Near Field and Subwoofers

[Yorkshire Mouth]

So the idea of near field listening is that, with traditional seating distances, you’re listening to a combination of the speaker and the room. But the closer you sit to the speaker, you’re changing the balance - effectively making the speaker louder and the room quieter. The knock-on effect is clearly that your room won’t matter (at least not as much), and so you don’t need to worry as much about acoustic treatment, etc.

Okay, I’ve got that.

But what about subwoofers, non-directional, and possibly under a desk? Do they follow the same rules? If you sit closer to your sub do you hear more of the sub and less of the room, with the sub contributing more and the room less?

Or do subs effectively not count? Can you ‘ignore the room’ from your main speakers, but have to treat the subs no differently to if you weren’t sat do close.

I’ve used the inevitable level of imposed ‘internet shorthand’ there.

 

[NTK]

Near-field sub is the strategy Dr. Toole is going to employ when he moves into his new condo.

Yes, there is a substantial efficiency gain when using multiple subs. Many people end up with more sound power than they actually need. I'll take four modest subs over the single most grandiose sub any day. In addition, there are some clever compact designs out there using vibration cancelling designs - good for those in multiple dwellings, as I will be sometime next year. Paradigm is one, and Sonos another - there may be more. In my case, moving into a "luxury condominium" my scaled down media room and limited maximum sound level (a good neighbor policy) should be well served by four such loudspeakers. I will be employing a trick I learned many years ago - near-field subwoofing - place the subs close to the listeners. That will let us hear decent bass quality and levels with less energizing of the entire room. The mechanical vibration cancellation won't hurt sound transmission to adjacent properties - floors are notoriously difficult to isolate without access to the floor below.

I am willingly downsizing and changing my life style - at age 84 it seems reasonable - but there are many, many people who have no choice. Methinks there is a product category that needs more attention.

Meanwhile, while I am still in my detached home with my 7.4.6 system I am enjoying last flings with a 10 ft screen and my four not-large 12-inch closed box subs that can lift me out of my seat.

 

[Yorkshire Mouth]

Cheers, that sounds good.

 

[Berwhale]

But what about subwoofers, non-directional, and possibly under a desk? Do they follow the same rules? If you sit closer to your sub do you hear more of the sub and less of the room, with the sub contributing more and the room less?

My sub sits under my desk on a solid bamboo floor (with a concrete subfloor). The desk is made from 40mm solid beach worktop and my PC is suspended under the desk, above the sub. The sub is also next to the sidewall. I'm guessing that this isn't optimal, but I don't have much choice given the current configuration of my study.

I set the levels on the sub using a UMIK-1 and REW (at the same position as I measure my MTMs for EQ), but I found the sub too loud so I have it turned down a bit (maybe 5dB).

I'd be interested some technical opinions on sub placement under a desk; most, if not all of the advice i've seen relates to subs in far field listening setups.

 

[Yorkshire Mouth]

Yes, and while we’re here…

A front-ported, down-firing sub. Obviously the port can’t go right up to a wall. But how about at 90° (port facing left or right)?

 

[test1223]

So the idea of near field listening is that, with traditional seating distances, you’re listening to a combination of the speaker and the room. But the closer you sit to the speaker, you’re changing the balance - effectively making the speaker louder and the room quieter. The knock-on effect is clearly that your room won’t matter (at least not as much), and so you don’t need to worry as much about acoustic treatment, etc.

Okay, I’ve got that.

But what about subwoofers, non-directional, and possibly under a desk? Do they follow the same rules? If you sit closer to your sub do you hear more of the sub and less of the room, with the sub contributing more and the room less?

Or do subs effectively not count? Can you ‘ignore the room’ from your main speakers, but have to treat the subs no differently to if you weren’t sat do close.

I’ve used the inevitable level of imposed ‘internet shorthand’ there.

With a subwoofer in the near field you have to be aware that you are being able to localize the position of the subwoofer due to the tactile sensation of the bass frequencies and if the subwoofer is only left or only right due to inter ear level differences. The common "knowledge" that you can't localize the position of a subwoofer is only true for specific situations.

 

[MattHooper]

With a subwoofer in the near field you have to be aware that you are being able to localize the position of the subwoofer due to the tactile sensation of the bass frequencies and if the subwoofer is only left or only right due to inter ear level differences. The common "knowledge" that you can't localize the position of a subwoofer is only true for specific situations.

