Need more head room, long, narrow room

Lisa Lane-Collins

Lisa Lane-Collins

Sophomore
Dec 9, 2012
270
0
16
Adelaide, Australia
At present using two JBLPRX615s and two PRX618S-XLFs (placed together, centre stage) in a long narrow room, capacity 200 (rarely full), maybe 10 metres across, 30 or 40 long but already needing more volume 10 metres from foh at the mix position.

My wish rig for this room will be much louder speakers but I am about $4000 away from being able to buy that, so, in the mean time, I have a spare 615 lying around, I could buy one more and mount two aside, the main set back for this would surely be that, with the speakers next to the wall, I'm getting a lot of sound dispersion to the sides that's just hitting the wall and going nowhere. (Turning the speakers in, towards the centre seems like not so much of an option because I also need the sound to carry down to the back of the room.

An advantage to the two aside might be that, at the same volumes, no speaker is working as hard as the present two have to, and also, with each box well within it's comfort zone so to speak, in theory, everything will sound nicer.

The disadvantages would surely be more boxes adding issues with filtering and all that wasted energy going out to the sides, so, further thoughts were, maybe I should mount the two a side, have the outer two pointing to the back of the room, and the inner two turned in more towards the area in front of the stage.

The other alternative I suppose would be mounting speakers at intervals down the length of the room and putting them on a delay, I've hesitated with this one because from 10 metres onward, one side of the room is all bar, having additional sound sources there would surely make it harder for the bar staff to take orders. I really just want the person standing at the mix desk to find their desired volume before the master fader reaches unity.

What's the best approach?
 
Re: Need more head room, long, narrow room

With the equipment that you've got using delay is the best approach. Maybe you can aim them away from the bar. Even a single speaker mounted 10 meters forward of the stage could help a lot at the back of the room.
 
Re: Need more head room, long, narrow room

Sounds like you are describing a bar - where it's not always particularly desirable to have uniform SPL from the front to the back of the joint.

Punters that want to listen at a loud volume can get closer to the stage, and those that don't can be more comfortable toward the back of the room. Toeing the speakers in a bit, to help with clarity, seems like a good thing to try, too.
 
Re: Need more head room, long, narrow room

Lisa Lane-Collins said:
already needing more volume 10 metres from foh at the mix position.
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You should be easily hitting 105dBC at 10 meters - if not you are doing something wrong. Are you freaking out when the clip limit lights flash once in a while and turning down? And definitely toe the mains in a bit (it won't appreciably affect their "throw") - and have their bottoms at head height. There's a bunch of silly advice floating around that you only have to have the horns above people's heads, that's BS.
 
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Re: Need more head room, long, narrow room

I agree that the room doesn't necessarily need full sound front to back. If it were me, I'd just relocate the sound booth closer to the mains. With my DL1608, that's as easy as walking a few steps forward. Also agree that you should mount the tops very high, and point them in just a bit, to match the power-alley coming from your subs. I haven't tried the "tilt-down" method yet, but plan to the next time I'm in a loud, ambient room.
 
Re: Need more head room, long, narrow room

The PRX615M is a nominal 90 degree horizontal box. With a long, narrow room you definitely don't need even that wide a pattern, much less wider, so you're apparently talking about both boxes greatly covering the same area. That would theoretically provide a nominal 3dB increase at most frequencies along with some resulting combfiltering. Getting a single box up higher and aimed down at the listeners so that you direct more of the energy at the listeners as well as potentially reducing the difference in levels from the front-to-rear seems to be a much more effective solution.

The PRX615m is supposedly capable of a peak output of 135dB at 1m as a full range box, so at 10m that should be 115dB, probably greater than when used with subs and with the spill hitting the side walls. The two PRX618s-XLF are supposedly capable of 133dB peak, with them clustered together in a typical space that would be greater than 119dB at 10m. I don't know how dynamic your sources are or what headroom you're leaving but do you really need much more than those levels?
 
