Tips to get a deeper Soundstage

abhi.pani schrieb:

Hi All, I have been playing around with speaker positioning for sometime now. My room size is 13.5 x 13.5. There is a 7 feet opening to the dining hall on one side. My major concern seems to soundstaging. To be more specific, the soundstage depth. Currently the speakers are around 4 ft from the rear walls and 2.5 ft from the side walls. The depth of the soundstage currently is limited by the rear wall. I have not yet done any room treatments. Moving the speaker any further into the room is not possible as it would restrict movement. I was wondering if room treatments can really help in getting a deeper stage ? Or are there other ways to achieve it ?? When I place the speakers such that it doesnt have a immediate rear wall i.e the dining hall opening...then I do get a very deep soundstage, however that configuration is a bit too awkward for other members of the house. Though I am not looking to achieve similar depths but at least something better than what I am getting now with a rear wall. Does treating the rear wall help in this case ? Please suggest.

Hi Abhi,

From what I remember you had the best soundstage when you had set up your system in one corner of the room. It is also an old trick to reduce possible standing waves with the side effect of getting a deeper soundstage. In your room I would recommend the corner just opposite the entrance door. Futher dampen the points of first reflection. You know the mirror methode to find this point I presume. To dampen the corner between the speakers further will also help to get a more three dimensional image. Just start with some experiments and see what happens. Just remember the rule of thumb to heavily dampen the space behind and beside the speakers and keep the space behind your listening place light and reflective. Try to keep some space between your listeneing place and the rear wall. If possible don't sit with back right against the rear wall.And an absolute must is to dampen all corners of the room. Start with the corners of the walls and ceiling and watch what happens.

Regards,
Jochen

Abhi,

Yes, you are correct ... you need to stop sound bouncing off the wall behind the speakers, back to yo, at the listning position.

You have 2 options :

1. Put an absorbant panel ( 2 inch Fibre Woll, mounted 2 inches away from the wall ) to cover the area between yr speakers.

2. Shift to Corner placement, as Jochen has recommended.

Option 2 is ofcourse the best and most elegant.

In cases where there is a window behind the speakers, opening the window, opens up a Huge soundstage ...

Amp_Nut schrieb:

In cases where there is a window behind the speakers, opening the window, opens up a Huge soundstage ...

Absolute correct Amp Nut

Hi Amp_Nut,
So if we can prevent the rear wall (wall behind the speakers) and the side walls from reflecting will that effect in a deeper soundstage ?
I dont have any window behind the speakers. Corner placement is my last choice as the rest of the members in my house are not happy with the overall aesthetics of the Living room. It is also making the placement of other furnitures of the living room difficult.
I will do that only if nothing else works out .

Hi,
Dont forget the wall behind your listening position, damping that wall do help in increasing depth and imaging. More space behind the speakers are not a sure shot way for increased depth. Pls check my avathar pic, at that placement some speakers do have shallow depth.

Abhi, Stevieboy had recommended the Decaware site, a few days ago.

I have read a lot of stuff on the net ( havent we all ! ? ) and a fair amount of it is contradictory... so use your descretion.

I would recommend the following page :

http://www.decware.com/paper39.htm

Cheers

On this topic I've had a fair bit of experience as I have treated my listening room for improved RT60 which has lead to improved sound-staging. What I have found works is
* corners behind speaker must be reflective. If you make the corners absorptive the room will become dead.
* location immediately behind the speaker should be fully absorptive.
* location in the middle but behind speaker should be reflective so that it enhances the center image.
* location immediately behind listener should be fully absorptive.
* locations behind the listener on either side should be be gradually reflective as one moves away from the listener.
* if you are able to treat the locations in between the 2-ch system & the listener's position then those locations should be a mix of absorption & reflection. The 1st reflection point off the wall to the side of the speakers should be absorptive. This reflection does the most damage as the sound from the speakers bounces off this side wall & reaches your ears a few mS after the direct sound & smears the overall sound. Some people avoid this by toeing-in the speakers so that bulk of the sound is direct but that has the disadv of a very narrow sound-stage. You can find the 1st reflection pt off the wall using a mirror (as suggested by Goolimangala) - sit in your seat & have your wife move a mirror along the wall from the speaker side to your side. At some point you'll see the speaker in the mirror. That's the reflection point off the wall. Supress it ASAP for better sound!
FWIW.

Thanks a lot everyone.

