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Old 25th April 2010, 05:13 AM   #1
taj is offline taj
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Default A Club Band PA system

About a hundred years ago I was a soundman working for a small concert sound company, and over the 15 yrs I did that, I estimate that I mixed about 2700 performances of every description in every type of venue one can imagine from very large concerts to theatrical tours to (ahem...) hair salon openings. A bunch of those shows were in nightclubs and I always considered clubs/pubs to be the worst case scenario for mixing live bands, particularly for loud 70's/80's rock bands whose stage volume was so high. The variables at play hindering good sound in that situation are truly daunting.

Besides the high stage volume, a major problem was using PA system modules designed for concert venues or at least venues quite unlike the night clubs they were being used in. There didn't seem to be any suitable PA systems designed specifically for clubs. This has always nagged at me. Now there are probably lots of solutions out there, but it would be a fun mental exercise to design a DIY club band PA system that answers to the many challenges.

This thread is about overcoming those particular challenges in a DIY brainstorming session. I'm hoping to get the input of other experienced live sound mixers and pro sound engineer types. I don't know if many pro sound folks hang around here, but I guess I'll find out. I've suggested/requested a separate Pro Sound forum on DIYaudio but it hasn't happened yet.

Such a PA would probably suit DJ use as well, but I have no experience with that so I won't go too far down that road. But I think the final solution would certainly kick butt for DJ purposes as well.

Luckily pro sound technology has come a long way since I 'got a life' as my wife puts it. The internet gives us tons of great driver suppliers, access to copious product information, valuable expertise and even research data. Computers give us scads of great software to design and model audio systems and do the math for us. So in that sense DIY is infinitely more do-able now than it was in the 80's. Back then we could only clone existing designs that we did not understand the theory behind. My, how times have changed!

Here are some basic requirements for a club band PA that I would like to discuss...

1. Loud/Clean/Accurate. Club bands can still be very loud. The PA must produce & tolerate high output with as little [audible] distortion as possible, and maintain fairly flat reponse throughout the range of say 40Hz to 16KHz. It doesn't have to be used loud, but must handle that as a constant.

2. Versatile. Night clubs come in ALL shapes and sizes; no two are alike. Speakers must be able to be positioned such that they cover -- as evenly as possible -- long/narrow rooms, shallow/wide rooms, L-shaped rooms, C-shaped rooms, trapezoids, multi-levels, etc., etc. The audience can be seated ANYWHERE -- including behind or above the band. Structural posts and large mirrors can be anywhere. Walk-up bars that need to be kept quieter (or at least off-axis) so the bartender can hear the orders, can be anywhere. It's a complete crapshoot. Clubs will usually have a pre-determined PA stack area that must be used. Sometimes there is some wriggle-room there, but not usually too much.

3. Compact. The PA needs to be set up and torn down often, and transported to the next gig -- with the least amount of expended calories and pulled muscles. Long, steep staircases are frustratingly common. Self-levitating would be ideal, but a relatively small and light form factor is a good goal

4. Narrow vertical dispersion. Club ceilings are typically quite low with hard reflective surfaces. It's imperative that we keep as much sound (mid/highs) from reflecting off the ceiling back into the main audio 'beam' in order to reduce all sorts of nasty sounding interactions.

5. Ideal height. It must have the midrange and high frequency drivers above audience head-height so the mid-highs are not absorbed by, for a common example, people dancing directly in front of the speakers. And again it cannot be too high because there usually isn't a lot of ceiling height available. 8 ft ceiling minimum, 10-12 ft is probably more typical.

So that's the basic criteria. Next up, my first kick at the can.
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Old 25th April 2010, 05:16 AM   #2
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Here's a conceptual design that I came up with that deals with those criteria as best I know how. Bear in mind the actual construction and component brand specifications are somewhat irrelevant at this stage; it's a higher level conceptual plan -- just kicking ideas around.

It's a 4-way active system. I would personally prefer a DSP based (digital) crossover for its vast control and versatile capabilities. The subs aren't considered in this post but you can assume they exist. So low-mid, high-mid and highs are combined into a single enclosure as shown in this drawing. The cabinet, when stacked onto the subs, ends up with most of the mid-highs above the 6 ft height. Trapezoidal vertically standing cabinets will allow versatile horizontal splaying configurations. Two or even three side-by-side would cover a lot of horizontal area if needed. I've assumed one stack will go on each side of the band's stage. Flying a club band PA is rarely practical unless it's a semi-permanent installation. But one-nighters were a very common occurence in my career, so I'm going with quick and simple stacks. There simply isn't time to get fancy.

I chose a front-loaded sealed 15" low-mid driver primarily to handle the power and output level of the range between say 120 to maybe 700 Hz. I want to avoid the ragged cone breakup mode region above that.

