Low ceiling, long room - delays or louder PA?

R

Randy Pence

Freshman
Oct 25, 2011
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6
Berlin, Germany
Hey all,

So in the next round of my house guy hustle I am getting involved with an artsy venue looking to branch out more into live music. The room in question has a 3m x 6m stage. FOH is about 10m back, and the back wall is about 15m from the stage. Where it gets tricky quite quickly is that the ceiling is about 3.45m.

Current PA is a set of ancient 10"/1" jbl sound power speakers, which would have basically worked, but a wall was removed to increase the dancefloor size. The owner wants to invest in a better system. An issue with the current system is that the highs are basically gone after 6m. The owner also had a pair of rcf art310a's to test with, and the same issue is there. I was not involved in the deployment of either. The subs are fine for now.

Potential powering is just a driverackPA and the available amps are nothing id want to depend on, so something like an inuke dsp amp for passive speakers would be ideal.

Would you guys recommend a louder top with a wide (say 60 degrees) vertical horn angle and/or delayed speakers? Based on the venue design, the delays would likely be 6m away from the stage, a few meters in front of foh. Music ranges from jazz to indie rock

Budget is ideally 2k€, but arrangements up to 8k€ can be done if it is special enough. I know this will be tough with new speakers, so i am scouring what is available used. Rider friendliness is not a concern, only potential resell value (i.e. nothing homemade, not matter how nice).

thx for any ideas
 
Re: Low ceiling, long room - delays or louder PA?

Randy Pence said:
The room in question has a 3m x 6m stage. FOH is about 10m back, and the back wall is about 15m from the stage. Where it gets tricky quite quickly is that the ceiling is about 3.45m.
An issue with the current system is that the highs are basically gone after 6m. The owner also had a pair of rcf art310a's to test with, and the same issue is there. I was not involved in the deployment of either.

Would you guys recommend a louder top with a wide (say 60 degrees) vertical horn angle and/or delayed speakers? Based on the venue design, the delays would likely be 6m away from the stage, a few meters in front of foh. Music ranges from jazz to indie rock
Click to expand...
Randy,

A 60 degree vertical will waste too much energy up close and in ceiling reflections.
A horn with about 25 degree vertical dispersion up as high as possible, pointed at approximately the mix position will cover well.

A 3.45m by 15m deep room with 3m taken up by the stage is not what I would consider low and long, can't see the need for delays there.
With narrow vertical coverage horns you can cover twice that depth without delays.

Art
 
Re: Low ceiling, long room - delays or louder PA?

Art, thx. i understand, and agree based on previous experiences. However, im still bewildered why the sound currently drops off so fast. Those 15m are all dancefloor, the stage is separate from that, but of course that is not a big difference in this case. I will be going in tomorrow and can do a bit more troubleshooting.

but 25 degrees? What else besides funktion one commonly uses such horns? A dsl sh-25 would probably not be right speaker for the room;)~;-)~:wink:
 
Re: Low ceiling, long room - delays or louder PA?

Art Welter said:
Randy,


A horn with about 25 degree vertical dispersion up as high as possible, pointed at approximately the mix position will cover well.


Art
Click to expand...
Assuming it is large enough to actually control the pattern-and a narrower pattern requires a larger horn. So size could start to be an issue.
 
Re: Low ceiling, long room - delays or louder PA?

Randy Pence said:
Art, thx. i understand, and agree based on previous experiences. However, im still bewildered why the sound currently drops off so fast. Those 15m are all dancefloor, the stage is separate from that, but of course that is not a big difference in this case. I will be going in tomorrow and can do a bit more troubleshooting.

but 25 degrees? What else besides funktion one commonly uses such horns? A dsl sh-25 would probably not be right speaker for the room;)~;-)~:wink:
Click to expand...
With the coverage area only 5m wide by 12m deep (after deducting the stage depth) the SH-25 coverage pattern (25 x25) would be better than the 90 x 70 RCF ART310A for your room.

After installing some Maltese high frequency horns to a "Shotgun Shack" club similar in dimensions to yours (though a bit deeper), the sound man was pleased, for the first time he could hear the highs clearly at the mix location in the back of the hall.
The 90 x 40 HF horns he had previously were putting too much of their energy on the reflective brick side walls and plaster ceiling, the direct to reflected ratio made it sound like there was no (useful) high end.

