Room treatment

[Eric Teh]

Sharing some pictures of my room. Pardon for posting the link instead. My office servers block picture hosting sites.  :(

 

http://singaporehifi.blogspot.com/2010/06/acoustic-treatment.html

 

My listening room is very modest in size. Its about 3 x 3.5 m.

[naimster]

very nice improvement. 15-20db improvement at 55hz is something no cables change can give. I will be taking my room measurement soon too and am pretty sure the improvement is big given what I am hearing now.

[naimster]

Here's mine after....I do one "before treatment" by removing all my panels another day :)

 

 

After smoothing, the results looks good...less than 10db between min and max for the bass frequencies. ;)

[zaek]

any online newbie guide to get me started?

 

I don't even know the relationship between db and Hz (from the graph).  :-[

[naimster]

Posted a while back....quite a good read...at least to me.

 

http://www.gcmstudio.com/acoustics/acoustics.html

[zaek]

Thanks. I will "dive" into it. hahha

[naimster]

More to share...left and right speaker ONLY frequency response plots without smoothing. Red curve is for left and black is for right. Obviously, the left side of my room is more problematic than right. Now I know where to improve further in my next phase of treatment, if I feel like pushing the performance further. :P

 

[1AngMoh]

Thanks for the nice comment ,sorry for late reply, was busy at some family issue...

 

would like to add, the improvement we heard and measured not only came from the diffuser, the bass trap base under the diffuser at 2 side wall, also help to flatten the response between 100-300hz range , [glow=yellow,2,300]maybe 1angmo could post the graph at watchdog thread to show what has happening in actual... :)[/glow]

 

 

Yes Joamonte.  Details on my small listening room and measurements of the same can be found HERE

 

Still a work in progress.

[naimster]

1angmoh,

 

Thanks for the for the informative writeup.

 

Interesting that you prefer diffusion at the 1st reflection points (sidewall). I personally have tried switching between RPG BAD diffusors and RPG Absorbors at the sides and it was clear to me I much prefer absorption while BAD gives more liveliness, it has tendency to mess up the imaging and sounded shouty at higher SPLs. Maybe BAD is not the ideal diffusor or it's a case of personal preference here. One thing to note is that as I am using RealTraps, one of it's  advantage is that it doesnt absorb as much highs as other bass traps, so in a way, I have enough of "liveliness" in room.

 

One area we're in agreement is that for small rooms, having bass traps is a better option that diffuse at the back of listener. There's simply not enough distance for the diffusors to work well in my experience.

 

Glad to see that you're taking a step further by purchasing the XTZ kit. Myself also purchased the Omni Mic kit set (with a few friends) and use it with Room EQ Wizard for optimizing my room further. Still contemplating what should I do for the ceiling which so far I have done nothing. ;)

[joamonte]

1angmoh,

 

Thanks for the for the informative writeup.

 

Interesting that you prefer diffusion at the 1st reflection points (sidewall). I personally have tried switching between RPG BAD diffusors and RPG Absorbors at the sides and it was clear to me I much prefer absorption while BAD gives more liveliness, it has tendency to mess up the imaging and sounded shouty at higher SPLs. Maybe BAD is not the ideal diffusor or it's a case of personal preference here. One thing to note is that as I am using RealTraps, one of it's  advantage is that it doesnt absorb as much highs as other bass traps, so in a way, I have enough of "liveliness" in room.

 

 

 

 

 

 

 

Not surprise , your front wall are using whole rows of BAD and  if you look at the  Adsorption Coefficient of BAD panel...

 

 

Above 1Khz it's adsorbing power is getting weak , if already use a lot of BAD at the other part of the room,  using it again in on the early reflection point will tend to "tilt up" the sound power response of the speaker because it "eat" up too much mid/lower midrange and "left over" too much mid-high ... :)

 

..I prefer to using BAD at non-early reflection point or at listener back wall (if sitting close)...... not on side wall early reflection point.

