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Author Topic: VRX vs STX for Ballroom  (Read 12254 times)

Alex Litwack

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VRX vs STX for Ballroom
« on: January 30, 2015, 02:30:38 PM »

I'm looking at two different systems to purchase for corporate/educational events in conference centers and hotels. Only to be used for voice reinforcement.

Room size estimate of about 100' x 75' and around 500 people. Usually setup in tables of rounds or half-rounds. Will these setups be big enough?

I was looking at either 4 of the VRX928LA or 2 of the STX812M. Either set ran by the Crown XTi 6002 (slightly under program for the STX).

VRX928LA -> 800w 100°x 15°
STX812M -> 1600w 70°x 70°
XtI6002 -> 4-ohm 2100w and 8-ohm 1200w

I like the idea of the 4 VRXs to get a little more level in the back but they are more expensive than the STXs. Will the 2 STXs be enough for this room?
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Robert Healey

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Re: VRX vs STX for Ballroom
« Reply #1 on: January 30, 2015, 02:54:38 PM »

I'm looking at two different systems to purchase for corporate/educational events in conference centers and hotels. Only to be used for voice reinforcement.

Room size estimate of about 100' x 75' and around 500 people. Usually setup in tables of rounds or half-rounds. Will these setups be big enough?

I was looking at either 4 of the VRX928LA or 2 of the STX812M. Either set ran by the Crown XTi 6002 (slightly under program for the STX).

VRX928LA -> 800w 100°x 15°
STX812M -> 1600w 70°x 70°
XtI6002 -> 4-ohm 2100w and 8-ohm 1200w

I like the idea of the 4 VRXs to get a little more level in the back but they are more expensive than the STXs. Will the 2 STXs be enough for this room?

 For speech reinforcement, I think either of these choices will make enough volume for 500 people. Your issue is going to be coverage. Draw out your coverage patterns - what will you need? Are you usually trying to cover the room along the long axis or the short, wider axis?

Two VRXs per side is 110 x 30 degrees (theoretically) of coverage. That's pretty narrow vertically so I would go with at least three a side. JBL doesn't provide a beamwidth chart for two elements, but looking at the spec sheet 3 boxes a side is really only 40 degrees of vertical coverage in the vocal range. I wouldn't expect a two or even three element VRX928 array to behave as a theoretically perfect line array. Don't count on getting extra sound in the back due to line array effects. A single STX812m is 70 x 70 and holds that 70 degrees pretty well from 1k - 4k which is where your vocal intelligibility lies.

If 40 degrees vertical is right for you and you are OK with wide horizontal coverage, then the VRX could be a good fit. If you need more vertical coverage, go with the STX.
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Scott Harris

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Re: VRX vs STX for Ballroom
« Reply #2 on: January 30, 2015, 03:00:02 PM »

Are you stacking, pole mounting or hanging these?
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Alex Litwack

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Re: VRX vs STX for Ballroom
« Reply #3 on: January 30, 2015, 03:08:53 PM »

Are you stacking, pole mounting or hanging these?

These will be poll mounted either on the floor or on a 18" riser stage.
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Alex Litwack

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Re: VRX vs STX for Ballroom
« Reply #4 on: January 30, 2015, 03:13:25 PM »

For speech reinforcement, I think either of these choices will make enough volume for 500 people. Your issue is going to be coverage. Draw out your coverage patterns - what will you need? Are you usually trying to cover the room along the long axis or the short, wider axis?

Risers will be usually on the long side of the room.
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John Penkala

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Re: VRX vs STX for Ballroom
« Reply #5 on: January 31, 2015, 07:59:59 AM »

Risers will be usually on the long side of the room.

        I would go with 4 speakers for this setup. You won't properly cover the 100' horizontal with 2. I normally use 4 EAW JFL210's for this type of setup. Depending on the client, sometimes I use 8 with subs, 2 per stick. Being that you are puting them on the ground, the 70deg vertical dispersion of the STX is mostly wasted. I would likely go with 4 VRX or EAW JFL's, although just about 4 of anything will work for your application. However, you will want a delay for the back speakers when you shoot the 100' direction.

JP

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Matt Vivlamore

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Re: VRX vs STX for Ballroom
« Reply #6 on: January 31, 2015, 11:52:28 PM »

I would take 4 VRX over 2 STX812.  The VRX is the king of small-medium corporate events.

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Ray Aberle

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Re: VRX vs STX for Ballroom
« Reply #7 on: February 01, 2015, 12:16:12 AM »

Any subs? If not, I would definitely shoot for 932LAs. If you do, I probably would still want the 932s, but you could swing by with the 928s.
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Randall Hyde

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Re: VRX vs STX for Ballroom
« Reply #8 on: February 01, 2015, 12:46:52 AM »

One other thing to consider:


VRX928LA -> 800w 100°x 15° [Sensitivity 90 dB @ 1w/1m]
STX812M -> 1600w 70°x 70° [Sensitivity 95 dB @ 1w/1m]

Don't know if the 90 dB figure is correct (though it comes from JBL's documentation). This suggests that the VRX cabinets would require almost 4x the power to achieve the same SPL (not that 95 dB sensitivity is very good, mind you).  I wonder if a pair of Danley SM80s would be sufficient here?
Cheers,
Randy Hyde
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Jonathan Betts

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Re: VRX vs STX for Ballroom
« Reply #9 on: February 01, 2015, 07:58:41 AM »

We use the SM 80 in a similar size ballroom for loud rock shows. Coverage is excellent, with plenty of headroom while using a modest size amplifier.
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ProSoundWeb Community

Re: VRX vs STX for Ballroom
« Reply #9 on: February 01, 2015, 07:58:41 AM »


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