Advice needed - PA/Speaker ratings

[stevie axeman]

Hi guys - hoping on of the forumites has some experience in this area - probably Paul Marossy or Noodler being as techie as they are :-)

I know a fair bit about guitar amps - but little about PAs

Hi - we have recently bought a Allen & Heath Powered mixer/Desk - 500w RMS per side output - and have managed unsurprisingly to blow one of our existing speakers rated at 200watts (RMS). Whilst this isn't major issue ( we were going to upgrade anyway) - the whole issue of amp/speaker matching is new to us and we are looking for advice on what kind of speaker wattage to go for.

We play rock music as some of you kno already - typically with vocals, kick drum, snare, bass synth pedals and guitar synth, acoustic guitar running thru the PA - other instruments (electric guitar, bass) use the backline only.
So its a mix of "peaky" sounds such as drum, vocals and continuous sounds such as synth sounds.
We can't find any information in the Allen&Heath manual - and googling useful sites gives information varying from matching power rating (in RMS) for speakers and amp ( so 500w RMS speakers for the A&H desk) - to the speakers being half the amp power, and still able to handle peaks.
Any advice you guys can give would be appreciated.

We do however understand the difference between RMS and peak power etc rating, and undettsand the nature/rules of impedance matching  :-)




Caparison Horus,  Schecter C7 Hellraiser ,  Blue/green-burst 09 Fly Deluxe , Natural Mahogany Fly Mojo, Brian Moore i9.13 ,Godin ACS-SA
Bogner XTC Classic (in Purple!),Fishman Performer amps
Roland GR33/Digitech GNX/Fishman Aura Blender, Sequis Motherload Elemental

[lucgravely]

Stevie, I have bought and sold PA equipment for years, and I have a couple of ideas for you.

In your situation having 500 watts per side, I would run those 500 watts to a 500 watt+ handling speaker. I like Carvin. I have their subs right now and they handle 800 watts, 1600 peak, and 3200 programmed. Their mains would be the same, or you could order similar neodymium magnet speakers that would handle accordingly.  

Secondly, does your mixer have inserts for a master compressor or EQ? If you had your main line out compressed/limited you would save yourself on peaks and extend the life of your speakers by protecting them from unnecessary volume spikes. With compressors/limiters you could possible also use lower than 500 watt speakers and just run enough volume to make them sound good without the speaker distorting. The compressor would limit the peaks thus making your handling more ideal for a lower watt speaker.

my 2 cents. Also, what ohm load does the A&H board put out? You never want an ohm load lower than the ohm output from the amp. And remember ohm loads double when you daisy chain speakers together.

Luc Gravely
Parker Fly Mojo Single Cut
Parker Fly Deluxe
Mesa/Boogie Mark I
A few pedals...

[wkcchampion]

The best thing is to have a speaker that can handle at least 1.5x or double the RMS power of the amplifier. This way, you're pretty sure that the speaker is not overdriven and will likely last forever.

Impedance MUST always be matched. Nothing to say more here. A 8 ohm amplifier must see a 8 ohm total load. Combining the speakers in series or parallel must match the total impedance load.

---------
Marco
http://pregnosplatter.altervista.org

Pearl White 2008 Fly Mojo
"Eldy" / Majik Blue 1995 Fly Deluxe (Gen1 Di Marzio PUs)
1993 Japanese "lawsuit" 1959 replica Les Paul
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Marshall JCM800 1959 SuperLead (1981)
Marshall JCM800 2203 (1983)
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2010 Laney CUB12
Palmer PDI-03
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"I haven't got a 1968 Plexi, but.. I've got 1968 Rayban Aviators! "

[908ssp]

In A PA you can't have too many watts and you don't have to worry about having more watts than the speaker can handle. It is the opposite for guitar don't confuse the two. Amp distortion is more dangerous for speakers than speaker distortion and in a PA you want neither.

[bno]

Only thing to add is that is obviously possible to use speaker cabs with lower rated power handling than what the amp can put out, just don't turn the output level up.

Kick Drums and Keyboards can easily destroy a 12" 2-way.  If you're running them through the PA then consider getting subs and a crossover.

Consider injection molded for the weight.  You may have a local DJ equipment supplier that can hook you up.

[Patzag]

quote:Originally posted by stevie axeman

Hi guys - hoping on of the forumites has some experience in this area - probably Paul Marossy or Noodler being as techie as they are :-)

I know a fair bit about guitar amps - but little about PAs

Hi - we have recently bought a Allen & Heath Powered mixer/Desk - 500w RMS per side output - and have managed unsurprisingly to blow one of our existing speakers rated at 200watts (RMS). Whilst this isn't major issue ( we were going to upgrade anyway) - the whole issue of amp/speaker matching is new to us and we are looking for advice on what kind of speaker wattage to go for.

We play rock music as some of you kno already - typically with vocals, kick drum, snare, bass synth pedals and guitar synth, acoustic guitar running thru the PA - other instruments (electric guitar, bass) use the backline only.
So its a mix of "peaky" sounds such as drum, vocals and continuous sounds such as synth sounds.
We can't find any information in the Allen&Heath manual - and googling useful sites gives information varying from matching power rating (in RMS) for speakers and amp ( so 500w RMS speakers for the A&H desk) - to the speakers being half the amp power, and still able to handle peaks.
Any advice you guys can give would be appreciated.

