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loudspeaker distance from front wall...guidelines?

I generally adhere to the often-recommended convention of having front L & R loudspeakers form an equilateral triangle with me, the listener, with the Center (my setup is 5.1) lying midway between them. A separate question is how far this front line (L C R) is from the front wall. I'm lucky enough to have free rein in a dedicated room. In my 15-foot x 14-foot room, I've generally left a distance of 2-3 feet between the front baffle of the speakers and the wall behind them (the front wall, from the listener perspective). There's no solid rationale behind that distance other than a vague idea of reducing boundary interference which creates 'comb filtering' cancellations. Lately I've been trying to get a little more science behind front line speaker positions. One reference I've found are pages on this site.

My listening seat is generally placed according to the so-called 38% rule . So my seat is at a point 5.7 ft from the rear wall (38% of 15 ft) . I also have 4" thick , 2' x 4' absorbers on the walls between me and the front line, at the 1st reflection points, and between the L&C and C&R . My subwoofer is in a front corner, which excites maximally excites room modes, which is OK since I can then use DSP (Audyssey) to tame excessive bass frequencies.

In some high-end recording studios, speakers are mounted within the front wall so the baffles are flush with the surface (a so-called 'infinite baffle'). This eliminates front-wall boundary effects . I can't do that. Another way is to place the speakers far enough from the wall to reduce the effects to inaudibility. This distance can be calculated. For my room and loudspeakers, that would be a bit over 5 feet ....not great, since to basically places me just five feet from the front line... a true 'near field' setup, but rather claustrophobic! (Though I might try it for fun...IME actual 'near field' setups create incredible deep images at the expense of having speakers right in your face).

Another way is to position the speakers very close to the front wall, which raises the cancellation notch frequency as high as it can go, then insert 4" absorbers behind them to reduce those frequencies*. I've now tried this (adjusting the side absorber positions too, to cover the new 1st reflection points.) It has two effects. One, given that my listening position stays the same, the equilateral triangle becomes huge, and thus the soundstage too, as the speakers are >11 ft apart. Two, there seems to be a loss of image depth; the sound is spread out across the stage but it's 'flat', lacking front to back image depth. I'm not at all sure I like it, but plan to experiment more. One undeniable good thing it does is to open up more free space in the room itself.


Has anyone else experimented with front speaker /wall distance, and have impressions to report?


*Interesting to note that in the relevant room setup/treatment diagrams in Floyd Toole's book, speakers are positioned with their backs right up against the walls.

Re: loudspeaker distance from front wall...guidelines?

Reply #1
Don't forget the main purpose is enjoyment!!!  (That's assuming you're not talking about a studio used for music/sound production.)      You can start by "following the rules" but then you can do whatever sounds best to you!

Before you go too crazy trying to "calculate" reflections (and the results of reflections) I'd recommend you measure the room.     You don't have to do that but if you are adding acoustic treatment (especially if you are spending money on treatment) remember that "diagnosis comes before treatment."   (You would need to buy a calibrated microphone, but you can use free software.)

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My subwoofer is in a front corner, which excites maximally excites room modes, which is OK since I can then use DSP (Audyssey) to tame excessive bass frequencies.
You can tame antinodes (peaks) to some extent but you can't fix nodes (dips/cancelations) because it takes nearly infinite amplifier power and huge woofers/subwoofers to overcome the cancelation.    You also can't fix ringing with EQ.     These things can be fixed (or at least improved) with bass traps.   Bass traps trap the reflected bass, which means less cancelation and tamed peaks.  

I'm not saying you need bass traps (or any acoustic treatment) but bass traps and woofer placement is the best way to deal with "bass problems".    

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One reference I've found are pages onthis site.
There is one thing I'm highly skeptical about - He recommends isolation stands.     I've only seen ONE measurement-test of speaker isolators and there was essentially no difference (with the speakers at the same height-location without the isolators).  These (skeptical) testers also didn't hear any difference.        ...I've read lots of worthless positive reviews with non-blind, non-scientific, listening tests.   And of course the isolators may change the height or angle of the speaker which CAN change the sound, especially if the listener is close to the speaker/monitor.