Hi Bombaywalla,
A couple of questions:
1. Regarding the side walls, what if we put absorptive material on a major part of it ? I ask this because you have suggested only to arrest the first reflection.

2. What is the effect of damping the area exactly behind the listener ?

3. When you say toeing in the speakers result in narrower soundstage, what if I toe in the speakers and also move them further apart so that the distance between the speaker faces (between the left-right tweeters) remains more or less same as they were when they were not toed in ? Will it still result in a narrower soundstage ?

Hi Ani,
I understand that some speakers do give a shallow soundstage even if they have a open space behind them but thats not the case here. Whenever I have given space behind the speakers, I get a very deep soundstage and that is missing when I have a wall behind the speaker (3-4 ft behind).


I am still wondering if the depth of the soundstage is always limited by the rear wall .
Please someone answer this...

abhi,

if rear wall is untreated yes limited depth. you can enhance depth by placing diffusion panels. my experience is absorption panels will tend to give you a more pinpoint stage. diffusion panels will make a slightly bigger soundstage. your choice. your place you really have limited space behind speakers. either flat diffusion in middle row & absorption panels top and bottom rows or a bookcase filled with different size books would do wonders for a start.

doing the side panels would give you a more focused soundstage since you'll hear more primary soundwaves and less of the confusing reflections. mix and match diffusion and absorption.

Abhi

This is what I have learnt thru trial and error, whatever you do if you don't have wall depth, there is not much one can do for soundstage depth.

You can toe in the speakers, spread them apart etc...every speaker has a threshold over which you will find big gaps/holes in the stage and image diffused.


Some speakers throw a stage that is quite forward which would give you a bit of advantage in terms of depth with limited space around.others will need space at the back.

Manek

Manek schrieb:

Abhi This is what I have learnt thru trial and error, whatever you do if you don't have wall depth, there is not much one can do for soundstage depth. You can toe in the speakers, spread them apart etc...every speaker has a threshold over which you will find big gaps/holes in the stage and image diffused. Some speakers throw a stage that is quite forward which would give you a bit of advantage in terms of depth with limited space around.others will need space at the back. Manek

Or use speakers which are specially designed to be positioned right against the wall or very close to the wall such as Naim, Rogers etc. Those also throw a deep and wide soundstage though.

Even one of the audio note spkrs I am told are designed with their backs to the wall

Hey how are siva's amps doing ?


Manek

goolimangala schrieb:

Manek schrieb: Abhi This is what I have learnt thru trial and error, whatever you do if you don't have wall depth, there is not much one can do for soundstage depth. You can toe in the speakers, spread them apart etc...every speaker has a threshold over which you will find big gaps/holes in the stage and image diffused. Some speakers throw a stage that is quite forward which would give you a bit of advantage in terms of depth with limited space around.others will need space at the back. Manek Or use speakers which are specially designed to be positioned right against the wall or very close to the wall such as Naim, Rogers etc. Those also throw a deep and wide soundstage though.

And to add 1 more popular speaker to Goolimangala's list" Audio Note AN/E & AN/K - both are designed to be against the wall.

abhi.pani schrieb:

Thanks a lot everyone. Hi Bombaywalla, A couple of questions: 1. Regarding the side walls, what if we put absorptive material on a major part of it ? I ask this because you have suggested only to arrest the first reflection.

The 1st reflection is the worst. Succeeding reflections have reduced power hence are less damaging.
You can try to absorb all the reflections along the side wall & see how you like the overall sound balance. I *think* that it might get too dead. The side wall needs to have some reflections. So, when you place the absorption panels place them 3-4' apart rather than 1 long panel.
Also remember that these absorption panels will absorb freq above 400Hz only because they will be affecting affecting signals that have acoustic velocity (in contrast bass has acoustic pressure. Thus to increase bass people put subwoofers in the corner where 2 walls meet & acoustic pressure builds up). Thus, having a fully absorptive wall might be overkill.

abhi.pani schrieb:

2. What is the effect of damping the area exactly behind the listener ?

arresting all the reflections off the back wall that smear the sound.

abhi.pani schrieb:

3. When you say toeing in the speakers result in narrower soundstage, what if I toe in the speakers and also move them further apart so that the distance between the speaker faces (between the left-right tweeters) remains more or less same as they were when they were not toed in ? Will it still result in a narrower soundstage ?