Re: Need more head room, long, narrow room

Brad Weber said:
Getting a single box up higher and aimed down at the listeners so that you direct more of the energy at the listeners as well as potentially reducing the difference in levels from the front-to-rear seems to be a much more effective solution.
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Tilting the speaker down can result in more sound towards the front and less at the back. I only use tilters if I want to "light up" the dance floor but let folks in the back converse easily - private parties tend to want that.
The PRX615m is supposedly capable of a peak output of 135dB at 1m as a full range box, so at 10m that should be 115dB, probably greater than when used with subs and with the spill hitting the side walls. The two PRX618s-XLF are supposedly capable of 133dB peak, with them clustered together in a typical space that would be greater than 119dB at 10m. I don't know how dynamic your sources are or what headroom you're leaving but do you really need much more than those levels?
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Generally the actual SPL with music ends up about 10dB below the "peak" rating - hence my earlier post that she should be seeing 105dB at 10m no prob even outdoors free-field. Something else going on here for sure...
 
Re: Need more head room, long, narrow room

Ron Kimball said:
Tilting the speaker down can result in more sound towards the front and less at the back. I only use tilters if I want to "light up" the dance floor but let folks in the back converse easily - private parties tend to want that.
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If you get a speaker up higher and tilt it down so that the speaker is aimed at or near the back of the listener area then due to affecting the distances involved and off-axis effects that can typically provide more even front-to-back coverage. If you tilt the speaker too much then you may get the scenario you note with increasing levels up front and decreasing levels in back, but that is not what is being suggested.

Think about it, if you take the furthest listener from being some amount off-axis with the speaker pointed straight out to their being on-axis with it tilted down then you are increasing the level the furthest listeners receive and that is often more of an increase than the associated change up front. When you raise the speaker and tilt it down you also typically direct more of the speaker's output at the listeners and less at the walls and ceiling.

This is the concept behind flying speakers to get better coverage, get the speaker up higher to minimize the difference in distance, and thus the losses related to those distances, from the speaker to the various points in the listener area and then tilt the speakers down to use the speaker pattern to compensate for any remaining differences in distance and loss. All while trying to keep the majority of the speaker energy directed at the audience where you want it and reducing the energy aimed at the ceiling and walls where you usually don't want it.

Ron Kimball said:
Generally the actual SPL with music ends up about 10dB below the "peak" rating - hence my earlier post that she should be seeing 105dB at 10m no prob even outdoors free-field. Something else going on here for sure...
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A 10dB crest factor is reasonable, but it could range from 20dB+ for some very dynamic music to 3dB or less for heavily compressed music.
 
Re: Need more head room, long, narrow room

Brad Weber said:
If you get a speaker up higher and tilt it down so that the speaker is aimed at or near the back of the listener area then due to affecting the distances involved and off-axis effects that can typically provide more even front-to-back coverage. If you tilt the speaker too much then you may get the scenario you note with increasing levels up front and decreasing levels in back, but that is not what is being suggested.
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We were talking about tilting on stands I think - nobody mentioned flying. Do the trig to calculate what tiltdown angle you need to aim at the ears of someone 40 meter back with a horn only 8 feet up off the floor at most - it is pretty close to zero (~1.4 degrees actually).
 
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Re: Need more head room, long, narrow room

Ron Kimball said:
We were talking about tilting on stands I think - nobody mentioned flying. Do the trig to calculate what tiltdown angle you need to aim at the ears of someone 40 meter back with a horn only 8 feet up off the floor at most - it is pretty close to zero (~1.4 degrees actually).
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Lisa has never given us the ceiling height of this venue, but I'd guess (given the other dimensions) that there's a good chance of at least a 10 foot ceiling, possibly more. But let's work with your "horns at 8 feet" spec.

The 615's have a nominal 50 degree vertical pattern. Your given figure is for directly on-axis sound. The actual pattern is more forgiving than that. The difference will tend towards the LF/HF balance at the rear. So I wouldn't worry a whole lot about the degrees of the tilt. The salient factors are height, angle, pattern control and SPL. Pattern control and SPL are set, so work with the height and the angle. And if you really must have more beyond this, delays are in order.
 
