PA set up Advice

Archived from groups: rec.audio.pro (More info?)

Sparky wrote:
> Hi All
>
> I have a few problems with our PA and I was hoping to get some advice
> as to the best way to set it up.
> We are a 4 peice, Drums, Lead guitar. Bass and Keys/guitar (depending
> on the song) all of us sing.
> We like to have all the instruments DI'd through FOH mix using amps as
> backline.
>
>
> Our main PA amp is a Yamaha EMX 5000-20ch mixer amp with 500W per side
> into 4 Ohms. Speakers are one pair of EV SX300's on stands and a pair
> of older cabs with a 15" driver and horn (rated at 200W - 8,Ohms) on
> floor. For monitoring we have a further 6 CH PA Amp with 4 soundlab
> speakers which we run from the main desk aux 1 (panned left on the
> monitor amp ch 1) and Aux 2 (panned Right on the monitor amp ch
> 2)Giving 2 different monitor mixes
>
> All sounds good so far.
>
> My problem is the FOH speaker set up.
> I'm not comfortable putting the Bass guitar and bass drum,Floor Tom
> through the EV speakers (don't want to damage them with relly heavy
> bass). So my thought was to take the EV's in a chain from the left
> side of the Yamaha amp and pan all vocals - keyboards, guitars and
> higher freq drums left - this will give me full poewr from the AMP, and
> put an EV on each side of the stage. Then the Bass and the lower freq
> drums panned right and then connect the 15" speakers in a chain again
> giving me 4 ohms and max power, again with one speaker on each side of
> the stage.
>
> BTW we haven;t tried any of this yet - but our first Gig is coming up
> so!!
>
> Does this sound the right thing to do - or is there a better way?
> The Yamaha output does have a Sub output and internal cross over - but
> the cct diagram shows that even with the LPF switched on the bass still
> goes through the main speaker outs - other wise we could get a single
> amp to drive the 15" speakers with everything below 120hz going only to
> the sub.
>
> thanks all and hope you can help
>
> sparky
>

With what you have you can do the following:

Run everything except the Bass guitar through the PA as normal and let the Bass play the space. It
(the bass) may be a bit louder on stage, but the overall sound out front should be fine. Just be
sure to balance the system and the Bass guitar so they blend. And then do not turn up any
instruments or the balance will be screwed up.

But if you are worried about overdriving the system, perhaps you are running the system too "hot" to
begin with.

Your idea is interesting, but not particularly practical in real terms. You still have a horn in
those 15" cabs, right? That makes them "full" spectrum (if I can use such a term) and you might
still run the risk of blowing the diaphram of the hi frequency driver.

A more practical solution is to learn how the cross-over network is supposed to work on that
particular system, see if it actually does what it's supposed to do and then employ that, making
those 15" cabs actual subs by dumping the horns. That way the 15's handle all the lower frequencies
and the EV's handle the higher range. You should be able to mix everything through such a setup
(I've done as much with a whole lot less). Just pay attention to gain structure, levels, eq and all
that stuff.

You are going to have frequencies from the Bass and the drums "cross over" into the higher frequency
realm anyway because of harmonics, transients and high frequencies that are present in percussive
instruments (the sound that gives it the "pop", "crack" or whatever) so you'll never "get rid" of it
completely and should not want to do so.

Hope this helps a bit; good luck with the gig.

--fletch