At a monthly event that myself and a friend have been running for some time now we have decided to bin his active sub and started using a couple of mine. We are somewhat limited by levels but his sub was just underpowered and kept smashing the limiter really before it had enough impact. The problem is, there is not really any way of avoiding having the subs located within that annoying 1 to 4 metre from the rear wall zone. The room isnt big enough to bring them further forward and they can't go back due to shape, other equipment, and the fact we have a large projector doing visuals behind the DJ. With my 2 subs there is more than enough available power to overcome their poor location just by simply turning them up, but the issue is that it does create a lot more bass outside of the venue, and this is less than ideal (potential complaints from nearby residents).
So I'm wondering if there is anything that can be done to increase the forward projection of bass to avoid having to turn them up too loud. I'm thinking of perhaps a false, heavy 1metre high or so panel that sits right behind them. Essentially an upright panel that sits say 6 inches or so behind them that would act a bit like a rear wall and reflect a good load of the soundwaves back again. I dont know. Has anyone done anything similar?
So I'm wondering if there is anything that can be done to increase the forward projection of bass to avoid having to turn them up too loud. I'm thinking of perhaps a false, heavy 1metre high or so panel that sits right behind them. Essentially an upright panel that sits say 6 inches or so behind them that would act a bit like a rear wall and reflect a good load of the soundwaves back again. I dont know. Has anyone done anything similar?
check out Art Welter's (weltersys) "barn door" horn extenders to increase output and directivity. they fit onto the front of the cabinet.
but IMO it's questionable how much they will really help, looks like they mostly add efficiency and just a little bit of directivity.
you could try turning the subs around 180 degrees to get a cabinet depth's closer to the boundary
but IMO it's questionable how much they will really help, looks like they mostly add efficiency and just a little bit of directivity.
you could try turning the subs around 180 degrees to get a cabinet depth's closer to the boundary
if the room is small and they are crossed to the mains quite low you could also try other room positions instead of having them at the front. They should not be localisable if correctly crossed over with an acoustic crossover 80-100Hz (not electrical setting the actual acoustic crossover point). You could also try adding subs to get more forward directivity. Perhaps a subwoofer array? https://www.merlijnvanveen.nl/en/calculators/28-sad-subwoofer-array-designer-en particularly check out the 'mind the gap' publications.
Very common problem.
More of a problem for live performers on the stage, and feedback.
but all together in many instances you need to control bass directionality
in a venue
In a nutshell the common solution is a Cardioid subwoofer setup.
Where you can obviously create a more directional cardioid pattern
instead of a omni directional pattern.
you need to have matching subs/ with same driver so phase response is the same.
then there is multiple ways of arranging matching cabinets 90 or 180 degrees
and if you have DSP it is more helpful to change phase and usually add a delay.
you might just have a huge cancelling node in the room.
from the subs being to far apart in a small room.
so the room might be creating a huge canceling node
and your basically overpowering the node.
can try placing the subs closer together and not spread apart.
that is very common too. since most run stereo mains
they assume you need a sub under each satellite.
then of course, it sounds like the typical blame game. " It's the room"
well kinda, it is the room. but it is usually the location of the subs.
and changing sub location can fix some/ most problems. way before yah get all crazy
with 180 cabinets and delays.
otherwise if you really do need directionality control.
then yes a cardioid system is how its done.
and you would need to do research on the many ways to do it.
with the equipment you have. the biggest importance is matching subs.
since you'll be using phase/ delay to control the direction.
likely you can just change the location within your confined space.
More of a problem for live performers on the stage, and feedback.
but all together in many instances you need to control bass directionality
in a venue
In a nutshell the common solution is a Cardioid subwoofer setup.
