PA Systems for dummies

Savman

In response to sei046's request for more discussion and more threads, I'd like to put forward some general pointers that might help with the frequent "What PA?" threads that pop up asking the same questions time and time again.
Disclaimer: the information below is purely based on one man's opinion and should not be taken as gospel. There are many systems better and worse than the ones posted, and there are a dozen techniques each engineer will apply (feel free to chime in) but I think it's a given that there is some very basic failsafe information that people need before they go jumping into PA System purchasing because it requires a lot more homework and research than some might think.
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Ok, so your band is out gigging and you all suddenly realise that a big part of how your gig-going faithful experience your rockin' music has to do with that big system thing that carries your deadly choons to their drunken ears. So you decide to invest in a "PA" even though you're not too sure what it stands for.

You think to yourself, "ah sure we'll just get something small for the time being". Wrong. Without you even knowing, the purchase of a PA system usually sets about a chain of events that will probably result in the demise of your precious band. See, you suddenly realise that your initial budget is barely enough to get a couple of Vocal Microphones and you failed to take into account the monitor rig you'll need to hear yourselves rawking out, along with these big ugly heavy bastard things called "Subwoofers" that will only reproduce 2 instruments in the entire band, as well as all the cases, cables, stands and tons of accessories needed to actually run and maintain a half decent bar-band quality PA. Before you know it, the band has broken up or you have to buy out Paddy's share cos he's fecked off with his new missus backpacking around Columbia.

If you really must buy a PA, here's what I'd recommend for a standard 5pc rock band consisting of Live Drums, Bass, 2 Guitars and some Vocals:

1. Drum Kit Mics: to get you started all you really need is a good kick drum mic (Shure Beta 52A, Beta 91 or AKG D112) and either a good basic and effective snare mic (SM57, Beta 57A, Sennheiser E604) or a pair of good overheads (AKG C1000S or similar condenser mic). Cost €500
2. Bass Guitar: get a cheap Behringer DI Box. It's not perfect but it'll do. Cost €40
3. Guitars: 2 x Shure SM57 - one on each amp and you're good to go. Cost €200
4. Vocals: 4 x SM58. Do not look any further til you learn to know the difference. Cost €400

SUBTOTAL: €1200

Mixing Desk: how many channels do you need? If you EVER plan mic'ing up a full band, then you need at minimum a 10ch, if not a 16ch desk. Just when you think you have enough channels, you will end up needing more. The best small scale mixer by far is the Allen & Heath Mix Wizard 16:2 http://www.thomann.de/ie/allenheath_wz162dx.htm
This desk has 6 Aux sends which will allow you do have a 4 way stage mix (Aux 1-4), as well as 2 built-in FX engines with Reverb, Delay etc etc.( Aux 5 & 6) Cost €1500 inc flightcase

SUBTOTAL €2700

Speakers: if you are an acoustic act, or a rock act that is not mic'ing up a full drum kit then you should get away with just 2 speakers on stands. If you're gonna mic that phat Kick Drum, then YOU NEED SUBS. Either way, you have 2 options for your FOH (Front Of House) and Monitor Speakers:

• Active (Powered) - where the amp is built in to the speaker and you plug the speaker into the wall, it needs no external amplification but requires 2 cables, one power cable (kettle lead) and one signal cable (XLR)

• Passive (Unpowered) - where you need an external poweramp which send power to you speaker via a Speakon cable, like those ones you saw in that rehearsal room or on stage in Whelan's

Option 1 - Active rig:
2 x Mackie SRM450 http://www.thomann.de/ie/mackie_srm_450.htm €500 per pc
2 x Mackie SWA1501 Subs http://www.thomann.de/ie/mackie_swa1501.htm €800 per pc
Cost €2600

Option 2 - Passive rig:
2 x HK Audio Premium PRO15X http://www.thomann.de/ie/hk_audio_premium_pro15x.htm €444 per pc
2 x HK Audio Premium PRO18S http://www.thomann.de/ie/hk_audio_premium_pro_18_s.htm €533 per pc
2 x Yamaha P7000S http://www.thomann.de/ie/yamaha_p7000s_endstufe.htm €738 per pc
Cost €3500

SUBTOTAL €5300 (add €1k for the passive rig)

Active Monitor Rig:
2 x Mackie SRM450 http://www.thomann.de/ie/mackie_srm_450.htm €500 per pc
It's a good idea to have your monitor speakers the same as your FOH speakers in case you blow a driver. "Multipurpose" and "interchangeability" are the buzzwords of the day.

