I have good results with Subwoofer corner placement.
But this can be room dependent.
It seems to me that the corner helps the bad efficiency of Subwoofers as it gives you theoretically +9db in relation to placements away from room boundaries.
What is your experience?
Is corner placement only a help for small subs or do profit also bigger ones?
https://www.diyaudio.com/community/...-concrete-loudspeaker-box.406856/post-7547864
But this can be room dependent.
It seems to me that the corner helps the bad efficiency of Subwoofers as it gives you theoretically +9db in relation to placements away from room boundaries.
What is your experience?
Is corner placement only a help for small subs or do profit also bigger ones?
https://www.diyaudio.com/community/...-concrete-loudspeaker-box.406856/post-7547864
when it comes to the boundary effect, it's all about wavelength. a high frequency with a 3 inch wavelength isn't going to benefit from the corner, but all sub woofers will.
at just 60hz the wavelength is almost 20 feet.
at just 60hz the wavelength is almost 20 feet.
'Tis true, the wider its desired BW the more you need to design your sub as if its a conical horn driver and why most are (XO) limited to < ~ 2 - 2.5 octaves.
I have xo at the satellite in a 2.1 setup at 100hz with 6db and bass with active xo 12db.
Bass moved from a position close to back wall to a corner the driver facing towards it.
First by ear I tuned the bass down in volume later I readjusted it to previous volume but slightly lower frequency.
The bass itself simply develops more authority I could not find a sonic default the sub being now in the corner.
Bass moved from a position close to back wall to a corner the driver facing towards it.
First by ear I tuned the bass down in volume later I readjusted it to previous volume but slightly lower frequency.
The bass itself simply develops more authority I could not find a sonic default the sub being now in the corner.
I built now several corner placed loudspeakers and subs with different bass drivers and box volumes.
Bass sweep tests showed always bass down to the lowest octave with low tuned reflex systems.
Bass sweep tests showed always bass down to the lowest octave with low tuned reflex systems.
looking around for some real measurement, here very nice from a scientific paper comparison 2 pi and 4 pi space, gain of six decibels(!)
For close to wall or even corner placement there are up to 12 db more to be expected.
https://www.researchgate.net/publication/306108014
Measuring absorption below 100Hz with a P-U sensor
Thesis · January 2016
Doug Shearer
London South Bank University
For close to wall or even corner placement there are up to 12 db more to be expected.
https://www.researchgate.net/publication/306108014
Measuring absorption below 100Hz with a P-U sensor
Thesis · January 2016
Doug Shearer
London South Bank University
FWIW, my own experience (as someone who moves around a lot) is that sub placement can be very room dependent. Room modes can occur quite differently in different rooms so, for example, a sub might result in a peak at the listening position in one room, yet placed similarly in different room it might result in a dip. The effect of this can be bigger in magnitude than the expected gain from 2pi over 4pi.
So, I personally try to place sub(s) wherever they work best (or at least well) with the particular room's modes and listening position(s). Which can sometimes happen to be a corner; where the room modes are conducive to this, I've not noticed any audible detriment from such corner placement.
A further step (where possible) is to have additional subs placed around, to even out the room response. In that case, I very often find that at least one in a corner near the main speakers can work quite well; again I've not noticed audible detriment. Though I do tend to low-pass them no higher than 80hz in this scenario.
So, I personally try to place sub(s) wherever they work best (or at least well) with the particular room's modes and listening position(s). Which can sometimes happen to be a corner; where the room modes are conducive to this, I've not noticed any audible detriment from such corner placement.
A further step (where possible) is to have additional subs placed around, to even out the room response. In that case, I very often find that at least one in a corner near the main speakers can work quite well; again I've not noticed audible detriment. Though I do tend to low-pass them no higher than 80hz in this scenario.
The measurement is from the JBL ASB6112 12" subwoofer spec sheet.
https://jblpro.com/en-US/site_elements/asb6112-spec-sheet
It is interesting to see that the 2 pi (half space) condition imparts no gain above 1000 Hz, where the speaker baffle dimensions already create a half space condition similar to low frequencies on the floor.