The high-mids will be four 6" pro sound drivers (maybe from B&C or 18-Sound, etc.) arranged in an MTM configuration with the high freq. drivers. This to provide a tighter vertical pattern. They will handle the range from 700 Hz up to maybe 2-3K where those driver's break up modes start to get ugly.

For high's I used a pair of vertically stacked 1" throat compression drivers mounted onto elliptical OS waveguides. 1" drivers extend the response upwards better than 2" throat compression drivers, which don't go high enough for my taste. I don't like them without tweeters, and I don't want to go there. So I stacked 2 such driver/waveguides to couple and produce/handle the high level.

I greatly prefer the sound of front mounted, direct radiating cone drivers, that includes the subs. They just sound much better to me than any horn, scoop, W, or whatever other configuration I've used. And since the venue is small compared to a concert, we simply don't need the efficiency gained by those configurations. I've used everything known to man I think, and direct radiating always wins out for my taste. (Your mileage may vary).

I used waveguides (ala Geddes) here rather than any other HF horn configuration, because I believe the science behind them is sound (bad pun sort of intended) and I have a great respect for Earl Geddes' research and experience. Having said that, I've never used them, but I have used every size, shape and form of traditional horn and they ALL sound spitty and harsh if given the opportunity. Actually getting one's hands on an elliptical OS waveguide may be quite a challenge, but this is just conceptual, and DIY, so I'm going with it.

And since this is conceptual, money is not a big object yet. If it ever comes time to build one, then compromises will necessarily start to appear. For example, the price of those 6" drivers will add up quickly if one decides to build 4 of these enclosures.
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Old 25th April 2010, 05:18 AM   #3
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The sub is simply a pair of 18" LF drivers front-mounted into a vented rectangular box. The tricky part here is to find just the right driver to give us the LF extension, excursion capability and power handling in as small a package as possible. The driver T/S parameters would necessarily have to provide us with suitably large diameter vents that are of reasonable length. So four vents (2 per driver) of maybe 4" diameter and some reasonably short length (under say 10").

Neo magnets would be nice to keep the weight down. But I've heard they are unstable in cold temperatures, so winter touring in the back of a truck might be a problem. I don't know anything more about this. That's all I've heard, though it did come from a respectable E.E.

That's not too much to ask is it? McCauley used to offer a perfectly suited driver for this design, but I see they have recently dropped that particular model, and their others don't quite suit this box. I like McCauley drivers. The ones I have used were exceptional. But there are plenty of other brands to model into this box.

One alternative to this design is to split the cabinet into 2x single driver boxes. That would provide more versatility in case you need to (or want to) scatter the subwoofers around the venue to help reduce room mode cancellations. That is usually not practical in-situ but would be a nice option to have on occasion. I have experienced one or two clubs whose room modes made developing any LF response almost impossible. It's a very frustrating problem when you have neither the time nor the resources to adequately deal with it.
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Old 25th April 2010, 05:24 AM   #4
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My first question would be: Could we employ lobing to provide a downward tilt to the mid-highs? How?

..Todd
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Old 25th April 2010, 06:11 AM   #5
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Before anyone mentions it, yes, you can assume the midrange cone drivers will be isolated into their own sealed air space.

..Todd
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Old 25th April 2010, 08:16 AM   #6
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well ...in another life ..... let us say real life PA life and not the one your wife has in mind ( he he ) your system will not make it for a number of reasons ....

i think one will be the midle .... designing the satelite as a 3 way will stress the midle that actually may present a flat responce ( as a total speaker ) from to.... but in real life and especially in rock band either the midle units have to be made out by something really speciall or they will fail after presure or abuse

most of systems are designed ( in this level of power ) as 2 way and try to share the load of midle between a 15" low mid bass and 1-2" driver .... this will not be exactly flat but doesnt make any sense anyway since human hearing will understand it as flat ...

then again stacking everything on a top of each other will never achive the "disipation" of line arey .... meaning that the person that is located 3 meters away and a bit to the left or right of a speaker stack will not hear much ... ( situation quiet common in smaller clubs )

this types of enclosure will guaranty very nice sound in a club where size of venue is a fact, location of speacers is also a fact , sweet spot importand as for a dance floor is a fact , and probably some more satelites to cover details around here and there is a fact.... xmmmmm also design like that will happily work for disco house or anyother of this type of music but not rock or heavy metal bands ....

