Stereo Sub Vs Dual Mono

[audiofooled]

This track has hard panned effects that contain some lower frequencies. It is made for headphones but on a stereo system lower frequency cues should track nicely and present depth information in front and behind the speakers:

 

[goat76]

I have created one more sound file for you guys to try out, but this time it's the same signal throughout the whole track, so you must do the necessary changes in the setup of your subwoofers when you do the comparisons.

1. First I like you to listen to the track with your subwoofers set up in a stereo configuration. I like you to concentrate on how you perceive the envelopment of the sound, not necessarily on any directional cues, just how you hear the spatiality of the sound and if you think it surrounds you in the room, or if you perceive it just as a "wall of sounds" from the front of the room where the main speakers and subwoofers are located.
2. Now I like you to turn off your subwoofers but keep any high-pass filter on for your main speakers if you normally use that in your system, but if you do not usually have any high-pass filter applied to your front speakers you can just let them play however deep they go on their own. Listen to the track, do you perceive the same envelopment and spatiality of the sound now when you have turned off your subwoofers (set up in a stereo configuration)?
3. Now you can turn on the subwoofers and listen to the track again. Does this bring back a greater spatial sensation or no change at all?
4. Now I like you to change the configuration of all your subwoofers from stereo to mono. Do you perceive the same spatial sensation and the envelopment of the sound, or do you now perceive it more as a "wall of sounds" from the front of the room where the main speakers and subwoofers are located?
5. You can repeat everything how many times you like until you are sure about the differences you hear.

Dropbox - File Deleted - Simplify your life

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Information about the sound file:

• It's the same pink noise sound as in the previous test, but now it's the same signal throughout the whole track.
• The sound file has a Low-Pass filter at 80 Hz with a roll-off slope of 24 dB/octave. This is probably the most common crossover setting for subwoofers which most people use in their sound systems.
• The left channel is delayed by 35 ms (about the wavelength of 30 Hz) and attenuated by 3 dB to simulate that the bass sound originates from a position to the right side field to simulate a stereo signal (to apply at least some necessary differences to make it simulate a "stereo" signal). This is of course not a perfect simulation as these two mono sounds (which they truly are at their core) share too many similarities, which most probably reduces the sensation of spatiality sensations to what would otherwise be perceived if the track was from a true/real stereo recording (which would include a lot more parameters that differentiate the signals coming from the right respective the left channel).
• And one more thing! If you don't find the Low-Pass filter at 80 Hz with a roll-off slope of 24 dB/octaves representative of your subwoofers crossover settings, you can always apply a different Low-Pass filter of your choice to the file (as long as you don't have your crossover at a higher frequency point than 80 Hz).

(As can be seen in the picture, there are not enough differences between the left and the right channel, a real stereo recording will therefore most probably give us greater spatial differences. Do any of you have a recording like that, that we can use?)

And this is what I hear/perceive from this listening test:

1. When listening to the track with my subwoofers ON, I perceive the sound as having envelopment and spatiality that surrounds me without any sense of a sound coming from a specific direction in the room.
2. When turning OFF the subwoofers the spatiality of the sound is reduced compared to having the subwoofers on. The spatiality doesn't "die off" completely but is severely reduced when the sound no longer reaches as low in the bass.
3. Turning ON the subwoofers again gives me back the more enveloping sensation of the sound in the room.
4. This is what you with a regular Low-Pass/High-Pass crossover system can try, I can't do this because of how my subwoofers are connected and configurated. Can your main left and right speaker maintain the spatiality sensation in the bass region even though the subwoofers are summed to mono?

So, the main two questions I'm asking you are the following:

1. Are your main Left and Right speaker able to provide enough low-end information from 80 Hz and down, with or without the high-pass filter you have set for them, and still maintain the sensation of spatiality and envelopment that your subwoofers set up in stereo provide?

2. If you find that your main Left and Right speaker can indeed provide you with enough energy in that frequency range at 80 Hz and below, do you find that that energy is enough to dominate the sensation factor even when your subwoofers are at play and are set up in mono?

