Speaker positioning for bass

RBFC

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Apr 20, 2010
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We've generally come to agree on the forum that the main speakers, when positioned for optimal imaging, are not always in the spot that produces the best bass performance. Additional subwoofers are often used to supplement/smooth bass response in this case.

Has anyone experienced the opposite, where the speakers are positioned for optimal bass response and the system/room tweaked for best imaging? I believe it was in reading about the Wisdom Audio in-wall speakers that there was a claim that imaging did not need to rely on speaker position out into the room.

I'm currently of the camp that believes in positioning for imaging, then "fixing" the bass.

Thoughts?

Lee
 

JackD201

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Apr 20, 2010
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I take the opposite route. I fix bass first since it requires more physical movement of the speakers then imaging later which takes smaller adjustments. Generally I find that when I get good midbass focus the upper registers are not to far off from very good. It is then that I adjust my active subwoofers to just flesh out the foundation.
 

tony ky ma

Industry Expert
Aug 21, 2010
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my system only have two sub woofers, they are JBL 15" driver in a modified Empire box, face down to get 360 degree in direction but a breath hole 3.6" with pipe and fully stuff with drinking straws that is face to the back wall cross over 80HZ 12db/oct, place behind the mid-low and mid-high horn in same axle, cross over for this two horns is 600 and 1K in two way setting sub is in add on style and super high 15Khz also add on in 12db/oct, 4 passive filters drive by a 300B to 4 power amps direct to speakers . in this set up I didn't make any change of positioning from the first time, I got a very good sound stage and image already, I always check my system by turning pre-amp's volume control up to see the sound stage is coming closer to me beside the sound getting louder and turn down will make sound stage go further away, that will tell me everything is still OK
tony ma
 

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Mark (Basspig) Weiss

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Aug 3, 2010
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Position for optimal imaging is almost never optimal for bass. Speakers are in toward the middle of the room in this case, whereas for bass reinforcement, woofers prefer to be in the corners.
I compensated for this by adding more woofers. :) I never could get the transient response of percussion to have 'immediacy' with subs facing the corners. Clustering them all together enables them to behave as a unified sound source, alleviating the many phase cancellations that plagued me when I had woofers spread out to the corners and in the middle. Also, due to mutual coupling, I picked up 6dB of additional sensitivity and the LF response did not suffer that much after all.

Tony, are those JBL 2403s with diffusers mounted in front?
 

flez007

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Aug 31, 2010
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I take the opposite route. I fix bass first since it requires more physical movement of the speakers then imaging later which takes smaller adjustments. Generally I find that when I get good midbass focus the upper registers are not to far off from very good. It is then that I adjust my active subwoofers to just flesh out the foundation.

Same here, since my Guarneri's favour imaging I work from there to get the best midbass (body) response and then ask my Velodyne sub to work from there.
 

RBFC

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Although I appreciate all the responses, nobody has addressed the actual question directly. Has anyone set up main speakers alone in the position that provides good bass performance, and then worked on the room acoustics, etc. to optimize the imaging?

Lee
 

Steve Williams

Site Founder, Site Owner, Administrator
Although I appreciate all the responses, nobody has addressed the actual question directly. Has anyone set up main speakers alone in the position that provides good bass performance, and then worked on the room acoustics, etc. to optimize the imaging?

Lee

I did
 

naturephoto1

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May 24, 2010
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Although I appreciate all the responses, nobody has addressed the actual question directly. Has anyone set up main speakers alone in the position that provides good bass performance, and then worked on the room acoustics, etc. to optimize the imaging?

Lee

I guess that I am basically doing that. I do not have enough space to move things around with the size of the main speakers (but each of the main speakers have 2 15" woofers), subwoofers, and the number and size of all of components. I have tried to place the main speakers for their best optimized overall sound, timber, imaging, and bass all at once. At this point the big subwoofers are in the rear of the room in the corners facing the seating, but they are at least at this point only used for the multichannel and home theater usage (they could be set up for the two channel usage as well). We will be incorporating Acoustic room treatments hopefully in the near future to optimize imaging, overall sound and bass for the room. But, we have to start to prepare the treatments which will be incorporated into the room.

Rich
 

Ethan Winer

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Jul 8, 2010
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Has anyone experienced the opposite, where the speakers are positioned for optimal bass response and the system/room tweaked for best imaging?

To my way of thinking that's the most sensible approach. Imaging and mid/high frequency issues are easy to solve with relatively thin absorption at key places. Versus bass response which is much more difficult to get right, and changes drastically with small changes in placement. So my approach is to position the loudspeakers for the best bass response, symmetrically of course, and then deal with the reflection points.

--Ethan
 

DonH50

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Jun 22, 2010
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^ +1.

Bass is much more a function of the room than mid/high frequencies, and much harder to correct with anything other than placement. Once the bass is good, the highs are much easier to tweak by small speaker movements, room treatment, or both.

