The ABC of speakers - Room treatment. You hear the room as much as you do your speakers

[siddharthdas]

So how important is it. As usual, "kiss" in the answer - keep it simple and stupid - haha.
If the speaker interacts with the room much then the answer is yes, and if not then no. What kind of speakers might help minimize room interaction? - controlled directivity speakers i.e. dipoles, kii3, dutch & dutch. Alas for most conventional box speakers or even omni radiators (like MBL), the answer is decisive "yes." Then, of course, comes the question - what do you need -
1. Diffusion and absorption done right - Diffusive rear, absorptive floor (rug will do), symmetry preferred, and bass management (traps not really necessary - although they do help as do helmholtz filters).

2. Speaker placement is important - the first reflections need to be delayed enough - so about a meter away from everything, at least.

3. Boundary woofers help a lot in managing room interactions and making room response smooth, although could mean delaying the primary speakers to ensure time coherence.

4. DSP - For most who listen to sound in real-world environments like living rooms - DSP and boundary woofers are probably the best solutions.

Believe it or not, science and engineering really help - that's how good products get built. The other thing one needs to know in all this - individual hearing varies a lot. So no system by itself or room treatment by itself can please everyone. YMMV.

Meanwhile, don't forget DSP. It's the killer app for 21st century audiophilia.

Easy enough?

 

[MasTerasTrix]

So how important is it. As usual, "kiss" in the answer - keep it simple and stupid - haha.
If the speaker interacts with the room much then the answer is yes, and if not then no. What kind of speakers might help minimize room interaction? - controlled directivity speakers i.e. dipoles, kii3, dutch & dutch. Alas for most conventional box speakers or even omni radiators (like MBL), the answer is decisive "yes." Then, of course, comes the question - what do you need -
1. Diffusion and absorption done right - Diffusive rear, absorptive floor (rug will do), symmetry preferred, and bass management (traps not really necessary - although they do help as do helmholtz filters).

2. Speaker placement is important - the first reflections need to be delayed enough - so about a meter away from everything, at least.

3. Boundary woofers help a lot in managing room interactions and making room response smooth, although could mean delaying the primary speakers to ensure time coherence.

4. DSP - For most who listen to sound in real-world environments like living rooms - DSP and boundary woofers are probably the best solutions.

Believe it or not, science and engineering really help - that's how good products get built. The other thing one needs to know in all this - individual hearing varies a lot. So no system by itself or room treatment by itself can please everyone. YMMV.

Meanwhile, don't forget DSP. It's the killer app for 21st century audiophilia.

Easy enough

Great place to start with. Would you also be kind enough to give a few examples for Diffusion/Absorbtion gear that would come in handy even for noobs .
For example- Diffusive Rear ( Few products that are commonly used / sourced ) so that we can get started.
Bass Traps -( few products that we can start with - easily available brands)
Examples that you would find appropriate to start with since you have exposure to so many products in the market.

 

[Yelamanchili manohar]

Great place to start with. Would you also be kind enough to give a few examples for Diffusion/Absorbtion gear that would come in handy even for noobs .
For example- Diffusive Rear ( Few products that are commonly used / sourced ) so that we can get started.
Bass Traps -( few products that we can start with - easily available brands)
Examples that you would find appropriate to start with since you have exposure to so many products in the market.

It is unfortunately not so simple mas terras trix. Ive been doing my arm chair research for close to a year now. Though iam still as dumb as when I started, I've noted down some musts and must not's along the way. Iam busy with work currently, so will post a detailed reply late in the evening. This topic is too wide, so in the mean while I would suggest your goodselves to Google the under mentioned two principles when it comes to addressing small rooms specifically :

1. The LEDE principle - live end dead end
2. RFZ principle - Reflection free zone.

Both the above are self explanatory. I will post about selecting between absorption and diffusion. And which type of diffusion to use, later in the night.

 

[MasTerasTrix]

It is unfortunately not so simple mas terras trix. Ive been doing my arm chair research for close to a year now. Though iam still as dumb as when I started . However, I've noted down some musts and must not's along the way. Iam busy with work currently, so will post a detailed reply late in the evening. This topic is too wide, so in the mean while I would suggest your goodselves to Google the under mentioned two principles when it comes to addressing small rooms specifically :

1. The LEDE principle - live end dead end
2. RFZ principle - Reflection free zone.

Both the above are self explanatory. I will post about selecting between absorption and diffusion. And which type of diffusion to use, later in the night.