Re: loudspeaker distance from front wall...guidelines?

Reply #2
I've been in this hobby a looong time.  I only do things I enjoy at this point.  And one thing I like to do is see how what you are 'supposed' to do, sounds to me.

Most of your points are things I know already (e.g. antinodes, ringing, physical treatment vs DSP)

Certainly REW or analogous measurement tool  would be the way to go for diagnosis.    It's in my future.  Btw I have seen many go 'too crazy' using it.

But for now this is why I put the word 'guidelines' in the title.  I know there's no ironclad here.  For once, I'm interested in hearing about other people's investigations into this, with their own setups, even sighted-only.   (Usually I couldn't care less.)

The site I linked to -- Arquen -- is new to me and has some more or less quasi-substantive stuff on it, as every audio site I've ever been to does, none are perfectly objectivist; he's also trying to cater to home studio users *and to* home audio listeners, which is tough.  But it's one of the few that attempts to give testable 'guidelines' and he's at  least aware of relevant audio research (unless he's faking having read Toole's book), and he does recommend taking actual measurements to go beyond simply 'guidelines'.




Re: loudspeaker distance from front wall...guidelines?

Reply #3
Where you are "supposed" to place your speakers is where it sounds "good" to you. The End.

What page in Tooles book does it show the diagrams and/or side absorbers like you have in your attempted studio recreation room?
Loudspeaker manufacturer

Re: loudspeaker distance from front wall...guidelines?

Reply #4
I have to say the DSPs in AVRs these days has come a long way. I appreciate they're not perfect but they do a damned good job of sorting stuff out. Certainly going from a top end pre-lossless surround AVR with an early version of Audyssey onto a nearly bottom of the range one with 15 years between them, I would never go back to the old one even if it is supposed to be technically better.

Re: loudspeaker distance from front wall...guidelines?

Reply #5
Where you are "supposed" to place your speakers is where it sounds "good" to you. The End.

What page in Tooles book does it show the diagrams and/or side absorbers like you have in your attempted studio recreation room?


Third edition, p. 423, Figure 15.10a, illustrating an apparent 9-channel system* in a home theater with three rows of listeners. 
'(a) shows the horizontal plan for room acoustical treatment based on the notion of assisting spatial illusions. The materials described here apply to a horizontal band around the middle of the room, around and above seated ear height. Front side walls** are 'optional' territory'.  If stereo listening is to be part of the entertainment in the room,Chapter 7 discusses the choice of reflecting, absorbing, or diffusing the first reflections from the side walls.  For dedicated multichannel/home theater use, absorption is advised. [...]"


Mine is a 'dedicated multichannel' room, not a 'studio recreation room', unless Toole's diagram is too -- his diagrammed room has a *sh-t*-ton of treatment, comprising absorbers and diffusers (mostly for diffusing sound from the surround speakers).  Currently I'm trying absorption on the front and rear walls (shown in Toole's diagram) and on the side walls in the 'optional' area.  I don't have any purpose-built diffusers.  The room is carpeted as recommended by Toole as well, in this same book (look it up yourself).

And again, you don't have to be an ankle-biter all the time, AJ. 


*with corners reserved for 'low-frequency absorbers if they are needed, or for subwoofers in a multi-sub configuration'.

**the side-wall areas between the loudspeakers (which are shown positioned against front wall, L&R toed in) and the first row of listeners.

Re: loudspeaker distance from front wall...guidelines?

Reply #6
Some distance between speakers and front wall usually creates a soundstage with more depth. Here you have the freedom to do so, and you can also move the listening position back closer to the back wall, allowing you to keep the distance in width between the speakers.

The dip caused by front wall reflection will move down in frequency, and depending on distance and acoustic properties of other boundaries - sidewalls - the response may be better in the range the main speakers are working. Measurements will show what happens to the frequency response.

Even if you now have acquired measurement equipment, it is still evaluation by listening that will have the final say on what works best for you. But measurements can be very helpful to find what is causing the sound you hear.

 

Re: loudspeaker distance from front wall...guidelines?

Reply #7
Where you are "supposed" to place your speakers is where it sounds "good" to you. The End.

