Positioning speakers with the help of Spinorama

[Keith_W]

I have done a search in many other threads to find the answer to my question and learnt a lot about Spinorama measurements. From what I gather, Spinorama is more useful as a design and purchase tool. My understanding is that you want a low directivity index with early reflections, the listening window, and sound energy closely matching in shape the axial response. I have already purchased my loudspeakers, so the "design" and "purchase" aspect of interpreting Spinorama measurements is of no concern to me.

However, it got me wondering whether knowledge of the Spinorama might affect how much I should toe-in my speakers. This is a photo of my speakers from the listening position:

Not so apparent in this photo: the speakers are both toed-in so that they point slightly behind my head at the listening position.

The wide angle distortion from my camera makes the speakers look closer to the wall than they actually are. However, they are positioned well away from the wall. As a side note, I initially positioned the speakers in the room using traditional rules of loudspeaker placement and then refining the position and toe-in by ear. Today I found a loudspeaker positioning tool which confirmed that where I placed the speakers is not a problem:

So let us assume that the speakers are correctly and optimally placed in the room, and focus the questions on toe-in.

I do not own a Klippel NFS, nor do I know where I can access one or hire an anechoic chamber. I DO own an Earthworks M30 mic, mic tripod, and can use REW on my laptop. If I have to, the ONLY way to find out my speaker's off-axis response would be to take them outside and do multiple sine wave sweeps with the help of a protractor and some string. However, given the size and weight of my speaker this would require a massive effort as they weigh 110kg each.

Now, toe-ing my speakers out, but still within the listening window, would reduce the axial response and increase the early reflections, but should not change sound energy (correct me if I am wrong please). Without knowing the Spinorama measurements, is there a way to accurately measure or predict the optimal amount of toe-in? Of course, I could just experiment with toe-in and just listen and adjust to my preference (which I have already done), but I would like a more "objective" way to find out the answer.

 

[ernestcarl]

I have done a search in many other threads to find the answer to my question and learnt a lot about Spinorama measurements. From what I gather, Spinorama is more useful as a design and purchase tool. My understanding is that you want a low directivity index with early reflections, the listening window, and sound energy closely matching in shape the axial response. I have already purchased my loudspeakers, so the "design" and "purchase" aspect of interpreting Spinorama measurements is of no concern to me.

However, it got me wondering whether knowledge of the Spinorama might affect how much I should toe-in my speakers. This is a photo of my speakers from the listening position:

View attachment 269148

Not so apparent in this photo: the speakers are both toed-in so that they point slightly behind my head at the listening position.

The wide angle distortion from my camera makes the speakers look closer to the wall than they actually are. However, they are positioned well away from the wall. As a side note, I initially positioned the speakers in the room using traditional rules of loudspeaker placement and then refining the position and toe-in by ear. Today I found a loudspeaker positioning tool which confirmed that where I placed the speakers is not a problem:

View attachment 269150

So let us assume that the speakers are correctly and optimally placed in the room, and focus the questions on toe-in.

I do not own a Klippel NFS, nor do I know where I can access one or hire an anechoic chamber. I DO own an Earthworks M30 mic, mic tripod, and can use REW on my laptop. If I have to, the ONLY way to find out my speaker's off-axis response would be to take them outside and do multiple sine wave sweeps with the help of a protractor and some string. However, given the size and weight of my speaker this would require a massive effort as they weigh 110kg each.

Now, toe-ing my speakers out, but still within the listening window, would reduce the axial response and increase the early reflections, but should not change sound energy (correct me if I am wrong please). Without knowing the Spinorama measurements, is there a way to accurately measure or predict the optimal amount of toe-in? Of course, I could just experiment with toe-in and just listen and adjust to my preference (which I have already done), but I would like a more "objective" way to find out the answer.

Those are very nice looking speakers! So very unlike some of my boring, black vinyl wrapped and commercially massed-produced speakers.


Anyway, in addition to taking the usual mental subjective listening notes…

Maybe just take in-room measurements while you gradually change the angle of your speakers — and label them accordingly. Study how the graphs change… including the detailed reflection-decay characteristic and envelope and how it changes over time. Granted, it helps to know which outstanding peaks correspond with their originating wall boundaries.

