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Paradise_Ice 14th December 2012 07:38 PM

PA system for a huge Church with no budget!
I've been asked to spec out and install a PA system in 4 halls in a Church. There huge, not Westminster Cathedral but its the biggest church I've ever been in.

The main hall is 160 ft by 150 ft, the ceiling height is 180ft. Its a morbid damp stone building with fine acoustics for a bunch of choir boys I'm sure. Yet I've never done a church with echo for days.

They have no budget to speak of and want massive monoliths with drive units stacked to heaven. My plan is to install four (12 inch 4 ohm) drive units per side to just flood the place with sound from 40Hz/2.5Khz, maybe some horn drivers and strap a Cloud type PA amplifier to them. All made from 18mm ply. There will be no cross overs on the 12 inch drive units. I'll wire them into dual series and then parallel loads per side to maintain 4 ohms for the amplifiers. This must be as cheap as possible, I know they probably won't pay for all the hardware never mind my time and labor. This is a real charity case and a personal challenge for me.

Any suggestion on the best bang for the buck are welcome as I've never done PA systems on a shoe string budget.

adason 14th December 2012 08:06 PM

no budget ha?
in that case I highly recommend you go ahead and buy remaining AURA 3" fullrange drivers
they deliver wonderfull midrange, I know, I used them in many projects
and you get them for $1 each!
they are 16 ohm, so just slap 4 in paralell and you get 4 ohm, that you make as many 4 ohm sets you need to get coverage
you will not regret it!
The Madisound Speaker Store

cyclecamper 14th December 2012 10:32 PM

And for cheap bass, you can never beat the used market.

Unfortunately, you're not going to achieve acceptable speech intelligibility without extreme pattern control, and that's counting on the congregation being absorptive.

bear 14th December 2012 11:20 PM

Yep, echo for days?? ha ha...

You will need *extreme* control over dispersion at minimum.

If you can you need to convince the powers that be to hang what would be called "tapestries" from the side and rear walls...

In reality to do this job, I'd consider a down firing system... perhaps time delayed as it goes back down the hall...

Also you have to watch how much power you dump into this echo box... once you reach a saturation point all you will hear is hash and noise...

Bass is easy if there is space for a horn under a riser or similar...

Got pix??

What is the program material?? just voice, or is there some rock band??

Cheap... ha ha ha... what sort of cars do the people who run this place drive, just asking...


cyclecamper 15th December 2012 07:30 PM

Require the women to wear hats, and the men to wear suits. Pad the seating. Carpet the aisles.

Then add some pitch shifting to that natural reverb for that darth-vader fear-of-God sermon... Nobody will understand a word, but they'll all suddenly become believers. "Death Comes Unexpectedly..." Excuse me if I push the list rules, staying on the acoustic attributes and not getting into the realm of the supernatural.

cyclecamper 15th December 2012 07:32 PM

There's reasons so many curches have added so many cheesy felt banners and wall hangings produced by the nuns with help from the grade school and the churchladies' auxiliary.

cyclecamper 15th December 2012 07:35 PM

Seriously, you need to start with some real acoustical measurements of the room and an attempt at acoustical treatment then re-measurement.

turk 182 15th December 2012 10:06 PM

i'd like to know if they have an existing pa and what it consists of i.e. mixer/amp,music sources,speakers 70 v distributed or...
in reading your initial post it sounds like your determined to make this rig stereo but given your architectural acoustic situation stereo imaging and original sources like an open mic may not mesh well unless properly implemented.
central clusters (speakers) hung over the source area generally yield the best overall coverage while minimizing comb and reflec room effects.if i am picturing the room as stated it's as wide as it's deep with a high centrally vaulted ceiling correct?
then two vertical (column) arrays of four 12's in a coincident pair would be the cat's meow.

vacuphile 15th December 2012 10:52 PM

Adason's suggestion for the Aura's is a good one. Used in long line array's would help beaming in the vertical plane so you can throw less energy on the floor and into the ceiling, reducing echo. Best way to achieve some modicum of intellibility at reasonable cost. Forget modern music. The acoustics of a large church belongs to a certain kind of music, in effect, choir/organ mucic and the acoustics of churches grew up together. Modern music is just too fast and the whole place will just muddy up with reflections, whatever PA you put in.

bear 15th December 2012 11:14 PM

actually that will be certain death, vacuphile, since it will throw way too much energy into the side walls, which are hard stone... (I assume). Ceiling echo is likely fairly easy to discern as a separate sound compared to side echo which will arrive much closer in time to the original signal, more so the farther back you get...

You might want to study those phased arrays that they are using in stores now to put sound directly in front of the screens, etc... that might be a solution in such a situation...


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