View Full Version : PA problem
01-03-2008, 04:18 PM
So i quit the band i was in and am now forming my own along with my cousin and the ex-bassist from the band i was in but just realized that we know nothing about pa's. Can anyone please explain the basics of it? like the whole watts and ohms stuff? We're planning on micing up two vocals, an probably 6 mics for the drumset. So far i found this andseems to fit our budgets and looks rather good to me. Would this give us good quality for medium-sized venues and practice?
First one's the pa package and the other is the monitors we'd add (2 of them).
thanks a lot for listening!
EDIT: later we'll probably upgrade to Shure SM57 mics. Oh, and the band consists of a drummer, bassist (has a good sized combo amp), vocalist, and guitarist/backup vox (me; i'd use the pa as an amp with the podx3 until i buy a tube amp...actually, i'll buy two different tube amps and set one on each side of the drumset once i have the money)
01-03-2008, 04:26 PM
i'll buy two different tube amps and set one on each side of the drumset once i have the money
A PA should kind of eliminate the need for this.
01-03-2008, 04:31 PM
A PA should kind of eliminate the need for this.
I know, but since i can send two different processed signals with my multieffects processor and i'm the only guitarist i wanted to create a rich full sound. Plus i do NEED to buy at least one amp since i only have a small practice one...the other one's just so that the band won't sound so flat with only one guitar.
01-03-2008, 06:15 PM
01-03-2008, 06:47 PM
Wish I could help.
01-04-2008, 04:45 AM
01-04-2008, 05:19 AM
Ohms law can be stated as volts/ohms = amps. Now as your volts will always be what comes out of the wall the only two things that will affect each other are ohms (resistance) and amps (current)
The current is related to the flow of charge to the speaker and the resistance is related to how much power it uses (kind of)
The speakers here are rated at 4 ohms each so you have a power ration of 200w/4ohms this is kind of related to the volume from these main speakers. As soon as you add the wedges the resistance will increase, you're asking the same amount of power to do more work so you'll get less volume from the front of house. Can't say how much because the specs for the wedges don't include resistance.
If you don't get the ohms/amps stuff don't worry just be aware that to get the best result from your 400W your speakers and amp need to be matched. Presumably in the initial setup they are but as soon as you add anything else they won't be.
You can fix this by getting a separate amp to power your monitor or getting a powered wedge.
The other problem with this rig (for me at least) is that the desks with these powered amps are usually pretty crappy. You'd be better off to get some powered speakers, you know then they'll all match each other, and a small desk. I've got a little Behringer and it is a beauty.
This one may suit you though, it looks pretty simple and it's cheap. You'll outgrow it pretty soon though I think if you want to put your kit through it.
01-04-2008, 05:31 AM
Ok...thanks now that kinda makes sense...
Do u think we should go ahead and get the monitors as well? we're on a budget since we only have part time jobs and powered speakers are more expensive and so is getting a power amp and then a mixer for it.
EDIT: i found specs on the power mixer and it can send 200 watts to the main speakers and another 200 to the monitors OR 400 to only one. The impedence on the monitors will most likely be 8 ohms. Will this be loud enough? to me it sounds like it'll be perfect but i'm quite inexperienced with this
01-04-2008, 05:42 AM
You won't need an extra mixer for the wedge but you need to make sure that the desk has a monitor out or an auxiliary out (preferably 2) if you want to drive it with it's own amp. If it only has 1 and you use it for the monitor you won't be able to run a separate effects or EQ.
It's hard to tell how much power you'll lose from the front if you decide to drivie your wedge from this amp, could be as much as half which will probably make the whole thing pretty useless. You might be able to pick up a second hand power amp somewhere for the wedge.
01-04-2008, 05:53 AM
Hmm...i think it'll be fine. I remember my old band's pa system was 200 watts/4 ohms if i'm not mistaken (they were peavey and the speakers were 15") and it was loud enough for 1 vox and two guitars running directly into it.
If so then the main speakers should sound as loud as that once the monitors are plugged in and take up half of the 400 watts. Plus, the main speakers have two 15" speakers which would mean that they'll be able to spread and cover the area better than the speakers i used in my old band.
I hope i'm right about this...does it seem like it?
thanks by the way with everything...now i kinda understand how the ohms and watts relate to the 'loudness' of the system.
01-04-2008, 05:57 AM
oh, and the higher the ohms the less volume will be produced right? say 200watts/4ohms would be louder than 200watts/8ohms?
01-04-2008, 06:34 AM
If you add more speakers you're increasing the total resistance and you'll get less volume from each but don't quote me on the numbers, you might want to check before you spend your money.
01-04-2008, 07:37 AM
If you add more speakers you're increasing the total resistance and you'll get less volume from each
That depends on the wiring. If you wire two speakers parallel, each rated at 8 ohms, the result will be a 4 ohm load. If you wire the same two in series, it will be 16 ohm. Parallel divides the impedance by the number of units (speakers in this case) series adds them together. That's why it's not easy to find a 4x12 cabinet wired 4 ohm, which is what I need. I'm running a 2x12 Kustom cabinet now, two 8 ohm Emminence speakers wired parallel, for a total 4 ohm load to match my 4 ohm output amp. If you check, the dual speaker outputs on most guitar amps are wired parallel, so if you plug in two speaker cabinets, each 8 ohm, it's now 4 ohm load. I think PA amps work the same unless they're set up to run stereo. Those will be marked Left and Right.
That brings up another issue, you need to keep the speaker load close to the output impedance of the amp if possible, you can overwork the amp at best and blow transformers at worst. With tube amps it's best to stick to the amp's output impedance, solid state is a bit more forgiving, but if you put a 8 ohm speaker on a 4 ohm amp, you're overworking the amp to get the same volume, running a chance of overheating it.