When your speakers are toed-in you get direct sound (mostly) 'cuz of the speakers are made directional. However, you are limited to a soundstage that lies only between the speakers. You can widen the distance & the width will increase.............upto a point depending on the size of the speaker & then you will detect a "hole" in the middle because the 2 radiation patterns of the L & R speaker no longer overlap.
One of the reasons that one gets a wide & deep soundstage is that the sound from the speakers reflects off the walls. We want to control the wall reflections; we do not want to eliminate them. As a simile: Think of your car headlights at night time. What if the black asphalt road absorbed *all* the light coming from your car headlights. Would you be able to see the road @ night? The answer is "no". You see the road at night because you get a reflection off the black asphalt road (a lot of light gets absorbed but enough gets reflected). Similarly with sound from the speakers interacting with the wall. By mixing & matching absorption & reflection we are able to create a wide & deep soundstage. (This is why many people state that the room plays a pivotal role in the sonic experience of music playback).

abhi.pani schrieb:

I am still wondering if the depth of the soundstage is always limited by the rear wall . Please someone answer this... :(

Not always. I've noted that tube amps are better than s.s. amps when it comes to soundstage depth given the same spacing of the wall behind the speakers. Further, within tube amps, SET amps are the absolute champs in soundstage depth. In this case it has to do w/ distortion (or the lack of it).
If you treat the room correctly you should be able to improve your soundstage depth upto a certain degree. Having the speakers atleast 3' out helps a lot. Having them 5' is even better. Of course all depends on the size of the speaker - if a small speaker is moved too much out into the room it could sound thin.
In Bhagwan's room (which is a challenge for anyone) I've heard very good soundstage depth. In his case, however, he does have a window behind which is always open with curtains drawn when we did critical listening. So, it is possible - you need to work on this aspect. Won't happen the 1st time you treat the room but will happen with 2-3 or more tweaks to the room treatment (assuming the boss allows you to )

Good point bombaywala.

No soundstage experimenting without the boss approving ! He he....most crucial tip !

Manek

abhi.pani schrieb:

2. What is the effect of damping the area exactly behind the listener ?

A wee bit more on this FWIW:
* control the reflections off the wall behind speaker to create sound-stage depth.
* control the reflections off the side wall to create soundstage width.
* control the reflections off the sidewall & add controlled diffusion closer to the listener to create hall ambience.
* Control the reflections off the wall behind listener to once again create hall ambience.
* add reflections in the space between the speakers (usually where a rack is commonly placed) to enhance the midrange, get midrange clarity & holographic imaging.

bombaywalla schrieb:

abhi.pani schrieb: 2. What is the effect of damping the area exactly behind the listener ? A wee bit more on this FWIW: * control the reflections off the wall behind speaker to create sound-stage depth. * control the reflections off the side wall to create soundstage width. * control the reflections off the sidewall & add controlled diffusion closer to the listener to create hall ambience. * Control the reflections off the wall behind listener to once again create hall ambience. * add reflections in the space between the speakers (usually where a rack is commonly placed) to enhance the midrange, get midrange clarity & holographic imaging.

Thats highly informative sir...Thanks .
You have mentioned in a previous post that the wall behind the listener shouldnt be fully treated...it should be progressively treated with highest damping just behind the listener. In my place the wall behind the listener is 13ft and I was planning to put on an acoustic (glasswool woven) curtain that has an absorption factor of around 80% for frequencies above 300hz for 10ft of the area leaving the corners out. Will that have a negative effect on the over all response (since its not a progressive treatment) ?

abhi.pani schrieb:

bombaywalla schrieb: abhi.pani schrieb: 2. What is the effect of damping the area exactly behind the listener ? A wee bit more on this FWIW: * control the reflections off the wall behind speaker to create sound-stage depth. * control the reflections off the side wall to create soundstage width. * control the reflections off the sidewall & add controlled diffusion closer to the listener to create hall ambience. * Control the reflections off the wall behind listener to once again create hall ambience. * add reflections in the space between the speakers (usually where a rack is commonly placed) to enhance the midrange, get midrange clarity & holographic imaging. Thats highly informative sir...Thanks . You have mentioned in a previous post that the wall behind the listener shouldnt be fully treated...it should be progressively treated with highest damping just behind the listener. In my place the wall behind the listener is 13ft and I was planning to put on an acoustic (glasswool woven) curtain that has an absorption factor of around 80% for frequencies above 300hz for 10ft of the area leaving the corners out. Will that have a negative effect on the over all response (since its not a progressive treatment) ?