Bro it's really sweet of you to even bother replying.Much appreciated.Please do it (whenever it's possible) & when your free ,without it affecting your work schedules.
Will do....going through the principles mentioned.
Cheers.

 

[Yelamanchili manohar]

Bro it's really sweet of you to even bother replying.Much appreciated.Please do it (whenever it's possible) & when your free ,without it affecting your work schedules.
Will do....going through the principles mentioned.
Cheers.

Absolutely no worries bro ...

Have sometime on my hand now. So will get started. But I will try to keep it concise, or it will become a long bloaty boring lecture .

The purpose of treating our room :

1. To arrange the placement of our speakers and listening position in such a way, that the primary reflections ( first reflections) reach our ears 15 milliseconds after the direct sound from the speakers. Converting 15 milli seconds into distance, give us 5.1 mtrs or 17 ft.
So if "distance from speaker baffle to first reflection point" + "distance from first reflection point to ear" > 17 ft. Then no treatment is required at this first reflection point.

2. However in small rooms, the above required 17 ft will not be possible. So the solution then is to treat the first reflection point, with either absorption or diffusion such that the amplitude of the reflected sound is 10 dB less than the amplitude of the direct sound from the speaker.

3. So absorbtion or diffusion at first reflection point - The recommended ratio between absorption vs diffusion vs reflection ( bare walls or ceiling) is 33%:33%:33%.

So the total surface area of the room, which is all the walls + ceiling + flooring should be computed. In my 15ft long x 11.5ft wide x 8.5ft high room, the total surface area will be 833.75 ft. So by the 33% ratio, I will need 278 SQ, ft of absorption and diffusion each. This 278 SQ. Ft translates to 35 nos of 4x2 ft panels, which as we can see is impossible to place. So the only solution is to keep equal amounts of diffusion and absorption. By equal amounts, I don't mean equal area of diffusers and absorbers.

The max effeciency of a diffuser is taken as 0. 6 NRC, where as a proper absorber designed for that same frequency can have a NRC of 1.0. Which means, for every 1 SQ.ft of absorption used, we will need 1.66 SQ. Ft of diffusion to have the same effect. Thus, diffusion will take up more surface area than absorption. Thus, absorption is recommended for smaller rooms.

4. 1D or quadratic diffusers - These are the easiest DIY diffusers with plans readily available online. Every quadratic diffuser is designed with a target frequency range in mind. The lower frequency where the diffusion starts is called as its design frequency. Let us take an example of a 5 inch deep quadratic diffuser, whose effective frequency usually starts at 900 hz. The wave length of a 900 hz sound wave is 37 cms. We multiply this by 3, to get 1.11 mtrs.

So we should not have any sound source or listener within a distance of 1.11 mtr from the boundaries of a, quadratic diffuser. A quadratic diffuser is called as a RPG - reflection phase grating. The phase of the diffused wave is offset from the direct sound. And when source or listener are within 3 wave lengths of the diffuser, then the interaction between the direct and reflected sound will cause a tingy note to the treble and will damage imaging of the system.

I have previously read that diffusers have to be placed at a minimum of 8 ft from the listener. Then recently on a different forum, a designer of studio's mentioned that he would never use a quadratic diffuser, unless the listener was at least 10 millisecs from the quadratic diffuser. That translates to 3.4 mtrs or 11.3 ft. But since he was referring to a studio where 100% acoustics are required, I would like to think that for a domestic small room 8 ft might be doable

5. 2D or skyline diffusers - Where room size doesn't permit quadratic diffusers, the skyline diffusers come to the rescue. The skyline diffusers are less effective than quadratic diffusers, but don't come with a minimum distance requirement ive seen so far. Actually skylines don't diffuse, they apparently only work via staggered reflection. So these can be used without a minimum distance requirement probably. But I would still stick with a minimum of 8 feet distance to the ear in my room, because it is possible at 2 points.

6. Another types of diffusers recommended for small rooms are poly diffusers. These look like a hlaf cylindrical PVC pipe. And the inside can be stuffed with glass wool to absorb bass as well. These poly's don't alter the phase, and thus don't have a minimum recommended distance again.