 

[sarumbear]

Some other member has a question as to how spatial sensation can be measured, and I provided an answer. You have a problem with that?

But there is no explanation on the paper on how it is measured. A possible method is suggested that may be used to measure the new metric (DFT) the author invented but the measuring it was not explained on the paper. He only explained the calculations. Here is the quote from the paper.

The design of this detector is beyond the scope of this paper. Persons interested in its design, or in the Matlab code for the whole DFT measurement apparatus, should contact the author.

 

[NTK]

But there is no explanation on the paper on how it is measured. A possible method is suggested that may be used to measure the new metric (DFT) the author invented but the measuring it was not explained on the paper. He only explained the calculations. Here is the quote from the paper.

I see no upside for me to waste my time arguing with you. You can contact the mods and have them remove my posts if you feel they are not up to the scientific rigor of this internet forum.

 

[anotherhobby]

My mind has been coming back to this thread some recently, because I've set up a small display with two spectrum audio visualizers using cava. The display requires a little explanation with a photo so you'll know what you are seeing in the video below it.

The screen has a top spectrum and a bottom one, and both are in stereo.

• The top visualizer is full spectrum, with 20 Hz being the center of the display for both the right and left side, and then extending to 20 kHz at the outside edges.
• The bottom visualizer works the same, except the center is only 10 Hz and the outsize is only 80 Hz. I love this because it gives me a stereo view of my subs.

With that explained, let's see what stereo bass looks like. Since I can swap between stereo and mono subs at the flip of a switch, and I can also see what's happening in real-time, the A/B testing has been very interesting. I am aware that this is the polar opposite of blind testing.

This is 10s clip from the track Timbres off Yosi Horikawa's Spaces album (about 40s in). What you'll see below is a sub bass musical event that starts somewhere around 20-30 Hz in the left channel, sweeps up to about 80 Hz, then passes over to the right channel to fall back down to the 20-30 Hz region.

This is very audible to me between mono/stereo bass, with the stereo being more enjoyable. One of the interesting things I keep hearing and reading from people with mono bass setups is something to the effect of "most bass is mixed down to mono anyway." I've been watching these dancing bars for days now, and I have to say, most of what I listen to so far is nearly all stereo bass. There are obviously exceptions, but most of it is full stereo all the way down. I'm guessing most people don't know at all if what they listen to has stereo bass and are just dismissing it in a way that makes them feel okay.

The display has let me very quickly identify stereo bass visually, and A/B testing constantly confirmed audibility to me on my system, and the stereo bass always sounds better. This has been a fun little road for me to go down, and I'm very happy with my setup. I'm going to nuke the mono bass configuration off my miniDSP because I have yet to find a single circumstance where it sounds better, let alone as good as the stereo setup.

 

[goat76]

My mind has been coming back to this thread some recently, because I've set up a small display with two spectrum audio visualizers using cava. The display requires a little explanation with a photo so you'll know what you are seeing in the video below it.

The screen has a top spectrum and a bottom one, and both are in stereo.

• The top visualizer is full spectrum, with 20 Hz being the center of the display for both the right and left side, and then extending to 20 kHz at the outside edges.
• The bottom visualizer works the same, except the center is only 10 Hz and the outsize is only 80 Hz. I love this because it gives me a stereo view of my subs.

View attachment 282842

With that explained, let's see what stereo bass looks like. Since I can swap between stereo and mono subs at the flip of a switch, and I can also see what's happening in real-time, the A/B testing has been very interesting. I am aware that this is the polar opposite of blind testing.

This is 10s clip from the track Timbres off Yosi Horikawa's Spaces album (about 40s in). What you'll see below is a sub bass musical event that starts somewhere around 20-30 Hz in the left channel, sweeps up to about 80 Hz, then passes over to the right channel to fall back down to the 20-30 Hz region.

This is very audible to me between mono/stereo bass, with the stereo being more enjoyable. One of the interesting things I keep hearing and reading from people with mono bass setups is something to the effect of "most bass is mixed down to mono anyway." I've been watching these dancing bars for days now, and I have to say, most of what I listen to so far is nearly all stereo bass. There are obviously exceptions, but most of it is full stereo all the way down.

