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Facing cabs inwards

#2
After he's through adjusting them, the cabinets are at roughly 90 degrees to one another. One effect is to give fairly uniform coverage over a wider horizontal arc, in this case roughly 90 degrees. Not knowing what's under the grillecloth I can't say for sure how uniform that coverage will be.

Since most bass cabs (and guitar cabs) beam significantly in the upper frequencies, off-axis listeners hear a different tonal balance than on-axis listeners do. Imagine a listener on the centerline of the two angled-in cabs, another off to the left at 45 degrees, and another likewise off to the right. The centerline listener is somewhat off axis of either speaker but not too much, so he's getting some highs from each. The far left and right listeners are getting full highs from one speaker but nothing but lows from the other. So each of these three locations is getting a roughly similar tonal balance, which would not be the case with a single cab nor with two side-by-side. It's not perfect, but it's a significant improvement.

Assuming the PA system is doing the heavy lifting, the improved coverage is probably for the benefit of the band members rather than for the audience. But the same geometry could be beneficial in a much smaller gig where the bass cabs don't have PA support. So this is a good geometry to make note of and include in your bag of tricks.

This geometry is a type of "splayed array". Splayed arrays are usually angled outward instead of inward, but an outward splay can give you a partial high frequency dead zone up close in front of the central axis.

I have done some work with splayed arrays, and in my opinion they usually degrade the clarity a bit. So, like most things involving loudspeakers, it ends up being a trade-off - but no doubt a worthwhile one in some applications.

Duke
 
#4
DukeLeJeune said:
After he's through adjusting them, the cabinets are at roughly 90 degrees to one another. One effect is to give fairly uniform coverage over a wider horizontal arc, in this case roughly 90 degrees...
This geometry is a type of "splayed array". Splayed arrays are usually angled outward instead of inward, but an outward splay can give you a partial high frequency dead zone up close in front of the central axis.

I have done some work with splayed arrays, and in my opinion they usually degrade the clarity a bit. So, like most things involving loudspeakers, it ends up being a trade-off - but no doubt a worthwhile one in some applications.

Duke
Click to expand...
He's doing it the right way by cross-firing his cabs. It delivers a far wider upper midrange and HF dispersion, closer to 120 degrees, than a straight firing a pair of cabs placed side by side, and introduces a bit of horn loading of the midbass for greater output there. I suspect he moved the cab a bit to remove some of that loading, probably he was getting a bit of midbass boom. As for outward splaying, that should never be done, as it narrows midrange dispersion and causes massive comb filtering. True, the PA industry did it that way for 30 years, but not because it was correct, but because it's what uninformed buyers demanded.
 
#6
From the FOH engineer point of view, it is even better if they face sideways directly at the drummer. This makes it almost possible for FOH to mix for the audience by significantly reducing those raging on-axis hot spots.

As Bill notes, the cross-fire technique is far more constructive than is splaying. On the other hand, if you have PA support, all this does is torque off FOH and make his job more difficult.
 
#8
sometimes we have to line our cabs on the side wall and face inward. its usually when the house doesnt have monitors or is a really small club and they want everything run through their massive PA system. i think there are better alternatives, i dont understand either of the scenarios.
 
#10
I wonder if these theories were behind the design of one of my favorite cabinets; the Sunn Magna 4X15. It was a relatively small cab considering it had 4 15's in it. The speakers were mounted on a 90 degree angle to each other. I always thought the outstanding 'punch' of these cabs was due to a lack of airspace behind the speakers. An SVT head with one of these cabs is truly impressive.
 
#18
tom once dead said:
now for a simpleton question. How can changing the angle of the cabs effect which frequencies you hear?
Click to expand...
It's called "beaming." Larger speakers have much narrower dispersion of upper mids and highs than smaller. So if you're off to the side of the cab rig, unless you have a smaller mid driver and/or tweeter, you will hear a lot less high and upper mid that when you're standing dead in front of it. So cross-splaying the cabs will send those higher freqs across the stage more.
 
#19
Not a fan myself, its usually at the FOH engineers request, so they dont have to compete with stage volume. Not great if your Guitarist(s) insist on turning up their AC30's or 100w stacks so the high freq's take off your ears... On a medium / small stage , its hardly ideal in my experience.
 

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