More PA questions!

johnnysmack

hi guys how are things? once again i have some PA questions that need to be dumbed down for me.

found a peavey bundle on thomann and the specs for the tops were 250W (RMS), 500 W program and 1000 W peak at 4 ohms.
the subs were 500W program and 1000 W peak also at 4 ohms.

what size power amp would i need to power the set up?

also when for example when it says 250W, is that 250W going to each speaker so 500W altogether and the subs are 500W so 1000W altogether. does that mean between the 4 of them 1500W is needed to power them or do i have it all totally arseways?

johnnysmack

forgot to add in too. when you add monitors to the set up can they draw they're power from the same amp or do they need a separate power supply?

could you use active monitors in a passive set up?

Savman

'ello again.

johnnysmack wrote: »

found a peavey bundle on thomann and the specs for the tops were 250W (RMS), 500 W program and 1000 W peak at 4 ohms.
the subs were 500W program and 1000 W peak also at 4 ohms.

what size power amp would i need to power the set up?

1.5 times the RMS rating as a guideline but so long as each speaker sees a power figure between the RMS and Program ratings, it should suffice.

If your speakers are 4ohms then running 2 per channel off an amp will put you in dodgy territory (most entry level amps will not like a 2ohm load).

also when for example when it says 250W, is that 250W going to each speaker so 500W altogether and the subs are 500W so 1000W altogether. does that mean between the 4 of them 1500W is needed to power them or do i have it all totally arseways?

Don't quite get you here.

artvandulet

johnnysmack wrote: »

also when for example when it says 250W, is that 250W going to each speaker so 500W altogether and the subs are 500W so 1000W altogether. does that mean between the 4 of them 1500W is needed to power them or do i have it all totally arseways?

Ok I'll give you a setup using gear I use which will hopefully explain some of this...

I am going to use rounded, simplified numbers here and not take resistance of cables etc into account...

Using an LA17 amplifier and EV SX300 speakers.
The speakers are 300w 8ohm each and the Amp is 1200w into 2ohms
So if I use 1 pair of speakers with this amp, the speakers require 300w. The resistance is 8ohms. At this much resistance I think the amp produces 400w per channel so I'm good.
If I double the speakers, I halve the resistance, so I now have 600w per side at 4ohms. The amp can produce about 800w, I'm still good.
If I use three SX300's per side I now have 900w per channel at 2ohms. The amp produces 1200w.
(jaysus I hope I'm right with all this. Someone correct me!)

Re: Monitors
you won't use the same amp because you dont want to route the same signal that way. That amp will be taking signal from the main outs of your desk to the speakers. This isn't what you want to send to your monitors.
You'll need 1 amp per 2 monitor mixes (not physical monitors necessarily) generally, so you can route signal from the mon/aux outs on the desk to the required wedge. You can use powered wedges if you want, just means there's no seperate amp in between.

Does that answer anything??!:D

johnnysmack

cheers lads that helps. Savman i knew i could rely on you for help!

artvandulet, i think i understand what your saying alright, the more speakers the less resistance ie the ohms get halved with each new speaker you add where as with the amp the watts get havled each time the ohms get doubled. its starting to come together now alright.

im basically trying to understand as much as i can about the stuff cas im in the market for a PA and dont want to end up getting a melon or something useless to me.

was talkin to guy last night too who suggested instead of gettin a mediocre set up that would probably have to upgrade in a yr or so, to instead spend the same amount of money on really good set of tops now and then down the road add really good bass bins or good mixer and so on. he was emphasising the quality of good speakers would be more benefical then a second rate full rig.

what do ye guys think?

Savman

johnnysmack wrote: »

was talkin to guy last night too who suggested instead of gettin a mediocre set up that would probably have to upgrade in a yr or so, to instead spend the same amount of money on really good set of tops now and then down the road add really good bass bins or good mixer and so on. he was emphasising the quality of good speakers would be more benefical then a second rate full rig.

what do ye guys think?

+1

It's vitally important you make sure you choose the right gear now that allows itself to be included in any further expansion. If you plan adding Subs, you need to decide whether you want 15" or 18" because that will limit your options for buying Tops now.

If you want 15" subs down the line, it's pointless getting 15" Tops now, might as well get 12's. Similarly if you get 15" tops now, you're pretty much deciding you want 18" subs come next upgrade time.

Getting 12" tops now gives you more room for manoeuvre, all things considered.
Getting 15" tops now allows you to send some Kick n' Bass thru them where need be, without need for Subs (12s wont do this faithfully).

'tis six of one and half dozen of the other tbh...