The display has let me very quickly identify stereo bass visually, and A/B testing constantly confirmed audibility to me on my system, and the stereo bass always sounds better. This has been a fun little road for me to go down, and I'm very happy with my setup. I'm going to nuke the mono bass configuration off my miniDSP because I have yet to find a single circumstance where it sounds better, let alone as good as the stereo setup.

And as I mentioned earlier in the thread, in cases when the bass is truly mixed down to mono, there's really no "downgrade" in having the subwoofers set up in stereo, they will just receive the exact same signal anyway in the same way as if they where set up in mono.

So with the subwoofers set up in stereo, you both get the true effects of stereo bass if the recording contains such information. And if not, you still get the same mono signal to both subwoofers if the bass in the recording is summed to mono, or if the bassy content is right down in the middle of the music mix.

 

[Deleted member 48726]

My mind has been coming back to this thread some recently, because I've set up a small display with two spectrum audio visualizers using cava. The display requires a little explanation with a photo so you'll know what you are seeing in the video below it.

The screen has a top spectrum and a bottom one, and both are in stereo.

• The top visualizer is full spectrum, with 20 Hz being the center of the display for both the right and left side, and then extending to 20 kHz at the outside edges.
• The bottom visualizer works the same, except the center is only 10 Hz and the outsize is only 80 Hz. I love this because it gives me a stereo view of my subs.

View attachment 282842

With that explained, let's see what stereo bass looks like. Since I can swap between stereo and mono subs at the flip of a switch, and I can also see what's happening in real-time, the A/B testing has been very interesting. I am aware that this is the polar opposite of blind testing.

This is 10s clip from the track Timbres off Yosi Horikawa's Spaces album (about 40s in). What you'll see below is a sub bass musical event that starts somewhere around 20-30 Hz in the left channel, sweeps up to about 80 Hz, then passes over to the right channel to fall back down to the 20-30 Hz region.

This is very audible to me between mono/stereo bass, with the stereo being more enjoyable. One of the interesting things I keep hearing and reading from people with mono bass setups is something to the effect of "most bass is mixed down to mono anyway." I've been watching these dancing bars for days now, and I have to say, most of what I listen to so far is nearly all stereo bass. There are obviously exceptions, but most of it is full stereo all the way down. I'm guessing most people don't know at all if what they listen to has stereo bass and are just dismissing it in a way that makes them feel okay.

The display has let me very quickly identify stereo bass visually, and A/B testing constantly confirmed audibility to me on my system, and the stereo bass always sounds better. This has been a fun little road for me to go down, and I'm very happy with my setup. I'm going to nuke the mono bass configuration off my miniDSP because I have yet to find a single circumstance where it sounds better, let alone as good as the stereo setup.

People are quick to adopt oppinions of others even without experience. This is a great experiment and a nice nerdy setup. I would like that in my system but know any thing like that will make me more focused on the visualization than the music.

 

[Chr1]

I am very doubtful that much music these days has the bass downmixed to mono...

Well, music made this century, anyway.

 

[sigbergaudio]

@anotherhobby Cool experiment! Depending on your viewpoint, this could however lead one to the opposite conclusion. One of the arguments for mono bass is to get a more even frequency response in the bass by utilizing dual sources of the bass (reducing the effect of room modes).

If your conclusion is that a lot of your music contain stereo bass, this would be an argument FOR dual mono based on your findings.

The theory is that you would still perceive the stereo bass effects in a blind test due to audio cues from higher frequency elements (fundamentals or harmonics) of the same instrument, and/or low end bleeding into the speakers (as their high pass filter is typically not a brick wall filter).

TL;DR:
If your music contains lots of stereo bass, you should run them in dual mono for the most even bass reproduction. You will still be able to enjoy a perception of stereo bass.

 

[Birdy]

@anotherhobby Cool experiment! Depending on your viewpoint, this could however lead one to the opposite conclusion. One of the arguments for mono bass is to get a more even frequency response in the bass by utilizing dual sources of the bass (reducing the effect of room modes).

