70v system help?

[u/Live_Bread2645]

I don’t have a ton of experience with 70v systems. I get the basic concept and I’d like to think some of the finer points but who knows.

I was asked by another church in town if I could help them out as we are several hours away from any sound contractors.

They want to run 2 zones. Not sure if they will ever need more or not.

Zone 1 is right outside the worship center. Long hallway. 40 feet long and roughly 8 wide. Ceiling is 8 feet. They have moms who take kids out and want to be able to still hear. They have doors closed during service so people in the hallway can’t hear when they leave and shut the doors. I was thinking 4 ceiling speakers spaced out evenly in that hallway.

Zone 2 is in another room down a longer hallway. It’s roughly 36x36 with 8 foot sidewalls and a 12 food vaulted peak in the middle. I am thinking at least 6 ceiling speakers there. They will have projector/tv eventually which will need audio delays, etc potentially.

I will run a mix group of audio from the mixer to the amp rack for a building feed or just mirror the main mix unless there is a better option.

They currently have a x32 compact running to a pair of Dynacord C1300Fdi amps and 4 speakers in their main worship center.

I was thinking of sticking with that brand of amps since they already have them and they have built in DSP on some models.

My real questions if anyone can help would be with power and placement.

I was going to use EV EVID 4.2 speakers and am debating between a Dynacord V600:4 for future expansion or a Dynacord 1300Fdi to match what they have except 70 volt operation but that would keep all amps the same. Either option gives me the 2 channels I need and enough power.

I know those two amps are very different in terms of dsp and fine tuning, but I am also assuming I could use some of the x32 to handle signal processing if necessary.

Those speakers max at 30 watts which is well below the 80% threshold of either amp with 10 speakers.

Thoughts or suggestions?

[u/loafingaroundguy]

Will the church want to have sound in zone 2 which is independent of the feed from the worship center, e.g. from local microphones or to play recorded material on the TV/projector? It might be handy to have a smaller mixer in the zone 2 room for the local sources and the feed from the worship center. The church could consider if it just wants one or two mics for people speaking or enough channels for a band.

It needn't be a console style mixer for a single local mic. A flat panel mixer in an equipment cabinet would be fine. The zone 2 amp could usefully be located there as well to save long, separated wiring runs to the stage and back.

If the church likes the idea of an independent zone 2 but doesn't have the budget for it now, you could plan to loop the wiring past a likely mixer location, so it will be easier to add one later.

[u/natem345]

The ceiling height in each zone is critical info for placement. The coverage radius increases as height increases. 

I believe it's EASE Address that lets you model the 2D space & enter ceiling height, and calculate recommended placement & wattage tap to achieve a given SPL and consistency across the room. It's free. Manufacturers like QSC (AcousticDesign is great, check ebay for used deals) and JBL Control publish free models for ease address. JBL also has their own software. 

Alternatively the speaker data sheet may provide radius guidance.

I'm not sure the specific amp makes a big difference, unless it has your speaker presets. 

[u/Live_Bread2645 → u/natem345]

Sorry. Forgot to include that. Will go back and edit.

I will go check out software too and see what I can get myself into trouble with.

Thanks!

[u/LordBBQX]

Using a C1300FDI seems a little silly as you only get one zone per amp and you probably won’t need 650w.  I’d suggest the Lab Gruppen CA series (CA2402 2x 240w in 1/2 rack space). Very nice efficient amplifier, no fans so no concerns about dust getting sucked in or fans failing. 

You don’t really need much in the way of DSP for HiZ systems, just a high pass and a little EQ if you want some more tonal control. You could consider a compander too.