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Paul McGowan - getting speaker close to wall changes tonal balance?

Music1969

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In this new video Paul says numerous times that moving a speaker closer to sidewall changes tonal balance.

How is this possible?

He doesn't mention diffiusion or absorption which obviously can change tonal balance.

Unless he means bass can change, which of course we all know from experience from moving speakers around in the room.

But he doesn't really talk about bass.

 

Doodski

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Paul says numerous times that moving a speaker closer to sidewall changes tonal balance.
With the location of those bass towers in the corners and nearly against the walls I can't imagine they would sound as good as can be. So yes, moving them around will change things.
 

Doodski

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so old and pregnant??
On May 13, 2016 he was quoted as being, "closer to 70." That would make him ~70-72 maybe. So he's in pretty decent shape for his age plus he's a vegetarian so he should be even more slender I think.
 
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Music1969

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With the location of those bass towers in the corners and nearly against the walls I can't imagine they would sound as good as can be. So yes, moving them around will change things.
Noted, I already mentioned in my opening post its easy to understand how tonal balance will change as bass will change with moving speakers around room.

But its unclear if hes only referring to bass in his video or 'other' tonal balance

As I mentioned, he doesn't specifically mention bass can change with changes in speaker position.
 

Doodski

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its unclear if hes only referring to bass in his video or 'other' tonal balance
Him moving around the room causes his voice to change in tone so I think that room has some strong tonal qualities. The position of the high freq columns indicates they do change in tone when placed away from the walls or he would have them spaced further apart nearer the walls. So going on that I think he means overall tone of both columns.
 

Duke

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In this new video Paul says numerous times that moving a speaker closer to sidewall changes tonal balance.

How is this possible?

In addition to boundary reinforcement of the longer wavelengths, there is this:

If the off-axis energy bouncing off the side wall has a different spectral balance from the direct sound in the mids and highs - which is virtually always the case - then the stronger that sidewall reflection, the more it will affect the perceived tonal balance. In addition, the wall's surface may be more absorptive at shorter wavelengths than at longer ones, altering the spectral balance of the reflections.

For instance, suppose we have a 6" two-way with a 1" dome tweeter. The dome tweeter's radiation pattern will be very wide in its bottom octave or so, typically the 2.5-5 kHz ballpark. So the stronger that sidewall reflection the more energy we will be getting in the 2.5-5 kHz region, which in turn will skew the perceived tonal balance accordingly.
 
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Music1969

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Him moving around the room causes his voice to change in tone so I think that room has some strong tonal qualities. The position of the high freq columns indicates they do change in tone when placed away from the walls or he would have them spaced further apart nearer the walls. So going on that I think he means overall tone of both columns.
Thanks that makes more sense than came across in his video
 
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Music1969

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In addition to boundary reinforcement of the longer wavelengths, there is this:

If the off-axis energy bouncing off the side wall has a different spectral balance from the direct sound in the mids and highs - which is virtually always the case - then the stronger that sidewall reflection, the more it will affect the perceived tonal balance. In addition, the wall's surface may be more absorptive at shorter wavelengths than at longer ones, altering the spectral balance of the reflections.

For instance, suppose we have a 6" two-way with a 1" dome tweeter. The dome tweeter's radiation pattern will be very wide in its bottom octave or so, typically the 2.5-5 kHz ballpark. So the stronger that sidewall reflection the more energy we will be getting in the 2.5-5 kHz region, which in turn will skew the perceived tonal balance accordingly.

Thanks, this is significantly more helpful than Paul's video. Not that I have anything against him.
 

abdo123

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Yes that’s absolutely true, once I’m a little bit more awake I can quote the relevant pages of Dr. Toole’s book with the supporting data and measurements.

Bring your speaker close to a boundary is the worst thing you can do to it.
 

MakeMineVinyl

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If nothing else, keeping speakers away from boundary walls can improve imaging. I don't notice a great amount of timbre differences when my speakers are close to a wall, but then again, my speakers are very directional horns. I would expect speakers with wider dispersion to be more affected by close-wall placement.

And yes, it looks like Paul needs to get out and do a lot more aerobic exercise.
 

youngho

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From first/second edition of Sound Reproduction by Floyd Toole:

Screen Shot 2021-11-07 at 11.55.50 PM.png


Screen Shot 2021-11-07 at 11.56.05 PM.png

"The overall conclusion is that mounting this excellent little loudspeaker in a wall has left its overall performance substantially intact, but the bass output has been greatly increased, making it sound fat, thick, and tubby."

Screen Shot 2021-11-07 at 11.56.23 PM.png
 

Tangband

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Something that somewhat mixes up the results from measurements done with sinesweeps or pink noise, is the precedence effect and the ”law of the first wavefront” - the HAAS effect.*

We, as humans, dont hear like a microphone at all when the distance from the soundsource ( loudspeaker ) to the ear is longer than 5 ms ( 1,7 metre ) . The brain locks to the first arriving sound, often the direct sound from the loudspeaker, and attenuates all other sounds about 10 dB.
The brain starts to select sounds, but the microphone takes up all the sound.

This is one of the reasons why loudspeakers located away from the walls appear to sound clearer . The reflexes from the walls arrive later than 5 ms in time to the ear, and is also attenuated as much as 10 dB by the brain. The direct sound from the speaker will dominate the listeningexperience in a big room with freestanding loudspeakers.

*So measurements from a certain distance can only tell you something if you are aware of this.
 
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Tangband

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Are you sure that's the case for reflections in the 10ms window?

Your information kind of conflicts with everything people experience with small rooms acoustics.
Well, this is about physics and how the brain works. As a record engineer ( semiproffesional ) Ìm very aware of this phenomen.

