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Best way to run a 4 channel amp/speaker PA?


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Hey guys,

I'm helping out a guy at work who is setting up a PA/Sound system for an office.

He wants to run 4 speakers and be able to use 2-3 mics, and a couple line level stereo music sources. It needs to be fairly simple and easy to use. The best part is he already started ordering parts. Fortunately they're all returnable if necessary.

He got a Sure combo wireless mic package which is cheap, but should be fine.
http://www.bhphotovideo.com/c/produc...bo_System.html

DBX DriveRack Processor (overkill? no preamps)
http://www.bhphotovideo.com/c/produc..._Complete.html

Crown XLS1000 Power Amp (stereo, not 4 chan)
http://www.bhphotovideo.com/c/produc...re_Stereo.html

(4) Klipsch PA speakers (85W, 6.5" + horn drivers)
http://www.crutchfield.com/p_714AW65...te.html?tp=188

The room is 75ft wide and 100ft deep open space with at least a 20ft high open ceiling.

The problem we face is that (as far as i can tell) the DBX has no mic preamp. It's also probably quite a bit overkill for his application. I'm suggesting he return it and get a simple mixer with built in mic-pres like a Mackie VLZ. This should all how to easily connect all his input devices and easily use the faders to control volume. The only problem is that most only have a single stereo main output. Assuming he wants to be able to fade the speakers front/back, is there an easy way to do this so that controlling the fade or rear volume is clear? Ie, i don't know if he'll know how to work Aux sends or something.. a nice clear fader set for front an a set for back would be nice.

OR, maybe use some kind of very simple 4 channel sound processor with a basic 4-chan mic preamp? Any suggestions on this front?

I'll talk to him about the need for fading. If not we can maybe gang up speakers on his two channel amp. Otherwise he'll need a second amp or a 4-chan of course.

Thanks!

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Make it much easier. Get a little Yamaha MG124C and 4 powered speakers. Run the mice on 1,2,&3. Then run the stereos into the rest. And if these speakers are going to be spread out mono would be the best way to set it up. Run the front speakers off the main out and the rears off of an aux. Quick, easy, and much cheaper than what he bought so far.

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OK, I'll take a whack at this.

1. If I understand correctly, the primary purpose is to allow the boss to make announcements to everybody in the office at once. The secondary purpose is to have pre-recorded "background" music playing when announcements are not being made. How often are announcements likely to be made? Daily, hourly, or once in a blue moon?

2. How big is the office space involved? One big room, or something else? Open, or cubicles? How many people in the office?

I suspect that everything purchased already should be returned to the seller, but I'll withhold judgment pending your responses.

Mark C.

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Additional info:
Speakers: http://www.crutchfield.com/p_714AW65...te.html?tp=188 (6.5" 85W outdoor speakers.. oh boy).

The room is quite big. Its a converted industrial space above South Station in Boston. One giant room, at least 20ft high unfinished ceilings. I'll get dimensions, but it holds about 60 people in an open workspace type environment. They have three 96" projector screens on the front wall. I'd guess the front wall wall is 3x the width of the three screens so a good 40ft wide and similarly deep.

They'll be doing presentations, have guest speakers, play movies/TV/video. They have occasional parties and play music. The kitchen has a kegerator if that paints the picture. Its a young start-up company.

I'm thinking the speakers are too small, what do you guys think? I'm not fully convinced they need four speakers. I guess they'd really only shine when playing low level music to fill the room. Anything focused up front "on stage" will only need front speakers. What kind of speakers and power would you guys recommend?

I like that Yamaha mixer, it looks perfect and easy to use. A mixer + power amp setup sounds good to me.

No, i'm not legally liable for the outcome of this operation. The VP in charge of this is a friend of mine and he's in way over his head trying to DIY it. I told him i'd help him out.

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Quote Originally Posted by TXBDan

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The VP in charge of this is a friend of mine and he's in way over his head trying to DIY it. I told him i'd help him out.

 

Have you considered the possibility that the most effective help that you could offer to your friend is to help him select a qualified AV contractor?
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His quote from a contractor was $125k. I think we can do a little better than that.

I've run sound and lights for two university theaters, run sound at small venues, and had a small recording studio. I know how this stuff works in general, but i haven't been active in 5-6 years. Shaking off the rust here. What i don't have is experience specing out a system for a room this large. I was hoping you guys would enjoy helping me out here.

Update for those still playing: room is 75ft wide and 100ft deep.

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Quote Originally Posted by TXBDan View Post
His quote from a contractor was $125k. I think we can do a little better than that.
I call total bull{censored} on this.

