How many watts for a Rock PA

[alcohol_]

I have a loud rock band. The setup we have is a very loud drummer, Lead guitar Marshall 50 watt amp, second guitar 30 w amp, bass 700 amp.

 

I'm using a Peavey PV 900 amp, bridged, and going into two JBL 15" speakers.

 

Only the vocals and the lead guitar are miked. I just don't seem to get enough volume from this setup.

 

Should I replace the power amp? Get additional speakeres?

[Lee Flier]

Errhhh have you thought about reducing your stage volume?

[fantasticsound]

First, what impedance is each speaker? Are you sure your amp is designed to handle the combined impedance load in bridging mode? You may be burning out the power supply. (Many amps are solely designed to bridge with a 4 ohm load. If you present two 4 ohm speakers to your amp in bridging mode it will see a 2 ohm load.)

 

Second, what is feeding this amp? What's the signal chain. It is not uncommon for novices (and sometimes experienced mixers) to misunderstand gain stages in their system. If you aren't taking advantage of headroom elsewhere in the system, you may be amplifying a weak signal at the amp. This limits the amps ability to provide higher output. This is often the case where a -10 dbv output is fed into a device that expects a +4 dbv reference level.

 

You should have plenty of power for your use, so long as you lead guitar player isn't trying to kill people with low end. (A common problem these days. Guitar players want to do the modern, drop D or 7 string setup with tons of low end.) This interferes with the bass guitar as well as sucking up major resources from the PA amp. If you don't have an adequate mixer (flexible eq) then the guitar player may just have to get used to playing with the appropriate amount of low end for the PA.

 

Other than that, you could buy more gear and spread the sound out more evenly, but it sounds like Lee's right, too. Get the drummer to reign it in. I know that sounds anti-rock 'n roll, but frankly, this is the difference between good drummers and bad ones. I don't care how good your chops are, if you can't (or won't) play to the room and the sound system, you're useless. The only place you'll find work is with bands that have overpowering PA or garage bands with no gigs... and the latter wonder why they can't get gigs. This is a major impediment for many bands.

 

That's my two cents. Do with it what you will or toss it out.

[KHAN]

I've heard Country, Oldies, and Jazz groups sound OK with your type of set up. I've never heard a "Loud Rock Band" sound good without the drums mic'd up through a PA with Subs, and enough power to run them comfortably.

 

Lee's point is absolutely right though. With your current set up you should get what you can out of the vocals, and then bring up the volume of the instruments until you get a good even mix.

 

Playing too loud for the PA system is selfish and unprofessional.

[Lee Flier]

Unless you are playing in some pretty large venues, I'd recommend doing the following: next time you rehearse or soundcheck at a gig, bring an SPL meter and take some measurements from 15-20 feet away (without the PA on). If you're averaging louder than the 105 to 110dB range without the PA being turned on, your stage volume is going to overtax most small club PA systems and you're going to sound like crap. There are a lot of bands these days that are at 120-125dB before the PA is even turned on, and that's just out of control. It's nothing but an invitation to damage your hearing and your audience's hearing, not to mention sound like crap.

 

Rather than address this problem at the source, most people just buy bigger PA systems and start wearing earplugs. WTF kind of solution is this? You spend a shitload of money on PA gear, have to buy a bigger truck to haul it all around, and it's still going to be way too loud for a small venue. Since most people in your audience are going to be wearing cheap earplugs, you're still going to sound like shit to them, considering that anything but expensive custom earplugs are going to cut the high end drastically. So all your expense and hard work will be for naught by the time it reaches your audience's ears.

 

Furthermore, several large booking agencies have recently done surveys to try to determine why club attendance has been down the past few years. One of the top reasons was excessive volume and bad sound (which are very much related - it's near impossible to get good sound at the kind of volumes many bands/venues run at these days).

 

The saddest part is all this can be easily fixed by simply managing your stage volume. It's not that hard, just get yourself an SPL meter and work to get your average down at least below 110. If your PA still doesn't cut it at that point, THEN maybe you can think about more gear.

[fantasticsound]

What Lee said.. only bring that level down to about 100 db SPL. Keep in mind that large concert PA's typically ride at 95 dB SPL or less. I've heard ones considerably louder. It didn't matter who the act was, it always sounded like sh*t.

[Lee Flier]

Originally posted by fantasticsound:

What Lee said.. only bring that level down to about 100 db SPL.

NOW you're getting WAY too optimistic. But you gotta start somewhere.

 

Keep in mind that large concert PA's typically ride at 95 dB SPL or less. I've heard ones considerably louder. It didn't matter who the act was, it always sounded like sh*t.

Yep. Of course, with large concert PA's you're likely talking 95 dB at the FOH position. The stage volume might be considerably louder.

[alcohol_]

Thanks for the advice. I've got to check the impedences.

 

The drummer is the culprit for my son's band.

 

However, last night I was providing the sound for a country act. Everyone lthought it sounded good but I had just enough sound. I was feeding the sound from a Soundcraft RaqPaq, which I believe has a -10dbv output, into a DBX 321 Graphic EQ then into the PV 900 and the PV LEDs were occassionally going into the red triggering it's internal compression. So I think I was maxed out and it wasn't that loud, it was only loud enough for this band with a comfortable volume. I only had an electric piano going into the system besides three vocals,

 

I believe these speakers are rated at 8 homes, so I had them in parrallel, giving me a 4 ohm load.

 

Thanks for the comments.

[fantasticsound]

Originally posted by Lee Flier:

Keep in mind that large concert PA's typically ride at 95 dB SPL or less. I've heard ones considerably louder. It didn't matter who the act was, it always sounded like sh*t.

Yep. Of course, with large concert PA's you're likely talking 95 dB at the FOH position. The stage volume might be considerably louder.[/QB]

That would be correct. But they also had much better monitoring systems. It's not the watts that count when you're using a biamped monitor of the Clair Bros, High End EAW, or McCauley, etc. variety. The product is so clear, when properly mixed, that less stage volume is often the case, because everyone can hear each instrument in their monitor so clearly. These two way monitors routinely cost around $2k, and they're worth every penny if you can afford it.

 

Big acts also have much larger stages to work with.

[Philip OKeefe]

Stick me into the "speakers and amps sufficient for the venue, and watch your stage volume" camp... far too many bands have far too much stage volume going on - especially in small clubs, and it's out of the soundperson's hands at that point - there's nothing they can do - the stage volume is just too loud for the venue and directly overwhelms any PA. Not to mention it ends up sounding like poop.

[Lee Flier]

Yeah exactly Neil. That was kind of my whole point... trying to replicate the capabilities of large arena systems in a small venue (including the stage volume) is folly. It just doesn't work, financially or sonically, yet so many bands try to do it and then wonder why people don't want to see bands in clubs anymore but will spend hundreds on a ticket to an arena show.