If the primary consideration is at the central MLP and speaker toe-in only, then it should not take too long to find a pattern that looks as close to something more objectively “better”.

At the extreme end of the spectrum, I’ve done something like this… but it definitely took a long, long time (multichannel speaker setup and hundreds of measurements over time) as I had to consider other listening positions — moving some acoustic treatment panels around as well — while all trying to reach for a subjectively as well as objectively derived best speaker-listener room arrangement.

Others may find this all a bit too tediously unnecessary, though.

 

[Flaesh]

With regard to subjective perception, the objective optimum of the angle of rotation does not really exist. Remember the crowds of aggressive audiophiles who put speakers in parallel and listen 30º off axis.
Soundton doesn't say anything about the effect of rotation, see FAQ.

 

[Keith_W]

With regard to subjective perception, the objective optimum of the angle of rotation does not really exist. Remember the crowds of aggressive audiophiles who put speakers in parallel and listen 30º off axis.
Soundton doesn't say anything about the effect of rotation, see FAQ.

I am aware that Soundton does not say anything about rotation. I used it as a point to show that I have optimally positioned the speakers.

What I find really interesting about your statement is that you say that the "optimum angle of rotation does not really exist". My interpretation of what you are saying is: as long as the speakers are pointed towards the listener somewhere along the cone of the listening window, it does not matter how much toe-in/out is applied? I need to make sure I understand your point correctly, so I will illustrate with a Spinorama I found by googling (NOT my speaker):

For this particular speaker, as long as it is pointed -30 to +30 towards the listener, it does not matter? Please correct me if I have misinterpreted your statement. I have to say that it intuitively does not make sense. It is something that I will have to confirm for myself by doing some sweeps with the speakers pointed at various angles.

Maybe just take in-room measurements while you gradually change the angle of your speakers — and label them accordingly. Study how the graphs change… including the detailed reflection-decay characteristic and envelope and how it changes over time. Granted, it helps to know which outstanding peaks correspond with their originating wall boundaries.

If the primary consideration is at the central MLP and speaker toe-in only, then it should not take too long to find a pattern that looks as close to something more objectively “better”.

Thank you for your input.

Could you please clarify what you think I should be looking for when you say it should look objectively better?

I will tell you why I am asking these questions. Until recently, I thought that excessively long ringing after an impulse was a bad thing. Then I had the opportunity to listen to a pair MBL 101e's which are omnidirectional. My subjective perception of them was that they sounded amazing. They were clear, sounded relaxed, had a really wide sweet spot, and in fact it did not really matter where you were standing in the room. This lead me to question my assumption that a speaker that had a narrow dispersion was good, which lead me to this thread on ASR about omnidirectional speakers. I read the first 10 pages of that 32 page long thread which taught me plenty about how I was wrong about my assumptions. Specifically, that early reflections which are spectrally correct actually helps with the illusion of soundstage. This then lead me to doing some more googling about Spinoramas which made me wonder about whether I could increase early reflections by toe-ing them out a bit more. Hence my question in this thread.

I hope that nobody misinterprets my intentions, because I am not trying to challenge you. I have just had some of my long held assumptions turned on its head and I am trying to make sense of it all.

 

[ernestcarl]

Could you please clarify what you think I should be looking for when you say it should look objectively better?

Well, at the very least you can get an idea how the ER is modified with toe-in angle change of the speakers (at the measured microphone position) by looking at other graphical views e.g. wavelet spectrogram, cumulative spectral decay vs windowed responses for instance while varying the setting/filter parameters.

I would expect for you to see at least a good range of angles where you simply won't see much of any obvious significant difference -- but if you look at other varied positions in the room, moving away axially and closer to wall boundaries, for example, while changing speaker angles you absolutely should see and/or hear an effect. Same thing when adding or removing acoustic panels.

Somewhere in my hard drive I have measurements where I performed such gradual angle adjustments -- can't find them at the moment -- but here's something I know is a little less subtle and much more obvious -- just to give some illustration of what may be objectively measurable and observable after a "modification":



Measurements were taken at same date and time. No EQ changes other than adding and removing three small 4" foam wedge square acoustic panels at a first reflection point to a direct opposing wall.

I thought that excessively long ringing after an impulse was a bad thing.

