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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => LAB Lounge => Topic started by: John Roll on October 05, 2013, 11:33:13 AM
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I recently got a pair of JBL PRX 635s to go on top of my QSC HPR181s. It became obvious that I need to raise them up. I got a pair of onstage speaker poles to go into the pole cup on the HPRs. The JBLs are way too high in the air now. I'm probably going to have to cut the poles down, but where do I want the max height to be (top of the JBLs) from the floor?
John
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I recently got a pair of JBL PRX 635s to go on top of my QSC HPR181s. It became obvious that I need to raise them up. I got a pair of onstage speaker poles to go into the pole cup on the HPRs. The JBLs are way too high in the air now. I'm probably going to have to cut the poles down, but where do I want the max height to be (top of the JBLs) from the floor?
John
How High is your way to high from the ground? Is it wobbly, unsafe?
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I typically position mains with the high frequency horns overhead and I'm 6'4", but depending what the room requires and the type of box I'm using they could go even higher than that.. sometimes it's beneficial to get the tops up really high and angle them down so an adjustable pole would be best.
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I always try to put the mains as high as safely possible if it's anything bigger than a "coffee house" kind of thing.
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I always try to put the mains as high as safely possible if it's anything bigger than a "coffee house" kind of thing.
+1, as high as is safe, tilted down. Tilting directs the sound at the audience instead of the ceiling. Up high makes the sound pressure slightly more even from the front to back of the room, e.g. instead of standing in front of the speaker 1 foot away and getting blown away, the speaker is 5 feet over your head and you are receiving a lower, off-axes sound pressure.
For starters, tilt so a line coming straight out the middle of the horn hits the middle of the audience (or the most important part of the audience) at ear level (standing or sitting), or wherever you want the 'best sound'.
Optimizing the tilt is a little more complicated because it depends on the actual off-axis response of the speaker, few speakers output a uniform frequency range over the specified horn angle. But a 'tilt to the middle of the audience', followed by walking around and listening will help you adjust the tilt.
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I hate to hijack here.But I have a similar problem with my EAW cabs. But mine have no pole sockets and I really don't wanna take a hole saw to my SB subs.
What would you guys use to get them up about 12-15" that looks a little more pro than Old Milwaukee Tavern cases covered in a blk bedsheet(done that befor LOL).
I want the Mid 15" about head level to me(6 foot).
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I hate to hijack here.But I have a similar problem with my EAW cabs. But mine have no pole sockets and I really don't wanna take a hole saw to my SB subs.
What would you guys use to get them up about 12-15" that looks a little more pro than Old Milwaukee Tavern cases covered in a blk bedsheet(done that befor LOL).
I want the Mid 15" about head level to me(6 foot).
I've seen people make plywood boxes with the same shape as the tops. Paint 'em black, they look nice. Could carry cables inside them...
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+1, as high as is safe, tilted down. Tilting directs the sound at the audience instead of the ceiling. Up high makes the sound pressure slightly more even from the front to back of the room, e.g. instead of standing in front of the speaker 1 foot away and getting blown away, the speaker is 5 feet over your head and you are receiving a lower, off-axes sound pressure.
For starters, tilt so a line coming straight out the middle of the horn hits the middle of the audience (or the most important part of the audience) at ear level (standing or sitting), or wherever you want the 'best sound'.
Optimizing the tilt is a little more complicated because it depends on the actual off-axis response of the speaker, few speakers output a uniform frequency range over the specified horn angle. But a 'tilt to the middle of the audience', followed by walking around and listening will help you adjust the tilt.
There are some fixed-position cabinet tilters out there, and a few adjustable ones. This one is the absolute best, because it maintains the existing center of gravity, but it's not cheap compared to the others.
http://www.bt-12.com/
I replaced the pole cup that I previously had in my sub with a screw-in base and rod from K&M (this has a metric M20 thread on the base and pole). The difference in stability is night and day and I'd never want to go back to a pole cup on both ends. K&M makes both a fixed rod and an adjustable rod, but neither has a "short" setting and you might have to have a machine shop mod it for you if the height is too much for your app. We played an outdoor pavilion a few months ago and barely made it with the clearance. Here are the K&M parts #s
K&M 21337 Adjustable distance rod (36"-57")
K&M 21334 Fixed distance rod (31-1/2")
K&M 24116 Speaker cabinet connecting plate
They also make a crank up adjustable rod, but I suspect it would be much more difficult to modify if it needed to be shortened.
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K&M makes a couple of poles that are adjustable. Even one that cranks up.
It makes life a bit easier and more flexible.
With poles-one size does not fit all.
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I've seen people make plywood boxes with the same shape as the tops. Paint 'em black, they look nice. Could carry cables inside them...
Hmmm cord box lift boxes,I think I like....
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I recently got a pair of JBL PRX 635s to go on top of my QSC HPR181s. It became obvious that I need to raise them up. I got a pair of onstage speaker poles to go into the pole cup on the HPRs. The JBLs are way too high in the air now. I'm probably going to have to cut the poles down, but where do I want the max height to be (top of the JBLs) from the floor?
John
I think you want them the height equal to the amount a Yorkville ES-115 placed face down on the sub raises them to.
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Hmmm cord box lift boxes,I think I like....
Make sure you all the cords you will need out of the boxes first.
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Make sure you all the cords you will need out of the boxes first.
You dont like lifting cabs 6 extra times I take? ;)
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You dont like lifting cabs 6 extra times I take? ;)
That's an easy fix. Make the cord box with a side-opening lid rather than a top-opening lid so you can get back in there if need be, with the speaker still sitting on top.
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While not a solution for everyone, I ran my tops like this for years: http://tcsys.com/production/html/o-frames.html This design was thought up by one of the guys at Polar Focus rigging, and it worked perfectly from the very first show.
Nowadays, I use my rack covers as spacers between my subs and tops: http://i303.photobucket.com/albums/nn135/timtrace/TC%20Systems/4QP3CXS7.jpg Custom-fabricated frames of 2" angle iron are used to center (and retain) the rack lids on top of the subs. When I need to angle a top box downward, I screw a 6" length of threaded rod into the mounting points on the bottom-rear corners of the top box.