What page in Tooles book does it show the diagrams and/or side absorbers like you have in your attempted studio recreation room?
Third edition, p. 423, Figure 15.10a, illustrating an apparent 9-channel system* in a home theater with three rows of listeners. 
'(a) shows the horizontal plan for room acoustical treatment based on the notion of assisting spatial illusions. The materials described here apply to a horizontal band around the middle of the room, around and above seated ear height. Front side walls** are 'optional' territory'.  If stereo listening is to be part of the entertainment in the room,Chapter 7 discusses the choice of reflecting, absorbing, or diffusing the first reflections from the side walls.  For dedicated multichannel/home theater use, absorption is advised. [...]"

Mine is a 'dedicated multichannel' room, not a 'studio recreation room', unless Toole's diagram is too
So you don't listen to stereo music, or upmix any more as you stated previously. Got it. Didn't know you listen only to discrete MCH, where indeed, treatments/absorption are recommended. Again, for discrete MCH (DVD, SACD, Bluray, etc), where spatial "effects" are inherent to the surround channels.

And again, you don't have to be an ankle-biter all the time, AJ. 
And you don't have to be all butt hurt for being an iso-ward padded cell type. No shame in that being your audio-visual fashion preference.
FYI, said Dr Toole's room for "dedicated MCH/HT"...using upmixed stereo, rather than discrete MCH, using ultra-wide dispersion Salon 2s.


 No *sh-t*-ton of treatment. YMMV

Also, a cardioid high frontal directivity speaker will not interact with the wall behind speaker like a typical monopole. So distance has something to do with the polar characteristics of the sound sources too.
Don't get all more butt hurt on us now ;-)

cheers,

AJ
Loudspeaker manufacturer

Re: loudspeaker distance from front wall...guidelines?

Reply #8
Where you are "supposed" to place your speakers is where it sounds "good" to you. The End.

What page in Tooles book does it show the diagrams and/or side absorbers like you have in your attempted studio recreation room?
Third edition, p. 423, Figure 15.10a, illustrating an apparent 9-channel system* in a home theater with three rows of listeners. 
'(a) shows the horizontal plan for room acoustical treatment based on the notion of assisting spatial illusions. The materials described here apply to a horizontal band around the middle of the room, around and above seated ear height. Front side walls** are 'optional' territory'.  If stereo listening is to be part of the entertainment in the room,Chapter 7 discusses the choice of reflecting, absorbing, or diffusing the first reflections from the side walls.  For dedicated multichannel/home theater use, absorption is advised. [...]"

Mine is a 'dedicated multichannel' room, not a 'studio recreation room', unless Toole's diagram is too
So you don't listen to stereo music, or upmix any more as you stated previously. Got it.

Wrong.  Stereo music is all upmixed, preferably by DPLIIx.  Now amuse me and argue that that's not 'multichannel'. 

AJ, why can't you admit that in his book, Toole actually does have a 'multichannel/home theater' (his words) room plan where multiple dedicated absorbers to the front, rear, and side*, play a role -- as either optional or 'advised', depending on preference and listening habits.   You asked, I provided.    Do you need me to upload a scan of the page?

*To be very clear about 'side':  front sidewall -- 1st reflections -- is the 'optional territory':  for stereo listening Toole refers readers to CHapter 7 to read about the choice of reflection, absorbing, or diffusion in this territory.  For multichannel, he simply writes 'absorption is advised' in this area.  Progressing toward the back from there, Toole shows ear height *diffusers* lining the walls to the side of the three rows of listener heads.  Their stated purpose is to 'aid in perception of envelopment by listeners seated away from the center of the room'"  I sit on the center line of the room, facing the center loudspeaker.  The sidewall space *above* the diffusers, Toole reserves for 'patches of absorption'.  The sidewall space *below* the diffusers  is 'optional' for treatment, "because  the carpet or seating will likely capture sounds reflected" from there.

As you see, Toole isn't doctrinaire about absorption/no absorption at frontline first reflection points, especially for multichannel listening.  I'm using it for now, possibly I favor 'detail' over 'envelopment', a more studio-like goal (which Toole acknowledges).  Where I've bigly deviated from Toole is replacing his diffusers with absorbers to the direct side of me, the sole listener.  I don't need the 'envelopment' enhancement, but in my carpeted but very sparsely furnished, nearly square space, I do need amelioration of slap echo, and since I haven't built diffusers, the absorbers to either side of me provide that.   I think Floyd would grant me that dispensation.