Art
Looking further for someone who really did do measurements
https://www.jobst-audio.de/artikel/messtechnik-entwicklung/groundplane-nahfeld
light blue is fullspace
dark blue is halfspace
grey is quarter space
not measured is corner placement
Here what he wrote in german:
Hier sehen wir eine 2-Wege-Box im Vollraum (Hellblau),
im Halbraum (Blau) und im Viertelraum (Grau) - (Letzteres leicht unsauber gemessen, aber zur Veranschaulichung tut's das).
Wir erkennen ab wann es die +6dB gibt und bis zu welcher Frequenz hin wir Pegelzuwachs erhalten.
Die Schallwand entspricht hier 35x50cm.
in english
Here we see a 2-way box in full space (light blue), in the half-space (blue) and in the quarter-space (grey) - (the latter slightly uncleanly measured, but for illustration it does). We can see when the +6dB exists and up to which frequency we get level increases. The baffle here corresponds to 35x50cm.
Full Space - Actually like free field, we don't have a solid angle.
Half-space - There is a solid angle (e.g. the floor), the sphere (radiation from the bass) becomes a hemisphere.
Quarter space - 2 room angles, e.g. the box is on the floor and against a wall, the ball becomes a quarter sphere.
These are the solid angles, per solid angle we get +6dB level.
https://www.jobst-audio.de/artikel/messtechnik-entwicklung/groundplane-nahfeld
light blue is fullspace
dark blue is halfspace
grey is quarter space
not measured is corner placement
Here what he wrote in german:
Hier sehen wir eine 2-Wege-Box im Vollraum (Hellblau),
im Halbraum (Blau) und im Viertelraum (Grau) - (Letzteres leicht unsauber gemessen, aber zur Veranschaulichung tut's das).
Wir erkennen ab wann es die +6dB gibt und bis zu welcher Frequenz hin wir Pegelzuwachs erhalten.
Die Schallwand entspricht hier 35x50cm.
- Vollraum - Eigentlich wie Freifeld, wir haben keinen Raumwinkel.
- Halbraum - Es gibt einen Raumwinkel (z.B. der Boden), die Kugel (Abstrahlung vom Bass) wird zur Halbkugel.
- Viertelraum - 2 Raumwinkel, z.B. steht die Box am Boden und an einer Wand dran, die Kugel wird zu Viertelkugel.
Dies sind die Raumwinkel, je Raumwinkel erhalten wir +6dB Pegel.
in english
Here we see a 2-way box in full space (light blue), in the half-space (blue) and in the quarter-space (grey) - (the latter slightly uncleanly measured, but for illustration it does). We can see when the +6dB exists and up to which frequency we get level increases. The baffle here corresponds to 35x50cm.
Full Space - Actually like free field, we don't have a solid angle.
Half-space - There is a solid angle (e.g. the floor), the sphere (radiation from the bass) becomes a hemisphere.
Quarter space - 2 room angles, e.g. the box is on the floor and against a wall, the ball becomes a quarter sphere.
These are the solid angles, per solid angle we get +6dB level.
Attachments
That location will of course provide a great deal of boost at low frequencies. Depending on the upper frequency point of the subwoofer, deep corner placement will reduce the size of the notch due to room boundary interference effects.
I suppose that's because the room's low-frequency modes are dependent on the geometry of the room and whatever absorption may be present.
I guess that it will help smaller subwoofers more, as these are likely to be driven closer to their linear operational limits.
At very low frequencies where the radiation is non-directional there is a theoretical +6 dB improvement in both power and pressure response each time that the solid radiation angle is halved. 3 dB is due to the improved acoustical loading conditions (enabling twice the power to be radiated), and the other 3 dB is due to the doubled power radiating into half the space. Going from free space to eighth space therefore results in an 18 dB increase overall.
At very high frequencies the acoustical loading conditions do not change when the solid radiation angle is halved. There is a +3 dB enhancement in power response due to the same power now radiating into half the space, but there will be no gain in pressure response once the directivity pattern becomes narrower than the solid angle.
The chart below compares 2 Pi (black trace) and 4 Pi (grey trace) power responses:
The chart below compares 2 Pi (black trace) and 4 Pi (grey trace) on-axis pressure responses: