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

[asliarun]

IF you can only do one of those, then behind & between the speakers will be more helpful because it will reduce boundary interference (that can cause dips in the frequency response) and minimize reflections in general off the front wall (that can muddy the front soundstage).

I've wondered about one thing. If the main concern is minimizing reflection from the front wall (wall behind the speakers), especially for rear ported speakers, perhaps it might be a better idea to plug the port itself - partially or fully - with foam or cloth or something else that has small holes in it so it makes it a near aperiodic kinda enclosure. Of course, I have no idea if it will mess up the speaker performance itself - mess up its T/S perhaps.

However, just using simple logic, i feel that if we are trying to minimize the reflection from the wall behind the speaker, why not eliminate it from the source itself (the port)? That is far easier to do.

For example, these aperiodic vents might be a good solution (and i feel would work far better than completely blocking the port). Perhaps there could be a homegrown solution for this as well - a port plug that does not fully block the port but lets some air through.

P.S. This will not work at all with my speakers as they are TL design and have a very large rear opening. But for bass reflex ported designs, this should work.

 

[renjith lal]

Thanks for the clarification. I will treat the front wall with absorbing panels and will add bass traps if possible.
I used to get confused always .Thanks for giving clarity on convention.

Did I got it wrong again?
For two channel listening treating front wall (behind listener) gives better results than treating rear wall (behind speaker)?

 

[sdurani]

However, just using simple logic, i feel that if we are trying to minimize the reflection from the wall behind the speaker, why not eliminate it from the source itself (the port)?

Bass is non-directional, so it radiates like a growing sphere around the speaker. Plugging the port doesn't change that dispersion pattern. Absorption behind the speaker is still needed to stop boundary cancellations (SBIR) from creating a cancellation notch in the frequency response.

 

[square_wave]

I've wondered about one thing. If the main concern is minimizing reflection from the front wall (wall behind the speakers), especially for rear ported speakers, perhaps it might be a better idea to plug the port itself - partially or fully - with foam or cloth or something else that has small holes in it so it makes it a near aperiodic kinda enclosure. Of course, I have no idea if it will mess up the speaker performance itself - mess up its T/S perhaps.

However, just using simple logic, i feel that if we are trying to minimize the reflection from the wall behind the speaker, why not eliminate it from the source itself (the port)? That is far easier to do.

For example, these aperiodic vents might be a good solution (and i feel would work far better than completely blocking the port). Perhaps there could be a homegrown solution for this as well - a port plug that does not fully block the port but lets some air through.

P.S. This will not work at all with my speakers as they are TL design and have a very large rear opening. But for bass reflex ported designs, this should work.

From my understanding, port of the speaker is not the reason for treating the area behind the speakers. The speakers are supposed to be placed well into the room ( with a lot of space behind it ) for one to attain sound stage depth. If one can afford to have that kinda space, you don't need much treatment behind the speakers. Minimal treatment with some curtains, plants should work. But if you don't, it is wise to treat it well if you value a large soundstage with depth.

 

[asliarun]

From my understanding, port of the speaker is not the reason for treating the area behind the speakers. The speakers are supposed to be placed well into the room ( with a lot of space behind it ) for one to attain sound stage depth. If one can afford to have that kinda space, you don't need much treatment behind the speakers. Minimal treatment with some curtains, plants should work. But if you don't, it is wise to treat it well if you value a large soundstage with depth.

Again, pardon my ignorance. If the port is not the issue, then it must be the bass waves that are passing through the cabinet backwards. And then getting reflected from the back-wall. My question is - if the bass wave is capable of passing through a foot thick cabinet, it should also be capable of passing through the back-wall. I am not able to understand why the bass wave would get reflected instead and why the back-wall would need absorption treatment.

To your point, my understanding is that it is the back-wall reflections that end up muddying the soundstage.

Anyway, I am obviously missing something so I will shut up now.

 

[sdurani]

If the port is not the issue, then it must be the bass waves that are passing through the cabinet backwards.