My main speakers (Magnepans) are notoriously room-sensitive, so I start by finding their bass "sweet spot", then adjust their position in small increments to fine-tune the image and sound stage. I have found that generous treatment behind and on the early reflection points (walls and ceiling; carpeted floor) has made my current listening room one of the best I have had in terms of imaging, sound stage, and frequency response.

I have said and will again (after this time ;) ) that far too many audiophiles pay far too little attention to their room treatment and speaker placement.

FWIWFM - Don
 

rbbert

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Dec 12, 2010
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Interestingly enough, I found the best bass response (i.e. smoothest, not necessarily the deepest) for my main speakers (VMPS RM-40) to be at one of the spots calculated from an old article in The Audio Critic (Issue 13; 1989). I'm still in the process of treating the room, so far with corner ASC Tube Traps/Towers, 2 ASC Matrix panels on the sidewall first reflection points and RoomTunes triangles in 3 upper corners (there's a Tube Trap in the 4th ceiling corner). Right now, in a 166" x 274" room, the speakers (middle of front panels) are 62" from the front walls and my listening seat is 62" (ear position) from the rear wall; I was a bit surprised when the distances measured the same because my listening seat was determined purely by listening, not measuring. I may still end up with it farther from the rear wall (i.e., closer to the speakers); the rear wall is CD/book shelves, therefore mostly reflective and a little diffusive (since the shelves are mostly about 8" apart).

The VMPS RM40's have very good bass response, and I run them full range with an additional Velodyne Optimus-12 (LP filter at 40 Hz) in the same plane as the speakers slightly to the right of center of the mid-line (again at a point suggested by the equations in that old Audio Critic article). I've run an RTA using Behringer equipment, and the bass is fairly smooth to about 20 Hz, with some unevenness in the under 50 Hz range and a broad, smooth, small (~3-4 dB) hump from about 60 - 120 Hz (where there are a couple of room nodes).
 

dougsmith

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Sep 5, 2010
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I 'd say: get the imaging right first (placement & accurate coincident impulse response at the prime listening position) and then perfect the bass response by adding subs at appropriate positions for any given room (using measurements to help optimize placement, levels & EQ for the best response). I would start adding room treatments only after doing these things, but of course it would be best to start with a room that incorporates acoustic elements like bass damping and broadband ceiling traps in the original construction.
 

booboobaer

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Aug 22, 2010
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I have come to find a formula that seems work very well with a lot of speakers. First I would like to let you know what speakers I have owned personally. Mirage M3 / a bipolar speaker, Magnapan 1.6 / magnetic planar, maggies 3.6, maggie 20.1, Sound Lab Millenium ones / electrostatics. I know own the JM Labs Focal Utopias. This formula has yet to let me down! First I believe nearfield listening is a good method. Second an equallateral triangle will give great clarity and sound stage depth and layering. Position the listening chair in such a place that the distance from your head to the woofer is the same distance that the two speakers are from each other ( an equallateral triangle) and toe the speakers so they focus at your nose. Then move the triangle forwards or backwards from the back wall for more or less bass. This will keep the focus and layering and allow for base adjustment. Right now I have the speakers 8 feet apart ( center hole to center hole of bass speaker ) and 8 feet from the center of woofer to my nose. You can fine tune the mid range by focusing at nose and slowly focusing further back like the back of your neck etc. This has proven to be very effective. Then when you have found the desireable position have some one use a mirror and on the right speaker have them put the mirror on the right wall untill you see the right speaker in it frome the listing position and that will be the position for absorbers for the first side reflections. Do the same for the left. You can see my room on Audiogon under" virtual systems", then "all out assault", my handle is Booboobaer. Give it a try it is pretty darn amazing!
 
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Mike Lavigne

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Apr 25, 2010
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my speakers are positioned based on a calculation from the speaker designer for optimal bass performance. he has the exact dimentions of my room. he gave me three different spots to try; which i did.

using the front face center bottom as the measuring point; my speakers are 9' 9" from the wall behind and 58" from the sidewalls. about exactly on the rule of thirds front to back.

my speakers; the Evolution Acoustics MM3's, have integrated dual 15" powered subwoofers (in a sealed box) that are fully adjustable for any room. you can adjust crossover, bass gain, 'Q', and bass extension which is a 25hz loudness contour. these 1000 watt powered subs move lots of air and are very articulate.

one sits behind the speaker with a laptop connected to my PAA3 RTA on a tripod at the listening position and make adjustments until things are pretty flat; one speaker at a time. we were able to get it pretty flat from 20hz to 20kh except for a very narrow 4-6db dip at 30hz and a even narrower 3-4 db bump at 60hz. as it decends below 20hz (+1db at 20hz) it is rising and the speakers are rated at -3db at 10hz.

subjectively the bass is flat and what is amazing is that the 15" powered woofers completely integrate with the Accuton ceramic mid-range. you do not hear any muddled mid-bass and no sense of separate drivers. male and female vocals and Cello's are stunning.

the speaker position for ideal bass also works in my room for soundstaging and tonal balance. my room is good sized, 29' x 20'8" x 11'. so with a tweeter to tweeter distance of 124" (10' 4") there is still almost 5' from each tweeter to the sidewall.

the room is a 'clean sheet of paper' ground up design built in a barn. it's main characteristic is diffusion. the room's shape most resembles an oval, with no flat opposing surfaces.

i did take about 2 days working on toe-in before i was satisfied.
 

silviajulieta

Well-Known Member
Jul 6, 2010
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México city. rauliruegas@hotmail.com
We've generally come to agree on the forum that the main speakers, when positioned for optimal imaging, are not always in the spot that produces the best bass performance. Additional subwoofers are often used to supplement/smooth bass response in this case.