Is it really ringing you are describing or the overall reverb or extended reflection decay produced by the omni speakers? Don't really have any experience with those...

 

[Flaesh]

as long as the speakers are pointed towards the listener somewhere along the cone of the listening window, it does not matter how much toe-in/out is applied?

Not certainly in that way. In some limits, the differences will be small, further changes in lateral reflections can be noticeable as changes in soundstage\ambience\articulation even with "perfect" speakers. Although the reasons for what is happening are objective, the choice of the preferred option depends on individual preferences.
Do you want to replace Acapellas with MBLs or other omnis?..

confirmed that where I placed the speakers is not a problem

Here I want to argue about the objectively good reproduction of low frequencies, although the rotation of the speakers does not affect this. Soundton does not confirm approximately nothing. A simple measurement at the listening position may or may not confirm.

 

[Tom C]

Your speakers are absolutely beautiful. Saw them in person at a show in Windsor sponsored by HiFiNews.
It is my understanding that, regardless of design, the best sound attainable from a system is when you position the speakers so that the listener (or, at least, MLP) is on-axis. The number one factor in the listener’s perception of sound quality is the direct sound from the speaker.
The direct sound is the first arrival from the speaker. The reflections arrive at the listener’s ear later than the direct sound, and get compared by the brain to the first arrival. The reflections are important in that if they differ significantly in spectral balance from the first arrival, the brain says, hey, this is new information, I better focus on it. But if the reflections are very similar to the first arrival, the brain says, cool, more of the same, I already know this, I can relax and enjoy. It is for some reason bothersome when reflections and first arrival don’t match, but when they do match, it is not bothersome. If your speakers have off-axis behavior that is not smooth, you can’t use EQ or positioning to fix. Room treatments may help, to the extent reflections and their attendant aberrations are reduced at the MLP.
The other thing is that when speakers are measured on axis, measured errors in the FR include phenomena that can be corrected with EQ, and phenomena that cannot be corrected with EQ. The peaks and dips can be caused by resonances, which are minimum phase and correctable with EQ, and by acoustic interference, which is not minimum phase, and not correctable using EQ. The resonances will show themselves in the spins: they will persist in the on-axis and in the off-axis measurements. Conversely, acoustic interference may be seen on-axis, but then drop out on off-axis measurements. This is where a complete set of spins can help after purchase of the speakers. You can EQ using the listening window FR, since that should include just the correctable, minimum phase errors.
In summary:
The best sound is when the speakers are toed in to on-axis with respect to the listening position.
Spins are useful after purchase if the anechoic FR on-axis isn’t flat, to guide EQ settings.
If the speakers have off-axis response that isn’t smooth, the only real fix is replacement with better performing speakers. Maybe room treatments can help you hear less of the problems at the listening position.

 

[Keith_W]

Do you want to replace Acapellas with MBLs or other omnis?..

The cost of MBL's is prohibitive but I would certainly consider other omnis. I have to learn a lot more about them first though. I am quite happy with the Acapellas, after many years of tweaking and climbing various learning curves I finally have them sounding right. As they were delivered, the bass was muddy and all over the place. I have not had to touch Acourate for a few years and my microphone is gathering dust.

Here I want to argue about the objectively good reproduction of low frequencies, although the rotation of the speakers does not affect this. Soundton does not confirm approximately nothing. A simple measurement at the listening position may or may not confirm.

Haha well the position of the subwoofers was determined by placing a sub in the LMP and going around the room making sweeps. It was fortuitous that the ideal position for the sub was where they are most aesthetically pleasing. I could place a third or fourth sub off to the side of the LMP but bass reproduction at the LMP is good enough for me not to bother.

As for the other replies - thank you but I think I will have to post some measurements before I make any more replies to this thread. I will do so in a few days.

 

[Flaesh]

Acourate

AFAIK Acourate may to get an objectively good result.
A simple objective metric (IMO independent of individual preferences)) of bass' goodness is C50\D50. https://www.audiosciencereview.com/...n-rew-and-tell-us-how-your-bass-sounds.22567/
C50>10 dB or D50>90% (that's the same, I'm used to using D50) are minimum hi-fi requirements.