SUBTOTAL €6300

Cabling, cases & misc accessories €1000

TOTAL SYSTEM COST €7300

Optional Extra: http://www.thomann.de/ie/behringer_mdx4600_multicom_proxl.htm €138
-you might want this if you want to mic, compress and gate a drum kit

So, what started out as a brainwave idea to buy a PA has now turned into a €7000 shopping bill, not forgetting you're gonna need to transport your lovely new rig around the place so you can probably add a small van to that list too.:eek:

Here's some FAQ that pop up:
Q: Can't I just use 2 speakers for a PA?
A: Yes, but if you don't know what you're doing you will most likely run your speakers and amps harder than they would like. This would include trying to mic a full drum kit, including your 24" bass drum from the 80's.

Q: Why do I need to spend that much? Wouldn't the cheapest stuff be ok?
A: Yes. No. Maybe. Who knows. There's nothing "wrong" with the entry level stuff from 'thebox' or 'Fame' or even Behringer, but the audio industry is no different from any other in the sense that you get what you pay for. Or, as the saying goes, "buy cheap, buy twice".

Q: What is the purpose of Subs?
A: To accurately project low frequencies, that's basically it in a nutshell. Usually that means Kick Drum, Bass Guitar, Keys and pretty much any instrument that goes lower than 100Hz.

Q: What is a powered mixer?
A: A mixing desk which basically has built-in amplification. They are popular for their simple operation but don't leave a lot of room for upgrading.

Q: What is better, Active or Passive?
A: This question has no answer.

Q: Where can I realistically save a few quid when buying a PA?
A: In truth, you should start small but leave yourself options should you wish to expand because odds are you will. Start with a small Vocal PA and factor into your plans how you can add Subs at a later stage without having to buy a whole new rig.

Q: What is a Graphic EQ and why do I need one?
A: It's a rack-mounted thingy with some knobs and faders, you'll see DJs with the popular "smiley face" curve but that is not how a Graphic is properly used. In reality, it's merely a tool to help you fix anomalies in your system or in a given venue. It is also helpful in fighting feedback because you can locate and cut the offending frequency.

Q: What's the deal with compressors and gates?
A: If you have to ask this question, don't use either.


Bottom line is that you really need to get educated on a whole range of issues. If you go with Passive speakers, you have to match the ohms rating of your speakers with that of your amp.
Generally you will see the following ratings:
400W RMS / 800W Program / 1200W Peak
In lay mans' terms, RMS is the continuous power your speaker runs at, Peak power is what it might hit once in a while for a brief milisecond (like transients, but thats way off yet) and you should use the Program power number to decide how much power you need to supply it with. Basically, a speaker rated at 400W RMS will require an amp that can give it 600-800w of power. The rule of thumb is RMS x 1.5

I won't go into the ohms thing yet, it's a bit of a bitch to explain in simple terms. There's a wealth of info available, Google is your friend, or just ask if unsure.

PA SYSTEM Manufacturers:
Dynacord - german made, very reliable but expensive, you will pay extra for the badge. Very popular in Ireland, esp the corporate scene. Part of the Bosch/Telex group with EV, Midas & KlarkTeknik www.dynacord.com

Electrovoice (EV) - same umbrella company as Dynacord so lots of very similar products, USA made I believe. Still make great stuff and you can do no wrong. Also very popular, you'll see EV's pretty much everywhere you go. Part of the Bosch/Telex group www.electrovoice.com

JBL - USA made, try avoid the EON (plastic) and JRX range it's not the may west. Otherwise, great gear, use it myself - part of the Harman International umbrella group which includes DBX, AKG, BSS Audio, Soundcraft & Lexicon www.jblpro.com

HK Audio - german made, affordable, will sound pretty good for the price. The company is related to Hughes & Kettner the guitar amp makers www.hkaudio.com

Turbosound - British I think, reknowned for their dance club systems, maybe not as popular as they once were but still very good stuff. www.turbosound.com

Nexo - fairly prestigious and very expensive. If you can afford this then you probably arent reading this www.nexo-sa.com

RCF - Italian, very well respected gear and moderately priced too. www.rcfaudio.com

dB Technologies - fairly affordable entry level systems, a cheaper version of RCFs except dBs dont sound great when pushed but can still do a job without breaking the bank. Italian made, not to be confused with 'd&b audio'(!) www.dbtechnologies.com