If your conclusion is that a lot of your music contain stereo bass, this would be an argument FOR dual mono based on your findings.

The theory is that you would still perceive the stereo bass effects in a blind test due to audio cues from higher frequency elements (fundamentals or harmonics) of the same instrument, and/or low end bleeding into the speakers (as their high pass filter is typically not a brick wall filter).

TL;DR:
If your music contains lots of stereo bass, you should run them in dual mono for the most even bass reproduction. You will still be able to enjoy a perception of stereo bass.

If i run my sub woofer under 40 Hz, not considering room nodes, would stereo or mono make a difference? The bass from my main speakers will go down to about 35 Hz.

 

[goat76]

@anotherhobby Cool experiment! Depending on your viewpoint, this could however lead one to the opposite conclusion. One of the arguments for mono bass is to get a more even frequency response in the bass by utilizing dual sources of the bass (reducing the effect of room modes).

If your conclusion is that a lot of your music contain stereo bass, this would be an argument FOR dual mono based on your findings.

The theory is that you would still perceive the stereo bass effects in a blind test due to audio cues from higher frequency elements (fundamentals or harmonics) of the same instrument, and/or low end bleeding into the speakers (as their high pass filter is typically not a brick wall filter).

TL;DR:
If your music contains lots of stereo bass, you should run them in dual mono for the most even bass reproduction. You will still be able to enjoy a perception of stereo bass.

I'm sorry but you still not getting it.

If you read David Griesinger's papers that was posted earlier in the thread, you will realize that stereo bass got very little to do with pinpointing the direction of the lowest bass, those directional cues will (as you point out) come with the higher frequencies.

What stereo bass will bring to the party is envelopment to the sound, thanks to phase differences. Envelopment is something that will give you a feeling of being surrounded by the sound, it’s more a diffuse sound that doesn’t have a any obvious directional information in it.

Please read the papers Griesinger have written about envelopment, and the importance of bass frequencies for this sensation to occur.

 

[sigbergaudio]

If i run my sub woofer under 40 Hz, not considering room nodes, would stereo or mono make a difference? The bass from my main speakers will go down to about 35 Hz.

No.

 

[audiofooled]

What stereo bass will bring to the party is envelopment to the sound, thanks to phase differences. Envelopment is something that will give you a feeling of being surrounded by the sound, it’s more a diffuse sound that doesn’t have a any obvious directional information in it.

That is my observation as well. My mains are -3db at 35Hz and for most music and normal listening levels they are sufficient in extension, also this cool effect of stereo bass on some recordings is quite enveloping. However, without the sub, it's the mono bass that has an uneven response at MLP because of room modes and it's mostly detrimental to the transients. Not so much of an audible difference but particularly the tactile feel is quite different with sub, which I tried to somehow measure and explain it this other thread:

Big subs vs Small subs

I now show how the port output contributes to the total output here: https://www.kvalsvoll.com/blog/forum/topic/t6-a-t6-compact-horn-subwoofer/#postid-495 This is how it works: References to another manufacturers product were mentioned, I found the product page, looking for specifications...

audiosciencereview.com

IMHO, stereo bass is nice to have but it's mono that first has to be done right.

 

[sigbergaudio]

I'm sorry but you still not getting it.

If you read David Griesinger's papers that was posted earlier in the thread, you will realize that stereo bass got very little to do with pinpointing the direction of the lowest bass, those directional cues will (as you point out) come with the higher frequencies.

What stereo bass will bring to the party is envelopment to the sound, thanks to phase differences. Envelopment is something that will give you a feeling of being surrounded by the sound, it’s more a diffuse sound that doesn’t have a any obvious directional information in it.

Please read the papers Griesinger have written about envelopment, and the importance of bass frequencies for this sensation to occur.

We've discussed this at length already. I couldn't find a free link to those papers, does one exist?