At the time I had been calling the Maltese a 30 x 30, after better measuring later found they are only about 15 x 15 above 1000 Hz, even tighter than the SH-25, which looks surprisingly similar.
 
Re: Low ceiling, long room - delays or louder PA?

Okay, feeling a bit silly. Went in last week and the rcf's were hanging. It wasnt possibly to play with the jbl angles, but with the hard ware provided for the rcf's, I could. I dont think a minute went by on my miles davis cd before i had already aimed and set the speaker with the cymbals doing their thing at hte back of the room.

The owner was quite happy that PA design wouldnt need to get complex.

While I get Art's point about not spilling onto the ceiling, a pair of sh-25s are simply not going to be a financially practical possibility. The owner is now hot for a different pair of active speakers (90x55 nominal dispersion) and the price is too good to pas up. If something else down the line will be a better solution, these can be used for dj monitors in one of the other rooms.

But Art, you don't think 25 degrees of vertical isnt a bit too narrow to cover the front rows? Stage wash can be a magical thing, but DIed instruments dont make much noise on their own. Many of the performances are seated, too.

I've been in dj systems engineer for over 13 years, and had come to favor wider vertical dispersion for hte given rooms and equipment I had available to work with. The requirements for what i consider a good dj/strictly electronic performance and foh based mixdown are different. Live mixing is still something im getting my head around the last 5 years or so, and virtually all of the rigs were heavily compromise somewhere, so im still learning what parameters to define for myself.
 
Re: Low ceiling, long room - delays or louder PA?

Well, the easiest way to work out what kind of vertical coverage you need is to either do some trigonometry, or draw a pretty picture to scale. You'll probably find that the recommendation of narrower vertical coverage is correct. Remember to improve quality and intelligibility you should try and minimise reflections.
 
Re: Low ceiling, long room - delays or louder PA?

Randy Pence said:
Okay, feeling a bit silly. Went in last week and the rcf's were hanging. It wasnt possibly to play with the jbl angles, but with the hard ware provided for the rcf's, I could. I dont think a minute went by on my miles davis cd before i had already aimed and set the speaker with the cymbals doing their thing at hte back of the room.

The owner was quite happy that PA design wouldnt need to get complex.

While I get Art's point about not spilling onto the ceiling, a pair of sh-25s are simply not going to be a financially practical possibility. The owner is now hot for a different pair of active speakers (90x55 nominal dispersion) and the price is too good to pas up. If something else down the line will be a better solution, these can be used for dj monitors in one of the other rooms.

But Art, you don't think 25 degrees of vertical isnt a bit too narrow to cover the front rows? Stage wash can be a magical thing, but DIed instruments dont make much noise on their own. Many of the performances are seated, too.

I've been in dj systems engineer for over 13 years, and had come to favor wider vertical dispersion for hte given rooms and equipment I had available to work with. The requirements for what i consider a good dj/strictly electronic performance and foh based mixdown are different. Live mixing is still something im getting my head around the last 5 years or so, and virtually all of the rigs were heavily compromise somewhere, so im still learning what parameters to define for myself.
Click to expand...
The thing that many people forget-is that the sound does not stop at the rated pattern-at any freq.

It is the point at which the level is 6dB down from on axis.

So you can be "completely out of the pattern" and still hear just fine. Granted some freq will be louder than others- and that largely depends on the size of the horn.

If the horn is large enough (always a good idea and seemingly forgotten these days) then all of the freq will roll off together.

This is a GOOD THING-when you are pointing the main axis at the rear of the room and have people up close. You WANT the level coming out of the speaker to be lower up close-because inverse square will be louder up close-so the two will "cancel each other out"-if everything lines up correctly.

The problem is that people are so used to small horns-when they get out of the pattern all the hear is the lower freq coming from the cabinet-that are not on a horn and spilling all over the place.

That is not a function of the pattern-but rather a function of a poorly designed cabinet that does not have the same pattern over a wide range of freq. A VERY common problem these days.

So if a narrow pattern horn is "blamed" for not having good coverage up front-then most likely it is the design of the cabinet (and lack of a large enough horn) that is to blame-NOT the pattern.

Kind of like using a #1 phillips screwdriver trying to drive a #2 phillips screw. You can't get enough torque. Don't blame the phillips-blame it on the fact you are using the wrong size.