JBL has systems as small line areys where how high ,pan and tilt is adjustable (probably other companies also) that will make the system versatile to fit almost any venue now JBL was never the company for good rock sound but i will setle with the fact that sound is perfect for club music ....


kind regards sakis
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Last edited by east electronics; 25th April 2010 at 08:19 AM.
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Old 25th April 2010, 01:11 PM   #7
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Well you got my interest. Since you mentioned Earl Geddes I'm curious to hear why you don't think his Summa would make a good PA speaker? I don't know much about PAs but I always thought his design looked like the ones I usually see at local shows.
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Old 25th April 2010, 04:07 PM   #8
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Hi,

Geddes' speakers are, in a sense, domesticated PA speakers. There are "professional" versions of Geddes' speakers, look at Audio Intelligence.

As for OP design, 1 HF horn per speaker will sound better and will keep up easily with the rest. Also, two 8" instead of four 6,5" would be better sound-wise, most pro 8" can be crossed at 2...3 kHz with no problems. Another option is to use really high-efficiency 6,5" and only two of these, crossing at 3...4 kHz to a smaller horn - Ciare 6.38MR3 has the sensitivity of 100 dB and takes 100 W, 2 of them would certainly keep up with one 15" low-mid and have potential to sound very nice. I would also make hi-mid and low-mid as separate boxes - easier to move around and stack up, and more configurable. Though it does look a bit old-school in the age of "PA-on-the-stick".
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Old 25th April 2010, 04:23 PM   #9
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Sakis,

Line arrays will not meet the requirements. They would only work in a club if it has a nice symmetrical design (like a concert) with the stage located at the center/back and the audience is where you want them to be. That NEVER happens. They would also have to be very small arrays so you could use lots of them aimed in every direction, that's not practical. Line arrays just are not versatile enough for club band use.

There is no problem with using good 6" pro mids. Some of my old sound company's largest concert line array boxes use four 8" cone drivers (from PHL), and they are used for MUCH larger venues. You obviously cannot use cheap drivers there, but B&C, 18Sound, PHL, etc. no problem. The frequency range these ones will operate in is very comfortable for them. Not much below 500 Hz. No real excursion required.

Hi Poptart,
That's a good question. Earl's current products are not really designed for this purpose. The round waveguide would provide too much vertical dispersion, bouncing too much sound off the ceiling. That's not a big problem for home theatre where you can tilt and aim them exactly where you want them. But it's a big problem for club band use; tilting them downward is not easy to do in club without flying them or putting them in a dangerous precarious position.

Also, I would rather not use a passive crossover for power levels this high. At power/volume levels this high, it's important to break up the spectrum into more/smaller ranges to spread out the load and operate each driver well within its comfort zone.

I would love to have Summa's in my home theatre though.

..Todd

Last edited by taj; 25th April 2010 at 04:31 PM.
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Old 25th April 2010, 04:56 PM   #10
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Quote:
Originally Posted by technofreak View Post
Geddes' speakers are, in a sense, domesticated PA speakers. There are "professional" versions of Geddes' speakers, look at Audio Intelligence.
They seem to be commercially produced identical products to me.


Quote:
As for OP design, 1 HF horn per speaker will sound better and will keep up easily with the rest.
I haven't done the arithmetic, but intuitively that doesn't sound correct (the keeping up with the rest part, I mean).

Quote:
Also, two 8" instead of four 6,5" would be better sound-wise, most pro 8" can be crossed at 2...3 kHz with no problems. Another option is to use really high-efficiency 6,5" and only two of these, crossing at 3...4 kHz to a smaller horn - Ciare 6.38MR3 has the sensitivity of 100 dB and takes 100 W, 2 of them would certainly keep up with one 15" low-mid and have potential to sound very nice.
Two 8" drivers in this MTM configuration would be somewhat better for sound (dispersion pattern and phase interactions) but would provide less output, handle less power and not make as efficient use of the available baffle area. The Ciare drivers are certainly equivalent to what I was thinking about. They are pretty typical of high-end Pro Audio drivers.

Quote:
I would also make hi-mid and low-mid as separate boxes - easier to move around and stack up, and more configurable. Though it does look a bit old-school in the age of "PA-on-the-stick".
I thought about that too. But I couldn't think of a situation where they would not stack exactly under the rest. And it would mean more trips to the truck, but obviously smaller/lighter trips. It's a trade-off worth considering, but then I thought about carrying versus rolling on wheels and went with the low-mids included.

Old school in looks only. Any PA on a stick configuration is not going to handle the huge power/volume requirements. Speaker technology has advanced a lot, but only in refinements (Neo magnets, carbon fiber or Kevlar cones, waveguides over horns, etc.), but drivers are still the same approximate size as they were in the 80's. But this system is easily HALF the size of the 80's equivalent.

I mentioned earlier that club band PA's used to use concert gear for club use. That was big and bulky -- horn loaded mids, etc. That part has evolved a lot. And concert gear has also evolved a lot, but there's not much there we can re-purpose (See my comments about line arrays) for club band use.

..Todd

Last edited by taj; 25th April 2010 at 05:12 PM.
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