Two subwoofers with a single, fixed listening position

[Yorkshire Mouth]

If I’m in a desk set up, where listening will be at the apex of an equilateral triangle (3 x 60° angles), is there any use to having two/multiple subwoofers, or does this just help with multiple seating/listening locations?

 

[sigbergaudio]

If I’m in a desk set up, where listening will be at the apex of an equilateral triangle (3 x 60° angles), is there any use to having two/multiple subwoofers, or does this just help with multiple seating/listening locations?

It helps with a single location as well, if it is needed. You may already have good / even bass response in a single position with just one subwoofer. Only way to know for certain is to measure.

 

[Flaesh]

What kind of room do you have?
Will you use only one sub out?..

 

[Yorkshire Mouth]

What kind of room do you have?
Will you use only one sub out?..

3m x 5m, seating distance c.1.2m, probably only 1 sub out.

 

[anotherhobby]

If I’m in a desk set up, where listening will be at the apex of an equilateral triangle (3 x 60° angles), is there any use to having two/multiple subwoofers, or does this just help with multiple seating/listening locations?

In my office there was a big benefit to 2 subs, with diminishing returns for adding more than that in a single-seat mono bass setup. However, for a stereo sub setup, it took 4 subs for me to get a good response at my single seat (which I vastly prefer).

 

[jaakkopetteri]

It helps with a single location as well, if it is needed. You may already have good / even bass response in a single position with just one subwoofer. Only way to know for certain is to measure.

Define "good". I don't think I've ever seen a single sub response without noticeable nulls

 

[617]

I think the question is how 'fixed' a fixed position is. Realistically your ears are probably moving back and forth a few feet, and side to side a similar amount.

Bass can be equalized to a fixed point, but will exhibit increasing variability with distance from that point.

Anyone with a lot of subs measured want to chime in? I'm curious how far you can move from a measurement position and expect good performance.

 

[Yorkshire Mouth]

Define "good". I don't think I've ever seen a single sub response without noticeable nulls

Right. So a null, by definition, is in a specific place. If you only have one seating position, and you’ve ensured you’ve moved your sub so it’s not in a null…

I’ve spent a few days reading up, watching videos, trying to sort the wheat from the chaff, etc.

And pretty much all the advantages of a second sub appear to…erm…disappear if you’ve placed your sub where it doesn’t create a null or peak at your seating position.

There’s extra volume, but that doesn’t apply to me - I’m not going to get close to maxing out - and this is music, not films.

Less localisation with two subs, but this applies less to 2.1 than 5.1, and less still if your sub is placed centrally, between your mains (where almost all bass is placed in the mix anyway).

I’m posting here as I fear there may be a flaw in my logic, but so far I’ve seen a lot of great science in my reading, and none of it says I need two subs, given my set up.

But obviously, this being ASR, I’m waiting for more science.

 

[Yorkshire Mouth]

I think the question is how 'fixed' a fixed position is. Realistically your ears are probably moving back and forth a few feet, and side to side a similar amount.

Bass can be equalized to a fixed point, but will exhibit increasing variability with distance from that point.

Anyone with a lot of subs measured want to chime in? I'm curious how far you can move from a measurement position and expect good performance.

I’ll let others answer definitely.

But given everything I’ve read, I believe you’ve got a bit of a window, and don’t need your head in a vice.

 

[617]

Generally speaking I think that near field bass is a good option for this use. I believe room effects are diminished the closer you are to the source; obviously headphones don't suffer from these issues even though they radiate into the room in many cases; you also need less output.

The kali behind-the-monitor bass unit is very clever from this perspective.

 

[sigbergaudio]

Define "good". I don't think I've ever seen a single sub response without noticeable nulls

Here is one subwoofer with EQ crossed at 100hz, admittedly there's a dip here at 95hz:

Here is another single subwoofer with automatic EQ (Antimode 8033):

Here are two speakers with no subwoofer at all (no smoothing):

 

[jaakkopetteri]

And pretty much all the advantages of a second sub appear to…erm…disappear if you’ve placed your sub where it doesn’t create a null or peak at your seating position.

Apart from the increased output, sure. But that's a huge assumption you're making. Rooms tend excite so many modes in several ways so that in practice it's very difficult to find a far-field placement that would not benefit from a second sub.

Here is one subwoofer with EQ crossed at 100hz, admittedly there's a dip here at 95hz:
Here is another single subwoofer with automatic EQ (Antimode 8033):
Here are two speakers with no subwoofer at all (no smoothing):

To me these mostly prove my point. Even without the 95Hz dip you have 6dB of variation in the response - quite manageable with EQ, but some of those small dips could be excited way more just a head's (or two heads') width off. I don't really buy into optimizing a single measurement point even if you have a single listening position Would be cool to see some MSO action here, even with a single sub and maybe just delay and a PEQ or two

The two speakers' pic also shows pretty significant dips around 80Hz and 20Hz... I don't doubt those responses sound great IRL, but I would claim adding a sub would still make a significant improvement even if you account for reduced IMD and such

 

[sigbergaudio]

To me these mostly prove my point. Even without the 95Hz dip you have 6dB of variation in the response - quite manageable with EQ, but some of those small dips could be excited way more just a head's (or two heads') width off. I don't really buy into optimizing a single measurement point even if you have a single listening position Would be cool to see some MSO action here, even with a single sub and maybe just delay and a PEQ or two

The two speakers' pic also shows pretty significant dips around 80Hz and 20Hz... I don't doubt those responses sound great IRL, but I would claim adding a sub would still make a significant improvement even if you account for reduced IMD and such

Are you serious?