 

And I will recommend using enough high frequency absorber spreading around the room to balance out the RT/late reflection of the room.

 

 

 

One area we're in agreement is that for small rooms, having bass traps is a better option that diffuse at the back of listener. There's simply not enough distance for the diffusers to work well in my experience.

 

 

 

 

If you are referring to the Adsorbing panel Vs Diffuser at the listener back wall, I would say it depend on

 

1) How you treated the other part of the walls and ceiling...

2) you are comparing what type of Diffuser and what type of Adsorbing panel

3) your listening preference

 

I believe no hard rule on how a listener back wall SHOULD use at all.. 

 

And talk about space that need for a diffuser to work.... ::)

 

...IMHO If you are using the Traditional 7 step QRD, than of course you need a distance for it to work , because those diffuser only work from 300Hz to 3Khz ,  the wave length of these range of frequencies is too long for a acoustic diffuser to "disappear" if you are seating too close to it ; but some boarder band Acoustic diffuser that work at higher frequency above 3Kz , would work pretty well even if you seat very close to it, the high frequency wave length above 5Khz is short enough to diffuse well in short distance.

 

...BAD should also work well if place it behind listener , just you still need to have enough high frequency absorber at  the other part of the room wall/ceiling to  balance out the RT.

 

 

 

Below this is the concept's from Swedish Acoustics expert Mr. Matts Odemalm ( http://www.performanceacousticslabs.com/PAL/Home-Acoustics_Listening_Rooms.html ) , who is a firm believer of full diffuser + bass trap treatment method , it explain well how Full diffuser different from traditional adsorption method....

 

 

 

 

 

As for me I figure his full diffuser concept don't would too well for Asia (OK .... at least in Singapore  ;D ) audiophile for some reason, maybe because I haven't heard a higher level full diffuser room using his concept yet  ..

 

My concept of 2 channel Audio room is approx 70% diffuser 30% adsorption , with as much bass trap as possible.....the ETC should somewhere between the Red and the green line in that graph.

 

:)

 

 

 

 

 

[joamonte]

 

Yes Joamonte.  Details on my small listening room and measurements of the same can be found HERE

 

Still a work in progress.

 

WOW, nice thread!!

[naimster]

Yeah, BAD panels pretty much doesn't absorb beyond 1khz and it's precisely that I prefer the RPG Absorbers for the side walls. Maybe a pure diffuser (unlike BAD which diffuse and absorb) would work better for side walls.

 

I am actually using BAD for the side wall 2nd reflection points now as well. ;)

 

I have tried BAD right behind listener .... Doesn't work well.... The absorbers still work better but it's probably a preference thing.

 

I concur with your strategy of using as much bass trap as possible in the room. Many folks think that excessive bass traps will take away the low bass. On the contrary, what I experienced is deeper, faster and more well defined bass. As long as the bass traps doesn't kill the highs, they are definitely all positive.

 

Not surprise , your front wall are using whole rows of BAD and  if you look at the  Adsorption Coefficient of BAD panel...

 

Above 1Khz it's adsorbing power is getting weak , if already use a lot of BAD at the other part of the room,  using it again in on the early reflection point will tend to "tilt up" the sound power response of the speaker because it "eat" up too much mid/lower midrange and "left over" too much mid-high ... :)

 

..I prefer to using BAD at non-early reflection point or at listener back wall (if sitting close)...... not on side wall early reflection point.

 

And I will recommend using enough high frequency absorber spreading around the room to balance out the RT/late reflection of the room.

 

If you are referring to the Adsorbing panel Vs Diffuser at the listener back wall, I would say it depend on

 

1) How you treated the other part of the walls and ceiling...

2) you are comparing what type of Diffuser and what type of Adsorbing panel

3) your listening preference

 

I believe no hard rule on how a listener back wall SHOULD use at all.. 