IMO if the wall behind you is 13' I have a strong hunch that its effect will be minimal. Try your glasswool woven curtain approach & see what effect it has on the overall sound. If you do not like it, tweak it. Without actually listening it is impossible for me to for-tell whether or not it'll have a negative impact.
Both my posts offer guidelines to treating your room - they are NOT hard & fast rules. They can't be as each room is different & the surroundings are different. If you follow the guidelines I wrote you will have a good starting point & it should reduce your tweaking time to come to your final solution.

Thanks Bombaywalla.
My speakers are placed about 8.5ft apart and I sitting about 9ft from the speakers. Both speakers are 3ft from the back wall and 2ft from the side wall. I have placed a thick curtain on the rear wall (behind the speaker) and that has done a terrific job of keeping the soundstage/image laidback (its no more jumping at me as it was with the bare wall behind). Currently I have nothing much on the side walls with just some cane furnitures around.
Apart from that I was playing around with some toe-in/out yesterday and what I found was:

1. With a little more toe-in, i.e when the speaker is almost facing at the listening position I get a sharper center image but the overall soundstage width is limited to within the speakers and that too not the entire width but just about 7ft out of the 8.5ft. At this position image of individual instruments are very focussed and defined but they seem to be very closely tucked hence a smaller stage.

2. As I toe out the speakers I get a drastic improvement in soundstage width. Things open up a lot. But the center image is also widened, it is no more as sharp as before. One can still pin point the singer but you do feel that his mouth has widened up a bit (typical case of smear).

I was wondering if this is always the case ????????
Cant we have the speaker firing straight but still get a sharp center image (along with the associated wide soundstage ) ?
My first guess is it is possible if the side walls and the wall behind the listener is treated. Would be nice if others could comment on this situation.

abhi.pani schrieb:

Thanks Bombaywalla. My speakers are placed about 8.5ft apart and I sitting about 9ft from the speakers. Both speakers are 3ft from the back wall and 2ft from the side wall. I have placed a thick curtain on the rear wall (behind the speaker) and that has done a terrific job of keeping the soundstage/image laidback (its no more jumping at me as it was with the bare wall behind). Currently I have nothing much on the side walls with just some cane furnitures around. Apart from that I was playing around with some toe-in/out yesterday and what I found was: 1. With a little more toe-in, i.e when the speaker is almost facing at the listening position I get a sharper center image but the overall soundstage width is limited to within the speakers and that too not the entire width but just about 7ft out of the 8.5ft. At this position image of individual instruments are very focussed and defined but they seem to be very closely tucked hence a smaller stage. 2. As I toe out the speakers I get a drastic improvement in soundstage width. Things open up a lot. But the center image is also widened, it is no more as sharp as before. One can still pin point the singer but you do feel that his mouth has widened up a bit (typical case of smear). I was wondering if this is always the case ???????? Cant we have the speaker firing straight but still get a sharp center image (along with the associated wide soundstage ) ? My first guess is it is possible if the side walls and the wall behind the listener is treated. Would be nice if others could comment on this situation.

Is this curtain behind the speakers covering the entire wall or just behind each speaker? Some special material ? I have a similar issue of the sound being a bit forward. I have bare wall behind with just 2ft behind each speaker.

square_wave schrieb:

abhi.pani schrieb: Thanks Bombaywalla. My speakers are placed about 8.5ft apart and I sitting about 9ft from the speakers. Both speakers are 3ft from the back wall and 2ft from the side wall. I have placed a thick curtain on the rear wall (behind the speaker) and that has done a terrific job of keeping the soundstage/image laidback (its no more jumping at me as it was with the bare wall behind). Currently I have nothing much on the side walls with just some cane furnitures around. Apart from that I was playing around with some toe-in/out yesterday and what I found was: 1. With a little more toe-in, i.e when the speaker is almost facing at the listening position I get a sharper center image but the overall soundstage width is limited to within the speakers and that too not the entire width but just about 7ft out of the 8.5ft. At this position image of individual instruments are very focussed and defined but they seem to be very closely tucked hence a smaller stage. 2. As I toe out the speakers I get a drastic improvement in soundstage width. Things open up a lot. But the center image is also widened, it is no more as sharp as before. One can still pin point the singer but you do feel that his mouth has widened up a bit (typical case of smear). I was wondering if this is always the case ???????? Cant we have the speaker firing straight but still get a sharp center image (along with the associated wide soundstage ) ? My first guess is it is possible if the side walls and the wall behind the listener is treated. Would be nice if others could comment on this situation. Is this curtain behind the speakers covering the entire wall or just behind each speaker? Some special material ? I have a similar issue of the sound being a bit forward. I have bare wall behind with just 2ft behind each speaker.

