so I understand that it can be foolhardy to put a horn and a reflex, or a reflex and a sealed sub next to each other and have them play the same passband. i have a situation where I would like to place a sealed and a reflex sub about 15-20 feet from each other in a somewhat small room. i would like the reflex to handle the lowest frequencies by itself, so they would blend in the 40-80hz octave. the sealed sub (Dayton UMII-18) crosses over quite high at 250hz. is this a bad idea? thanks.
LF response indoors is dominated by room dimensions and subwoofer positions because the wavelengths in question setup a complex interference pattern of peaks and nulls, so a single sub position has no chance of delivering consistent levels around the space. Multiple subs in different positions are necessary to achieve anything remotely close to an even distribution of LF energy, in theory subs with different magnetude and phase response don't sum well but in this case it could prove to be benificial... or not. Try it out, it will be obvious immediately if it's not going to be beneficial, and if it isn't you just need to change processing so each sub covers a different part of the spectrum.
I would keep life simple
UMII-18 is 90 dB if I remember. In a corner facing straight up low to the ground really would not even need EQ.
In a small room 50 watts will rattle the house. Or at least anything in the room
We made the joke in old car days, yeah I got a dual voice coil license plate. LOL
Would use carpet pad and long screws to make the thing shut up.
UMII-18 is 90 dB if I remember. In a corner facing straight up low to the ground really would not even need EQ.
In a small room 50 watts will rattle the house. Or at least anything in the room
We made the joke in old car days, yeah I got a dual voice coil license plate. LOL
Would use carpet pad and long screws to make the thing shut up.
I should have provided more detail, especially since I posted this in the live sound forum... this is a weirdo install in the restroom lounge of a club. The room is a narrow corridor about 8 ft wide by 30 ft long with one end open and stalls with full doors. The original system I built has a sealed UM18 as the subwoofer but it isn't enough, they have already blown it during a DJ set. (They have a DJ booth cart they roll in there, and they pack the room full of people and rock out to house music. I don't judge.) So I need more low end in there, and I want to bring the vented sub in just for DJ performances, keeping the UM18 in use for regular washroom service. Both subs would be playing at rather high levels overlapped in the 40-80hz range. The cabinets will be like 15 feet apart, so I am thinking the phase will be uncorrelated anyway.
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Oh, then you have 2 separate problems, you have inadequate protection for the sub and not enough output. In this case don't repeat your initial mistake of using a home theater sub for a much more demanding DJ application, you need a Pro driver in a Pro style cabinet(ported or horn loaded) that is appropriately powered and processed/protected. And in this case no you should not use 2 different sub designs in the room 15ft apart at the same time, that will reduce overall bass levels which is exactly what you don't want. If you are adding a dedicated DJ sub it has to be capable of delivering all the needed output.
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yes, that's the problem, i didn't expect they would want to push everything as far as they do and I painted myself into a corner using a sealed sub. but it XO's at 250hz to meet the mains (the mains are each 21X 3" full rangers in a horizontal line source at the ceiling ends of the room) so I feel I am stuck with it.
the new vented cabinet would be tuned to 25-30hz. do you think I could use a high-order XO somewhere 60-80Hz and have a chance of keeping the two sub bands from interfering? turning the sealed sub into a kick for the DJ events...
my other option is just to build another sealed cabinet and limit aggressively. the people that run the venue realize now that they need to keep the DJ under control in there.
the new vented cabinet would be tuned to 25-30hz. do you think I could use a high-order XO somewhere 60-80Hz and have a chance of keeping the two sub bands from interfering? turning the sealed sub into a kick for the DJ events...
my other option is just to build another sealed cabinet and limit aggressively. the people that run the venue realize now that they need to keep the DJ under control in there.
If there is a system weakness a DJ will find it.. "if it ain't redlining you ain't headlining" sort of thing. I run a company doing Pro sound and lighting for DJ's, they will always push a system to it's limits.. doesn't matter how big it is.
What do you have to power and process this system?
Do the ceiling speakers deliver enough mid-high output for the DJ events or are other speakers brought in for that too?
It may make more sense to put together a complete portable DJ sound system for this, you can try partching the installed system into that rig but there has to be separate control for it that the DJ doesn't have access to so that it is never pushed too hard. And if that were done and the installed rig only sees background SPLs most of the time then is that big 18" sub really needed? You might consider installing several 8" or 10" subs in the ceiling along the length of the room.
They still play the house mix pretty loud in there with a DJ in the main room so I think I need to keep the 18. The installed mains have plenty of headroom, and all the equipment is located in another room. There's enough processing to handle 4 channels with a Crown 1502 for the 21" and a 1002 for the 18"
I think I am going to make this a straight up 4 way system for the DJs - cross the bass cabinets at 80hz and turn the sealed cab into a kick. They can move the 21" in the space when they need it. The sound tech should be able to switch between the 4 way DJ setup and 3 way for the regular house mix fairly easily. I was fixated on making it a one size fits all setup for simplicity.
I think I am going to make this a straight up 4 way system for the DJs - cross the bass cabinets at 80hz and turn the sealed cab into a kick. They can move the 21" in the space when they need it. The sound tech should be able to switch between the 4 way DJ setup and 3 way for the regular house mix fairly easily. I was fixated on making it a one size fits all setup for simplicity.
Yeah simplicity is better for an installed setup, if there is any way to mess it up they will. I was suggesting the smaller subs as an alternative to the 18 assuming it had not been replaced yet, but if it has then don't bother. Is that an XTi 1002 powering the sub?