Graph #1: +/-2.5dB from 20-80hz in-room at the listening position

Graph #2: +/-2.5dB from 20-100hz in-room at the listening position

Graph #3 could also easily have been +/-2.5dB from 25-100hz with a bit of EQ.


I think all of these would be considered "good" by most people, considering that they are not multi-sub setups I would go as far as call them pretty great. And yes they will also sound good.

Don't get me wrong, I recommend at least dual subs (we do sell them after all), but if you can't accept these graphs as proof that it is possible to get good response with only one sub, then you have just made up your mind in advance.

 

[jaakkopetteri]

Graph #1: +/-2.5dB from 20-80hz in-room at the listening position

More like +-3dB, i.e. variation of 6dB

Graph #3 could also easily have been +/-2.5dB from 25-100hz with a bit of EQ.

That's what I said, right? You're conveniently omitting the 20Hz null

but if you can't accept these graphs as proof that it is possible to get good response with only one sub, then you have just made up your mind in advance.

Like I said, I definitely accept those as "good" but not to the extent where I would not consider adding a sub a significant improvement, which was OP's question

 

[sigbergaudio]

More like +-3dB, i.e. variation of 6dB

That's what I said, right? You're conveniently omitting the 20Hz null

Like I said, I definitely accept those as "good" but not to the extent where I would not consider adding a sub a significant improvement, which was OP's question

I am omitting the 20hz null because there isn't a significant null there, the speakers start to roll off at 25hz. The stuff happening below 20hz is measurement noise, not the response of the speakers / room modes.

Beyond that, you are twisting my words. I said "You may already have good / even bass response in a single position with just one subwoofer. Only way to know for certain is to measure."

Then you said you haven't seen that happen, and then I provided evidence of such.

I have never said adding a sub will not be a significant improvement in his case, I said he needed to measure. +/-3dB with small variations like in my examples is a good bass response, and not necessarily a response a typical listener will find to improve significantly with a second sub. He is asking about one or two subs for his desktop setup, he isn't bulding a subwoofer array. The expectations and suggested requirements should match his situation.

 

[olieb]

I think all of these would be considered "good" by most people ...

I would assist that. If this is valid for at least a region of 0,5m^3 for some movement I would be more than happy with this kind of FR in sub bass. Really good for one sub.
Do you have room dimensions and positions of sub and mic for #1 or #2?

 

[sigbergaudio]

I would assist that. If this is valid for at least a region of 0,5m^3 for some movement I would be more than happy with this kind of FR in sub bass. Really good for one sub.
Do you have room dimensions and positions of sub and mic for #1 or #2?

The first one I'm not positive I remember room or position. The second is a front corner placement in a room that's about 20-25m^2 with somewhat low ceiling (around 210cm ceiling).

 

[jaakkopetteri]

I am omitting the 20hz null because there isn't a significant null there, the speakers start to roll off at 25hz. The stuff happening below 20hz is measurement noise, not the response of the speakers / room modes.

I stand corrected, although below 20Hz being noise seems quite convenient again

I have never said adding a sub will not be a significant improvement in his case, I said he needed to measure.

My point is, of course, that having a response even as good as yours is very unlikely. Unless they plan on a measurement mic anyway, they likely should just get a second sub.

+/-3dB with small variations like in my examples is a good bass response, and not necessarily a response a typical listener will find to improve significantly with a second sub.

I disagree, at least with a single measurement point.

He is asking about one or two subs for his desktop setup, he isn't bulding a subwoofer array. The expectations and suggested requirements should match his situation.

I don't understand your point here, I never implied an array

 

[sigbergaudio]

I stand corrected, although below 20Hz being noise seems quite convenient again

My point is, of course, that having a response even as good as yours is very unlikely. Unless they plan on a measurement mic anyway, they likely should just get a second sub.


I disagree, at least with a single measurement point.

I don't understand your point here, I never implied an array

I'm not sure what you mean by convenient. I don't have an agenda to push with regards to people having single subwoofers. Given the fact that we manufacture subwoofers, if anything I should have an agenda to push multiple subwoofers?

The point with the array is that the definition of good is relative to the situation and setup.

 

[olieb]

The first one I'm not positive I remember room or position. The second is a front corner placement in a room that's about 20-25m^2 with somewhat low ceiling (around 210cm ceiling).

I tried to simulate that. This is the best I could come up with in 4 x 5m and a reasonable listening position.
I assume this could be EQed to nearly flat, as there are no nulls below 160 Hz?

But this example also shows the limits of a single sub, if one switches on the results for positions around the point measurement from above.
Now there are differences of up to 12 dB from positions half a meter apart.
That puts things into perspective a bit (as I grew quite envious already ;-)