The precedence effect and the HAAS effect is the dominant reality for our hearing as humans. The attenuation of later arriving sounds in our brain keept us alive in the stoneage and saved us from being eaten or killed by enemies.
One cant discuss spykoacoustics without knowing of the precedenceeffect, so for all of you who hasnt read about it yet, here is good reading:

”the apparent location of the perceived sound was dominated by the location of the sound that reached the ears first (i.e. the first-arriving wavefront). The second-arriving sound had only a very small (albeit measurable) effect on the perceived location of the fused sound. They designated this phenomenon as the precedence effect, and noted that it explains why sound localization is possible in the typical situation where sounds reverberate from walls, furniture and the like, thus providing multiple, successive stimuli. They also noted that the precedence effect is an important factor in the perception of stereophonic sound.
Wallach et al. did not systematically vary the intensities of the two sounds, although they cited research by Langmuir et al.[4] which suggested that if the second-arriving sound is at least 15 dB louder than the first, the precedence effect breaks down.”

and…..

”A single reflection arriving within 5 to 30 ms can be up to 10 dB louder than the direct sound without being perceived as a secondary auditory event (echo). This time span varies with the reflection level. If the direct sound is coming from the same direction the listener is facing, the reflection's direction has no significant effect on the results.”

 
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abdo123

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Well, this is about fysics and how the brain works. As a record engineer ( semiproffesional ) Ìm very aware of this phenomen.

The precedence effect and the HAAS effect is the dominant reality for our hearing as humans. The attenuation of later arriving sounds in our brain keept us alive in the stoneage and saved us from being eaten or killed by enemies.
One cant discuss spykoacoustics without knowing of the precedenceeffect, so for all of you who hasnt read about it yet, here is good reading:

”A single reflection arriving within 5 to 30 ms can be up to 10 dB louder than the direct sound without being perceived as a secondary auditory event (echo). This time span varies with the reflection level. If the direct sound is coming from the same direction the listener is facing, the reflection's direction has no significant effect on the results.”

I'm not arguing that we don't perceive one single auditory event, ofcourse we do.

I'm arguing that the impact of the early reflections on that one single auditory event is HUGE.

you can't use the precendence effects to say it doesn't matter where you put your speaker or whether you treat the room or not because that is simply not true. If that is not what you originally intended to imply, then because of the topic of this thread that's what you actually ended up implying.
 

Tangband

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I'm not arguing that we don't perceive one single auditory event, ofcourse we do.

I'm arguing that the impact of the early reflections on that one single auditory event is HUGE.

you can't use the precendence effects to say it doesn't matter where you put your speaker or whether you treat the room or not because that is simply not true. If that is not what you originally intended to imply, then because of the topic of this thread that's what you actually ended up implying.
No, I didnt mean to say that it doesn matter, the placement of your loudspeakers near or away from walls makes a big difference . But after reading about the precedence effect, one also understands that its much easier to have good sound in a big room than in a small room.
The brain cant select the reflective sounds if it arrives within a certain short time-span, making the sound smeared and indistinct instead.
 
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abdo123

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No, I didnt mean to say that it doesn matter, the placement of your loudspeakers near or away from walls makes a big difference . But after reading about the precedence effect, one also understands that its much easier to have good sound in a big room than in a small room.

I mean i would love to build a room with a 10 meter ceiling to avoid the 5-30ms window you mentioned but we have to be realistic here, the only buildings with rooms of such magnitude are concert halls and places of worship.
 

Tangband

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I mean i would love to build a room with a 10 meter ceiling to avoid the 5-30ms window you mentioned but we have to be realistic here, the only buildings with rooms of such magnitude are concert halls and places of worship.
Yes thats true .:)
But in my opinion one can use the reflective walls and use the time-span 20 ms to fill up the flawed stereo system , ofcorse this is a kind of coloration, but Its a very nice one. And one needs a big room to do it.

Edit: 5.1 sound with six recorded channels are much easier to deal with, no need for trix, just have acoustical damping everywhere cause theres no need for helping-reflections.
 

Tangband

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In addition to boundary reinforcement of the longer wavelengths, there is this:

If the off-axis energy bouncing off the side wall has a different spectral balance from the direct sound in the mids and highs - which is virtually always the case - then the stronger that sidewall reflection, the more it will affect the perceived tonal balance. In addition, the wall's surface may be more absorptive at shorter wavelengths than at longer ones, altering the spectral balance of the reflections.

For instance, suppose we have a 6" two-way with a 1" dome tweeter. The dome tweeter's radiation pattern will be very wide in its bottom octave or so, typically the 2.5-5 kHz ballpark. So the stronger that sidewall reflection the more energy we will be getting in the 2.5-5 kHz region, which in turn will skew the perceived tonal balance accordingly.
This is very true.
And combining this with the precedence effect , it makes sence that the distance from loudspeakers to the walls have a very big impact on how we hear the sound. We can somewhat separate the reflective sound from the direct sound if the time difference between them is bigger than about 5 ms ( 1,7 metres of soundtravel ) .

And localization dominance: for delays between 2 and 5 ms, listeners perceive only one sound; but its location is determined by the location of the leading sound.

Putting the loudspeaker really near the wall, the brain will hear only one sound. And wall-reflections between 2- 5 ms from the direct sound in that case, is a bad thing for soundquality, that will make the sound ”flat” and undistict. In this cases, using a deep waveguide or constant directivity horn will make the perceived sound quality much clearer and better.
 
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BrokenEnglishGuy

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Are you sure that's the case for reflections in the 10ms window?

Your information kind of conflicts with everything people experience with small rooms acoustics.
I have a R7 in a 3x3.3 meters ( weird shape not a rectangle, also the ceiling have a angle ) bedroom, they can sound very good without any treatment.., i only Eq the in room bass, 50 cm distance from sidewalls
1,6m triangle.
 
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