I tried a sub behind my listening sofa and it integrated surprisingly well. I couldn’t locate it as behind me. If I use a sub again someday it will likely go in the same location, and for one of the reasons cited by Floyd Toole: our bedroom is above my listening room and sometimes my wife is sleeping when I’m listening. A closely placed sub will mean it’s not as loud and that much less likely to disturb her.

 

[test1223]

I tried a sub behind my listening sofa and it integrated surprisingly well. I couldn’t locate it as behind me. If I use a sub again someday it will likely go in the same location, and for one of the reasons cited by Floyd Toole: our bedroom is above my listening room and sometimes my wife is sleeping when I’m listening. A closely placed sub will mean it’s not as loud and that much less likely to disturb her.

If the sofa blocks the direct path you usually don't feel the direction of the impact of the subwoofer.

I have had a subwoofer under my desk and I could feel the bass with my legs and feet. There are several different factors like the distance and if you have a bass reflex port pointing at a body part or the spl level.

I did some simple experiments later by walking and sitting next to a subwoofer and trying to figure out what distance is okay. Everyone can simply try such things out.

 

[Berwhale]

My Sub8 and MTMs power is switched from the same IR controlled outlet, however the MTMs take a few seconds longer to produce any sound (i'm guessing because of the DSP starting up). Occasionally I have something playing before powering them on, so I hear only the sub for a few seconds. Perceptually, it seems like the sub is playing from a little beneath my monitor, but it is central, not to the left where the sub is. This means that I haven't felt the need to tinker with the sub location.

 

[dasdoing]

I tried sub right behind sofa and it was anoying. the FR is great, and you don't have to turn it up much, but it will make the sofa vibrate, which might sound positive, and at first it is great, but will get anoying pretty fast. it's just too much

 

[digitalfrost]

I've been listening in the near field for years and I have been using subwoofers for most of the time. My personal experience is, all that talk about how you cannot locate where sounds under 80hz are coming from are just not true.

I still use subs, but I have them on the desk next to the speakers. I've had subwoofers off to the side, like 90° to the seating position, that was a catastrophe and even a subwoofer under the desk you will notice.

If you do this in the nearfield, get the subs as close as possible to the satellites and also make sure you use 24db/oct filters or better, because otherwise you will notice that the sub is playing.

 

[dasdoing]

all that talk about how you cannot locate where sounds under 80hz are coming from are just not true.

I agree, it is not even logic.
I have a single sub and place it right in the middle between the two mains. unless we are talking about pure sine waves, panned bass will still sound like coming from the mains because of Haas Effect. and most bass is mono-ish anyways.

 

[dasdoing]

sub behind sofa didn't sound like bass from behind though. lateral displacement seams to be more audible, especially if it builds up energy in a single corner

 

[test1223]

I've been listening in the near field for years and I have been using subwoofers for most of the time. My personal experience is, all that talk about how you cannot locate where sounds under 80hz are coming from are just not true.

I still use subs, but I have them on the desk next to the speakers. I've had subwoofers off to the side, like 90° to the seating position, that was a catastrophe and even a subwoofer under the desk you will notice.

If you do this in the nearfield, get the subs as close as possible to the satellites and also make sure you use 24db/oct filters or better, because otherwise you will notice that the sub is playing.

If I remember correctly the work of David Griesinger and others showed that you need stereo subwoofers and that the location of subwoofer needs to be close to the position of the speaker. Otherwise the stereo image is not as good as it could be at least for good recordings. The issues are phase differences in stereo subbass which contain room cues of the recording room.

 

[jaakkopetteri]

I had my second sub right between my sofa and the wall behind it for a while. It worked pretty well other than the bass response varying quite a lot depending on how you sit, despite optimizing things with MSO. Smooth response, but exaggerated when closer to the sub.

 

[jhaider]

Have you tri

My personal experience is, all that talk about how you cannot locate where sounds under 80hz are coming from are just not true.

That’s possible, but unless the subs are terrible what you’re hearing is probably re-radiation from something excited by the sub.