Bass goes around the cabinet. It is radiating spherically (like an expanding balloon). In the animated graph below, the speaker is where the lines meet in the middle of the sphere.



Keep an eye on the changing frequency and compare it to the directivity balloon. Easy to spot which direction is the front of the speaker, since the directivity in that direction doesn't change.

 

[square_wave]

Again, pardon my ignorance. If the port is not the issue, then it must be the bass waves that are passing through the cabinet backwards. And then getting reflected from the back-wall. My question is - if the bass wave is capable of passing through a foot thick cabinet, it should also be capable of passing through the back-wall. I am not able to understand why the bass wave would get reflected instead and why the back-wall would need absorption treatment.

To your point, my understanding is that it is the back-wall reflections that end up muddying the soundstage.

Anyway, I am obviously missing something so I will shut up now.

In a setup,

Bass ( low frequencies) are managed by speaker placement and / or bass management via bass traps or software.

All frequencies higher than the bass are managed by room treatment ( professional or otherwise ). These are the mids and highs in the frequency range.

When we usually talk about treatment of wall behind speakers, we are referring to managing the mid and higher frequencies. Reflections in the mid and high frequencies can muddy the soundstage. So the bass port or anything to do with bass is not in the picture. But you can also place bass traps along the wall or corners behind the speakers to manage bass. But bass traps are not usually referred to as wall treatment.

 

[essrand]

What do you guys think about room correction software instead of room treatment?

Has anyone tried any of the existing solutions? Sometimes a room (especially our living rooms) can't be treated

I am considering trying a digital amp that has room correction built in to see how it works.

 

[sud98]

Has anyone tried any of the existing solutions? Sometimes a room (especially our living rooms) can't be treated

I have bought a minidsp nanoavr to handle some more complex room modes which I know adding room treatment wont help. I have a huge bump at 37hz which is far too low for most bass traps but can be handled by treatment. I am not sure totally avoiding room treatments is a good idea except in areas where room treatments cant help.

 

[heliumflight]

I also would like to share my experience of this realization. Firstly we get caught up with brand names thinking that at a change with amplifier, source, dac or speaker cable will eliminate the basic crux, i.e reflection. We leave that to the last, atleast I did, and it costed me dearly.

To overcome the above issues keep the speakers far away from the side walls and at least 3 feet from rear wall when you listen sitting very close to the speakers, you can bypass the issue of first reflections. The Piega's need a lot of air to breathe. Now I'm happy

HiFi Rig: Cambridge Audio CXN > Musical Fidelity X10 V3 > Arcam FMJ A32 > Piega Classic 3.0

 

[heliumflight]

I've wondered about one thing. If the main concern is minimizing reflection from the front wall (wall behind the speakers), especially for rear ported speakers, perhaps it might be a better idea to plug the port itself - partially or fully - with foam or cloth or something else that has small holes in it so it makes it a near aperiodic kinda enclosure. Of course, I have no idea if it will mess up the speaker performance itself - mess up its T/S perhaps.

However, just using simple logic, i feel that if we are trying to minimize the reflection from the wall behind the speaker, why not eliminate it from the source itself (the port)? That is far easier to do.

For example, these aperiodic vents might be a good solution (and i feel would work far better than completely blocking the port). Perhaps there could be a homegrown solution for this as well - a port plug that does not fully block the port but lets some air through.

P.S. This will not work at all with my speakers as they are TL design and have a very large rear opening. But for bass reflex ported designs, this should work.

Very interesting way of closing the port. Wonder if the midrange gets clouded?

 

[heliumflight]

From my understanding, port of the speaker is not the reason for treating the area behind the speakers. The speakers are supposed to be placed well into the room ( with a lot of space behind it ) for one to attain sound stage depth.

I'm in full agreement. This actually solved the reverberance.

 

[oracle1974]

https://olga66.files.wordpress.com/2017/12/contemplationaudio.jpg

Would putting something like this on the rear ( behind the listener ) help?
Thanks

 

[square_wave]

https://olga66.files.wordpress.com/2017/12/contemplationaudio.jpg

Would putting something like this on the rear ( behind the listener ) help?
Thanks

That is a diffuser. It will help in all places where there is a primary reflection point. I have seen these being used behind the speakers as well as behind the listener in many high end systems. I guess it works since you have a direct reflection point there !

