Anyone Ever Thought of This?

[Gizmot]

Search "comb filtering" on here - you increase greatly the odds that parts of the audience hear little if anything...

If you separate the cabinets, you will greatly decrease comb filtering. Comb filtering is destructive interference caused by colliding waveforms at upper mid and high frequencies with short wavelengths.
The bad part about separating the cabinets is that you don't get the reinforcement of low frequencies that happens when the cabinets are placed close to each other.

 

[Wasnex]

If you separate the cabinets, comb filtering will occur at lower frequencies.

Fixed it for you.

 

[BogeyBass]

I wouldn't do it with single 15s but I have run 2x15s on both sides of the
stage and 2 8x10s.
iI used one amp for the 8x10s. but with the 15s I bought this dirt cheap road amp to power the cab on the other side of the stage. I just ran the inputs in parallel since most amps have parallel input jacks. dude when you run two heads like that I had insane sustain and it sounded like a monster. turns out somebody bypassed the fuse on the road amp with tin foil lol. the thing started smoking and still worked the whole show and one of the bouncers stood next to it laughing with a fire extinguisher the whole show. lol the show was amazing and I was keeping up with 2 guitars with full stacks. And yes the loved actually hearing me onstage and not in the wimpy monitors.

 

[Wasnex]

Here's an article you may be interested in. Figures 41 and 42 should be especially interesting as they show the resultant dispersion pattern at 50 and 100 hz for two sound sources spaced 13.1 feet apart. Also see figures 43 and 44 for the same frequencies with spacing at 26.2 feet.

Link Removed

Comb filtering and the development of lobes is determined by the spacing between acoustic centers in relation to the wavelength of the sound being produced. Keep in mind that as frequency goes up wavelength decreases. If the acoustic centers of two sound sources or within 1/4 wavelength of each other you get near perfect summing. As the spacing increases you get comb filtering.

Notice the dispersion pattern in figure 42 (100 hz at 13.1 feet spacing) looks almost identical to the dispersion pattern of figure 42 (50 hz at 26.2 feet). Note the change is half the frequency and double the spacing between acoustic centers. The dispersion pattern of 200 hz at 13.1 feet would look a lot like figure 44 (100 hz at 26.2 feet). Once again, the change is half the frequency and double the spacing between acoustic centers.

Here's an attachment that gives wavelength by frequency.

http://www.jdbsound.com/art/frequency wave length chart 2013.pdf

As others have pointed out you can't eliminate comb filtering, but IMHO you can take some steps to reduce it. It's up to you decide if this is something you can use as a bass player.

 

[rufus.K]

Comb filtering can be either destructive or constructive. It's the uncertainty that gets you when you play a new location. If you have the time to play with it before a show, then why not exparament.
I did it only once, with a 410 and a 210.

 

[leonard]

If there are THREE or more point sound sources it will reduce the comb filtering effect somewhat. For example a live gig might have one bass cab and two subs on the sides.

 

[fantasticplanet]

put a cab in front of each member of the audience
hella bass

 

[-Asdfgh-]

Despite what you've read so far- the band will hear you better. You don't both PA speakers on one side do you ? Can you hear the PA speakers when they are separated?

Ideally both subs should be on one side, though, although it's rarely done.

 

[Ox Boris]

Move around and things change. IT'S LIVE SOUND!!

A quite staggeringly good point.

 

[-Asdfgh-]

yes - I know about power allies, combing and such. Take this entire thread in context- 99% of sound people are doing it wrong? Manufactures are giving bad advice? Most every show/concert I've ever been to has been set up incorrect?

Very often at gigs I hear combing effects on the bass.

So in a bar gig, you'd set the subs in the middle of the floor in front of the singer?

Often you can just set up the sub on one side in a small venue as long as the crowd aren't right on top of the PA.

 

[Watchootognbout]

Here's the solution!