7. I've saved the best for the last - RPG BAD - Binary amplitude diffusers - these are patented by RPG systems, and haven't seen same being offered by anyone else. These are thin, almost 1 inch thick panels, with a, mathematically calculated cuts in the baffle plate They diffuse from mid frequencies upwards and absorb bass at the same time. So these would be most ideal.

8. Now coming to absorption - I don't think ive learnt anything extra. So I will let it pass.

The first reflective point treatments, only come after bass treatment. Unless RT60 times below 400 hz are brought down below 0.5 secs. We won't be able to hear the full benefits of the panels at first reflection points.

I guess I will take a break now .. Not easy typing long posts on a tablet

 

[MasTerasTrix]

Absolutely no worries bro ...

Have sometime on my hand now. So will get started. But I will try to keep it concise, or it will become a long bloaty boring lecture .

The purpose of treating our room :

1. To arrange the placement of our speakers and listening position in such a way, that the primary reflections ( first reflections) reach our ears 15 milliseconds after the direct sound from the speakers. Converting 15 milli seconds into distance, give us 5.1 mtrs or 17 ft.
So if "distance from speaker baffle to first reflection point" + "distance from first reflection point to ear" > 17 ft. Then no treatment is required at this first reflection point.

2. However in small rooms, the above required 17 ft will not be possible. So the solution then is to treat the first reflection point, with either absorption or diffusion such that the amplitude of the reflected sound is 10 dB less than the amplitude of the direct sound from the speaker.

3. So absorbtion or diffusion at first reflection point - The recommended ratio between absorption vs diffusion vs reflection ( bare walls or ceiling) is 33%:33%:33%.

So the total surface area of the room, which is all the walls + ceiling + flooring should be computed. In my 15ft long x 11.5ft wide x 8.5ft high room, the total surface area will be 833.75 ft. So by the 33% ratio, I will need 278 SQ, ft of absorption and diffusion each. This 278 SQ. Ft translates to 35 nos of 4x2 ft panels, which as we can see is impossible to place. So the only solution is to keep equal amounts of diffusion and absorption. By equal amounts, I don't mean equal area of diffusers and absorbers.

The max effeciency of a diffuser is taken as 0. 6 NRC, where as a proper absorber designed for that same frequency can have a NRC of 1.0. Which means, for every 1 SQ.ft of absorption used, we will need 1.66 SQ. Ft of diffusion to have the same effect. Thus, diffusion will take up more surface area than absorption. Thus, absorption is recommended for smaller rooms.

4. 1D or quadratic diffusers - These are the easiest DIY diffusers with plans readily available online. Every quadratic diffuser is designed with a target frequency range in mind. The lower frequency where the diffusion starts is called as its design frequency. Let us take an example of a 5 inch deep quadratic diffuser, whose effective frequency usually starts at 900 hz. The wave length of a 900 hz sound wave is 37 cms. We multiply this by 3, to get 1.11 mtrs.

So we should not have any sound source or listener within a distance of 1.11 mtr from the boundaries of a, quadratic diffuser. A quadratic diffuser is called as a RPG - reflection phase grating. The phase of the diffused wave is offset from the direct sound. And when source or listener are within 3 wave lengths of the diffuser, then the interaction between the direct and reflected sound will cause a tingy note to the treble and will damage imaging of the system.

I have previously read that diffusers have to be placed at a minimum of 8 ft from the listener. Then recently on a different forum, a designer of studio's mentioned that he would never use a quadratic diffuser, unless the listener was at least 10 millisecs from the quadratic diffuser. That translates to 3.4 mtrs or 11.3 ft. But since he was referring to a studio where 100% acoustics are required, I would like to think that for a domestic small room 8 ft might be doable

5. 2D or skyline diffusers - Where room size doesn't permit quadratic diffusers, the skyline diffusers come to the rescue. The skyline diffusers are less effective than quadratic diffusers, but don't come with a minimum distance requirement ive seen so far. Actually skylines don't diffuse, they apparently only work via staggered reflection. So these can be used without a minimum distance requirement probably. But I would still stick with a minimum of 8 feet distance to the ear in my room, because it is possible at 2 points.

6. Another types of diffusers recommended for small rooms are poly diffusers. These look like a hlaf cylindrical PVC pipe. And the inside can be stuffed with glass wool to absorb bass as well. These poly's don't alter the phase, and thus don't have a minimum recommended distance again.