Its not behind the speaker. Its almost 7.5ft wide curtain covering the area right between the two speakers...pretty thick, non-shiny and a bit rough. Its no special material. However I know someone who does provide acoustic curtains of quite a few variety...if you want those, I can let you know.

abhi.pani said:

However I know someone who does provide acoustic curtains of quite a few variety...if you want those, I can let you know.

I would be VERY interested. Can you please post or PM me ?

Thanks

Great....do send me the info.
Thanks.

Thanks for the info. I spoke to the person.

However, he has Glass Wool Fabric ranging in thickness from 1mm to 4 mm only.

He recommends 1 mm for the curtains. Will this thickness be effective ? have you visited any install of this material ?

Feedback on the thickness required would also be most welcome from other forum members.

Thanks

Hi Amp Nut,

It's not the thickness of the material that is critical, it's the folds in the fabric that you allow when hanging it. Typically, the fabric is twice the width of the hanging area, so that folds develop when hanging it. Also, install it on hangers so that you have a 6 inch air gap between the curtain and wall. That increases the effectiveness and frequency range of absorption.

Viren

hi abhi,

please pm me the info too. thanks!

regarding the toe in versus straight i guess if you pull the speakers closer together you'll get a sharper rather a denser soundstage (but not as sharp as resulting from toe-in) image without having to toe in but then you'll sacrifice breadth of soundstage. dont think any amount of treatment will sort that out since sharpness in that regard is more from the toe-in angle. this is from personal experience so might not be applicable as a rule!

regards

Hi Viren,

Thanks for the advice.

1. Yes, the Gap, is essential, but typical gaps required ( Im told and seek your clarification on this ) are about 150% of the Glass wool thickness. Given a thickness of 2 mm for the glass wool, a 3 mm gap will happn almost anyway, without any special design.

2. I am told that even a 2mm thich Fibre cloth will be too stiff to push back horizontally, as a curtain. That would be possible Only with a 1 mm thick wool cloth...

The 2 Inch think would have to be Rolled up vertically, like a cane curtain ...

Any thoughts and advice ...

THANKS

Room correction using dampening materials can sometime fire-back. This can be considered as the equivalent of a "equalizer"....so while adding one advantage, it might add another problem.

Do be careful with your investments.

A better solution could be room-paramter based equalizers....Bhagwan, can you through some light here - from your experience.

Sivat,
Can you please elaborate on what you are referring to as " room-paramter based equalizers " ?

Thanks

Hi Amp_Nut,
Even I have ordered the 4mm thick curtain.
Well here is some more info about this curtain.
These curtains are imported. They has a certificate of testing associated with them and they are tested by some organisation in Germany. I typically forget the name of the organisation. I have seen the certificate and it has a lot of detail about the product being tested and one of the most important info is a chart which states the sound absorption percentage for frequencies from 100hz to 20khz.
As far as I remember the absorption was just around 15-17% at 100hz and that value increased to some 55% at 250hz and further increased to about 70% at 400hz. Beyond that it typically stayed between 80-85%. Which basically means sound waves which are beyond 400hz falling on this curtain is looses its strength by around 70-85% (depending on its property at that particular frequency).

The graph also tells that this curtain woudnt help in controlling deep bass in the range of 80hz and below. But it would/should do a tremendous job in controlling some areas of mid-bass, upper bass, lower mids and above frequencies. That is something that I would definitely need in my room which echoes a lot.

One more thing, I dont think its exactly the thickness of the glasswool that matters, it is also the weight of the glasswool which is used in a typical sq ft of curtain that matters. The 4mm curtain was pretty heavy and dense and hence the effect and cost.

I will post a detailed review once its installed at my place. Unfortunately this cant be used for floors (as walking on glasswool is not healthy ) so I need to think something else for them.

I'm talking about things like this ..Room Correction is another term used...i'm not very familiar in this area.

http://stereophile.com/reference/108tech/index1.html
http://www.stereotimes.com/acc110299.shtml
http://www.deqx.com/PDC26P-Preamp.html

I personally do not believe room-dampeing will help in smaller rooms.

I 've never tried Room Correction in my setup, but atleast by theory they might be a better bet in smaller rooms.

Please note that room correction is a very complex subject. It gets much more complex in smaller room...primairly because reflected waves and original ones will colliding to create complex ups and dips in Freq response. This problems gets more complex as the room becomes smaller. There is no way that any acoustic engineer can resolve these issues without resorting to DSP.

abhi.pani schrieb:

As far as I remember the absorption was just around 15-17% at 100hz and that value increased to some 55% at 250hz and further increased to about 70% at 400hz. Beyond that it typically stayed between 80-85%. Which basically means sound waves which are beyond 400hz falling on this curtain is looses its strength by around 70-85% (depending on its property at that particular frequency). .

Abhi,

Would'nt this cause an overall imbalance in the freq. resp in your listening room...

Regards
Siva.

Electronic eq devices definately have their advantages....I can see where sivas is coming from

Manek

Sivat,

I am from the "other side"....

1. I believe that Active room correction creates more problems than it creates.

Rooms ( IMHO Ofcourse ) are better corrected with Damping and diffusers, that prevent occurances of room resonances, rather than electronics, that allows the room resonances, and then sends out signals to cancel what has occured ....

From what I have read, Electronically corrected rooms play music analytically clean but lack emotion and punch. Maybe its a pointer why these relatively reasonably priced products have not been widely accepted and deployed in High end systems.

Room resonances can create dips and peaks of 20 dB or more at particular frequecies. Power Amps ( and the pre amp too ) can easily run out of steam correcting for a 20 dB dip, before it puts out any power into the music signal !



2. On the issue of in-equal absorbtion... ALL room materials have unequal absorbtion and relection, at different frequencies... Hence it is only logical to deploy absortive materials that behave differently at different frequencies. When deployed judiciously, it can correct a room pretty well...


A pointer.... The Taiwan Hi Fi show that I attended last month, was held in a Hotel, with the usual 5 Star Hotel rooms. Most rooms sounded good, and had atleast some room absorbant and or diffusers. NONE deployed active room correction...

Most of these rooms were SERIOUS Hi Fi, with a dCS stack as the front end... SOULTION pre and power ( in many rooms etc... so clearly, price was not a limitation to provide the best demo.... still no active room correction...

abhi.pani schrieb:

Thanks Bombaywalla. My speakers are placed about 8.5ft apart and I sitting about 9ft from the speakers.

Looks like there has been much activity in this thread while I was asleep!!
There are many theories on what the speaker separation should be & how far the listener should be from the speaker. However, after experimenting a little bit + reading the setup manual from my favourite speaker designer I found that one gets the best soundstage width when the speakers & the listener are in an equal-legged T i.e. distance between speakers (outer edge to outer edge) is equal to the distance of the listener from the center point between the speakers. This is for small to medium sized rooms - rooms upto 500 sq ft. The "theory" might still hold for still larger rooms but I have no personal experience.
So, in this case if you cannot move your speakers to be 9' apart then move your chair in to be 8.5' away from the speakers. This creates a 53 degree angle between the listeners ears & the 2 speakers. I believe, from my personal experience, that this situation is optimal (much better than the equilateral - 60 degree - case).

abhi.pani schrieb:

Both speakers are 3ft from the back wall and 2ft from the side wall.

I suppose that you are your limit bringing the speakers out any more?
If so, no further comment other than pulling the speaker out more will give you less wall interaction, which is usually good.

abhi.pani schrieb:

Apart from that I was playing around with some toe-in/out yesterday and what I found was: 1. With a little more toe-in, i.e when the speaker is almost facing at the listening position I get a sharper center image but the overall soundstage width is limited to within the speakers and that too not the entire width but just about 7ft out of the 8.5ft. At this position image of individual instruments are very focussed and defined but they seem to be very closely tucked hence a smaller stage. 2. As I toe out the speakers I get a drastic improvement in soundstage width. Things open up a lot. But the center image is also widened, it is no more as sharp as before. One can still pin point the singer but you do feel that his mouth has widened up a bit (typical case of smear). I was wondering if this is always the case ???????? Cant we have the speaker firing straight but still get a sharp center image (along with the associated wide soundstage ) ? My first guess is it is possible if the side walls and the wall behind the listener is treated. Would be nice if others could comment on this situation.

yes, your experiments pretty much exactly align w/ what I wrote in some of my prev posts. Thanks for re-confirming my hunches.
On your 2nd point - it depends. For example the speaker I have is designed such that optimal toe-in is when the drivers are firing over the listener's shoulders so that the point of focus is behind the listener.
If you have no such guidance from the manuf, you will have to experiment & find out what the optimum toe-in is. It can be a tedious exercise & you'll have to ascertain how much this matters to you.
From your post it *appears* that as the toe-in decreases the direct & reflected sounds begin to interact more thereby causing some smear. Room treatment will help some (as Amp_Nut wrote: you'll have to be judicious about how much & where) but if the issue is with the speaker design then room treatment will not be the total solution - I'm thinking that the speaker baffles are beginning to play a role in the reflected sound when toe-in decreases. You can reduce this by glueing on acoustic felt onto the baffle BUT WAF is going to plummet! If you still have smear after all the room treatments you are allowed to put in, experiment with acoustic felt.

sivat schrieb:

abhi.pani schrieb: As far as I remember the absorption was just around 15-17% at 100hz and that value increased to some 55% at 250hz and further increased to about 70% at 400hz. Beyond that it typically stayed between 80-85%. Which basically means sound waves which are beyond 400hz falling on this curtain is looses its strength by around 70-85% (depending on its property at that particular frequency). . Abhi, Would'nt this cause an overall imbalance in the freq. resp in your listening room... Regards Siva.

depends, no? if his room is very lively then these absorption rates will compensate. Lower frequencies can go thru the wall more than higher frequencies (which tend to bounce off the wall) hence higher absorption for higher freq is a natural.
To avoid the imbalance Abhi'll have to do as Amp_Nut wrote "When deployed judiciously, it can correct a room pretty well..."
Hence my suggestion of starting out w/ room treatments every 3' apart, listening to the results & then tweaking the separation & adding or removing treatment.

sivat schrieb:

abhi.pani schrieb: As far as I remember the absorption was just around 15-17% at 100hz and that value increased to some 55% at 250hz and further increased to about 70% at 400hz. Beyond that it typically stayed between 80-85%. Which basically means sound waves which are beyond 400hz falling on this curtain is looses its strength by around 70-85% (depending on its property at that particular frequency). . Abhi, Would'nt this cause an overall imbalance in the freq. resp in your listening room... Regards Siva.

Bombaywalla wrote:

depends, no? if his room is very lively then these absorption rates will compensate. Lower frequencies can go thru the wall more than higher frequencies (which tend to bounce off the wall) hence higher absorption for higher freq is a natural.

Exactly my situation Siva.
My room is very lively and significantly loads the sound especially the frequency range from upper bass-highs. Not the full range but a lot of it and that results in a very uncomfortable sound especially at higher volumes. You just know that the sound is all over the place and needs to be damped asap
The interesting part is I dont have any major issue with Bass (I mean low and mid bass). Its tight, clean and pretty well defined with very little overhang. Yes, some bass frequencies to tend sound boosted sometimes but thats rare and I am okay with it.
I would definitely use the curtains judiciously and I am already planning a flexi arrangement to be able to move them anywhere across the wall. Lets see..

My 2 cents here.....

From the above posts, it seems the objective here is to treat the room for say above 200-300Hz upwards which is easier than attacking below 200Hz downwards.

Using the LEDE concept, i.e. "Live-End Dead-End", area behind the speakers is Dead end while area behind the listener is Live end. One of the best ways to work for such problematic rooms is to make 4 x 2, 3 x 2 or 2 x 2 (ft) wooden beaded panels with 1 inch low-to-medium density foam cut & inserted in it (never high density foam) and fit them onto the walls, side walls where 1st reflection occurs (using the mirror method) and some portions of the wall behind the listener. One could use a nice speaker grille cloth in a colour of your choice to cover the foam panels for a better WAF

The method is cheap and it works. Ofcourse, the 4 corners must be treated too. Throwing in a wall-to-wall carpet helps.

It will also bring down the room's overall ambient noise down so you may not need to pump up the volume as high as you might think. You will need a "low noise split AC" to keep you in comfort though.....

audio_engr said:

ow-to-medium density foam

Is this the same as fibre wool ?

Can you please provide some more info on this product ?

Where can this be purchased ? ( In India ? )

Thanks

You could use fiber wool. I'll have to checkup by database for the manufacturer in UP.

Alternatively, try and use foam sheets of 1" thickness. Do not that when you go to buy the sheets, check for the density by pressing the foam with you fingers. The softer the better .....

Hi Amp Nut,

I am also planning to buy some glass wool for building diy panels and bass traps.