The PA you picked out should do ok, but you'll outgrow it pretty fast, 8 channels will barely get you onstage if you're using 6 of them for drums. You can go a couple of directions...a bit more expensive but this peavey (http://www.musiciansfriend.com/product/Peavey-XR-8300-PR-15-PA-Package?sku=631376) rig gives you a couple more inputs, and more power to boot, you can also get a used 6 or 8 channel PA for drums and run it into one channel of your main PA, no speakers needed, just the line signal, and hit the local pawn shops and look for a 150-200 watt monitor amp to push the monitors. I find the Peavey 4-8 channel head type PA amps at decent prices all the time, and don't be fooled by the fact that they're used, Peavey equipment has been top dog in the PA world for years because it holds up to road abuse. I find power amps now and then too, but you're looking at $400 or so usually for a CS 800. You can find the PA head type 6 channel for $200 pretty often. That will work for a monitor amp, I've used them before, all you need is one channel and you have a decent EQ to go along with it. One of the pawn shops here had a couple of Peavey 150 watt monitor amps a year ago for $100 each, both in very good condition.
The monitors you picked should work fine, but will need a power amp, 150-200 watts will be fine for monitors, but the more power you have the more headroom you have, and that means a better chance of eliminating feedback. still, 200 watts is usually plenty for monitors.
As for your two amp idea, I've run two amps before, to run stereo. The bass player kept complaining he couldn't hear me, (a 130 watt Peavey MX and he can't hear me???) so I rigged my Arion SAD1 Analog Delay through the effects loop, one side of the stereo out back into the amp, one side to a power amp and speaker on the other side of the stage. He loved it, I did too. I set it so I could hear stereo guitar standing at center stage, then no matter where I was I could hear guitar. Everything was controlled from the main amp, and already EQ'd, so there was no running over to the other side of the stage if I needed to turn up or down. (usually up as it got louder later in the night) I'd still be running stereo but my Super Reverb doesn't have an effects loop, that makes it difficult and expensive to put both sounds out in stereo. (Dual amp rig, the Peavey MX for clean, Fender Super Reverb for raunch 'n roll, A/B switch to swap to either) I'd have to split the signal after the A/B switch, then invest in another expensive Super Reverb, ($1200 for a silverface at the least, and that's in rough shape) and another stereo delay pedal that's hard to find, at least if I want the same one, which I do. The SAD1 is not a common pedal...none of mine are actually, if my SD 9 Ibanez distortion pedal ever bites the dust I think I'll sit down and cry...last time I looked them up they started at $75 on ebay, IF you can find one...and they're not easy to find. The Marshall Bluesbreaker overdrive is the only one I've ever seen, Schaller Fusschweller volume pedal ditto, and if I can ever rebuild it I have an ancient Morley power wah, (the old chrome one) I'll probably never see another one...in 20 years I've had it, I've seen exactly one in pawn shops. Should have grabbed that one too.
So running amps on both sides of the stage is great, if you can do it without spending a ton of money. If you have an amp with an effects loop, you can send the effects out to another amp, just a power amp will work fine, the EQ and effects are already there that way. (Effects loops usually take the signal after the preamp, so you have all your gain, EQ and effects already there) Or use a delay like I did with stereo out, that worked well. Effects out to pedal, one side back to effects in, one side to other amp. Set the volume then everything is controlled from the main amp. The second amp should be straight amp, no gain, no effects, no EQ, just a power amp works best. I used a Radio Shack 100 watt 4 channel PA amp, made for PA or DJ purposes, and a 1x12 cabinet, it worked great. All I had to do was tell the bass player DO NOT touch that amp, I'll control the volume from over here...so he wouldn't change the volume and change the stereo effect.
You can also just mic your guitar amp and send it through the monitors, but you don't have stereo, just a monitor signal everywhere. Still works well.
01-05-2008, 04:44 AM
Well, the Line 6 PODX3 i have can separate the guitar signal into two channels and send them separately (one per amp). Basically i plug in one guitar and it'll control two separate rigs at once and send them independently. Also i can control the master volume of the signals going out to the amps. Both amps i'm looking into buying are tube amps (50 and 60 watts) and have effects loops. One is a B-52at112 and the other is some Randall whose name i forgot. I like your idea of getting a separate mixer for the drum mics. I hadn't thought about that.
For now we're sticking to the pa package and monitors. They should do fine since my old band used a peavey pa system that was only 200watts @ 4 ohms (that is the same as the one i'm looking at buying ONCE the monitors are powered too and receive their own 200 watts @ 4 ohms too; or i could power only the mains at 400 watts @4 ohms). We won't mic the drumset for now since the drummer's short on cash, but i think we'll buy another mixer just for the drum mics and then plug that into one of the inputs of the power mixer. Also this will leave more free inputs in the power mixer that can be used to mic up the bass amp and two guitar amps if needed or to help us hear the amps through the monitors better.
01-05-2008, 10:28 AM
Are you micing up the drums in a practice situation, or a performance?
01-05-2008, 04:48 PM
Are you micing up the drums in a practice situation, or a performance?
Most likely both. for now we'll only be practicing.
01-05-2008, 05:57 PM
Well its just I don't see the point in micing up an entire drum in a rehersal space, especially if its not very big. Do you have a problem right now with not being able to hear drums, because I usually find its the opposite.
01-05-2008, 07:29 PM
Oh, the drum's gonna be miced only for shows but we're still getting the gear even if we won't use it yet.
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