 

[Rick James]

live sound cancellation issues are nonsense because, move your head one centimeter left or right or backward or forward and suddenly the cancellation becomes a reinforcement

That's right, a cancellation will become a reinforcement when you move your head 1/4 wavelength or more. But since one centimeter is 1/4 wavelength at 8500 hz your example has no relevance here.
For two sources to not interfere with each other they must be either less than 1/4 wavelength apart or more than two wavelengths apart. With subs that cover 40 to 100 hz that means less than 11 feet apart or more than 56 feet apart. For mains that cover 100 hz and up that means more than 11 feet apart. That's why you split mains but not subs, unless you're in an arena.
As usual there are two camps with respect to this technical issue, those who understand how the physics works and those who don't. Arguing either side is a waste of time for all, because neither side is going to budge an inch. All I can say to the OP, and anyone else who is on the fence, is to do your research, the answers are out there and not too difficult to find.

 

[hondo4life]

Line array - Wikipedia, the free encyclopedia
and stuff
I wonder how tipsy four vertical 210s would be.

 

[HaphAsSard]

or more than two wavelengths apart

I've seen this part mentioned by Bill FitzM., but I believe it to be just a rule of thumb, not an iron law: as the .pdf in @Wasnex's post above demonstrates, the two (stacks of) subs split at more than 2 wavelengths still interfere, but in practice the output of one prevails for many listening positions and destructive contribution from the more distant one cannot lead to total cancellation (for said positions). But please correct me if I'm off the mark.

 

[wmhill]

can somebody please spell manufacturer correctly? you're giving bass players a bad name. thanks!

EDIT: lol, i didn't even realize until i posted this that all the errors were from the same dude. raise your game, wmhill!

 

[jacolyte]

That's right, a cancellation will become a reinforcement when you move your head 1/4 wavelength or more. But since one centimeter is 1/4 wavelength at 8500 hz your example has no relevance here.
For two sources to not interfere with each other they must be either less than 1/4 wavelength apart or more than two wavelengths apart. With subs that cover 40 to 100 hz that means less than 11 feet apart or more than 56 feet apart. For mains that cover 100 hz and up that means more than 11 feet apart. That's why you split mains but not subs, unless you're in an arena
As usual there are two camps with respect to this technical issue, those who understand how the physics works and those who don't. Arguing either side is a waste of time for all, because neither side is going to budge an inch. All I can say to the OP, and anyone else who is on the fence, is to do your research, the answers are out there and not too difficult to find.

you're right and i was wrong. your time wasn't wasted after all. i understood the principles but not the scale involved. thank you for opening my eyes.

 

[BogeyBass]

when you have ridiculous stage volume with more than one guitar player on both sides of stage. stupid little monitors don't work. And being a drummer too the most annoying thing in the world is a cranked up drum monitor. I'd rather set my kit up off the riser forward on the stage and hear the amps. not a cracking crap monitor. the only thing needed on monitors is vocals and keyboards if you have them. yes I'm aware of comb filtering. but you standing in front of your amp. no comb filtering. You can't hear the other side. the guitar player won't hear the combing either cause he can't hear your side. the audience won't hear it cause of the mains. we didn't get signed and sell out shows cause we were so worried about comb filtering. we sold records cause we were powerful loud and energetic. And we paid our own sound man so we didn't have to argue with goobers that don't understand how rock n roll works lol. the points been made well how much combing do you think you get with the mains and a bunch of spread out cracking poop monitors. if your in a normal band at fairly low stage volumes. then no using a cab on both sides of the stage is pointless. but if your in a very very loud band with multiple guitar players then it works out rather well. And yes your gonna need a sound man that actually knows what he is doing. not some dude that sits there and argues " cause he's been doing this for 20 or
so years"

 

[MrBassman17]

Well, I've learned quite a bit from this thread, as well as from the set up at the gig yesterday! Thank you all for your input, the discussion was very informative! First, I discovered when I arrived at the venue, that we were setting up under an open pavilion, and, that we did, in fact have a PA and sound engineer there to handle that aspect for us! That was a great relief, as I hate having to play and make adjustments at the same time! As I'm sure you all know, it just doesn't work! That being said, the other thing I found out was just how great my rig sounds when I cranked it up! I didn't split the cabs, and had the room to stand far enough in front of it to actually hear myself as I sound to the audience! So, for what it's worth, I will stick with the traditional stacking and not be fooling around when I have the opportunity to play in an open outdoor space again!

 

[MrLenny1]

Sound dispersion out to the audience will be better
with the stack. A friend of mine uses this and I was amazed at how
well the bass carried out back through out the room.

 

[ofajen]

One other thing to consider, if the guitar players hear you better, will they think you are too loud and crank up their amps?

Otto