 

[sud98]

Is there a place where one can buy these panels absorption/traps/diffusers? In Bangalore esp.?

 

[Surrealistix]

I just found the High-End section of the forum. It's a treat! And this is a great thread.

I used to have a dedicated room with corner traps (mineral wool), absorbers for side reflections, cloud etc. Over time, I realized that I didn't like listening to music in that room, as it felt like a room for experimentation and not really for listening to music. I would keep fiddling with things, measuring room response, DSP room correction (using Acourate) and listening to very little music! Also, the room felt over-damped like a studio.

Three years ago, I decided to move the stereo and HT to my bedroom (largish room around 350 sqft) as part of an entire home renovation project. This time around, I wanted to make sure I tackle the bass problem and not over-damp the room. Here is what I did:

Front wall - 4 inches of glass wool (RFB) and a 4-inch air gap (entire wall). Finished with cloth paneling.
Back wall and side walls - 2 inches of glass wool and then another drywall in front of it. The drywall is completely reflective. The idea here was that walls will act as a membrane and absorb bass and reflect everything else back into the room.
Ceiling - A cloud (2'X6') on the first reflection point with 2 inches of glass wool. The false ceiling is two inches from the concrete slab filled with glass wool.
Floor - rug in front of the speakers
Bed with a 12-inch mattress, French window with curtains and blinds.

The room sounds very balanced, not overdamped and neither too live. The bass is a treat. It's tight and detailed.

I am pretty happy with the way things are. Well, at least for now

 

[rajesh srinivas]

I just found the High-End section of the forum. It's a treat! And this is a great thread.

I used to have a dedicated room with corner traps (mineral wool), absorbers for side reflections, cloud etc. Over time, I realized that I didn't like listening to music in that room, as it felt like a room for experimentation and not really for listening to music. I would keep fiddling with things, measuring room response, DSP room correction (using Acourate) and listening to very little music! Also, the room felt over-damped like a studio.

Three years ago, I decided to move the stereo and HT to my bedroom (largish room around 350 sqft) as part of an entire home renovation project. This time around, I wanted to make sure I tackle the bass problem and not over-damp the room. Here is what I did:

Front wall - 4 inches of glass wool (RFB) and a 4-inch air gap (entire wall). Finished with cloth paneling.
Back wall and side walls - 2 inches of glass wool and then another drywall in front of it. The drywall is completely reflective. The idea here was that walls will act as a membrane and absorb bass and reflect everything else back into the room.
Ceiling - A cloud (2'X6') on the first reflection point with 2 inches of glass wool. The false ceiling is two inches from the concrete slab filled with glass wool.
Floor - rug in front of the speakers
Bed with a 12-inch mattress, French window with curtains and blinds.

The room sounds very balanced, not overdamped and neither too live. The bass is a treat. It's tight and detailed.

I am pretty happy with the way things are. Well, at least for now [/QUOTE

Does glass wool cause any health hazardous effect ,eye irritation,itiching etc. since you are using it have you experienced any of these.

 

[tuff]

I just found the High-End section of the forum. It's a treat! And this is a great thread.

I used to have a dedicated room with corner traps (mineral wool), absorbers for side reflections, cloud etc. Over time, I realized that I didn't like listening to music in that room, as it felt like a room for experimentation and not really for listening to music. I would keep fiddling with things, measuring room response, DSP room correction (using Acourate) and listening to very little music! Also, the room felt over-damped like a studio.

Three years ago, I decided to move the stereo and HT to my bedroom (largish room around 350 sqft) as part of an entire home renovation project. This time around, I wanted to make sure I tackle the bass problem and not over-damp the room. Here is what I did:

Front wall - 4 inches of glass wool (RFB) and a 4-inch air gap (entire wall). Finished with cloth paneling.
Back wall and side walls - 2 inches of glass wool and then another drywall in front of it. The drywall is completely reflective. The idea here was that walls will act as a membrane and absorb bass and reflect everything else back into the room.
Ceiling - A cloud (2'X6') on the first reflection point with 2 inches of glass wool. The false ceiling is two inches from the concrete slab filled with glass wool.
Floor - rug in front of the speakers
Bed with a 12-inch mattress, French window with curtains and blinds.

