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What is the right approach for room treatment in high end audio ?

square_wave

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#1
How little or how much of room treatment do you do ?

At what point did you feel it is too much or too little ?

What are critical room treatments that you feel is necessaryfor the magic to happen ?

My thought process is like this :

A room with no treatment is a bare room with nothing in it. I mean totally bare concrete walls and a person sitting on a wooden stool in front of the speakers. Anything that is added to this will act as a some kind of treatment because everything has some absorption or diffusion properties.

Carpets, curtains, sofa, chairs, bookshelves with books in it, material of the walls / floor / ceiling. Everything changes the sound in someway. If you add professionally created treatment materials you are doing something in a scientific manner rather than putting a sofa or bookshelf with books which has got some unknown properties.

In the light of the above thought, I would like people whohave a lot of experience put forth the thoughts which govern their approach.
 
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Nikhil

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#2
Great topic and very misunderstood area of audio.
Would really like to hear from some of the room setup gurus on this.




.
 
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#3
I am no guru but I have certainly tried a lot of things. I would like to illustrate my conclusion with an example.

Imagine that you are painting a fresh wall. The painter will sand it, put putty, sand it again and repeat till he has a perfect surface.

I have found that room treatment is like the sanding. Room treatment will never provide perfection like a putty surface. But that is good enough for most of us.

For a perfect finish one needs to go in for Room Correction with a DSP device like MINIDSP. A combination of room treatment to remove the big issues and DSP based room correction for the finishing touch gets one closest to the ideal.

That has been my experience and represents my current approach.
 

sdurani

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#4
Even in this day and age of surround sound, the front soundstage remains critical: that's where your attention will be focused, whether listening to music or watching a movie. As such, you want clarity and articulation coming from the front speakers. That means placing absorption across the front walls to kill reflections that could muddy the front soundstage. Good idea to do this on the middle half of the back wall as well (to kill the reflections from the centre speaker).

Side wall treatment is optional (I prefer bare walls, you might like absorption or diffusion). Furniture can be considered treatment to the extent that it will break up the sound. However, if the furniture layout is asymmetrical, then you could end up with an unbalanced or lop-sided soundstage. Your ears are a good judge of what treatments are working and what is not.
 

sidvee

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#5
Not that I have a lot of experience or expertise in this but having had 3-4 listening rooms over the past 20 years (both in US and India) my biggest concern with room treatment is the taming of/controlling bass frequencies. Every room I have had which varied in size from 1500 cu.ft. to 3000 cu.ft. always had challenges in producing deep tight bass. To that end the for biggest bang for the buck, IMO, this would be the first problem to tackle (I am referring to stereo sound only without the aid of sub-woofers). I have always started with bass traps in the four corners of the room that has produced consistent results in cleaning up the bass.
Cheers,
Sid
 

square_wave

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#6
Hi Sid, I agree about the bass issue. Without solving that, the detail in the bass is lost. Bass is the foundation for music. I have heard tactile, detailed bass in very few rooms. I know a fantastic listening room in Bangalore where the highs and mids are fantastic but the bass sounds like a " thud ". The listener is so fascinated by the quality of the mids that he does not even bother with the bass.

I am curious to know about your approach with the frequencies above the bass range. Are there some critical things that you would do ?

I have found this page to be quite nice for dealing with reflection points.
http://arqen.com/acoustics-101/reflection-free-zone/
 
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elangoas

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#7
How little or how much of room treatment do you do ?
Until sometime back, i was of the belief that room treatment (Absorption panel) covers the entire spectrum of hearing.. After some reading, learnt that room treatment (Absorption panels) work only above 100 Hz, and it is practically impossible to treat anything below 100Hz in a living room (because of the thickness of absorption material) and it is very challenging to get the bass right at your listening position..

The only way, which i think to get the "bass right" in the room is by adding/positioning multiple subwoofers (which an amateur user can do), but also demands a DSP to tame the peaks (Which only a person with very good understanding of acoustic terms can do)..

At what point did you feel it is too much or too little ?
When i was considering buying subwoofer, most articles suggested atleast dual subwoofer as they do good in a room.. Once i got them (dual subs), i thought i had perfect bass in my room.. But only later found that they also need to positioned right in the room to get full benefits..

IMO, this would be the first problem to tackle (I am referring to stereo sound only without the aid of sub-woofers)
I think so (not very sure), getting bass with-out subwoofers in a room is possible only if "the distance of walls are symmetric w.r.t your listening position & right placement of speakers and your listening position" in the room.. Otherwise, it has to be addressed differently..
 

square_wave

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#8
Side wall treatment is optional (I prefer bare walls, you might like absorption or diffusion).
With bare walls on the side, don't you end up with issues with first reflections which will pretty much kill the soundstage ? Can you elaborate about your experiments here ?