Where you can obviously create a more directional cardioid pattern
instead of a omni directional pattern.
you need to have matching subs/ with same driver so phase response is the same.
then there is multiple ways of arranging matching cabinets 90 or 180 degrees
and if you have DSP it is more helpful to change phase and usually add a delay.
you might just have a huge cancelling node in the room.
from the subs being to far apart in a small room.
so the room might be creating a huge canceling node
and your basically overpowering the node.
can try placing the subs closer together and not spread apart.
that is very common too. since most run stereo mains
they assume you need a sub under each satellite.
then of course, it sounds like the typical blame game. " It's the room"
well kinda, it is the room. but it is usually the location of the subs.
and changing sub location can fix some/ most problems. way before yah get all crazy
with 180 cabinets and delays.
otherwise if you really do need directionality control.
then yes a cardioid system is how its done.
and you would need to do research on the many ways to do it.
with the equipment you have. the biggest importance is matching subs.
since you'll be using phase/ delay to control the direction.
likely you can just change the location within your confined space.
The 2 subs were located about 2.5 metres apart, and in satellite formation (poles and tops mounted above) for space saving reasons. One sub is pretty close to the side wall, the other not because its an L shape room and the setup is located in the middle of the L (totally awkward I know). I tried them both independently with the gain up 3db to give like for like when compared with both running together, but it didnt make any difference. I had anticipated and was hoping the one near the sidewall on its own would work the best and the other could just do nothing and be there for show / backup, but that turned out not to be the case.
Unfortunately, we don't really have the space to employ any of the cardioid ideas hence the idea of perhaps having a separate panel close behind each sub. Would it partially act like a rear wall. We could just about fit something like that in. if not, then I guess we will just have to keep going with it as is.
Unfortunately, we don't really have the space to employ any of the cardioid ideas hence the idea of perhaps having a separate panel close behind each sub. Would it partially act like a rear wall. We could just about fit something like that in. if not, then I guess we will just have to keep going with it as is.
I would research cardioid.
far as directionality control not much options.
bass wavelengths are very large. 20 to 60 feet
not sure what a wall would do.
put both subs side by side away from the corner.
or for cardiod with 2 subs you would stack one on the other.
it would save space.
have a feeling it is a huge node in the response.
subs need to be moved likely in non ideal location unfortunately
far as directionality control not much options.
bass wavelengths are very large. 20 to 60 feet
not sure what a wall would do.
put both subs side by side away from the corner.
or for cardiod with 2 subs you would stack one on the other.
it would save space.
have a feeling it is a huge node in the response.
subs need to be moved likely in non ideal location unfortunately
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To effectively block a soundwave a boundary has to be large relative to the wavelengths in question. Wavelengths in the 30-80hz range are 4-14m in length so the minimum boundary wall size would have to be at least as big as the longest wavelength but preferrably bigger. That simply isn't practical at subbass frequencies so I agree you need to revisit cardiod arrangements, the simplest version is just 2 stacked subs with one physically reversed and delayed.
how do you not have the space for cardioid? its usually a triple stack of subs with one turned backwards so the footprint is the same.
I could manage a 2 stack but not 3 as there wouldn't be the height for the tops above that. The room is barely 2 metres tall (basement). There is no room to the sides or rear for additional subs. It's a tight space with few options really.
Also, taking additional subs (and amps / processing to do this properly) also starts to present a challenge with getting everything to the venue. My car is already pretty full as it is.
I can live with it as is but its not ideal.
Also, taking additional subs (and amps / processing to do this properly) also starts to present a challenge with getting everything to the venue. My car is already pretty full as it is.
I can live with it as is but its not ideal.
definitely try the two cabinets together
the cancellation between the two separate sources might be a bigger issue than the boundary
and you'll get acoustic coupling gain as well
the cancellation between the two separate sources might be a bigger issue than the boundary
and you'll get acoustic coupling gain as well
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Damo, here's a bunch of fairly quick responses & thoughts. (from just "some guy on the internet," so FWIW, lol....)
1: You didn't give the dimensions of the room, but in most small venues, important nodal problems come from the SIDE walls just as much as the back wall. Even the far wall, to some extent, so....
2: Cardioid subs are rarely going to help in a small room, unless you get "real" ones. And by that, I mean large, heavy ones, because the smaller & lighter ones aren't truly cardioid at all frequencies. They simply can't be, even with fancy DSP. NEXO has a very 2-part good tutorial on such subs, if you want to learn more:
Also, even a perfect cardioid sub is going to be less than stellar in a small room, as you will still have nodal interaction from the sides and even the back of the room.
