any PA buffs in here???

gonzosc1

gonzosc1

Joined
Oct 24, 2007
Messages
412
Reaction score
12
I'm trying to put together a small PA for my band so we don't have to rent anymore...
my main question at this moment is wattage RMS ratings on speaker cabs. we got 2 yamaha 18" subs. but the RMS rating on the yamaha website shows this as wattage ratings.

(noise) 250watts
(program) 500watts
(peak) 1000watts.
these are US made speakers if that help any

I have done alot of reading on this and from what I see everyone says to forget about all the different names and just look for the RMS and peak wattage. all the other names are just there to not say what the true RSM wattage is! so where do I go from here? I need to figure out how big of an amp I need to run these.
after reading alot of different articles on this, the rule of thumb is to go with an amp that has around 2x the RMS wattage rating.....
I don't know the RMS,,,,HELP!!!!!!
 
Florin is correct. The RMS (or program) is half of the peak. It represents the wattage the speaker can handle for long periods of time. I'm no expert and there's many theories on how best to match an amplifier to speakers, just use caution initially that you're not overpowering (clipping) your speakers. Hope that helps!
 
Correct: RMS and Program are the same.

If you plan to run separate subs and mid/high cabs, then you'll likely want to impliment a crossover and two separate power amps. Run your amps in mono for the most headroom. To avoid over-working the amps, I'd probably go with something in the 2,000 watt range for subs and 1,000 watt range for your mid/high cabs. That way, your system will not strain to fill a medium sized room. For good PA clarity, there is no substitute for headroom. You can always turn it down or add a limiter in your send patch, but pushing a low-wattage amp sounds awful. The crossover is good to keep horns from distorting as well.
 
great, thanks for the replies guys.
yeah I am going with a bi-amp system.
I have the 2 yamaha 18" subs,
2 PV dual 15"+horn cabs rated at 700 watts rms. the amp I have for the 2 PV cabs is a QSC 2450. so I will look for another amp about the same power as that one.
was thinking of going with a BBE crossover just to kill two birds with one stone deal as it has the maximiser on it also.
Behringer mx 9000 mixer. it may be over kill but the price was right, and you can never have too many inputs,,LOL
alesis 230 EQ
alesis 3630 2 ch compressor
tc electronics triple C stereo compressor
2 digitech rack multi-efects units. both will run 4 in and 4 out.
fostex dat recorder for 2 track live recording

so I'm not too far off from getting this thing off the ground. used equipment has been a god sent for me. with hard times, comes good deals. I only give $350 for the behringer mixer...
thanks guys
 
Gonzosc1
...you really can't have too many inputs... however many you have, you always end up 1 short within 6 months :wink:

...it's those drummers... keep wanting extra mics on everything!
 
saxonbass said:
Gonzosc1
...you really can't have too many inputs... however many you have, you always end up 1 short within 6 months :wink:

...it's those drummers... keep wanting extra mics on everything!
Click to expand...


LOL. most times I would agree with you,,LOL but this behringer mixer has 24 inline ch's,, thats 48 inputs on the ch's alone. the 8 sub groups are tripled bused for 24 outputs,,,LOL overkill !!!!!!!!!!!!!!
 
Nice rig so far, I'd reccomend a stereo graphic eq of 30 bands or so aswell to notch out any feedback & to tune the system. :D
 
Bassman68 said:
Nice rig so far, I'd reccomend a stereo graphic eq of 30 bands or so aswell to notch out any feedback & to tune the system. :D
Click to expand...

I was just talking with my guitar player about that. I have the alesis 230 EQ which is dual 31 bands. we were gonna use one side for foh and the other side for stage monitors. but we are thinking of just going with a decent feedback destroyer for the monitors to get control of feedback and then use both the alesis ch's for foh.
we only play out about 5-6 times a year and we always play small to med venues and we want to keep it running in stereo for our effects.

we figure most feedback problems start on stage with open mics, so if we can cover that we should have little feedback problem on the foh..
with the number of inputs and direct outs I have I should be able to set up a good monitor mix with the board alone and let the feedback destroyer do its thing on auto mode for the monitors..
 