The room sounds very balanced, not overdamped and neither too live. The bass is a treat. It's tight and detailed.

I am pretty happy with the way things are. Well, at least for now

Pic's would be great.

 

[drkrack]

You can Check out the Artnovion Site or Bajao.com ; Artnovion has an app on iPhone for measuring the room acoustics and thereby suggesting the required room treatment. You can select every diffuser or absorber and virtually see the expected results after the selected room treatment is applied.

@square_wave I did a room treatment by a local professional ( though not a person very technically sound in my opinion). I did run the thread on HFV with most of the senior members contributing, which may be beneficial for your interest. Few important pointers from my side as far room treatment is concerned.
1. Problem Statement : what's the problem you're facing, is it the less shiny highs, muddy mid range or boominess of bass? Mentioning the problem correctly is very important.
2. Budget you're looking for
3. Type of treatment you're looking, permanent or a portable ones and how much of fiddling with interiors you're allowed to do
4. Health concerns, allergies of family members, etc

My problem was a lackluster highs, muddled midrange and booming bass. In fact, it was a worst for two channel stereo music listening. In My previous house, the listening area was more like an amphitheater, in the new house the rectangle dedicated room, I had a very bad listening experience. There's a large wardrobe on one side and a large treadmill on the other with two windows and thick curtains.

The professionals from nearby hifi dealers asked for Rs 20k for consultation for one visit. I found it quite high and decided to go on my own. Another local professional who specializes in room treatment, just clapped loudly in the room and suggested that room has too much reverberation and all walls need to be damped. No measurements of any kind. The artnovion and Dirac also showed the reverberation artifacts. @sound_cycle came up with the mic and the Dirac measurements were done. I hired the same professional to get the absorption panels setup.

I used 6-8 inch wood wool panels on front and back walls leaving the side walls without any treatment. I made four large movable wood wool panels from the same person to cover the sidewall reflections. The issues didn't settle completely after room treatment, until I moved the mammoth treadmill to another room. now the highs are much better and midrange is according to my liking. The booming bass doesn't seem to have changed much, which is quite expected. planning to add a bass trap and diffusers to sidewall and the ceiling when the budget permits. Though the local engineer pestered a lot to cover sidewalls but , making the room totally damp was a risk which I was unwilling to take. So covering the front speakers and reflection points with absorbers helped in my case. Now even the desk speakers and Bluetooth speakers sound better in that room over rest of the house. Though room treatment is a very complex and consuming addition, but the rewards are definitely worth in my opinion.

 

[Hari Iyer]

I built a new OB speaker couple of days ago and after listening to them in my room, i find no requirement for any room treatment currently. The OB speaker typically does not have much of room contributing to the overall sound stage. This may be because of the dipole polar pattern for the lows, mids and the highs with a perfect "8" pattern polar response.

In a box speaker (Sealed / Vented/ TL) the polar response is mono-pole for mids and highs and diople only for the low-end depending upon the baffle size. These speakers have more than 50% of the contribution factor from the room and hence speaker placement and the right treatment becomes crucial for a proper balance.

In OB speaker too, placement is crucial, only difference is that you dont require any much room treatment to get the right sound. An OB needs atleast 4 to 6 feet of uncluttered space behind the drivers for smooth dispersion of the lows and mids. In my room, i have done a golden ratio placement of 1:1.6 (front to rear). The distance between the front wall and the speakers are also same. The distance between the left and right speakers is 3.2 times the distance between front wall and speakers. This gave me minimum resonance effect and zero booming of the low end. Also stereo separation and center imaging and sound stage are quite good.

I would suggest, before investing on too many treatment material, try the golden ratio placement if your room permits and later discover what treatments will be required.

My 2 paise.