 

And talk about space that need for a diffuser to work.... ::)

 

...IMHO If you are using the Traditional 7 step QRD, than of course you need a distance for it to work , because those diffuser only work from 300Hz to 3Khz ,  the wave length of these range of frequencies is too long for a acoustic diffuser to "disappear" if you are seating too close to it ; but some boarder band Acoustic diffuser that work at higher frequency above 3Kz , would work pretty well even if you seat very close to it, the high frequency wave length above 5Khz is short enough to diffuse well in short distance.

 

...BAD should also work well if place it behind listener , just you still need to have enough high frequency absorber at  the other part of the room wall/ceiling to  balance out the RT.

 

 

 

Below this is the concept's from Swedish Acoustics expert Mr. Matts Odemalm ( http://www.performanceacousticslabs.com/PAL/Home-Acoustics_Listening_Rooms.html ) , who is a firm believer of full diffuser + bass trap treatment method , it explain well how Full diffuser different from traditional adsorption method....

 

As for me I figure his full diffuser concept don't would too well for Asia (OK .... at least in Singapore  ;D ) audiophile for some reason, maybe because I haven't heard a higher level full diffuser room using his concept yet  ..

 

My concept of 2 channel Audio room is approx 70% diffuser 30% adsorption , with as much bass trap as possible.....the ETC should somewhere between the Red and the green line in that graph.

 

:)

[1AngMoh]

Hi Naimster,

 

There seems to be two schools of thought when it comes to the rear wall.  One view is that nothing good can come from the rear wall and you should kill everything, especially if you are sitting close to it.  Another view is that some reflection or diffusion from the rear wall could add a degree  of spaciousness and 'surround sound' to the proceedings.

 

I did try BAD at the rear wall and it did nothing for me at all.  One possible reason is because I did not use enough of it.  So over the next few months I will be trying absorption and diffusion on the rear wall (and combinations) and letting my ears decide which they like.  In any case I will not be moving the bass trap which sits directly behind the listening chair.  I did try BAD there to and it was useless.

 

RPG describe their BAD panels as being "zero depth diffuser absorbers".  IMHO they do neither diffusion nor absorption particularly well and too your point - given the choice of BAD or RealTraps at the first reflection point I would probably opt for RealTraps too.  As you would have read from my comments I found nothing wrong with using absorption at the first reflection point (indeed some advantage with image) but overall I liked Joamonte's broadband diffuser combined with a bass trap much better.

 

Overall my playback system has such high resolution now it is scary.  ;D    Visitors to my house can't believe how much resolution RBCD really has.  They go back home and play their 24/192 files and can't understand why they don't hear so much detail as they heard on my 16/44 system.  The reason of course is not the front end of the system.  They simply don't realize that their room is killing them.

 

 

[naimster]

Correction, I am using RPG absorbers on the side walls 1st reflection points which purely absorbs and doesn't diffuse at all. It's essentially a BAD panel without the binary plates, so it absorbs even beyond 1khz.

 

Mine too is scary given my modest source. I now find many systems out there veiled. :P

And yeah, most folks are just not willing to take the plunge to treat the room even when the room decides 50% of the SQ. There's  just a lot lot more music information available waiting to be unlocked. All the cables and equipment upgrades are kinda wasted if the room is bad as their potential could have been much much higher.

 

RPG describe their BAD panels as being "zero depth diffuser absorbers".  IMHO they do neither diffusion nor absorption particularly well and too your point - given the choice of BAD or RealTraps at the first reflection point I would probably opt for RealTraps too.  As you would have read from my comments I found nothing wrong with using absorption at the first reflection point (indeed some advantage with image) but overall I liked Joamonte's broadband diffuser combined with a bass trap much better.

 

Overall my playback system has such high resolution now it is scary.  ;D    Visitors to my house can't believe how much resolution RBCD really has.  They go back home and play their 24/192 files and can't understand why they don't hear so much detail as they heard on my 16/44 system.  The reason of course is not the front end of the system.  They simply don't realize that their room is killing them.

[key]

Correction, I am using RPG absorbers on the side walls 1st reflection points which purely absorbs and doesn't diffuse at all. It's essentially a BAD panel without the binary plates, so it absorbs even beyond 1khz.

