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Begadoc 12th November 2009 02:58 PM

DIY PA installation in a church
 
We (local church) requested a quotation to upgrade our PA system, mainly the loudspeakers which I suspect have blown treble cones.
The suggestion which seems reasonable is for a pair of Electrovoice EV-ZX1-90 speakers mounted on a pillar on either side of the nave about 3 M high, a Crown LPS 1500 Power Amplifier and a Yamaha MG206C mixer. The price quoted for these are generally about 100 more than bought on the internet.
I would be inclined to accept this higher price were it not for the installation price which is quoted as 1200. Admittedly there is some high level work involved (accessible by ladders does not require scaffolding) but even so it does seem excessive. There is also an additional quote for replacing existing microphone cables with two 8-pair multicore cables. The labour is 600 to install and terminate these two cables.
Given that I am a competent wielder of a soldering iron, I am inclined to go down the DIY route.
My concern is whether or not the suggested equipment is good for the job. At least if the firm installs it and their recommended equipment proves unsuitable, they have to find an alternative.
The church building is approximately 50 M long and 25M wide. The roof is about 30M high (the biggest problem sound echoes from here.
Has anyone any thoughts on these speakers or experience of having put loudspeakers in churches? Speech amplification is the main need, music less so.
Thanks.

chris661 12th November 2009 03:46 PM

Smallish line source would do pretty well - good projection (that's why they're used at concerts), and the small size means that, while bass would be minimal, it wouldn't require much space.

richie00boy 12th November 2009 04:33 PM

The amp is 2x400W, not sure why you would need that for voice in a church? Maybe the speakers are similarly over-specced?

The labour costs does seem high. Are the mic cables buried or hard to reach? 600 labour for that part seems a lot.

Where are you? Maybe I could come and do it for 1/3 the cost :D

AndrewT 12th November 2009 04:56 PM

speech is intelligible with a 300Hz to 3kHz frequency range. This avoids all the bass and echo problems.

If you want more realistic speech then 200Hz to 5kHz is slightly better. Note the symetry around 1kHz.

If narrow band music is also wanted then maybe you could look at 100Hz to 10kHz as your dual purpose frequency range.

Do not skimp on the amplifier peak voltage capability. Clean unclipped transients help with giving pleasing live sound reinforcement. The dynamic range of speech can be enormous. Design for it.

AuroraB 12th November 2009 08:11 PM

There is a strange misconception by a lot of "PA installers" (quotes are deliberate) that PA is all about large to huge speakers in one end and lot's of power. If this was a band gig, it could be OK, but this surely isn't?
If the main aisle is, say 40 m long, in order for the listener in the rear to have an acceptable level, the poor folks in the front row should wear ear protection. I may be wrong, but if the system you're looking for is speech amplification during services and the likes, you don't need a PA system , - you need sound reinforcement. Not the same task! Using higher sound levels in a highly echoic environment ike a church, will only make the echo and feedback problems even worse.

If this system is not to be used for music PA, you'll be a lot better off using 4-5 ( the more the better) smallish speakers on each side, all mono fed by a 100V amp system. Bandwidth in the order of 100-10k Hz is plenty good enough for a task like this. The whole idea is not to make peoples ears wobble, but to present an acceptable and most uniform level of sound over the actual listening area. If this doesn't make any sense, like e.g. 100V amplifiers, drop me a PM, and I'll respond...
( I'm travelling, - away from home base and may not see direct post in this thread )

richie00boy 12th November 2009 08:29 PM

Exactly what I was thinking AuroraB.

Speedskater 12th November 2009 10:30 PM

Two good papers on church sound by Jim Brown of Audio Systems Group:

Audio Systems Group, Inc. Publications

Enzo 14th November 2009 08:33 AM

If you are planning to run a row of speakers or presence projectors down the side walls to cover the people towards the rear, then you should also invest in delay units to match the wavefront from the front speakers. Otherwise the people in the rear pews will hear the rear speakers first, then the mid-room speakers, then the front speakers in a sort of echo presentation.

AuroraB 14th November 2009 11:08 AM

Essentially, you're right, Enzo, but the trick is to keep levels just about right, and the delay is really no problem. There will also be so many reflections, that time smear is unbeatable anyway.
Has been used like this in thousands of cases , I think....
There is a JBL paper on this type of installation sound, but I just cannot find it...

User Name 14th November 2009 08:59 PM

If i may make a suggestion i know the Bose L1 works quite well... Bose L1 Model I Single Bass Package – Live Sound Loudspeakers - Professional Sound Systems There is a link there, a set of these although they are a bit more will fill that room with nice sound, and they take up little no room, there are powered and have a mixer build in, i think that a set of these would rock your church


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