PA question - monitoring with active speakers

[davehux]

I've just joined a new band and the singist has recently bought herself a new PA. It's a Yamaha passive mixer with 2 DFX15 active speakers

We want to run a pair of passive floor monitors off the desk, and obviously will need some sort of power amp to boost the monitor output signal from the desk out to the monitors. I have a Mackie powered mixer (500+500) which we could use, I suppose, but it's a bit of a lump to setup next to her mixer, just to run the monitors.

Any recommendations or advice? Yes we could all go IEM, but we've got all the stuff we need except a power amp, so it seems a bit of a waste not to use it

Cheers

[JTUK]

You could use any old amp as a mono amp to drive the monitors.
The mixer option is overkill simply in terms of size, IMO..unless you have gigs that
don't have space limits on stage.
£200 or so should get you a reasonable stereo amp that would prove more versatile.
How many sends/aux do you have to drive the monitor signal...?

[davehux]

It's a Yamaha MG166C, which seems to have 1 monitor and 3 send/aux outputs on it

[JTUK]

Well, any amp can then drive the passive monitors from those and you can run from mono to a mix.
The disadvantage of that is that you have no individual control from the amp so the mixer can..and should
be set up to control to do that instead. You have great control if you split the signal thru the aux outs
to a stereo amp so you can have more control to the individual cabs.... but you could get pretty close to that
effect anyway, running a mono amp signal to the pr on speakers.

[BOD2]

Sorry but more questions now than answers -

What power are ohms are the monitor speakers ? You'll want an amp that won't overpower the speakers and that matches the speaker impedances.

Do you want different monitor mixes in each monitor or the same in both ?

If different then you could feed the "monitor" output to one side of a stereo power amp and drive one monitor speaker then feed one of the "aux" outputs to the other side of the stereo amp to drive the other monitor speaker. Use the monitor and aux controls on the mixer channels to setup the different monitor mixes. If the aux channels have a "pre fader" setting then use this as it allows you to set the mix levels independent of the channel faders.

[Phil Starr]

I use the same mixer, I take from aux1 and use a jack splitter to feed to two sides of a stereo amp (Peavey IPR1600) if your budget is limited then there are some good classD lightweight amps from Thomann or even Behringer that would do the job for £200 or even less.

Conversely I've just tried the Behringer B205 active personal monitors and for vocals they are just the ticket at £139ea you'll need one each though. I'm buying a second one.

[brensabre79]

Yep those personal monitors are the bomb. We use two of the Thomann ones - similar to the Behringer i think.

I would seriously think about a graphic EQ between the desk and monitors though - and FOH for that matter, but definitely monitors.

If you're wedded to the passive wedges, then a class D power amp will do the job. the Behringer iNukes are pretty good (and cheap!), if you get the one with built in DSP there's a graphic EQ built in - it isn't that easy to use but it's only 2 rack units, it'll do bridge mode or dual mono from a single feed so you don't even need a splitter from the desk.

[thinman]

[quote name='brensabre79' timestamp='1397059874' post='2420268']
Yep those personal monitors are the bomb. We use two of the Thomann ones - similar to the Behringer i think.

I would seriously think about a graphic EQ between the desk and monitors though - and FOH for that matter, but definitely monitors.

If you're wedded to the passive wedges, then a class D power amp will do the job. the Behringer iNukes are pretty good (and cheap!), if you get the one with built in DSP there's a graphic EQ built in - it isn't that easy to use but it's only 2 rack units, it'll do bridge mode or dual mono from a single feed so you don't even need a splitter from the desk.
[/quote]

+1 about the EQ - mostly for feedback suppression - monitors tend to be the biggest source so you need an eq to remove the peaks in response that contribute to it (after making sure your mic/monitor placement is OK). If you use a graphic it needs to be a 31-band or some kind of 3 or 4-band parametric. Look up how to "ring out" your monitors - it makes a huge difference to how loud you can get your monitor levels and is not hard once you've done it a few times.

A few other things I've picked up over the years that help reduce feedback problems include:
1. Use the same monitor speakers (avoids having differing frequency responses that can make for more frequencies that will feed back).
2. Use the same make/models of vocal mic - same reason as above.
3. Try to not be too near a back wall - stuff reflects back and makes for a lot of spill and feedback problems.
4. I've used active speakers as monitors that are designed to be either PA tops (mounted vertically) or can be laid like wedges on the floor when used as monitors. Generally it's the higher frequencies that account for how intelligible the vocals are - when vertical the high end dispersion is not too bad so you don't have to be directly in front of them to hear stuff clearly. However, when laid on their sides that left-right dispersion often goes up-down and not left-right meaning there's only a narrow area where the clarity is best. So, such speakers can be better heard stood up and leant back - don't have them aiming at your knees as you won't hear them too well.

Someone may well jump in and say "if you had really good gear you wouldn't get all of these problems - it's your cheap gear that's peaky". Well, we can't always have what we want so these techniques are useful.