 

Mine too is scary given my modest source. I now find many systems out there veiled. :P

And yeah, most folks are just not willing to take the plunge to treat the room even when the room decides 50% of the SQ. There's  just a lot lot more music information available waiting to be unlocked. All the cables and equipment upgrades are kinda wasted if the room is bad as their potential could have been much much higher.

 

 

Agreed! Spending $5K on room treatment will give you improvements that no $5K worth of cables or tweaks can give (I dare say not even close). Yet unfortunately many audiophiles would rather spend on those than room treatment ::) If it is due to WAF or other constraints, that of coz is understandable.

 

[1AngMoh]

Correction, I am using RPG absorbers on the side walls 1st reflection points which purely absorbs and doesn't diffuse at all. It's essentially a BAD panel without the binary plates, so it absorbs even beyond 1khz.

 

 

Got it thanks Naimster.  I had thought from the above and your earlier note below that you were using the BAD at the first reflection point.  I guess you did at one point and made a change later?

 

In my experience, in a small room where speakers are close to side wall, it's not a bad thing. At least it's better than having too much reflection. Thus my final approach was to use RPG BAD panels to have diffusion and absorption within the same area so as to create some spaciousness and yet not sound messy as I bump up the volume.

 

 

Hi Key,

 

Do you have any details on your room?  Challenges and solutions?  I think we can all learn from from another.

 

 

 

[naimster]

Got it thanks Naimster.  I had thought from the above and your earlier note below that you were using the BAD at the first reflection point.  I guess you did at one point and made a change later?

1amgmo, sorry. You're right. At one time BAD was indeed at the side walls 1st reflection but that was when I was still short of a set of bass traps at the back of listener. With the traps added, the side effects of having BAD at the sides in my room was glaringly exposed in my room, thus the removal of BAD for 1st reflection and relegated to 2nd reflection points on the side wall.

 

[key]

Got it thanks Naimster.  I had thought from the above and your earlier note below that you were using the BAD at the first reflection point.  I guess you did at one point and made a change later?

 

 

Hi Key,

 

Do you have any details on your room?  Challenges and solutions?  I think we can all learn from from another.

 

 

 

I had gone through 2 rooms over the last 10yrs. And my views and thoughts have changed from the classic "Live End, Dead End" thinking to current thinking...loosely "Front Reflect/Diiffuse, Middle Absorb, Rear Diffuse", though some general concept still the same.

 

Quite busy recently. Need some time to compile my thoughts:)

[1AngMoh]

I had gone through 2 rooms over the last 10yrs. And my views and thoughts have changed from the classic "Live End, Dead End" thinking to current thinking...loosely "Front Reflect/Diiffuse, Middle Absorb, Rear Diffuse", though some general concept still the same.

 

Quite busy recently. Need some time to compile my thoughts:)

 

I look forward to reading your thoughts once you've had a chance to compile them. 

[Guest grarrgrarr]

I have observed that room acoustics are very highly subjective,  and the way you would go about treating your room would depend on if you are an analytical critical listener, or like to go about in a way that enhances everything to make it better.

 

If now you prefer diffusion in your front and rear,  compared to LEDE style rooms, then you are probably not into critical listening.  Usually audiophiles are similar to your case and so acoustic treatment schemes must be tailored accordingly.

 

In most cases a highly diffuse room would sound better than one with much absorption because our ears like to hear richer sound, which all the reflections cause.. The difference between having diffusers and just having a bare wall is that these diffused reflections don't cause any acoustical interference, but retain the spaciousness of the room.

 

Using LEDE method, you also remove acoustical interference by absorption, but the spaciousness of the room is reduced because of the smaller amount of reflection energy. However, in terms of being more accurate to the source, a "classical" treatment method would achieve greater performance.

 

For example, in a highly diffuse reflective room,  if the music was substandard production and lets say not have enough reverb added,  the reflections of your listening room would "fill in" for the problems in the recording, but in an LEDE room you would hear the poor recording in its truth.