And last, a cardioid sub, by its nature, is pretty inefficient. You are using a lot of power to drive the out-of-phase signal. So, with a typical DJ system that might be right on the edge of tripping that lousy 15a circuit you have (if you're lucky 😳 ) cardioid subs could possibly take you over the edge.
Probably not, given the efficiency of modern D-class amps, LED lights, and such, but it's something to figure in to the mix. In my case, running two computers on stage, along with some vintage halogen lights, cardioid subs would be impossible at many venues.
3: Since you work the same room all the time, you definitely should do as others suggested and experiment with placement. If possible, use some kind of software system that can show a waterfall display, as that shows you where the main nodal issues are. - But a simple RTA can work as well, since you will only be moving the subs around, not rebuilding the room.
3B: As a mobile DJ / band, I can't do the above, so I always choose the "power alley" method, where the subs are clustered in the center. This gives you the cleanest LF response in the front-center of the room, where people typically dance. The downside is that it also makes the very worse peaks and valleys in the rest of the room even worse.
4: In my limited experience, (and there could well be exceptions) "barn doors" don't do squat with bass reflex subs. Evidently, they DO help somewhat with horn-loaded subs (for interesting technical reasons) so you might consider switching to a TH design, and adding some heavy MDF doors to the sides. If you can deal with the size and weight, Art Welter's single 18" TH design looks like a real winner.
1: You didn't give the dimensions of the room, but in most small venues, important nodal problems come from the SIDE walls just as much as the back wall. Even the far wall, to some extent, so....
2: Cardioid subs are rarely going to help in a small room, unless you get "real" ones. And by that, I mean large, heavy ones, because the smaller & lighter ones aren't truly cardioid at all frequencies. They simply can't be, even with fancy DSP. NEXO has a very 2-part good tutorial on such subs, if you want to learn more:
Also, even a perfect cardioid sub is going to be less than stellar in a small room, as you will still have nodal interaction from the sides and even the back of the room.
And last, a cardioid sub, by its nature, is pretty inefficient. You are using a lot of power to drive the out-of-phase signal. So, with a typical DJ system that might be right on the edge of tripping that lousy 15a circuit you have (if you're lucky 😳 ) cardioid subs could possibly take you over the edge.
Probably not, given the efficiency of modern D-class amps, LED lights, and such, but it's something to figure in to the mix. In my case, running two computers on stage, along with some vintage halogen lights, cardioid subs would be impossible at many venues.
3: Since you work the same room all the time, you definitely should do as others suggested and experiment with placement. If possible, use some kind of software system that can show a waterfall display, as that shows you where the main nodal issues are. - But a simple RTA can work as well, since you will only be moving the subs around, not rebuilding the room.
3B: As a mobile DJ / band, I can't do the above, so I always choose the "power alley" method, where the subs are clustered in the center. This gives you the cleanest LF response in the front-center of the room, where people typically dance. The downside is that it also makes the very worse peaks and valleys in the rest of the room even worse.
4: In my limited experience, (and there could well be exceptions) "barn doors" don't do squat with bass reflex subs. Evidently, they DO help somewhat with horn-loaded subs (for interesting technical reasons) so you might consider switching to a TH design, and adding some heavy MDF doors to the sides. If you can deal with the size and weight, Art Welter's single 18" TH design looks like a real winner.
Actually, I found the "barn doors" worked equally well on BR, FLH and TH in outdoor testing, around 3dB increase in LF, as can be seen in post #16 here:
https://www.diyaudio.com/community/threads/multiple-cabinet-combined-response.204472/
The distance for low frequency waves to wrap around the barn doors and distance to rear walls reflection would affect response indoors, creating peaks and nulls at different frequencies than without. Hard to separate all the variables without extensive testing in different positions, and room response variations would swamp a 3dB gain.
Art
Hey, Art.
I don't doubt your results, only that mine weren't the same.
I used two 3/4" MDF "doors" of about 2' x 3', on both sides of one of my sealed 18" subs.