Dual 15"+horn cabs!! that's a no no in PA, might work in a disco, but the lack of middle in a very critical area is no good for PA. A 15" simply can not reproduce high middle to meet the horn, well some 15"'s can , but it can't spread the critical midfrequencies. So you'll have areas in the room were those frequencies simply won't be heard, typically vocal. Go for dual 12"+horn or 15"+8"+horn.
But if you must use the dual 15"+horn, you got to use the 18" cab as an ad on: Set up the dual 15"+horn with a highpass filter at 35Hz, letting it play all other frequencies. Then set up the 18" cab with also a highpass filter at 35Hz and a lowpass filter at 90Hz. Then you got 2x15"+ a 18" to reproduce the deep bass and the fundaments of the kick drum, giving you lots of extra headroom. NEVER EVER divide between a sub and a dual 15" cab.
 
Myh said:
Dual 15"+horn cabs!! that's a no no in PA, might work in a disco, but the lack of middle in a very critical area is no good for PA. A 15" simply can not reproduce high middle to meet the horn, well some 15"'s can , but it can't spread the critical midfrequencies. So you'll have areas in the room were those frequencies simply won't be heard, typically vocal. Go for dual 12"+horn or 15"+8"+horn.
But if you must use the dual 15"+horn, you got to use the 18" cab as an ad on: Set up the dual 15"+horn with a highpass filter at 35Hz, letting it play all other frequencies. Then set up the 18" cab with also a highpass filter at 35Hz and a lowpass filter at 90Hz. Then you got 2x15"+ a 18" to reproduce the deep bass and the fundaments of the kick drum, giving you lots of extra headroom. NEVER EVER divide between a sub and a dual 15" cab.
Click to expand...


the dual 15" cabs have built in crossover at 2.6k. the papers for the cabs also say its a quazi 3way system, whatever the hell that means.
the amp(qsc 2450) I use for the dual 15" cabs has a 30hz and 50hz filter on it so thats covered. was thinking of using the 50hz filter on the dual 15" cabs
was going to set up another cross over at around 100hz-125hz for the subs with a 30hz filter on that,,,thinking of getting another qsc 2450 for the subs....

if it turns out to not sound good it would be no problem to take one of the 15" speaker out of each cab and replace with 10" or 8" with the use of an adaptor ring in the speaker opening.
 
I'll second the 15"/horn cabs. Without some smaller drivers, your vox are never going to sound crisp, and in the process you'll probably overdrive the horns attempting to get some of the crucial mids out front. Overdriving horns sounds gawdawful.

Also, if you'll be running your mains in stereo, I think your monitor anti-feedback unit idea is a good one. That way you can simply slave the right side settings of your EQ off the left for good 2-channel stereo separation. Phaser/chorus/flange/verb will sound nice that way. However, running in stereo will drop your volume levels as the amps aren't going to be putting out as much power in stereo as they would in mono. Note - if you'll be playing at volumes above mid-level, then you'll lose most of the stereo benefit as the db's rise. Again - you can never have too much headroom, and on that front I'm as serious as a heart attack.

Sounds like you have a good plan working. Just not sure 'bout those 15's.
 
Quasi 3-way: the upper woofer cover lows and mids, and the lower woofer are crossed so it covers only lows, acting as built-in subwoofers. typicaly crossed intern passive at 250-300Hz, 6dB/oct. And that's why you should use the 18" cab. as an ad on.
 
great info,, thanks guys

I'll try to pull one of the 15" this weekend to see what the specs are. see if I can find a 10" or 8" in the same range for replacement... maybe a carvin speaker replacement,,,
 
You must log in or register to reply here.
Back
Top