Re: Need more head room, long, narrow room

Ron Kimball said:
We were talking about tilting on stands I think - nobody mentioned flying. Do the trig to calculate what tiltdown angle you need to aim at the ears of someone 40 meter back with a horn only 8 feet up off the floor at most - it is pretty close to zero (~1.4 degrees actually).
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Its not just a matter of aiming at their ears. A lot of the benefit of the down tilt to put the extra sound into the bodies where it can be scattered instead of having it reflected off of the ceiling and back wall.

I tend to shoot for the top 5 degrees of the horns pattern to be just above head height by about 1 foot at the back of the listening area. I think it is more appropriate to calculate the angles with the edge of the coverage pattern rather than the center of the coverage pattern. With most SOS setups, this gives more down tilt than most people would think is appropriate with their eyes.

One benefit of coaxial designs, that I don't think I have ever seen mentioned, is that a box that is not as tall is easier to get higher in a room with a lower ceiling.
 
Re: Need more head room, long, narrow room

Ron Kimball said:
So, you'd downtilt 90x45 mains by 20 degrees assuming the horn was one foot above head height?
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I would down tilt the speakers by what I thought was appropriate to the room size, ceiling height, audience location, seated vs standing, speaker characteristics, security/stability of the speaker on the stand, and a whole raft of other reasons. The fundamental idea remains increase the direct sound on the audience and reduce the reflected sound. I also want to consider where the front of the audience is.

Your 40 m example is a little extreme for covering on a SOS gig. If you have the horn just above ear height and want any level at all at the back of the audience, the front of the audience is going to be ear searingly loud. Increasing the height and adding down tilt moves the speakers farther from the front of the audience, without greatly increasing the distance to the back of the audience.

When I walk into a SOS gig as a fast one off show I would place my speaker stands to define the stage or performance area, raise the speaker as high as I can (I use TS99 stands) and then aim the center of the coverage pattern at the center of the audience area, and then confirm that both the back and front of the audience area are within the coverage patterns. For a SOS gig, the combination of Balanced tilters and the 7.5 built into the K series gives me 19.5 degrees of tilt to play with, and at times I feel like I would like some more tilt.

If your were to start with the speaker flat, with the horn at 7 feet, a person with their ears at 5 feet would have to be 5 feet back from the speaker to be within the coverage angles (as if that was actually a hard and fast edge) and the sound would have to travel about 5.5 feet. A person in the back of the room with ears at 5 feet, 75 feet from the speakers, would still be under the center line of the horns coverage and the sound would travel just a fraction over 75 feet to their ears. In other words, you are using less than 1/2 of the horns coverage pattern for covering the audience.

Changing to a 20 degree down tilt, with the speaker still at the same height, still leaves the person in the back of the room in the coverage pattern with the sound traveling 75 feet. However, the person at the front of the audience is at the coverage pattern when they are 2 feet back from the speaker instead of 5. But that for that person the sound is only traveling just under 3 feet.

My preference would be to raise the speaker to a minimum of 9 feet. At 9 feet, a person standing 4 feet back from the speaker is still at the edge of the coverage, but the sound is traveling almost 6 feet. The same person that was standing 5 feet back from the flat fronted speaker at the edge of the pattern is now well within the pattern and the sound is traveling 6.5 feet.

None of these changes significantly change the coverage pattern or the distance the sound travels at the back of the room. In addition, each degree of down tilt moves the point at which the HF reflects from the ceiling back in the audience, which may seem to reduce the overall level in the rear of the audience, but definitely helps with clarity.

Or for anyone seeking quick and dirty logic, if you can cover the audience with the speaker flat fronted only using the bottom half of the horns coverage, why couldn't you cover even more using the whole of the horns coverage?
 