Mackie - Some made in USA, some made in China these days. Mixed views but overall you could do a lot worse. The SRM450 is one of their best selling units, but it is known for shutting down when used as a monitor due to overheating, YMMV. Gets very screechy when cranked. www.mackie.com

Seeburg Acoustic Line - german made pro stuff at decent prices www.acoustic-line.de

Martin Audio - very pricey but gets rave reviews, considered a premium badge and UK made (now part of Loud Technologies) IIRC www.martin-audio.com

Edit:
d&B audiotechnik - german made, about as high end as you can get! www.dbaudio.com

Meyer - great US made, all the Cirque du Soleil productions use this stuff IIRC www.meyersound.com

L'acoustics - excellent systems, French origin I think www.l-acoustics.com

Yamaha Pro Audio - reliable stuff at a very good price point, esp the Club series speakers www.yamahaproaudio.com

Eastern Acoustic Works (EAW) - great USA made stuff, a relative of the Mackie/Loud Technologies brand which also includes Ampeg and recently acquired Martin Audio too. www.eaw.com

There's more but the above would be the main players in the UK & Irish market.

sei046

Brilliant Post Savman. We will definitely organise this stuff.
+1 for EV. Been rocking a Deltamax and Mt4 rig for a good few years now.

unclebill98

Great post....

ogy

nice one, ill try and do one or two in a couple of weeks when im finished college

Soundman

Q: What's the deal with compressors and gates?
A: If you have to ask this question, don't use either.

I kinda disagree with this as with a little research on how to use them, compressors can save a novice from destroying the PA they have just spent money on.

With regards PA Manufacturers. don't forget:

L'Acoustic
Meyer
D&B

I mention these ones especially as they are starting to make a large impact on the Irish market. Most of the large festivals lately are using L'Acoustic Arcs and so on. 3 of the main venues in Dublin have these systems too. Meyer are becoming more popular as are D&B (not to be confused with dB Technology).

Other than that, great post Savman. Nicely explained.

sei046

I would feel that for a sound man starting out, it is better he gets use to getting the surce sound right before he starts messing with gates. Once he really begins to understand how the sound works then the compressor and gate should be self explanatory

frobisher

Great stuff savman! Well done. We'll find a way to either include this into a sticky or make one for it.

If anyone has further thoughts to add that can be included too.

Soundman: I'm sure you've got some good stuff to share

Savman

Soundman wrote: »

compressors can save a novice from destroying the PA they have just spent money on.

A Soundman will always say that :pac::pac:
But for Muso's without a clue how to use them, they would be a luxury rather than a necessity IMHO. There's also more room for user error and more chance of squeezing the vocals down do a toneless yelp. I think on a small scale, comps are good for drums but folks should develop their skills with the very basic mic-cable-desk-speaker config then add the other toys later. Fair point though.

L'Acoustic
Meyer
D&B

Absolutely, although all three would be considered premium marques so not exactly ideal for your average Joe but I agree if we're compiling a list then all Manufacturers should be on there.

PaulBrewer

Good work Chief!

sei046

Hey Sav ( Or anyone? ) Does anyone want to post up some tips on stuff like bleeding the room? I will leave it to lads who can explain it better!

Savman

Someone else's go surely! I haven't heard the term "bleed the room" - do you mean system tuning and ringing out etc?

sei046

Yup, as in Eqing your Pa for the room your in

Savman

To be honest I think we'd be getting ahead of ourselves on a thread like this, maybe a new thread is in order for that discussion? We don't want too much tech talk flying over people's heads.

The inherent problem with joe bloggs sticking a Graphic EQ into their signal chain, is that they will more than likely feel the compelling need to fiddle with it needlessly when many rooms require little or no corrective action across the frequency range. OTOH if you're faced with a horrible room with awful acoustics, a Graphic will defo help but only to fix minor anomalies. If the room is shoite ain't nothing gonna fix it.

Comb filtering = hell

PaulBrewer

Savman wrote: »

T
The inherent problem with joe bloggs sticking a Graphic EQ into their signal chain, is that they will more than likely feel the compelling need to fiddle with it needlessly when many rooms require little or no corrective action across the frequency range. OTOH if you're faced with a horrible room with awful acoustics, a Graphic will defo help but only to fix minor anomalies. If the room is shoite ain't nothing gonna fix it.

Comb filtering = hell

Ain't THAT the truth ...