We do however understand the difference between RMS and peak power etc rating, and undettsand the nature/rules of impedance matching  :-)




Caparison Horus,  Schecter C7 Hellraiser ,  Blue/green-burst 09 Fly Deluxe , Natural Mahogany Fly Mojo, Brian Moore i9.13 ,Godin ACS-SA
Bogner XTC Classic (in Purple!),Fishman Performer amps
Roland GR33/Digitech GNX/Fishman Aura Blender, Sequis Motherload Elemental

Hi Stevie.
Been dealing with speaker systems and PAs for a loooong time (too long as my back will attest).
Be a pleasure to help you with that.  You can email me direct for my recommendations which will depend on a lot more data gotten from you.
Cheers,
Patrick


Trans-blue Mojo 2006, Pearl White Custom Dragonfly HSH 2010

[bembamboo]

As said, the distorting power amp blows the speakers!  Lord Valve: More amp power, less speaker.

[doombilly]

quote:Originally posted by lucgravely

I like Carvin.

I'm with lucg. I've been rocking 2 Carvin LS2153's (4 ohm, 2-15" + horn) for vocals and a pretty demanding drum machine. Not a problem for years. Worse thing I can say is when we didn't have a top for the truck the tarp wasn't the best at keeping them dry and the carpet glue kinda is coming up. More my fault, than carvin's. We're pushing them with an older Carvin DCM1000. Works great. Alesis has great mixers, at great prices (sub $200). I've got a 6 ch and an 8 ch USB. Get some heavy duty cabling. I think in 10 yrs I replaced one side's volume pot on the DCM1000.

http://www.sonicbids.com/illicitizen

[seedlings]

Also, this may sound counter-intuitive, but having too little amplifier power usually damages speakers easier than too much amplifier power.  If you use a 300W amp and 300W speakers, and need 300W of sound, you'll put that amp into distortion quite a bit of the time, and the distortion (not guitar distortion, but clipping) damages the speakers - always first to go are the horns.  However, if you have 1000W power and 1000W speakers, but operate them in the 300W range, then you're staying safely under the limitations of both the amp and speakers.

CHAD

[macmedic]

quote:Originally posted by stevie axeman

Hi guys - hoping on of the forumites has some experience in this area - probably Paul Marossy or Noodler being as techie as they are :-)

I know a fair bit about guitar amps - but little about PAs

Hi - we have recently bought a Allen & Heath Powered mixer/Desk - 500w RMS per side output - and have managed unsurprisingly to blow one of our existing speakers rated at 200watts (RMS). Whilst this isn't major issue ( we were going to upgrade anyway) - the whole issue of amp/speaker matching is new to us and we are looking for advice on what kind of speaker wattage to go for.

We play rock music as some of you kno already - typically with vocals, kick drum, snare, bass synth pedals and guitar synth, acoustic guitar running thru the PA - other instruments (electric guitar, bass) use the backline only.
So its a mix of "peaky" sounds such as drum, vocals and continuous sounds such as synth sounds.
We can't find any information in the Allen&Heath manual - and googling useful sites gives information varying from matching power rating (in RMS) for speakers and amp ( so 500w RMS speakers for the A&H desk) - to the speakers being half the amp power, and still able to handle peaks.
Any advice you guys can give would be appreciated.

We do however understand the difference between RMS and peak power etc rating, and undettsand the nature/rules of impedance matching  :-)

I recommend the Yamaha Pro Sound Manual for starters. When you mic anything that has massive transients like a kick drum or a bass guitar you better have a PA that is setup with electronic crossover (separate amps for low, mids and highs)and a compressor. There is not a powered PA head made (to my knowledge) that uses electronic crossover. There is no way around this because it is plane physics you are dealing with. If you can afford it some of the new powered speakers work really well, but are not cheep. Don't depend on your local music dealer because they out of ignorance or malice will try to sell you a newer version of what you already have and that will not solve the problem. If you have a local sound company in your area get real tight with them and see how they do it.


Caparison Horus,  Schecter C7 Hellraiser ,  Blue/green-burst 09 Fly Deluxe , Natural Mahogany Fly Mojo, Brian Moore i9.13 ,Godin ACS-SA
Bogner XTC Classic (in Purple!),Fishman Performer amps
Roland GR33/Digitech GNX/Fishman Aura Blender, Sequis Motherload Elemental

[stevie axeman]

Thanks Warren - we are looking into using limiters on somne of the channels - feeding kick drum, snare etc

Caparison Horus,  Schecter C7 Hellraiser ,  Blue/green-burst 09 Fly Deluxe , Natural Mahogany Fly Mojo, Brian Moore i9.13 ,Godin ACS-SA
Bogner XTC Classic (in Purple!),Fishman Performer amps
Roland GR33/Digitech GNX/Fishman Aura Blender, Sequis Motherload Elemental

[bembamboo]

Thinking about spending more than a thousand bucs some (4) eminence 10" and 12" kappalite high output neo PA (raw) speakers, about 400 watts rms.  would like to have all 4 ohm to get the most out of my power amp.  Want full range speakers but the 4 ohm models are low/mid frequency so i probably will have to go with 8 ohm speakers, in two sep small "schellpable"  2x10 or 2x12 cabs.  can i wire for two or four ohm loads mono or stereo??  downsides?  other thoughts.  already have separate 85 watt new horn drivers.

[jester700]

What driver on your speaker blew? Tweeter or woofer? If it's the tweeter (the horn), I agree with those who say you might have an underpowered amp and distortion was the problem. There's good advice above. Bi/tri amplify if you can afford it. Watch levels - and watch it all the way through the signal chain. I've seen setups where the amp wasn't distorting but they were driving digital effects into clipping - and that will also kill your horns.