However, I agree that if the speakers are far away from the side walls and you listen sitting very close to the speakers, you can bypass the issue of first reflections.
 

sidvee

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#9
I think so (not very sure), getting bass with-out subwoofers in a room is possible only if "the distance of walls are symmetric w.r.t your listening position & right placement of speakers and your listening position" in the room.. Otherwise, it has to be addressed differently..
@ Elangoas, speaker placement is very important but regardless of the best speaker placement I have seen that low, tight tactile bass (provided the speaker can produce it) can be best coaxed out of the listening room only by room treatment (whether passive or active).
Anyway as I mentioned I am not an expert by any means so perhaps you are right, but I am a (of the many) 2 channel listener who prefers to avoid sub-woofers for 2 channel listening (due to added expense and complexity) and have obtained controlled bass to around 30 hz at decent spl for music only in my rooms by treatment.
Cheers,
Sid
 
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sidvee

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#10
Hi Sid, I agree about the bass issue. Without solving that, the detail in the bass is lost. Bass is the foundation for music. I have heard tactile, detailed bass in very few rooms. I know a fantastic listening room in Bangalore where the highs and mids are fantastic but the bass sounds like a " thud ". The listener is so fascinated by the quality of the mids that he does not even bother with the bass.

I am curious to know about your approach with the frequencies above the bass range. Are there some critical things that you would do ?

I have found this page to be quite nice for dealing with reflection points.
http://arqen.com/acoustics-101/reflection-free-zone/
I like the LEDE approach Square, deaden the area around the speakers and liven the area around and behind the listener. This worked for me subjectively. Note that I say subjective because when it comes to acoustics, I have noticed different users prefer different options. Some feel absorbers at first and 2nd refelection deaden the room too much, others feel different. Also I feel it is important that one measure their room prior to treatment to get an objective handle of what their room/sitting position/speaker position is doing before embarking on a treatment plan, but regardless of measurements putting bass traps in corners will always help the most problematic frequency - the bass.
Cheers,
Sid
 
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elangoas

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#11
Anyway as I mentioned I am not an expert by any means so perhaps you are right,
Oops @sidvee . You have at-least tried/successful by adding room treatment.. Am just a beginner to acoustics, still trying to digest some terms and try some improvements in my room.. I said that as an example only based on my reading/understanding..

but I am a (of the many) 2 channel listener who prefers to avoid sub-woofers for 2 channel listening (due to added expense and complexity)
Agree here on the expense and especially complexity involved..

and have obtained controlled bass to around 30 hz at decent spl for music only in my rooms by treatment.
From the earlier threads discussed on bass issues, i understand you have bass traps in your room..But, i would like to ask (only for clarity) how do you say it is controlled bass? Is it only by ear? (or) thru room measurements?..

The reason i ask you is because, i have dual subs in front corners of my room (thought not ideal positions), been using them with Audyssey engaged.. When i tried REW measurements (without Audyssey), i observed 20dB peaks in my listening position at some freq between 20 Hz - 100 Hz in my room.. When i moved the subs to the ideal locations, the peak dropped by 10dB.. I don't know by how much (dB) Audyssey tames the peaks when engaged..
 

sidvee

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#12
Oops @sidvee .

From the earlier threads discussed on bass issues, i understand you have bass traps in your room..But, i would like to ask (only for clarity) how do you say it is controlled bass? Is it only by ear? (or) thru room measurements?..

The reason i ask you is because, i have dual subs in front corners of my room (thought not ideal positions), been using them with Audyssey engaged.. When i tried REW measurements (without Audyssey), i observed 20dB peaks in my listening position at some freq between 20 Hz - 100 Hz in my room.. When i moved the subs to the ideal locations, the peak dropped by 10dB.. I don't know by how much (dB) Audyssey tames the peaks when engaged..
Both i.e; when I plot my room response I do not see any severe peaks or troughs especially in mid bass and low bass range say 160hz - 20hz, but most importantly when I listen to music, for instance double bass player - the sound of the instrument is tight, taut, extended and many times tactile wherein I feel the bass rather than just hear it (and this is without a subwoofer). And I guess another feature I really love is I actually get bass imaging within the soundstage.
Cheers,
Sid
 

square_wave

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#13
Hi Sid, I have heard that when you dial in with the right bass traps, the response flattens and you actually get more bass but detailed and tactile rather than the boom before the bass traps came in. This can sound counter intuitive to many.
 

prem

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#14
With high efficiency speakers, life gets sucked out with traps. That’s been my experience. It’s probably because SPLs are low
 

square_wave

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#15
Hi Prem, Have you had this problem using a high eff speaker when trying to solve measured uneven response in a room ? Good bass traps only operate at certain frequencies and they need to be chosen after measuring the room well.