Sadly these days very few people understand even the basic ideas about freq size-wavelength-interaction and so forth.

When you start to understand how it all relates together-it will start to make sense.

But hey-it is a lot easier to just stick your head int he sand and "believe" that the simple numbers on the spec sheet are the "truth" and they exist across all freq.

It is that belief that causes sound system "design" to fail-NOT the physics. The sound waves are just doing what they have done for thousands of years-but don't blame them if the "designer" does not understand how they work.

Once people start to realize that audio waves have SIZE and that SIZE MATTERS (in how you control it), THEN things will start to make sense.
 
Re: Low ceiling, long room - delays or louder PA?

Ivan, correct if I am wrong, but while the rated dispersion of a horn is at its -6 dB edges, this is not necessarily across its entire bandwidth (some frequencies may be further attenuated) and that pattern control may vary even more radically beyond the mouth? Thus the inverse square law would more relevantly apply within the horn's direct output. If narrower controlled dispersion is truly the way to go, there is a lack of affordable products for 300 cap. jv level rooms.

at any rate, i am not afraid of fire-safe broadband acoustic absorption options, which anyway cut down on audience noise.
 
Re: Low ceiling, long room - delays or louder PA?

Randy Pence said:
Okay, feeling a bit silly. Went in last week and the rcf's were hanging. It wasnt possibly to play with the jbl angles, but with the hard ware provided for the rcf's, I could. I dont think a minute went by on my miles davis cd before i had already aimed and set the speaker with the cymbals doing their thing at hte back of the room.

The owner was quite happy that PA design wouldnt need to get complex.

While I get Art's point about not spilling onto the ceiling, a pair of sh-25s are simply not going to be a financially practical possibility. The owner is now hot for a different pair of active speakers (90x55 nominal dispersion) and the price is too good to pas up. If something else down the line will be a better solution, these can be used for dj monitors in one of the other rooms.

But Art, you don't think 25 degrees of vertical isnt a bit too narrow to cover the front rows? Stage wash can be a magical thing, but DIed instruments dont make much noise on their own. Many of the performances are seated, too.
Click to expand...
Sounds like your installation job there is pretty much done, so the rest is academic :^).

A 25 x 25 degree coverage would work for a standing audience, but may require a center down fill for seated audiences.
The diagram below shows a 22.5 degree pattern (90 degree paper folded twice, cheap protractor).

But as Ivan wrote: "The thing that many people forget-is that the sound does not stop at the rated pattern-at any freq", so it is not like the sound "turns off" in that area outside the 25 degrees. So the front rows are -10 dB in the HF instead of -6 dB, it's too loud up there anyway...
The SH-25 has a large mouth, so it has control to a fairly low frequency, a small narrow horn (as in most two way top speakers) will diffract (and go wide) at a higher frequency.

There is a lack of narrow dispersion products for 300 capacity Junior Varsity level rooms because they actually would require high rigging and an understanding of how to properly aim the cabinets, which seemingly seldom happens at that level.

A wide dispersion speaker like you aimed in a minute is a lot more forgiving of alignment errors.
 

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Re: Low ceiling, long room - delays or louder PA?

Randy Pence said:
Ivan, correct if I am wrong, but while the rated dispersion of a horn is at its -6 dB edges, this is not necessarily across its entire bandwidth (some frequencies may be further attenuated) and that pattern control may vary even more radically beyond the mouth? Thus the inverse square law would more relevantly apply within the horn's direct output. If narrower controlled dispersion is truly the way to go, there is a lack of affordable products for 300 cap. jv level rooms.

at any rate, i am not afraid of fire-safe broadband acoustic absorption options, which anyway cut down on audience noise.
Click to expand...

Actually it is the opposite. If the horn is not large enough-then the lower freq will be louder than the -6dB point-hence the reason for loss of pattern control. THe horn is no longer controlling the pattern-so the lower freq are louder.

That is why the horn has to be large to do any control-at least down to a decently low freq.
 
Re: Low ceiling, long room - delays or louder PA?

Art Welter said:
Sounds like your installation job there is pretty much done, so the rest is academic :^).

A 25 x 25 degree coverage would work for a standing audience, but may require a center down fill for seated audiences.
The diagram below shows a 22.5 degree pattern (90 degree paper folded twice, cheap protractor).