You are talking about a $1k DIY installation or a $125k contractor installed installation. I smell a stinking rat here.
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Quote Originally Posted by TXBDan View Post


OR, maybe use some kind of very simple 4 channel sound processor with a basic 4-chan mic preamp? Any suggestions on this front?
That's what you'll need to add to what you've got ... it's called a mixer. You'll need a channel for each mic plus a stereo input for each music source. I'd call that an 8 channel mixer.

https://www.google.com/search?q=8+ch...ient=firefox-a
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Quote Originally Posted by agedhorse View Post
I call total bull{censored} on this.

You are talking about a $1k DIY installation or a $125k contractor installed installation. I smell a stinking rat here.
That's what he said. Why would i make this up?

I remember this forum being a lot more friendly a few years ago.
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Quote Originally Posted by agedhorse View Post
I call total bull{censored} on this.

You are talking about a $1k DIY installation or a $125k contractor installed installation. I smell a stinking rat here.
That's what he said. Why would i make this up?

I remember this forum being a lot more friendly a few years ago.
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Quote Originally Posted by TXBDan

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His quote from a contractor was $125k. I think we can do a little better than that...

 

I'm not far from Boston and know the building you are talking about. Given your description on what you want to do, I will do it for $60k (to be renegotiated up depending on site visit). smile.gif
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Quote Originally Posted by TXBDan View Post
That's what he said. Why would i make this up?

I remember this forum being a lot more friendly a few years ago.
There's a huge discrepancy between the so-called quote and your parts list for the job. Sometimes the friendliest advice is to tread carefully. Sounds like there's some major miscommunication somewhere. Best to get that sorted before you're up to your chin in it.
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Quote Originally Posted by Mutha Goose View Post
I'm not far from Boston and know the building you are talking about. Given your description on what you want to do, I will do it for $60k (to be renegotiated up depending on site visit). smile.gif

I'll do it for $100k.

$20k for me, $20k for TXBDan, and we'll hire Mutha Goose to do it for $60k


idea.gif
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Late to the party, but I see what AH is saying, although I suspect it was directed more at the VP rather than the OP.

The quote of $125k sounds excessive, although permits, motorized lifts, building inspectors, engineering inspections, legal fees (for the contracts) and so on could all be driving that quote. The thing is... to go from $125k to gear that wouldn't work in a nursery school is strange.

So I'll ask, what is the VP's target budget? He might be able to do the typical multiple speakers on sticks ballroom/exhibition system (seen at auto shows...) for $10k to $30k. But once you start flying gear and doing "permanent installs, things get expensive - unless you do it the wrong way. Nothing against lawyers but you don't have to personally add to their coffers!

So let us know how much the VP will spring for. That will dictate any suggestions. In any case what he has already ordered needs to be returned or used for firewood.

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TBXDan,

Thanks for the additional information. The space you have described is gymnasium-sized. (7,500 sq ft; 15,000+ cu ft).

What is the budget? (I assume that if the company has three 8' projection screens in the room, it has some money to spend on the sound system.) What line of work does the company do?

One of the next questions I would ask is whether you even WANT a sound system big enough to fill the entire room. (If the walls, floor, and ceiling are all hard (non-sound absorbing) surfaces, the room is likely to sound like a gym if you have a big PA. Since you've done some recording, I think you can see the issues with a big reverberent space. 60 bodies in there will suck up some of the sound, but that's a damn big room.

I guess I can see why somebody might have quoted $125k to fully treat the space. I can also see that you might try to do it for a lot less. I would probably try to figure out a portable system that works for presentations (mostly spoken word), and can provide some sound for movie nights. If you want surround sound, and reasonably high SPL levels (and quality), then you are looking at big bucks. I suspect that for between $5k and $10k you could have a system that probably does "well enough" for the start-up's purposes. (Assuming it is not a media/entertainment business. If it is, my guesses are probably way wrong.)

I'm not a pro a/v contractor; take my input with however many grains of salt seem appropriate. Mark C.

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The speakers are the wrong choice. If he is set on Klipsch, tell him to look at their La Scala's. They are big, heavy and efficient as hell. The amp he has would be a good choice for them. Even then he would need a delay for the second set. Flying them would be a bitch to say the least.

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Quote Originally Posted by TXBDan View Post
That's what he said. Why would i make this up?

I remember this forum being a lot more friendly a few years ago.
Nobody has changed how they respond, especially Andy. You're stating a hundred twenty four thousand dollar difference between what you, and a pro AV company will charge. For the same level of system? No, of course not. But the point is moot, or will be as soon as some young "executive" of this startup overserves himself at the Kegerator and sues for negligence.....
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I think the animosity is coming from some of you thinking that i'm somehow making money off this situation and you thinking you're more qualified to make said money.

Well, sorry for the lack of drama, but there is no conspiracy here. I'm not charging him a cent. He asked for some advice and i thought it'd be fun to do some research and spend his money. I figured a bunch of people who hang out on an Pro Audi forum all day could relate, but i guess they'd rather sit around conspiracy theorizing and giving me {censored}. I first joined this forums in 2002 (under the name dannydigital) and it used to be awesome.

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