OT: FBT Line Arrays

Discussions about the use and operation of SAC (Software Audio Console)

OT: FBT Line Arrays

Postby randyhyde » Mon Aug 26, 2013 2:56 pm

Anyone have any experience with an FBT Modus 40 line array module?
Heard one at a show this past weekend and it sounded pretty bad (distorted vocals). Trying to determine if it was the equipment, "what you'd expect from a line array", or operator error.

FWIW, the area being serviced was way to small for a line array (about 50-75' deep).
Stage had two FBT line array modules hung per side (just one Modus 40; they're like constant curvature arrays so you generally wouldn't use a whole bunch of these things) and a couple of dual 18" subs per side (looked suspiciously homebrew).

Vocals for announcements were good; but when someone (Charlie Worsham) was singing over instruments it was kind of sad.
Board was a Yamaha M7.
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Re: OT: FBT Line Arrays

Postby jlepore » Mon Aug 26, 2013 5:36 pm

Hadn't heard or seen them before, but looking at the specsheets, I don't think I want to either.
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Re: OT: FBT Line Arrays

Postby gdougherty » Mon Aug 26, 2013 5:47 pm

Sounds like something was wrong in the signal chain or they had blown drivers. No experience, but looking at the charts on those it was probably a Modus 15 on top and a 40 on bottom. They claim 137db continuous and 141db peak with just one cabinet, so unless something was damaged it should have sounded just fine. That kind of output capability should be plenty for the area described with no distortion unless it was unreasonably loud.
http://softwareaudioconsole.wikidot.com The start of a wiki. It's slow going and there's a ton of info that should be in there yet.
Biggest item is the Command Reference on how to do most actions within SAC. It's 90% of what you need for UI proficiency.

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Re: OT: FBT Line Arrays

Postby BrentEvans » Mon Aug 26, 2013 9:09 pm

gdougherty wrote:Sounds like something was wrong in the signal chain


Probably too much compression on the vocals or a super-fast attack not letting transients through. It's an easy way to bash a mix.
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Re: OT: FBT Line Arrays

Postby IraSeigel » Tue Aug 27, 2013 7:56 am

randyhyde wrote:... Trying to determine if it was the equipment, "what you'd expect from a line array", or operator error.
...

Can you please explain what you meant by "what you'd expect from a line array"? Are you saying that they're inherently awful or inferior?

Whatever, I'd say the person running the sound for the singer has no clue as to gain structure.
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Re: OT: FBT Line Arrays

Postby randyhyde » Tue Aug 27, 2013 11:05 am

IraSeigel wrote:
randyhyde wrote:... Trying to determine if it was the equipment, "what you'd expect from a line array", or operator error.
...

Can you please explain what you meant by "what you'd expect from a line array"? Are you saying that they're inherently awful or inferior?

Whatever, I'd say the person running the sound for the singer has no clue as to gain structure.


Line arrays suffer from a lot of phase distortion that you don't get with point-source cabinets. So yes, they're inherently inferior to point-source speakers.
This is why I was a bit concerned about using a line array unit in such a small area.
OTOH, this particular unit was probably the equivalent (in size, not sound) of three JBL VRX 932 cabinets bolted together, so not much of a "true line array" either.
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Re: OT: FBT Line Arrays

Postby jlepore » Tue Aug 27, 2013 3:52 pm

randyhyde wrote:Line arrays suffer from a lot of phase distortion that you don't get with point-source cabinets. So yes, they're inherently inferior to point-source speakers.


WHAT?!?! :o

You might have a technical argument if you compare them to a single isolated conventional box, but no way against multiple boxes (and what kind of show is it really if you can do it with a single box)!
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Re: OT: FBT Line Arrays

Postby RBIngraham » Tue Aug 27, 2013 5:18 pm

I'm with Joe. Far more comb filtering going on with sort of array of conventional horn loaded cabinets. Some are far better than others, but there is always some undesireable effects where the boxes over lap. Far less so with any line arrays I've worked with.

I agree that line arrays are the flavor of the month these days and they are used far too often, in venues that would be better served with conventional boxes or a distributed sound system (done well). But that doesn't mean they don't have a very even coverage pattern and sound good.

Of course who knows what these things sound like... they look like so many of the "me too" line array want to be systems that are out there now.
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Re: OT: FBT Line Arrays

Postby randyhyde » Tue Aug 27, 2013 7:16 pm

jlepore wrote:
randyhyde wrote:Line arrays suffer from a lot of phase distortion that you don't get with point-source cabinets. So yes, they're inherently inferior to point-source speakers.


WHAT?!?! :o

You might have a technical argument if you compare them to a single isolated conventional box, but no way against multiple boxes (and what kind of show is it really if you can do it with a single box)!


One word: Danley JH90 :)
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Re: OT: FBT Line Arrays

Postby BrentEvans » Tue Aug 27, 2013 10:09 pm

randyhyde wrote:
Line arrays suffer from a lot of phase distortion that you don't get with point-source cabinets. So yes, they're inherently inferior to point-source speakers.
This is why I was a bit concerned about using a line array unit in such a small area.

The constructive and destructive interference that happens in line arrays is what makes them work. You ears don't hear phase, they hear amplitude. Phase affects amplitude, but it does so in predictable ways, and ways that can be designed into cabs to benefit the end result. This is what is done in a line array.. the drivers sum and null predictably, and flatten in frequency response the more of them you add, at the expense of phase response (which doesn't matter, as you can't hear it). Further, all of that happens in the vertical plane, so you don't hear it like you do with splayed standard cabs. In most cases, properly deployed lIne arrays are quite consistent horizontally and vertically. The vertical coverage comes from tight driver spacing which aids in coupling.



OTOH, this particular unit was probably the equivalent (in size, not sound) of three JBL VRX 932 cabinets bolted together, so not much of a "true line array" either.
Cheers,
Randy Hyde


The ability of the array to function as a line source instead of a point source is variable with frequency according to the height of the array. At 1 meter, they go to about 500hz before turning into a point source, 250hz at 2m, 125hz at 4m, etc.
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