Has anyone experienced the opposite, where the speakers are positioned for optimal bass response and the system/room tweaked for best imaging? I believe it was in reading about the Wisdom Audio in-wall speakers that there was a claim that imaging did not need to rely on speaker position out into the room.

I'm currently of the camp that believes in positioning for imaging, then "fixing" the bass.

Thoughts?

Lee



Dear RBFC: In an near " ideal " audio world I don't believe on passive full range speakers and I don't belive neither in full range speakers with integrated powered subwoofers. I believe in separates: good main active/passive speakers with separate powered subwoofers.
In this way you can/could have the best of both worlds: " optimal imagin " ( like you say ) and " optimal bass performance " with no single frequency range " sacrifice ".

I know that that was not what you are asking but this is an opinion.

In the other side when our system has not exactly the ideal " system speakers " then normally almost all choose to positioning first for best bass performance and as a second step for " imaging ".

Now, why do you choose to made it the other way around?

regards and enjoy the music,
Raul.
 

Nyal Mellor

Industry Expert
Jul 14, 2010
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Personally I think the best approach is optimize for bass response first and soundstage/imaging second.

The main reason is that bass quality is mainly governed by interaction with standing wave patterns in the room and speaker boundary interference (phase cancellation) effects. Speaker and listening positions generally need to be moved 6" or more to have an appreciable impact on bass response. Having access to acoustic measurement equipment means you can optimize bass much quicker than trying to set it up by ear.

The normal approach I use set up the speakers and listening position in a starting position based on experience and the type of speakers. Then layout a grid on the floor using masking tape, marking forward and back of the listening position. One can then systematically move the speakers, checking each position against a high resolution frequency response measurement. It helps to know what room modes exist in the space and where the phase related cancellations occur since this allows you to understand what positional changes need to be made to improve things rather than simply going by trial and error. After the best bass response has been found for the listening position then move the speakers to a good starting distance away, again this distance is informed by experience of the speaker type and brand, with some speakers being ok to listen to closer and some needing a greater distance to sound integrated. Then work on the speaker placement, again using a 6" spaced grid to see if bass response can be further improved. You will have inner and outer separation limits which you will need to work within (e.g. you can't have the speakers 15ft apart!).

Once bass is optimized, switch over to soundstaging. Here you are trying to optimize for the focus of instruments within the soundstage compared to the envelopment or spaciousness of the sound. Small changes (on the order of 1/2") can make a difference here. If you are installing mirror / reflection point treatment then generally I would find the location of best bass and then install acoustic treatment. After treatment is installed set the speaker separation, since treatment at mirror points changes the amount of energy reflected back into the room from these locations and therefore changes the separation you will need to optimize focus vs. envelopment.
 

Kal Rubinson

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May 4, 2010
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Personally I think the best approach is optimize for bass response first and soundstage/imaging second.
I agree but with implicit constraints. Specifically, we constrain the speaker space to an area opposite the listening position and place the speakers fairly symmetrically while adjusting to optimize the bass. This implicitely recognizes that good soundstage/imaging will likely be possible in that region. Surely, we do not entertain the possibility of putting one speaker in front of the room and the other in the back or on one side, even if such is what is often recommended for multiple subs, because we know that soundstage/imaging would be impossible.

So, rather, it is really a 3 step process in which we (1) choose a region where optimum soundstage/imaging is possible, (2) try to achieve good bass within it and, finally, (3) optimize the soundstage/imaging with toe-in, tilt, room treatment and/or anything else we can get our hands on.
 

Nyal Mellor

Industry Expert
Jul 14, 2010
590
4
330
SF Bay Area, CA, USA
I agree but with implicit constraints. Specifically, we constrain the speaker space to an area opposite the listening position and place the speakers fairly symmetrically while adjusting to optimize the bass. This implicitely recognizes that good soundstage/imaging will likely be possible in that region. Surely, we do not entertain the possibility of putting one speaker in front of the room and the other in the back or on one side, even if such is what is often recommended for multiple subs, because we know that soundstage/imaging would be impossible.

So, rather, it is really a 3 step process in which we (1) choose a region where optimum soundstage/imaging is possible, (2) try to achieve good bass within it and, finally, (3) optimize the soundstage/imaging with toe-in, tilt, room treatment and/or anything else we can get our hands on.

You are quite right Kal! The constraints are dictated by the need to keep speakers basically same distance from the listening position and by the limits of the space where the system is going. The majority of the time we are limited by where the listening position can go or having a small area in which you have to work with in terms of potential speaker positions.
 

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