 

[puppet]

My take on loudspeaker toe-in comes down to how much of the room you may want to include in the overall response. An untreated room may want more toe-in than a treated room does. This can also depend on the directivity characteristics of the loudspeaker itself.

A loudspeaker with higher directivity may need less toe-in than a loudspeaker with lower directivity. This attribute is baked into the design. What isn't baked into the design is the amount of sound stage you like while listening. This can be enhanced using toe-in. So, I don't think that there is a "perfect" toe-in as it really comes down to personal listening taste and room acoustics.

 

[Flaesh]

higher directivity may need less toe-in

On the contrary. See "Geddes aligment" and Klipsch. Mine [usually] are 45º toed in

 

[puppet]

On the contrary. See "Geddes aligment" and Klipsch. Mine [usually] are 45º toed in

Depends on personal preference. Some like loudspeakers L/R crossing in front of the listener, others may like it behind the listener. With higher directivity loudspeakers you have more toe adjustment latitude in this regard ... before the room gets involved.

 

[OCA]

I have done a search in many other threads to find the answer to my question and learnt a lot about Spinorama measurements. From what I gather, Spinorama is more useful as a design and purchase tool. My understanding is that you want a low directivity index with early reflections, the listening window, and sound energy closely matching in shape the axial response. I have already purchased my loudspeakers, so the "design" and "purchase" aspect of interpreting Spinorama measurements is of no concern to me.

However, it got me wondering whether knowledge of the Spinorama might affect how much I should toe-in my speakers. This is a photo of my speakers from the listening position:

View attachment 269148

Not so apparent in this photo: the speakers are both toed-in so that they point slightly behind my head at the listening position.

The wide angle distortion from my camera makes the speakers look closer to the wall than they actually are. However, they are positioned well away from the wall. As a side note, I initially positioned the speakers in the room using traditional rules of loudspeaker placement and then refining the position and toe-in by ear. Today I found a loudspeaker positioning tool which confirmed that where I placed the speakers is not a problem:

View attachment 269150

So let us assume that the speakers are correctly and optimally placed in the room, and focus the questions on toe-in.

I do not own a Klippel NFS, nor do I know where I can access one or hire an anechoic chamber. I DO own an Earthworks M30 mic, mic tripod, and can use REW on my laptop. If I have to, the ONLY way to find out my speaker's off-axis response would be to take them outside and do multiple sine wave sweeps with the help of a protractor and some string. However, given the size and weight of my speaker this would require a massive effort as they weigh 110kg each.

Now, toe-ing my speakers out, but still within the listening window, would reduce the axial response and increase the early reflections, but should not change sound energy (correct me if I am wrong please). Without knowing the Spinorama measurements, is there a way to accurately measure or predict the optimal amount of toe-in? Of course, I could just experiment with toe-in and just listen and adjust to my preference (which I have already done), but I would like a more "objective" way to find out the answer.

Optimal speaker toe-in amount is determined by tweeter directivity and dispersion and manufacturer's recommendation (the manual) should be closely followed. Some speaker's need to be turned directly towards the LP, some need to be toed-in slightly while some will need to be facing forward with no toe-in.

Although toe-in will have an effect on the strength of HF response at the LP depending on the speaker, its major effect is on the width and depth of centre (phantom) image because this is purely a function of side wall reflections. The beaming characteristics of the speaker's tweeter (which depends on the type, material, diaphram size, etc. of the tweeter) will determine the area HF is reflected from the side walls.

For fine-tuning of toe-in, I strongly recommend experimenting with these two songs:

Her Majesty – Beatles: An only 23 seconds long song. It helps to adjust the initial toe-in as well as the distance between the speakers. The vocals and guitar start off in one channel and slowly pan all the way to the other channel. If the vocalist gets closer towards the LP as it moves to the middle, there is too much toe in. If the vocalist moves away from the LP during the panning, there is too little toe in. It should sound as if McCartney's vocals roll smoothly and continuously across the sound stage. If it sounds like he jumps from Right - to - Center - to - Left, the speakers are too far apart.

Amused to Death – Roger Waters: Once speakers are roughly toed-in, use this one for optimization. The song starts with a conversation coming from a TV to your rear left! You will literally hear the whole conversation coming from behind you and this will ONLY happen with the most accurate toe-in.