But as Ivan wrote: "The thing that many people forget-is that the sound does not stop at the rated pattern-at any freq", so it is not like the sound "turns off" in that area outside the 25 degrees. So the front rows are -10 dB in the HF instead of -6 dB, it's too loud up there anyway...
The SH-25 has a large mouth, so it has control to a fairly low frequency, a small narrow horn (as in most two way top speakers) will diffract (and go wide) at a higher frequency.

There is a lack of narrow dispersion products for 300 capacity Junior Varsity level rooms because they actually would require high rigging and an understanding of how to properly aim the cabinets, which seemingly seldom happens at that level.

A wide dispersion speaker like you aimed in a minute is a lot more forgiving of alignment errors.
Click to expand...

Nothing new is hanging yet, so there is still some room for discussion. BTW, the room is 18m of total length. I might have earlier been unclear. Fill speakers would not sit well in the budget.
 
Re: Low ceiling, long room - delays or louder PA?

Ivan Beaver said:
Actually it is the opposite. If the horn is not large enough-then the lower freq will be louder than the -6dB point-hence the reason for loss of pattern control. THe horn is no longer controlling the pattern-so the lower freq are louder.

That is why the horn has to be large to do any control-at least down to a decently low freq.
Click to expand...

That is sorta the issue in my reasoning. At this price level, the hf horn will end up meeting a direct radiating woofer, which will almost certainly have a different dispersion. My rationale has been to get something with wider dispersion up as high as possible to take advantage of the inverse sq rule and an even frequency response both near the stage and into the room.

We are looking around at possible used fully horn-loaded speakers (say turbosound, martin w8c, etc). I've been in contact with the german danley distributor, but used danley cabs seem even scarcer in europe and new pricing is out of our range.
 
Re: Low ceiling, long room - delays or louder PA?

Randy Pence said:
My rationale has been to get something with wider dispersion up as high as possible to take advantage of the inverse sq rule and an even frequency response both near the stage and into the room.
Click to expand...
Notice in my sketch in #14 that the punter in the front row is at the -6 dB point of coverage, while the back of the room is on axis, -0 dB.
This evens out the inverse distance drop.

With a wide dispersion horn, the punter (and the side walls, floor and ceiling) in front gets blasted with nearly the full level of the HF, so the relative response is weaker in back compared to the front, and the direct to reflected level greatly reduced.
 
Re: Low ceiling, long room - delays or louder PA?

Art Welter said:
Notice in my sketch in #14 that the punter in the front row is at the -6 dB point of coverage, while the back of the room is on axis, -0 dB.
This evens out the inverse distance drop.

With a wide dispersion horn, the punter (and the side walls, floor and ceiling) in front gets blasted with nearly the full level of the HF, so the relative response is weaker in back compared to the front, and the direct to reflected level greatly reduced.
Click to expand...
That is just part of sound design 101-the basics. Yet the whole concept is beyond most people.

They forget that the level drops with distance-so the loudest part of the signal HAS to be pointed at the furthest listener. Then as you move closer the distance gets shorted-so the level out of the loudspeaker needs to be quieter (ie in the part of the horn that has less output) for the levels to be equal.

This way you get even coverage from front to back-IF that is what is intended. If that is NOT the intention-then one needs to accurately define what they want (they also like to forget that part and go with what others think about a particular product-whether it is right or not for the room/application).

It is amazing to me how many people say they want 1 level of performance and then settle on something completely different-because they got a deal on it.

So the original criteria wasn't important anyway then was it?

Don't say you want a sports car that can go from 0-60 in 5 seconds (and get peoples opinions from the internet)-and they buy a used minivan because "you got a good deal".

Not the same thing. But it happens all the time. You FIRST have to decide your budget-THEN start looking at what does the job and fits in the budget.
 
Re: Low ceiling, long room - delays or louder PA?

Art Welter said:
Notice in my sketch in #14 that the punter in the front row is at the -6 dB point of coverage, while the back of the room is on axis, -0 dB.
This evens out the inverse distance drop.

With a wide dispersion horn, the punter (and the side walls, floor and ceiling) in front gets blasted with nearly the full level of the HF, so the relative response is weaker in back compared to the front, and the direct to reflected level greatly reduced.
Click to expand...

what about the range below the horn xover frequency?
 
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