7. I've saved the best for the last - RPG BAD - Binary amplitude diffusers - these are patented by RPG systems, and haven't seen same being offered by anyone else. These are thin, almost 1 inch thick panels, with a, mathematically calculated cuts in the baffle plate They diffuse from mid frequencies upwards and absorb bass at the same time. So these would be most ideal.

8. Now coming to absorption - I don't think ive learnt anything extra. So I will let it pass.

I guess I will take a break now .. Not easy typing long posts on a tablet

Phew....simply amazing, you have jotted the pointers so well and I'm sure this would serve as a starting point for many people like me who have had zero knowledge about the above mentioned room treatments and how to go about it( at least be aware of what to look out for when starting room treatment) I'm sure there's lot more to it and that you can't fit it all in here ,but everything that you've shared here is a great place to start rather than having no clue about the various options available. You have got the ball rolling and i for sure will try and dig deep to get a better understanding of what would apply to my current room(setup).
Cheers to you for detailing it so well.

 

[Yelamanchili manohar]

Phew....simply amazing, you have jotted the pointers so well and I'm sure this would serve as a starting point for many people like me who have had zero knowledge about the above mentioned room treatments and how to go about it( at least be aware of what to look out for when starting room treatment) I'm sure there's lot more to it and that you can't fit it all in here ,but everything that you've shared here is a great place to start rather than having no clue about the various options available. You have got the ball rolling and i for sure will try and dig deep to get a better understanding of what would apply to my current room(setup).
Cheers to you for detailing it so well.

Thanks for your kind words. And all the best for your room treatment. A parting word of caution, don't fix anything permanently. Adding something somewhere might necessitate removing something you've added before. So it goes to and fro till everything is dialled in perfectly. Almost like manually biasing a tube amp. And please take it real slow with a lot listening. And That's when we go for fixed mounting. Iam no expert. But if you can post a schematic of your room with your distances, speakers and listening position. I can have a look. And maybe burrow through the tons of treated rooms pics I've downloaded, and can suggest something that might come close to your room and setup

 

[MasTerasTrix]

Thanks for your kind words. And all the best for your room treatment. A parting word of caution, don't fix anything permanently. Adding something somewhere might necessitate removing something you've added before. So it goes to and fro till everything is dialled in perfectly. Almost like manually biasing a tube amp. And please take it real slow with a lot listening. And That's when we go for fixed mounting. Iam no expert. But if you can post a schematic of your room with your distances, speakers and listening position. I can have a look. And maybe burrow through the tons of treated rooms pics I've downloaded, and can suggest something that might come close to your room and setup

Sure sir, as of now I am just reading through the concept and getting to know more about it. Plus it's very difficult to make changes while living in rented premises.Will also share schematics when I do plan to make changes or take to room treatment & will get your advice. A lot of it depends on the mood of the lady in the house& i wait to feel her pulse even before planning any changes. Hope you get what I mean.Thanks again for your help as it's a great starting point and you've explained(simplified) it so well.
Cheers

 

[Kannan]

NEAR FIELD SETUPs

Since i have been living all along in rental premises and have been shifting every 3/4 years, my chosen setup has been always been to suit nearfield listening with speakers placed along the longer wall if the room allows for it and my listening position well off from the wall behind me. Max db levels/dynamics vary depending on what the room allows as no treatments are possible.

In the present house, my listening hole is a 11x11 room, the active Dynaudio speakers are placed 4 feet apart with no toe-in (5 feet between the center axis of the drivers). As these are small speakers (10 inch x 6 inch x 6 inch), listening position is either on the floor (better) or on a chair of low height due to the height of my present stands.

 

[Yelamanchili manohar]

NEAR FIELD SETUPs

Since i have been living all along in rental premises and have been shifting every 3/4 years, my chosen setup has been always been to suit nearfield listening with speakers placed along the longer wall if the room allows for it and my listening position well off from the wall behind me. Max db levels/dynamics vary depending on what the room allows as no treatments are possible.

In the present house, my listening hole is a 11x11 room, the active Dynaudio speakers are placed 4 feet apart with no toe-in (5 feet between the center axis of the drivers). As these are small speakers (10 inch x 6 inch x 6 inch), listening position is either on the floor (better) or on a chair of low height due to the height of my present stands.

Even I prefer placement along the long wall and a near field 8 ft equilateral setup. Sounds better to me than placing speakers along the short wall and ending up with a isosceles triangle setup.