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Didn't know you listen only to discrete MCH, where indeed, treatments/absorption are recommended. Again, for discrete MCH (DVD, SACD, Bluray, etc), where spatial "effects" are inherent to the surround channels.

Tiresome pedantry.

Floyd Toole himself is fan of upmixing.  He calls the diagrammed room a 'multichannel/home theater' space.  Nowhere in the caption does he specify 'discrete' multichannel  (though I listen to quite a lot of that too).    He *does* distinguish between *stereo* and *multichannel*.  And IME, spatial 'effects' are quite often the synthetic result of upmixes too, unless you've got some special AJ definition for that word too. 

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And again, you don't have to be an ankle-biter all the time, AJ. 
And you don't have to be all butt hurt for being an iso-ward padded cell type. No shame in that being your audio-visual fashion preference.

Tiresome pugnacity and presumption.


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FYI, said Dr Toole's room for "dedicated MCH/HT"...using upmixed stereo, rather than discrete MCH, using ultra-wide dispersion Salon 2s.

Post this again, using all the words next time.  


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[picture of Toole's living room -- his old one, not his current one, I think]
 No *sh-t*-ton of treatment. YMMV

No sh*t ton of purpose-built treatment --  but gosh looks at all that furniture.  Toole here is going for a living room space that also serves as a 'home theater, something else he talks about.  That's great but not what he is describing in Fig 15.10, which, minus the three rows of seating, *is* analogous to my use case.  It's got a sh*t ton of treatment.


Re: loudspeaker distance from front wall...guidelines?

Reply #9
Now amuse me and argue that that's not 'multichannel'. 
Your strawman would argue that but I wouldn't. Of course I also know the difference between discrete MCH and upmix, 2 different things, 2 different requirements. "Wide" channels. "Height" channels. Clearly you don't. But regardless, if you prefer your stereo sound worse due to absorption, but better due to belief/visual effects, that's your prerogative.

AJ, why can't you admit that in his book, Toole actually does have a 'multichannel/home theater' (his words) room plan where multiple dedicated absorbers to the front, rear, and side*, play a role -- as either optional or 'advised', depending on preference and listening habits.   You asked, I provided.    Do you need me to upload a scan of the page?
discrete MCH, where indeed, treatments/absorption are recommended. Again, for discrete MCH (DVD, SACD, Bluray, etc), where spatial "effects" are inherent to the surround channels.

I give up, why can't your strawman "admit" this? What I actually stated is quoted.

And IME, spatial 'effects' are quite often the synthetic result of upmixes too
They are NOT the same, nor have the same requirements for "treatment". With discrete, the envelopment etc is generated from the effects channels, not reflections...hence the suggestion for dead "studio" type room/HT. For plain stereo, your room would be the opposite of good for the majority of blind listeners...but preferences rule here, including visual ones.

[picture of Toole's living room -- his old one, not his current one, I think]
No sh*t ton of purpose-built treatment --  but gosh looks at all that furniture.  Toole here is going for a living room space that also serves as a 'home theater, something else he talks about.  That's great but not what he is describing in Fig 15.10, which, minus the three rows of seating, *is* analogous to my use case.  It's got a sh*t ton of treatment.
That's his current room (his old one with bipolar M1s pic above) for HT and music...mainly upmixed stereo, not discrete MCH with dedicated effects channels for enhancement. No *sh-t*-ton of treatment. It's clear reading his books info and comprehending it are 2 different things.
But alas, it's your ears/eyes you have to please. Not Toole's, not mine. Enjoy.
Btw, have you considered Ethans mattresses on the ceiling thing?

Loudspeaker manufacturer

Re: loudspeaker distance from front wall...guidelines?

Reply #10
Now amuse me and argue that that's not 'multichannel'. 
Your strawman would argue that but I wouldn't. Of course I also know the difference between discrete MCH and upmix, 2 different things, 2 different requirements. "Wide" channels. "Height" channels. Clearly you don't. But regardless, if you prefer your stereo sound worse due to absorption, but better due to belief/visual effects, that's your prerogative.


