When not to corner or wall load

[gdougherty]

Just had a thought late at night. So often we drool over corner and wall loading the subs dreaming about the increased output. However, wall loading adds 6db and corner loading adds 12db. The inverse square rule says though that sound drops off by 6db for every doubling of distance. That'd be starting from the 1m base measurement, so by 2m (~6ft) you've lost all benefit to wall loading and by 4m (~12ft) you've lost all benefit to corner loading. So, when not to wall or corner load? When the distance from where you'd otherwise put them is longer than the benefit you'd gain from the boundary.

As an example. If I can center cluster my subs and put them right on the edge of a dance floor or next to an audience then a wall would need to be within 6ft of that spot, or a corner would need to be within 12ft. Of course, don't forget the placement guidelines of less than 2ft or greater than 8ft from a boundary. You'd still have better sound wall-loading than putting them 6ft-8ft from a wall.

It occurs to me that this might be part of the reason why putting the subs right next to the dance floor worked better than wall/corner loading for wiisounds on his first THT outing.

[Bill Fitzmaurice]

Just had a thought late at night. So often we drool over corner and wall loading the subs dreaming about the increased output. However, wall loading adds 6db and corner loading adds 12db. The inverse square rule says though that sound drops off by 6db for every doubling of distance. That'd be starting from the 1m base measurement, so by 2m (~6ft) you've lost all benefit to wall loading and by 4m (~12ft) you've lost all benefit to corner loading.

-1. If you start off at +12dB at 1m compared to half-space you remain +12dB compared to half space no matter how far out you go.

It occurs to me that this might be part of the reason why putting the subs right next to the dance floor worked better than wall/corner loading for wiisounds on his first THT outing.

The 'corner' in that case was too small to load, as noted in the thread.

[Tim A]

At first what gdougherty said made sense, then what Bill said made sense.

I wanted to 'see it with my own eyes', so I drew it out. I kept it very simple, two subs, both 100dB on their own. One is corner loaded 4 meters away and one is at the edge of the dance floor.

By the time Sub 1 made it to Sub 2's location it was a dead heat, but the magic happens after that. Since there is a 6dB drop for every doubling of distance, Sub 1 has the clear advantage in this particular circumstance.

Seeing it drawn out made it very easy for me to grasp, I thought maybe someone else could benefit.

I think I did this correctly, if not let me know and I'll remove it.

[SoundInMotionDJ]

If you start off at +12dB at 1m compared to half-space you remain +12dB compared to half space no matter how far out you go.

To add a few more words and another picture.

Remember that SPL falls by 6dB per doubling of the distance. In this case, both cabinets are producing 100dB @ 1m. The corner loaded cabinet is placed @ 0m, and gains +12dB. The free standing cabinet is placed at the 3m mark. The distance is measured from the corner.



--Stan Graves

[Strapping Young Stu]

Silly question here, but does corner loading boost frequency response at all frequencies?

My experience of putting bass cabs into corners is that it really helps the extension but to some extent choked the kick range somewhat - this looks like it happens with V-coupling as well.

From a corner loading perspective in particular might it have been the distance I had the cab placed from the corner that was affecting the sound, or is it just a trade off between kick and sub that the corner loading gives?

Stu

[dbaldock]

Silly question here, but does corner loading boost frequency response at all frequencies?

My experience of putting bass cabs into corners is that it really helps the extension but to some extent choked the kick range somewhat - this looks like it happens with V-coupling as well.

From a corner loading perspective in particular might it have been the distance I had the cab placed from the corner that was affecting the sound, or is it just a trade off between kick and sub that the corner loading gives?

Stu

You may have excited room modes that are in the kick range.

[Sydney]

room modes

This may be theoretical simulation of the TT presuming long ( over 56' ) uninterrupted flat planes.
The SPL graphs ( showing the loading differences ) posted in the original AudioXpress articles on the T24 and T18, look to be actual measurements.
As such they are NOT neatly separated by 6db at all frequencies.
This probably shows the interaction of the room in which the measurements were taken - reflecting the modes and nodes of that particular room.

[gdougherty]

Thanks for the corrections. Tim, the diagram was very helpful. So if anything the corner or wall loading helps provide more even coverage over a larger swath of the audience area since the doubling distances are growing larger and larger.

[Tim A]

As such they are NOT neatly separated by 6db at all frequencies.

I think we need to view boundary loading gain as a rule of thumb. Room nodes, etc will play a role. I didn't take the time to average those charts, but I'd expect it to be pretty close.

So if anything the corner or wall loading helps provide more even coverage over a larger swath of the audience area since the doubling distances are growing larger and larger.

Not sure what you mean by 'swath'? The curved lines in my sletch are there just to show distance. Bass in non-directional, so I'm not sure there's an advantage gained in dispersion. One of the experts will have to answer that.

But yes, the doubling of distance is the key. If we extrapolate the numbers to the next step, sub 2 drops to 82dB @ 8 meters, while sub 1 drops to 88dB @ 16 meters. Now, sub 1 is 6dB louder 4 meters further into the audience.

[gdougherty]

So if anything the corner or wall loading helps provide more even coverage over a larger swath of the audience area since the doubling distances are growing larger and larger.

Not sure what you mean by 'swath'? The curved lines in my sletch are there just to show distance. Bass in non-directional, so I'm not sure there's an advantage gained in dispersion. One of the experts will have to answer that.

But yes, the doubling of distance is the key. If we extrapolate the numbers to the next step, sub 2 drops to 82dB @ 8 meters, while sub 1 drops to 88dB @ 16 meters. Now, sub 1 is 6dB louder 4 meters further into the audience.

By swath, yes, that's what I mean. A larger band of the audience in relation to the sub is covered by a more even volume level.

[brodave2]

when I V-coupled my Titan 48s, it made the kick sound better. It also made the titans keep up with a pair of double 18s, which was my goal. I got 4db at 60hz and nothing at 80hz, which went a long way towards flattening the response of the titans.