I didn't use a meter, but instead my ears, for a general perception. Set up outside, I stood maybe 6-8 feet behind it with my eyes closed, with a looped dance beat playing, and had two friends move them in & out. IIRC, I could hear a slight difference, but could not tell which one was supposed to be the "less omni" one. - Probably because of selective frequencies being effected.
Anyway, I gave up on the idea. Especially since, as you say, small room nodes would likely minimize any possible gains, anyway.
It sounds, though, like I should try again with my dual 12" subs, and I'll definitely give it a go with the TH, if I ever get those built.
(As I've written before, and though I'm just guessing, I suspect that on a Horn sub, the doors could possibly act to make a longer effective mouth. That would certainly add somewhat to the effect.
I don't doubt your results, only that mine weren't the same.
I used two 3/4" MDF "doors" of about 2' x 3', on both sides of one of my sealed 18" subs.
I didn't use a meter, but instead my ears, for a general perception. Set up outside, I stood maybe 6-8 feet behind it with my eyes closed, with a looped dance beat playing, and had two friends move them in & out. IIRC, I could hear a slight difference, but could not tell which one was supposed to be the "less omni" one. - Probably because of selective frequencies being effected.
Anyway, I gave up on the idea. Especially since, as you say, small room nodes would likely minimize any possible gains, anyway.
It sounds, though, like I should try again with my dual 12" subs, and I'll definitely give it a go with the TH, if I ever get those built.
(As I've written before, and though I'm just guessing, I suspect that on a Horn sub, the doors could possibly act to make a longer effective mouth. That would certainly add somewhat to the effect.
A rough sketch of the venue. Because of the layout there isnt much else we can do with location of anything. We have manage to convince the club owner to let us use an otherwise unused backroom, which is actually a tiny bit bigger and the layout is such we can have the stacks back on the walls so this will no longer be an issue. We are probably going to trial this layout in March, but, its depending on me constructing some effective soundproofing that goes over the single glazed windows which open onto the road. Since these are basement windows they are quite large but the opening to the road is quite small. I plan to build something to temporarily block these up. For our techno nights where we want a bit more bass this will be prefect.
An update on cardioid subs:
I still stand by what I wrote above, except I had not yet seen Fulcrum's fairly recent PASSIVE cardioid speakers.
Check out, for instance, the Fulcrum Audio CS212L. (They also have similar subs with larger drivers)
Gunness is obviously one of the really talented audio guys out there, and the specs on this sub look WAY better than they should.
Reallly compact and light (by cardioid standards) and surprisingly efficient:
The sensitivity is only 95 dB, with a power limit of 700w per driver at 8 ohms, yet they claim a max continuous SPL, @ half space of 132 dB.
I don't see how that's even possible.
They also claim 8 dB of rear-rejection across the entire usable bandwidth, which is also sorta' hard to believe.
Anyway, these might be worth checking out. Mind you the retail cost is over $2800 for a single 2x12", and I THINK you need to run them in pairs, plus you need a qualified processor to run his TQ dsp. Still, wow ........
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I think I'll start a new thread just about this Fulcrum design. It sure is intriguing.
I still stand by what I wrote above, except I had not yet seen Fulcrum's fairly recent PASSIVE cardioid speakers.
Check out, for instance, the Fulcrum Audio CS212L. (They also have similar subs with larger drivers)
Gunness is obviously one of the really talented audio guys out there, and the specs on this sub look WAY better than they should.
Reallly compact and light (by cardioid standards) and surprisingly efficient:
The sensitivity is only 95 dB, with a power limit of 700w per driver at 8 ohms, yet they claim a max continuous SPL, @ half space of 132 dB.
I don't see how that's even possible.
They also claim 8 dB of rear-rejection across the entire usable bandwidth, which is also sorta' hard to believe.
Anyway, these might be worth checking out. Mind you the retail cost is over $2800 for a single 2x12", and I THINK you need to run them in pairs, plus you need a qualified processor to run his TQ dsp. Still, wow ........
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I think I'll start a new thread just about this Fulcrum design. It sure is intriguing.
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