I got in touch with a company called twiga fibre and they have a good selection of glass wool products including rigid fibre boards of 48 Kg and 64 Kg density.

Check out http://www.twigafiber.com/

Also, there is a company in Ghatkopar called Kavita Trading which sells glass wool products.

http://www.kavitatrading.com/

I will buying from one of these guys within the next couple of weeks.

[quote="surrealistix"]


I got in touch with a company called twiga fibre and they have a good selection of glass wool products including rigid fibre boards of 48 Kg and 64 Kg density.

Check out [url]http://www.twigafiber.com/[/url]


This is the company who makes compressed fiber wool - ideal for acoustical purpose. Do not use too much of the 64 kg dens stuff as it would start affecting sub 200Hz freq drastically. Ideally, 24-36 kg dens is fine for tailoring post 200Hz problems. The fiber wool is available in rolls &/or cut to their fixed sizes for the 64 kg dens. Check out the NRC figures. The higher the greater absorption and better for working for low freq. NRC of 0.50-0.65 are fine for post 200Hz work.

Also, watch out for fiber wool from Twiga that comes with lamination on either 1 side or both sides. Stay away from them as they are meant for HVAC industry.

Go ahead, make a few panels and have fun !!

P.S. There's this another company - OWA a German brand whose products are distributed in India. Check out this link: http://www.owa.de/en/menu/96/index.html

Thanks, surrealistix & audio_engr.

The info is timely for me and most helpful.

audio_engr, any contact details of where I can get OWA products in Mumbai ?

OWA used to available thro' Everest Industries. Give them a call to find out.
In Mumbai, they are in Andheri (E), around Sakinaka. Tel: 67250275. http://www.everestind.com/


After thought
IMO - its best to work with Foam for all treatment for Mids/highs and fiberglass wool for all work below 100Hz. A tip when working with foam, do not paste the foam with any sort of adhesives as they 'eat the foam' (foam rot) and also make the foam sheet coarser, thereby reducing the absorbency of the material. Just lay them in the framework in a snug fashion. (If you open the drivers of loudspeakers, you will find they too use foam sheets on the insides of the loudspeaker walls).

You can also use either plain or printed carpets positioned around the Center of the Rear-wall, say of size (5 x 4) or (6 x 5) (ft). Again, no pasting, just put up wooden strips along the 4 sides of the carpet and get fine nails to affix the carpet to the wooden beads. This works fabulously.... also very wife friendly esp. printed carpets.

This concept you can use in bits & pieces in other parts of the room too.

audio_engr schrieb:

IMO - its best to work with Foam for all treatment for Mids/highs and fiberglass wool for all work below 100Hz.

Hello Sir,
Could you please suggest why do you prefer not to use fiberglass wool for mids and highs ?
Also to treat frequencies below 100hz, whats the right way to use the fiberglass? Is it as simple as just putting up a roll of fiberglass on the room corners ? Are there more sophisticated home made tweaks we can work out ?

Hi Abhi,

From what I have read so far, you need to use high density 4 inch rigid fibre board betwee 48 Kg and 96 Kg density. You need to maintain a huge air gap in between the panel and the wall.

I am thinking of building diy tube bass traps based on John Risch's website.

Finally, if there are specific low frequencies you need to tame, then tuned traps can be usefull like the sealed panel traps. Check out: http://www.ethanwiner.com/acoustics.html

abhi.pani schrieb:

audio_engr schrieb: IMO - its best to work with Foam for all treatment for Mids/highs and fiberglass wool for all work below 100Hz. Hello Sir, Could you please suggest why do you prefer not to use fiberglass wool for mids and highs ?

Abhi,
I believe that the high(er) density glass wool will create too much absorption of the mids & highs & will suck the music out of the air & make the room quite dead. Your room will trend towards an anechoic chamber (which is good for speaker driver testing but not good for music playback! )

abhi.pani schrieb:

Also to treat frequencies below 100hz, whats the right way to use the fiberglass? Is it as simple as just putting up a roll of fiberglass on the room corners ? Are there more sophisticated home made tweaks we can work out ?

Surrealistix has the right idea - read & make Jon Risch's DIY tube trap receipe. I believe that Mr. Murthy has made some already that KB has in his apt. I'm sure that you have seen those already? Maybe Mr. Murthy can help you find the raw materials &/or make some for you to your specified diameter?
Type Jon's name (it's Jon & not John, just FYI) in your favourite search engine & it should find his website.