Re: Need more head room, long, narrow room

Jay Barracato said:
If your were to start with the speaker flat, with the horn at 7 feet, a person with their ears at 5 feet would have to be 5 feet back from the speaker to be within the coverage angles (as if that was actually a hard and fast edge) and the sound would have to travel about 5.5 feet.
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Having the folks up front "out of the coverage area" is a good thing IME if looking for even coverage with just a pair of SOS. I do understand all of what you are saying, but still contend that you will get the most even coverage front to back by having the speakers near untilted when you don't have the height to "go tall". The OP never came back (are we that scary? LOL) but I'm assuming from what little she posted that is what she's wanting. I'd tilt to keep the sound up front when folks want it quieter in the back - which is almost always the case except at a sit down concert. Usually it's only the band, groupies and soundguy that think everyone in the joint wants it "rock concert" loud LOL.
 
Re: Need more head room, long, narrow room

Ron Kimball said:
Having the folks up front "out of the coverage area" is a good thing IME if looking for even coverage with just a pair of SOS..
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HOWEVER!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

They may be out of the pattern of the HF horn-but WILL be IN the pattern of the low freq device.

THEREFORE the sound quality will be very muddy (all lows and maybe some mids and no highs) At least not enough highs to keep up and balance with the lows.

That theory only works IF the horn is large enough to have good low freq control-and THAT is coming via a PA on a stick.

You HAVE to look at the whole freq band and NOT just a small part of it.
 
Re: Need more head room, long, narrow room

If you're using a pair of SOS to cover a big room, not icepicking the folks up front is IMO more important that it being a bit muddy up front. In reality there's a fair amount of HF bounce off the back wall from the monitors and the horns don't brickwall past their stated coverage angles. If this was the Varsity forum and/or we were talking about a mega $$$ install that'd be a different conversation ;)~;-)~:wink:.
 
Re: Need more head room, long, narrow room

Ron Kimball said:
If you're using a pair of SOS to cover a big room, not icepicking the folks up front is IMO more important that it being a bit muddy up front. In reality there's a fair amount of HF bounce off the back wall from the monitors and the horns don't brickwall past their stated coverage angles. If this was the Varsity forum and/or we were talking about a mega $$$ install that'd be a different conversation ;)~;-)~:wink:.
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I really don't see the point of your debate. What forum we are in has nothing to do with using all the available tools and knowledge to get the best setup possible.

You might not mind mud directly in front of the stage. I do. My experience is that is where the people who care most about the band will end up. If you want any vocals to be heard or understood at all you need that HF coverage. If your system is properly setup there is not additional ice pick in the HF close in because the HF should be balanced to the LF, and as I showed with the math above, just a couple of extra feet in height actually moves the audience back from the speaker.

Relying on bleed from the monitors is a loosing game in these days of IEMs.

As I said before, aligning the axis of the horn parallel to the floor, if it is symmetrical, puts half of the energy it puts out into the ceiling and back wall. In my mind that is wasted energy.
 
Re: Need more head room, long, narrow room

Jay Barracato said:
You might not mind mud directly in front of the stage. I do. My experience is that is where the people who care most about the band will end up.
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IME that's where the event planner will put the old folks who would rather not hear the band at all x(~:dead:. I do use tilters and front fills on occasion when they are called for - almost never at a private party. If you ever get down to the casinos in Ct the Wolf Den at the Mohegan Sun has this bigarse line array focused on the mix position. The dance floor is out of it's pattern and would be fine if they didn't have the front fills almost off as are the fills off to the sides :?~:-?~:???:. Another compromise situation where it is in the middle of the casino floor and open on all sides. Sounds great at FOH though :D~:-D~:grin:. As far as wasted energy, who cares unless your speakers are crap or you need reflection control in a bad room - the OP mentions nothing about it being a gymnasium sounding room. In a bar I'm usually most concerned with steering sound away from the bar - the staff seems to appreciate that :)~:-)~:smile:. Nothing's ever perfect unless you are involved in the design of the room and have megachurch type $$$ to "do it right".
 
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