Upmixed stereo sound isn't stereo sound.  I know you know that, and you're just being tedious.

Wide and Height channels are a new-ish addition to plain old 5.1, which is what I use.  A plain old 5.1 setup also can play 'discrete' 5.1 content very nicely, unsurprisingly.  Most surround mixes available for purchase are still plain old 5.1, the extra channels can be upmixed by newer tech.  I know you know all this too, and you're just being tedious.





AJ, why can't you admit that in his book, Toole actually does have a 'multichannel/home theater' (his words) room plan where multiple dedicated absorbers to the front, rear, and side*, play a role -- as either optional or 'advised', depending on preference and listening habits.   You asked, I provided.    Do you need me to upload a scan of the page?
discrete MCH, where indeed, treatments/absorption are recommended. Again, for discrete MCH (DVD, SACD, Bluray, etc), where spatial "effects" are inherent to the surround channels.

At last count I own over 200 'discrete' 5.1 (and 4.0) audio-only MCH releases. I also play my >1000 stereo recordings exclusively with DPLIIx (and lately, the new Dolby Surround upmixer, though it's not as good for that).  You're being tedious.



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I give up, why can't your strawman "admit" this? What I actually stated is quoted.

And IME, spatial 'effects' are quite often the synthetic result of upmixes too
They are NOT the same, nor have the same requirements for "treatment". With discrete, the envelopment etc is generated from the effects channels, not reflections...hence the suggestion for dead "studio" type room/HT. For plain stereo, your room would be the opposite of good for the majority of blind listeners...but preferences rule here, including visual ones.

That's comforting, since I never play 'plain stereo'.  Drill it into your head:  my room is for playing a mix of 2 channel music releases  upmixed to multichannel, and discrete multichannel audio mixes.   In the rare case I play video, any 2-channel source is also upmixed, while the remainder of DVD/Bluray soundtracks are discrete 5.1 mixes, offered as either lossy encoded (DD/DTS) or PCM. As I don't employ a configuration beyond 5.1, these aren't upmixed. 

Have you actually used upmixers like DPLIIx?  Are you familiar with the sorts of 'effects' they can generate in the surround channels?



Quote
[picture of Toole's living room -- his old one, not his current one, I think]
No sh*t ton of purpose-built treatment --  but gosh looks at all that furniture.  Toole here is going for a living room space that also serves as a 'home theater, something else he talks about.  That's great but not what he is describing in Fig 15.10, which, minus the three rows of seating, *is* analogous to my use case.  It's got a sh*t ton of treatment.
That's his current room (his old one with bipolar M1s pic above) for HT and music...mainly upmixed stereo, not discrete MCH with dedicated effects channels for enhancement. No *sh-t*-ton of treatment. It's clear reading his books info and comprehending it are 2 different things.

It's clear you are being argumentative for the sake of it. As you do. 

But hey let's run with it.  Toole talks about how furnishings can supply the 'treatment' adequate for many consumer uses, which no  one can deny.  When Toole is talking about a room *dedicated* to 'multichannel/home theater', he came up with Figure 15.10, specifying quite a large amount of acoustical treatment mounted on 4 unbroken walls (and presumes carpet on the floor).   No one can deny that, either.  Also, Toole has a TV mounted prominently in photo you posted.  In this 'mainly HT and music' room, playing 'mainly upmixed stereo', though obviously arranged for socializing and other uses as well (couches facing each other, bookshelves, one wall open to the another room) ,  you imagine he's almost never playing discrete 5.1 soundtracks that accompany movies, nor ever any audio-only discrete mixes?  I play 'mainly upmixed stereo' music too simply by virtue of CDs being the vast majority of my music collection.

Btw thanks for posting the pic of Toole's older room -- that's the one I as thinking was new.  IIRC he fondly remembers the older one.  In any case it too is obviously a multi-purpose, multi-use listening space, and not the sort of space Fig 15.10 is about. I have the luxury of actually dedicating the room solely to (mostly single-user) listening. 