I am asking this because I have seen people just borrowing a bass trap from someone and trying it out in their room and eventually it does not work. I am guilty of this as well :)
 

prem

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#18
Hi Square wave, I haven’t done any measurements. For whatever it’s worth I had used Real Traps and had used their advice to set it up. It worked when I had a 200 watt amp. It failed miserably when I moved over to Rethms

As of now I concentrate only on speaker placement. I get decent bass in my room. Or at least I think it’s fine:)

FWIW, I spend a lot of time on speaker placement and try and get them to sing with the room. It’s to the accuracy of 0.5 cm
 

sdurani

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#19
With bare walls on the side, don't you end up with issues with first reflections which will pretty much kill the soundstage ?
Not according to any of the research out there. Couple of examples:
There seems to be consensus in the field that some early reflections actually help make speech more intelligible. However, it is also well documented that reflections within 5-10 ms of the main pulse in typical listening rooms are above the level where the primary source shifts or spreads (even when just listening to a single primary source). Reflections from the front and the rear (within ±40º) are perceived as detrimental to sound quality, whereas side reflections (within reasonable levels) often improve the perceived sound quality.
Above quoted from the Dirac room correction white paper: http://diracdocs.com/on_room_correction.pdf
  • Persuasive evidence points to several beneficial and few negative effects of early reflections.
  • Early reflections improve speech intelligibility.
  • Early lateral reflections increase our preference for the sound of music and speech.
  • Multiple reflections improve the audibility of timbral cues from resonances in the structure of musical and vocal sounds.
  • A room with abundant reflections is not likely to exhibit audible evidence of comb filtering from any single reflection.​
  • Reflections from central portions of the front and back walls have the least positive contributions to what we hear. Attenuating them may be advantageous.​
Above quoted from Floyd Toole's last paper at Harman: http://www.wghwoodworking.com/audio/loudspeakers_and_rooms_for_sound_reproduction.pdf
Can you elaborate about your experiments here ?
Tried absorption (6" OC703) and diffusion (9" skylines) at the lateral first reflection points and kept coming back to bare walls. Not what I was expecting, but I couldn't argue against my own preference.
However, I agree that if the speakers are far away from the side walls and you listen sitting very close to the speakers, you can bypass the issue of first reflections.
What if it turns out that early reflections are not an issue but instead a benefit? Should we ignore research (and personal preference) and pretend that it's a problem?
 

arj

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#20
Nice bearded topic :)
Personally, i have found treated rooms , even professionally done, to be pretty boring ..there is a clinical feel as though you are in a hospital despite it all being there- All meaning, attack, decay, soundstage, clean bass, extended highs etc.

It may be psychological as sitting in treated room takes away the relaxation of sitting in a comfortable room and I find it difficult to relax ! The reverberation of a plain 3-4 wall room is also definitely not the solution as the distortion especially of the highs and lower bass gets to you.

Regarding Room treatment many changes are obvious but some of them very subtle and sends you onto other problems whose fixes which just escalate over time
eg: i once changed a cartridge which gave high detail/dynamics but over time i found the naturalness reducing. not knowing it was the cartridge, played around with position of speakers, vibration control, power and even cables. After 3 months it had gone all wrong and i was not even sure what was wrong although the sound was amiss ( i blamed it all on the cable breakin !). Thankfully Prem and Square-wave dropped in one evening and thats when realisation to the extent of deterioration hit me with Prems expert help put it back. That has reduced a lot of experimentation and even if I do, I always keep the reference setup as a base and with a reference track to recheck.

Some other thoughts which I try to go by based on what I have tried
- Diffusers behind the head work well especially if seated close to the wall, else the brain ignores it
- Diffusers on the side work very well at giving a soundstage. I prefer Books/LPs there to break it up but not get rid of it ( i guess this is what Sdurani is talking about)
-Absorbers simply dont work for me at least have not so far..they always do a little bit extra and add in or take something else out as well and sometime that 'Something" takes ages to even understand. i prefer an artificial plant or a box in the corner + playing around with speakers to reduce bass but to the largest extent get the positioning of speakers right.

Unlike Prems 0.5cm i am still in the 1 cm space :)
 
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