I've done pretty extensive tests on this and the effect of spatial sensation is perfectly possible with dual mono subs crossed over as high as 100hz. I'm not convinced there's a perceptible change to this effect when switching between stereo and dual mono, I certainly can't reliably detect one. I'm not denying that there can be some recordings where some people may be able to detect differences here, but I'm confident it is not significant for the majority of people and setups.

Note again (as I've mentioned before), I'm talking about dual mono setups (typically set up as you would a couple of stereo subs), not single subwoofer setups or setups with one subwoofer in a corner and the other one behind you or something.

 

[anotherhobby]

@anotherhobby Cool experiment! Depending on your viewpoint, this could however lead one to the opposite conclusion. One of the arguments for mono bass is to get a more even frequency response in the bass by utilizing dual sources of the bass (reducing the effect of room modes).

If your conclusion is that a lot of your music contain stereo bass, this would be an argument FOR dual mono based on your findings.

The theory is that you would still perceive the stereo bass effects in a blind test due to audio cues from higher frequency elements (fundamentals or harmonics) of the same instrument, and/or low end bleeding into the speakers (as their high pass filter is typically not a brick wall filter).

TL;DR:
If your music contains lots of stereo bass, you should run them in dual mono for the most even bass reproduction. You will still be able to enjoy a perception of stereo bass.

Nope, you are wrong in this instance. My channels have no uneven parts of response and already use dual bass sources with four subs, so your comment toward me is just flat out wrong and misleading to say. I’ve posed graphs and everything else in this thread, yet you keep saying this. I know you are smarter and better than just arguing points that have already been answered and are clearly wrong. I even defended you as a good faith contributor, but this response is really starting to make me question that.

 

[anotherhobby]

I've done pretty extensive tests on this and the effect of spatial sensation is perfectly possible with dual mono subs crossed over as high as 100hz. I'm not convinced there's a perceptible change to this effect when switching between stereo and dual mono, I certainly can't reliably detect one. I'm not denying that there can be some recordings where some people may be able to detect differences here, but I'm confident it is not significant for the majority of people and setups.

I think all we can conclude here is that you don't hear or perceive stereo bass. That doesn't make it not a thing.

 

[dedobot]

I am very doubtful that much music these days has the bass downmixed to mono...

Well, music made this century, anyway.

Exactly. I can't think of electronic music artist who will constraint himself to mono LF.

 

[goat76]

We've discussed this at length already. I couldn't find a free link to those papers, does one exist?

I've done pretty extensive tests on this and the effect of spatial sensation is perfectly possible with dual mono subs crossed over as high as 100hz. I'm not convinced there's a perceptible change to this effect when switching between stereo and dual mono, I certainly can't reliably detect one. I'm not denying that there can be some recordings where some people may be able to detect differences here, but I'm confident it is not significant for the majority of people and setups.

Note again (as I've mentioned before), I'm talking about dual mono setups (typically set up as you would a couple of stereo subs), not single subwoofer setups or setups with one subwoofer in a corner and the other one behind you or something.

Already in my first post at the first page in this very thread, I linked to the pdf where you can read the report by David Griesinger.

Here you have it:

Loudspeaker and listener positions for optimal low-frequency spatial reproduction in listening rooms. http://www.davidgriesinger.com/asa05.pdf

 

[FrankW]

At some point one must concede that when someone repeatedly indicates in their posts that they are incapable of discerning between localization an lateralisation, these arguments will go no where. Add to that their "personal experience" ad hoc "tests" supersede AES papers and perceptual researchers.
Personal preferences vary too.

 

[sigbergaudio]

Nope, you are wrong in this instance. My channels have no uneven parts of response and already use dual bass sources with four subs, so your comment toward me is just flat out wrong and misleading to say. I’ve posed graphs and everything else in this thread, yet you keep saying this. I know you are smarter and better than just arguing points that have already been answered and are clearly wrong. I even defended you as a good faith contributor, but this response is really starting to make me question that.

If you have fairly flat response within the frequency range of your subwoofers for both channels when playing individually, this will of course not apply to you (not so common, so you are lucky). Then all you lose out on is capacity (one subwoofer playing as opposed to two).