As for Ethan's version of sound clouds  (ceiling absorbers common in studios), no, I haven't gone there.  The next step for me should really be measuring the effects of the various configuration experiments I do in my room.  Meanwhile might try close to wall placement again...without 1st reflection absorption this time.  AJ will be happy, or at least not.

Re: loudspeaker distance from front wall...guidelines?

Reply #11
Have you actually used upmixers like DPLIIx?  Are you familiar with the sorts of 'effects' they can generate in the surround channels?
Now who's being tedious? ;-)
You already know that I have and have been using L7 (for over a decade now), but not for the front direct channels. Only for the indirect radiation of the fronts and also rear channels. Since my system is biased towards music first, not discrete MCH HT/music, I use minimal "treatment" other than furniture/decor/storage/etc...same exact stuff that can be used in any dedicated HT room too.
Since I primarily upmix stereo>MCH, I do not use treatment.
If I were to do a dedicated discrete object based MCH HT...I would treat heavily. All the science on this has been clear way before Toole wrote any book. Obviously not all of us followed this research going back decades. I get it, some folks have other things to do.

But hey let's run with it.  Toole talks about how furnishings can supply the 'treatment' adequate for many consumer uses, which no  one can deny.  When Toole is talking about a room *dedicated* to 'multichannel/home theater', he came up with Figure 15.10, specifying quite a large amount of acoustical treatment mounted on all 4 walls (and presumes carpet on the floor). 
Yep, no disagreement there, ever. See above.

I play 'mainly upmixed stereo' music too simply by virtue of CDs being the vast majority of my music collection.
Exactly like Toole and I, yet only one of the 3 of us has a heavily treated room. Hmmm...;-)
As always, preferences do vary.

Btw thanks for posting the pic of Toole's older room -- that's the one I as thinking was new.  IIRC he fondly remembers the older one.  In any case it too is obviously a multi-purpose, multi-use listening space, and not the sort of space Fig 15.10 is about.
Yep, not heavily treated. A 2ch>MCH upmix type room. Btw, the upside down Salon2s (rather than upright M1s) should have been the giveaway. My understanding is he currently uses Auro3D, the one format I don't yet have (having dropped $4k on a L7 Immersion MC10, I'm pacing myself before jumping on another piece). According to Kal Rubinson, Auro leaves the front 2ch untouched, so obviously, my interest is there (and has been since it was intro'd).
Pity you're not in FL (aka outside the polar vortex). I'm exhibiting at a bling show next weekend...with speakers designed to put less sound behind them, so can still be relatively close to the front wall without detriment. By design.
Yes, there will be a L7 processor sitting there to confuse believers too.
Loudspeaker manufacturer

Re: loudspeaker distance from front wall...guidelines?

Reply #12

Yep, not heavily treated. A 2ch>MCH upmix type room. Btw, the upside down Salon2s (rather than upright M1s) should have been the giveaway. My understanding is he currently uses Auro3D, the one format I don't yet have (having dropped $4k on a L7 Immersion MC10, I'm pacing myself before jumping on another piece). According to Kal Rubinson, Auro leaves the front 2ch untouched, so obviously, my interest is there (and has been since it was intro'd).
Pity you're not in FL (aka outside the polar vortex). I'm exhibiting at a bling show next weekend...with speakers designed to put less sound behind them, so can still be relatively close to the front wall without detriment. By design.
Yes, there will be a L7 processor sitting there to confuse believers too.

I think the merry go round can stop here, because, again,  I do in fact play a lot of  *discrete multichannel mixes* as well as upmixed stereo, and my room isn't for socializing, or multitasking or stepping out into the kitchen next door.   And I don't leave the front 2ch untouched.  I touch the hell out of them. ;>  So it's worth it to me to experiment with a Toolean 'heavily treated room' , which I may or may not adopt in the end. That's why: experiments.

Sorry I couldn't make that demo, it would have been nice to hear, I'm sure.

Btw, my 2nd sub arrived a few days ago.   Off to the races...
 





Re: loudspeaker distance from front wall...guidelines?

Reply #14
Some "interesting" placements for sure.
Of course, how it all sounds is what matters
Loudspeaker manufacturer

 
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