 

This is the reason why there are some speaker manufacturers that like to prioritize very wide and constant dispersion characteristics.. Because if you use these speakers in a room which is "live" enough, it will enhance the number of room reflections in a beneficial way and you will get a system that makes all music sound better by filling in all the gaps by imposing the room signature on the music.

 

[joamonte]

Yes, I think when doing acoustic design we must bear in mind that for some audiophile/music lover, the reason for doing room acoustic treatment is to make their HiFi sound better , it is unlike sound engineer that need to use their Audio system and room as a tool to monitor their mixing/mastering......

 

To "sound right" or to "sound good"? That is the question.... :)

 

 

 

[1AngMoh]

I have observed that room acoustics are very highly subjective,  and the way you would go about treating your room would depend on if you are an analytical critical listener, or like to go about in a way that enhances everything to make it better.

 

If now you prefer diffusion in your front and rear,  compared to LEDE style rooms, then you are probably not into critical listening.  Usually audiophiles are similar to your case and so acoustic treatment schemes must be tailored accordingly.

 

In most cases a highly diffuse room would sound better than one with much absorption because our ears like to hear richer sound, which all the reflections cause.. The difference between having diffusers and just having a bare wall is that these diffused reflections don't cause any acoustical interference, but retain the spaciousness of the room.

 

Using LEDE method, you also remove acoustical interference by absorption, but the spaciousness of the room is reduced because of the smaller amount of reflection energy. However, in terms of being more accurate to the source, a "classical" treatment method would achieve greater performance.

 

For example, in a highly diffuse reflective room,  if the music was substandard production and lets say not have enough reverb added,  the reflections of your listening room would "fill in" for the problems in the recording, but in an LEDE room you would hear the poor recording in its truth.

 

This is the reason why there are some speaker manufacturers that like to prioritize very wide and constant dispersion characteristics.. Because if you use these speakers in a room which is "live" enough, it will enhance the number of room reflections in a beneficial way and you will get a system that makes all music sound better by filling in all the gaps by imposing the room signature on the music.

 

 

Excellent post Grarrgrarr, thanks for your thoughts on the topic.

 

As Joamonte points out the objectives of a mixing studio can vary from those of an audiophiles listening room - even though the backing acoustic theory remains constant. 

 

The configuration can be different too.  Picking up on your point of LEDE (which I am using) the studio is commonly the reverse of the audiophiles listening room.  An audiophile will commonly have live (diffusion) at the front and dead (absorption) behind the listening position and the mixing studio the complete reverse.

 

I think your comment on wide dispersion speakers is important and timely.  In my experience the wider the dispersion the more you need to spend on acoustic treatment!  Line source speakers are far easier to manage in this respect but unfortunately they typically need more space than most audiophiles can manage.

 

 

 

[key]

Yes, I think when doing acoustic design we must bear in mind that for some audiophile/music lover, the reason for doing room acoustic treatment is to make their HiFi sound better , it is unlike sound engineer that need to use their Audio system and room as a tool to monitor their mixing/mastering......

 

To "sound right" or to "sound good"? That is the question.... :)

 

 

 

 

 

Agreed that when doing acoustic design we must bear in mind that for some audiophile/music lover. But the fundamentals/general direction would be still more or less the same, with some adjustment ts for personal preference. I generally prefer a livelier and more dynamic sound. I now also listen to a much wider variety of music vs 10yrs back.

[Guest Zacmat]

Hi All

 

Here is a good and direct way to go about acoustic treatment. Saw it during the recent hifi show on Active Acoustics. From what i understand you still need passive acoustic but active acoustic solves problems that diffusor or absorbers does not such as phase problems. Here is a comprehensive report on 6 moon.

 

[jimi1624705950]

Hi Zacmat, do u have the link?

 

I only know of 1 bro using this and he seems happy. These systems all have the same limitation in that they can't deal with all the room characteristics due to the limitation of using the stereo pair to correct everything.