Savman

PaulBrewer wrote: »

Ain't THAT the truth ...

I dunno if you've ever been in The Westin, but christ jesus. It's a large dome-shaped room with a big high roof similar to a church. Crack a snare in that room and you'll hear it come back at you for about 6 seconds. Absolute nightmare. The only corrective tool is audio ignorance, aka find your happy place :pac:

sei046

There is a gig her in trim like that. The space where the kit goes has an extended room up about 2 floors. The biggest example of ignorance in architecture. That part was obviously for the band...

Soundman

Savman wrote: »

I dunno if you've ever been in The Westin, but christ jesus. It's a large dome-shaped room with a big high roof similar to a church. Crack a snare in that room and you'll hear it come back at you for about 6 seconds. Absolute nightmare. The only corrective tool is audio ignorance, aka find your happy place :pac:

Or (sometimes works)... Find a nice reverb and set the decay time to the same length of the room's natural reverb time and put it on everything in your mix. Can create a natural phasing with the room resonance which will in some cases deaden the room enough so you can have a reasonably happy mix.

thumpybum

Find a nice reverb and set the decay time to the same length of the room's natural reverb time and put it on everything in your mix. Can create a natural phasing with the room resonance which will in some cases deaden the room enough so you can have a reasonably happy mix.

when you say everything, dyou mean all channels? Ive a reverb unit nearly permanently set on "small room" but only on vocals and a bit of the snare if I think its a bit dead.

Ive played a couple of big rooms lately and have been having arguments with my "happy place".

unclebill98

If only gear had a "Happy Place" setting.....

Savman

thumpybum wrote: »

when you say everything, dyou mean all channels? Ive a reverb unit nearly permanently set on "small room" but only on vocals and a bit of the snare if I think its a bit dead.

Ive played a couple of big rooms lately and have been having arguments with my "happy place".

Not really the same thing I don't think, setting a verb to counter act a bouncy room is not something I would be fast to recommend unless you have the time and skill to get it right. The most powerful tool in your arsenal is your brain, everything else is secondary.

Personally I would never add reverb to anything if the room was naturally reverberent.

Soundman posted a tip to try that may help by using electronic reverb to fight natural reverb. It might be worth a try, only one way to find out if it's a solution that works for you.

Welcome to combat audio

justcallmemoses

I have two speakers at 1000 watts program
(500 watt rms @8 ohm each side)

Would the following spec power amp match the speakers?? (upcoming pub gig - need amp)


Power Amp Specifications:
4Ω stereo: 2 x 500Wrms
8Ω stereo: 2 x 250Wrms
8Ω bridged: 1 x 800Wrms
Max power: 1600Wmax @ 8Ω

wiggilicious

I know this thread is a few years old but i didnt want to open yet another thread on a topic that has most likely already been flogged.
I've gigged as part of original rock/ grunge bands over the years and we always strove for the biggest PA systems we could afford, never really knowing much about the science and never really having much $$$ either
Now i'm that bit older and looking to go back gigging a mix of tunes just myself and an acoustic, though i might add a second guitarist or maybe someone with one of those wooden drum box thingies over the years if i come across someone. For now lets just say its me and i might get a guest up the odd time to song etc. Maybe i'll go to using backing tracks in time if the stripped down thing doesn't work but who knows what will happen. As such, i don't want to throw all my eggs into a line array system as i'm not too sure i like the sound. I tried an L1 compact, thought i liked it until i realised there was no real highs or lows from it and i wouldn't fork out 2500 for the big one. I also tried the RCF Evox 8 and while better, i just didn't like the sound, it was warm but not rich if you know what i mean.
Anyway, what i really want to know is could i get away with using an RCF 12" and 15" active speaker together, just 1 of each. the 12" to really accentuate the voice and the 15" to fill out the rest of the sound including the guitar. I've tried both, the 12" just didn't handle the guitar as well as i would have liked and the 15" though nice didn't have the same sparkle as the 12" vocally. Couldn't find anything online similar to what im proposing.

Rig would be:
RCF 712a x 1
RCF 715a x 1
Allen & Heath Zed-10fx or a Zedi-10fx
Sennheiser E935
Acoustic guitar

Any thoughts would be welcome!
Wiggy

justcallmemoses

To mic a full drum kit, how many watts in PA system would you recommend? Curious if the below is strong enough

Current set up is 2 sx300 tops (300 watts) and 1 x 500 watt peavey bin.

Would you recommend a compressor?