolled with the top kit of 21 GIK panels (7 different products, 5 corner bass traps). The panels made a massive improvement.

For me, room treatment had the highest return to improve SQ. It cost less than a single component and with attention to layout design looks cool too.

I'm enjoying the music a lot more now.
 

DonH56

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#5
Ethan Winer's site also has a bunch of articles and DIY advice: www.realtraps.com There are also many texts on the subject from lay-level to engineering tombs.
 

pozz

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#6
I have to disagree. When I found Foley's products I was impressed. No one else makes claims about low frequency control like he does. But the data and testing information he posts is sketchy at best, and some of his claims don't make sense. He also has no formal training in acoustics or physics.

That said, I did find a paper at one point which attempted to measure bass absorption using activated carbon. The conclusion wasn't definitive, but it did indicate that this method is worth looking into further.

I can't support a manufacturer who claims superiority through innovation without providing suitable evidence.
 
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#8
I agree with Northrock above regarding GIK acoustics. The only thing I would add is focus on the speaker placement and seating first. Lock in the optimal speaker to listening position initially, THEN add in sound control room treatment. I think GIK products are a great value, they have a ton of education/videos and testing available on their site. You can speak to them directly. Biggest impact for me was controlling sound reflections from side walls and ceiling. I've kept my hard wood floors with no rugs/carpet. For me, that keeps the sound lively still, but very controlled with treatments placed strategically elsewhere. Many people initially said my room is to awkward to obtain great sound, I have since proved them wrong. I've had owners of audio shops come listen and are blown away. Keep in mind this didn't happen over night. It took me a lot of trial and error, research and using my ears. GET TO KNOW YOUR ROOM INTIMATELY. Don't expect to set it and forget it. You will need to explore and assume it's a journey if you are chasing optimal sound. But once you nail it, it is so worth it. Good luck.
 

pozz

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#9
There are guides on ASR for room measurement and interpretation here, here and here. This is a common topic of discussion, so you'll find plenty of resources easily.

Generally, you'll need the following:
  1. Measurement microphone (either USB-powered or phantom-powered through an external sound card). The miniDSP UMIK-1 and Behringer ECM3000 are common recommendations. Don't worry about getting the best or the most accurate—the Behringer is used by professional acousticians, for example. For your purposes, which will be largely low frequency and midrange measurement, these are more than sufficient.
  2. Measurement software. I find Room EQ Wizard to be the most comfortable. The creator is a regular poster as well.
You can post your results on ASR and we can help you interpret them, if you like. (This assumes you have already determined where you'll sit and where you'll place your speakers—if not, there other resources to help.)
 

DWPress

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#10
+1 for what @pozz said. No way to know what your new room needs before it is set up the way you hope to use it and properly measured to identify what the actual room dynamic needs - nulls, reflections, base treatment - then shop for the products that apply to the need. Wall/ceiling treatments can be tuned to specific frequency ranges for example.
 

Thomas savage

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#11
+1 for what @pozz said. No way to know what your new room needs before it is set up the way you hope to use it and properly measured to identify what the actual room dynamic needs - nulls, reflections, base treatment - then shop for the products that apply to the need. Wall/ceiling treatments can be tuned to specific frequency ranges for example.
Stuffing room treatment in without first knowing what and indeed if there's actual problems can end up making things worse .

I made this mistake, first thing to do is thoroughly investigate what's going on in your room.
 
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#12
Sound behaves in two ways in your room. The bass frequencies, roughly up to 300Hz, reverberates around the room; and the higher frequencies, which reflect like light in a mirror. They need separate consideration.

Bass issues are the most important to address. Once done it will also improve the higher frequencies.

This site will give you some idea of the bass issues in your room:

https://amcoustics.com/tools/amroc

Put in your room measurements and it tells you the possible problems. If you click on the link, top right, 'More about room modes...' there some information about this.

As pointed out above, speaker and listening chair placement is important. This is what I use:

http://www.barrydiamentaudio.com/monitoring.htm

And measuring is essential to do the job properly. REW again has already mentioned. I've used this for many years and still don't understand most of it but it works well.

So the principles are:

1. Position speakers and chair as best as possible.
2. Use room treatment to address problems, particularly in the bass region, but perhaps also reflections from the higher frequencies (there are a range of views on this which are worth exploring).
3. Careful use of DSP/EQ to complete the bass issues, and perhaps, very careful use to adjust the higher ones if you have problems there.

Use copious measurements as you move along this route, using frequency responses and decay time measurements - waterfall plots, spectrograms and others perhaps.

But, ultimately, don't get obsessed with measurements. They are just a guide. The real test is 'does it sound good to you'.

Books? Floyd Toole's 'Sound Reproduction, Third Edition'.

And perhaps this:

http://getbettersound.com/index.php

There are other solutions that you may want to consider and which I know little about. Using a number subwoofers to counteract the bass problems; and using only DSP. There are discussions around on these subjects.
 

pozz

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#13

Wombat

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#15
Over-furnished and cluttered seems to work, especially if there are filled tall bookcases and/or their CD/LP equivalents. Flat, hard, surfaces need to be minimised.