As for whether nearfield gets closer to, as the late Peter W. Mitchell wrote in Audio (US) decades ago, hearing the natural rolloff of the speakers and not the room, I don’t think that’s the case. I use three tiny subs (all Sonance D8) in a desktop/nearfield system under KH 80 DSP. Crossover, IIRC, is 100 Hz, 5th other BW (I was persuaded by Andrew Jones to try such filters.) Here is the response of each one, with no EQ. Ignore absolute SPL - subs 1 and 3 have been offset for clarity. Each measurement is a 4-point spatial average with the microphones covering 18" vertically and 12" horizontally. That probably wasn't necessary, but I was also practicing using REW Pro with 4 microphones, including all of the level calibrations for each mic. For reference, the three sub positions are:

Sub 1: centered between mains, directly in front of listener, behind monitor. Distance from nose ~30" with desk adjusted to either seated or standing height

Sub 2: about 8" outside side the left speaker. Distance from nose ~40" with desk adjusted to either seated or standing height

Sub 3: behind and on the right, about 4' off the floor. Distance from nose ~42" desk in seated height , 50" in standing height

As you can see, despite the close distances the response of each one shows significant room effects. Further, change in listening position from seated to standing height results in major differences around the crossover region, showing a need for separate calibrations for seated and standing height if you have a sit-stand desk.

 

[Yorkshire Mouth]

Thanks very much for the contributions.

I’d like to note this, though.

A lot of comments are about directionality. I don’t dispute those one way or the other.

But I’m not convinced they have anything to do with the question I posed. For clarity: I can imagine a scenario where directionality mattered, but the room didn't, and I can imagine a scenario where directionality wasn’t an issue, but the room did. Or vice versa for each.

What I’m asking is, is there are correlation between directionality/listening distance (specifically near field) and the effect of the room, outside of directionality.

 

[test1223]

Thanks very much for the contributions.

I’d like to note this, though.

A lot of comments are about directionality. I don’t dispute those one way or the other.

But I’m not convinced they have anything to do with the question I posed. For clarity: I can imagine a scenario where directionality mattered, but the room didn't, and I can imagine a scenario where directionality wasn’t an issue, but the room did. Or vice versa for each.

What I’m asking is, is there are correlation between directionality/listening distance (specifically near field) and the effect of the room, outside of directionality.

Directionality and the resulting (stereo) image are connected.

Envelopment is an issues with near field listening in particular. Stereo and multi channel need some room reflections to get the feeling to be surrounded by the sound called envelopment and with standard near field speaker it is next to impossible to get. More omnidirectional speaker in the middle of a room can achieve this.

You might like to read the discussion about the perfect room speaker combination https://www.audiosciencereview.com/...nt-wide-vs-narrow-directivity-and-more.15171/
There are some very interesting insides.

In the last post here I mentioned the need of two subwoofer which should be next to the stereo speakers. This preservers better envelopment.

Head movements in the nearfield are more a concern due to the bigger relative movement to the speakers.

There are plenty other advantages and disadvantages...

 

[Yorkshire Mouth]

Superb and knowledgable answers here. Many thanks for the contributions.

Okay, two things.

Firstly, if I have two subs, one for each monitor, and placed near them, should that solve directionality issues?

Secondly, I feel the discussion about directionality - important though it is - has detracted from the main question.

Forget directionality for a second. If a sub is close to your listening position, does that remove or reduce the impact of the room in what you hear, in the same way that having monitors in near field does?

 

[Yorkshire Mouth]

I have no idea whether this will be helpful to you.

I listen in the nearfield, or as Sarumbear likes to call it, the closefield. I experimented with an old 12' sub. I found out that I had trouble, in that the "normal" recommendations weren't specific enough. In short, I found that there are factors affecting that "80 Hz" standard.

1) There can be a huge (audible) difference between 12 dB/octave, 24 dB/octave and (if necessary) 48 dB/octave crossover slopes, due to differences in drive response.
2) If a sub has a sharply rising response one octave above the cutoff frequency, it will be able to be localized. That's where the steeper crossover slopes come in handy.
3) Some crossovers marked "80 Hz" are in reality far higher in frequency. I remember one that was marked at 80 Hz and actually crossed at 120 Hz.
4) Wall/floor intersections serve to increase the SPL of the bass pressure wave, increasing its efficiency. But they also increase the SPL of frequencies an octave higher in the spectrum. That can have a severe effect on directionality, especially if the listening distance is low.

At listening distances under 6 feet, I (myself) have never heard a well-designed sub that was crossed over at 80 cycles (checked by measurement) at 24 dB/octave or steeper that could be localized. And by "well-designed", I mean a sub that doesn't have a radical peak in response just above the crossover frequency.

Jim

The monitor/sub combination I’m looking at is the JBL 308p Mk.IIs and 310s. The sub was designed specifically for use with these monitors, and has an 80hz crossover setting, again recommended and designed for this combination.

Given JBL’s pedigree, and the fact that the monitors (and subsequently the sub) are designed for near field listening, I’d hope they had the crossover perfect.