Note, this is coming from a bachelor. :rolleyes:
 

pozz

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#16
Why do you say to avoid the Barry Diament link?
His descriptions of room acoustics problems and his proposed solutions are half-truths. Take these examples:
"The most efficient bass traps for most rooms are 'functional sound absorbers' first proposed by Harry Olsen in the 1950's"—such as "Art Noxon's excellent Tube Traps from ASC (Acoustic Sciences Corporation)".
He shouldn't make statements like these. Optimal absorbtion is room- and frequency-dependent. Tube traps have an internal cavity surrounded by high-density fibreglass, and are useful down to the upper bass spectrum at best. They are also very inefficient in terms of space and capability compared to membrane traps or Helmholtz resonators for low frequency control.
the Rule of Thirds ... George Cardas & the golden ratio ... the 29% approach
These are rough starting guides, but quickly become misleading nonsense if you take them seriously and fret over small distances without taking larger issues into account. You can far more easily estimate room effects with a calculator and then make well-informed adjustments after measurement.
power conditioning ... cables ... burn-in ... "Many loudspeakers however, can require as much as two months to hit their stride." ... vibration control
Nearly everything he wrote regarding those topics is either false or misleading.
  • Power conditioning is useful in broadcast, studio and other high-voltage environments. Not at home, not in developed areas.
  • Cables are cheap to produce. Like rooms and electronics, their effects can be measured. Those effects are largely negligible.
  • Burn-in. Consensus from manufacturers and other professionals is that in speakers, electronics and other components is that burn-in is negligible. Just consider that a 200Hz tone in the woofer means that that diaphragm is flexing two hundred times per second—any stiffness would disappear very quickly.
The intricacies of all these area are interesting and worth learning about, if only to dispel doubt and confusion.
 

pozz

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#17
Over-furnished and cluttered seems to work, especially if there are filled tall bookcases and/or their CD/LP equivalents. Flat, hard, surfaces need to be minimised.
Nothing like a bookcase for cheap diffusion.
 
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#18
His descriptions of room acoustics problems and his proposed solutions are half-truths. Take these examples:

He shouldn't make statements like these. Optimal absorbtion is room- and frequency-dependent. Tube traps have an internal cavity surrounded by high-density fibreglass, and are useful down to the upper bass spectrum at best. They are also very inefficient in terms of space and capability compared to membrane traps or Helmholtz resonators for low frequency control.

These are rough starting guides, but quickly become misleading nonsense if you take them seriously and fret over small distances without taking larger issues into account. You can far more easily estimate room effects with a calculator and then make well-informed adjustments after measurement.

Nearly everything he wrote regarding those topics is either false or misleading.
  • Power conditioning is useful in broadcast, studio and other high-voltage environments. Not at home, not in developed areas.
  • Cables are cheap to produce. Like rooms and electronics, their effects can be measured. Those effects are largely negligible.
  • Burn-in. Consensus from manufacturers and other professionals is that in speakers, electronics and other components is that burn-in is negligible. Just consider that a 200Hz tone in the woofer means that that diaphragm is flexing two hundred times per second—any stiffness would disappear very quickly.
The intricacies of all these area are interesting and worth learning about, if only to dispel doubt and confusion.
Thanks pozz.

I must admit I didn't take too much notice of what he wrote on these subjects except The Thirds. However I do agree that all these position plans are starting points. If a person wants to start from scratch using measurements and grids and home in on where its best - the least compromises - that's fine. These suggestions - The Thirds, Cardas etc. - just give a starting point. He claims success with his arrangements so I find it fair that he shares these ideas with us.

I also think his discussions on vibrations have merit.
 

pozz

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#19
Thanks pozz.

I must admit I didn't take too much notice of what he wrote on these subjects except The Thirds. However I do agree that all these position plans are starting points. If a person wants to start from scratch using measurements and grids and home in on where its best - the least compromises - that's fine. These suggestions - The Thirds, Cardas etc. - just give a starting point. He claims success with his arrangements so I find it fair that he shares these ideas with us.

I also think his discussions on vibrations have merit.
Agreed, as starting points those rules of thumb make sense. However, the reason why those rules were developed in the first place is to do with cancellations in the bass region relative to speaker/listener positions. Jumping into that topic headfirst will likely bring about better results.

On vibrations, I don't know but I'm skeptical about the magnitude of the described effects. It's major issue for high-budget studios, but those are very complicated builds (floating floors onto which the walls are mounted, floating ceilings) and vibration control there is specifically about lowering the noise floor (if you want to look it up, the issue is called "structure borne noise"). For the home, just for speakers and components, I haven't seen reliable measurements, although the foam decouplers I've put under my monitors seem to be worthwhile (my monitors are already set on adjustable stands, so we're not just talking about acoustic differences due to height).
 

mitchco

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#20
Agree with @pozz in post 9. Get a measurement mic and REW, setup the speakers the way you want and measure at the listening position. Aside from frequency response, REW has a plethora of views to help you better understand your room acoustics:

Waterfall view: will show you modal decay of low frequencies below the rooms transition frequency - ideally all low frequencies should decay at the same rate (but never will :). If you require bass traps, put them in the 4 corners of the room for maximum effectiveness.

Energy Time Curve (ETC): will show you the rooms early reflections for the first 40ms - rule of thumb, the reflections should be ~-15 dB down from the direct sound over that time period.

RT60 - while technically there is no reverb time in small room acoustics, REW has a good algorithm (Topt) for small rooms and this measure is useful above the rooms transition frequency to get an idea of how dead or live the room is. A nice flat response from 300Hz to 10 kHz will yield a neutral sounding room. Typical RT60 Topt ranges for small room acoustics is around 200 to 400ms. Note it is better to have a more lively room than a dead one. Most folks overdo it on the absorption rather than using diffusion. A overly absorbent room takes the life out of the music.

Those 3 basic measurements will help tune your room up. DSP, like in my sig, can shape the frequency response to a spec or taste.

I find https://www.atsacoustics.com/ offers quality products at an affordable price.

Like pozz says, once you measure your room, share your REW .mdat file here and folks can assist. Also agree with pozz on Barry Diament - awesome recordings/masterings - he should stick with what he he is good at.

Good luck!
 
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