Amp Advice

[Over the Hill]

My bar rock band is in the midst of upgrading our PA. We started out with JRX fronts, 2 Yamaha br12 monitors and a Yamaha EMX 5000 powered mixer. Our first upgrade was to replace the JRX speakers with MRX 512's, (what a huge difference). We are looking at replacing the mixer now. Based on what I've learned lurking here, we are going with a Mix Wiz. We would appreciate your advice on choosing the correct amp. The amp would be driving both the MRX's and the monitors. Our experience level is fairly low. We can get the PA set up and get good sound but thats about it. If we had too do it all over again, we would have gone with powered speakers, but the way it worked out we can only do a few bits at a time so we need to choose an amp that will get the best performance out of the mains while being sure we don't blow them up in our ignorance.

[335BoB]

 

My bar rock band is in the midst of upgrading our PA. We started out with JRX fronts, 2 Yamaha br12 monitors and a Yamaha EMX 5000 powered mixer. Our first upgrade was to replace the JRX speakers with MRX 512's, (what a huge difference). We are looking at replacing the mixer now. Based on what I've learned lurking here, we are going with a Mix Wiz. We would appreciate your advice on choosing the correct amp. The amp would be driving both the MRX's and the monitors. Our experience level is fairly low. We can get the PA set up and get good sound but thats about it. If we had too do it all over again, we would have gone with powered speakers, but the way it worked out we can only do a few bits at a time so we need to choose an amp that will get the best performance out of the mains while being sure we don't blow them up in our ignorance.

 

 

My advice will come with my direct involvement with an EMX5000 and Mpr415's which are the predecessor to the MRX series. The EMX5000 is one of the BEST investments I ever made. I didn't know anything before I bought that mixer. (Now I "barely" know anything) I foolishly thought I was going to power of pair of old EV1512's AND a pair of monitors with one amp of the mixer driving each pair. I quickly realized I needed at least a small power amp to power the monitors. A found a good deal on a used QSC QMX2450 to power the MAINS instead and used the EMX to power the monitors. WOW! What a difference the 2450 made!!!

Soon after I sold the RMX2450 and the EV's and bought a pair of MPro415's and a QSC PLX3402. Soon after again I got another 3402, a pair of MP418's and a DriveRack PA all while STILL using the EMX5000. I did some fairly large gigs with that. (Large for me)

 

My advice (unless you have the money) is to keep the EMX5000 for now and just add a nice power amp for your mains (like a LPX3402 or the newest replacement) and use the EMX to power your monitors "for now". You WILL notice the improvement!

 

I was just thinking and might opt to sell the MRX speakers and just buy a pair of PRX speakers. Might work out cheaper even with a loss on the MRX.

[Over the Hill]

Thanks Bob. The EMX has been a workhorse. We bought it used and have good experience. We are just getting concerned that one day it will just quit on us. Are you suggesting to run the PLX 3402(or similar) in stereo, providing 700 watts per channel or from 1 side providing 1100 at 4 ohms. this is the area where I think I am most confused. I read 1.5 to 2x RMS if you know what you know what you are doing. I don't know. What I am looking for is which amp to buy to give me that will give me drive the Mrx's properly without overpowering. I was hoping to use 1 amp for both the mains and monitors. Is that asking too much from 1 box?

[DaBender]

There are plenty of amps that will fill the bill, the problem is that your mains are capable of handling quite a lot more power than your monitors, so an amp robust enough to really tap the potential of the JBL 512s will have more than enough to blow your BR12s. to bits. As long as you keep that in mind and are careful, you could do it. The Yamaha P7000S would put 550 watts into each box, which would seem like a pretty good match. Of course, there are lots of other choices.

[335BoB]

 

There are plenty of amps that will fill the bill, the problem is that your mains are capable of handling quite a lot more power than your monitors, so an amp robust enough to really tap the potential of the JBL 512s will have more than enough to blow your BR12s. to bits. As long as you keep that in mind and are careful, you could do it. The Yamaha P7000S would put 550 watts into each box, which would seem like a pretty good match. Of course, there are lots of other choices.

 

 

I agree and is why I wouldn't suggest one amp for both FOH and monitor duty. Yes I was suggesting to run the amp stereo and use the onboard amps for monitors. The BR 12 is rated for 300 watts program and the EMX is rated at 325 watts per side (even if it's peak power) Even running 4 BR12's with 2 per side is a good match for the EMX. Getting the mains off the EMX will give you more available for the monitors and getting a good amp for the Maind will make you go WOW! I assume you are presently running 2 mains off one side and the 2 monitors off the other side. You WILL go WOW with the right amp.

I am NOT saying not to get a MixWix or any better board. What I AM saying is that can wait. Keep in mind that since the Mains and monitors will be a mismatch for any one single amp, that as soon as you get rid of the EMX not only will you need a new board but you will need another amp for the monitors. Wait until you are ready for that move. Meanwhile don't underestimate the longevity of that EMX. It's a GREAT board that most here on this particular forum will never understand!

 

I would be curious to know the opinion of the Pros here of matching the MRX512's with a PLX 3402. It's less than the Program rating.

(Please be gentle. I can't take much more pounding today)

[heath_eld]

 

I read 1.5 to 2x RMS if you know what you know what you are doing. I don't know. What I am looking for is which amp to buy to give me that will give me drive the Mrx's properly without overpowering.

 

 

Generally the advice given is around RMS. Personally i've always gone with that option (or say, below 1.5x RMS) and not had a problem. I have used my own MRX 512s with a Yamaha P7000 (so 700w a box) with extreme caution for acoustic music. THe truth is it probably won't blow them... but if you're talking about buying an amp, why would you pay more (in most cases) for a bigger amp when your speakers wont really take advantage of it anyway, and risk blowing the speakers?

 

I normally find i get good results with a different (no name brand) 500w a side at RMS amp. I've also used an old Yamaha P3200 (320 a side @ 8 ohm) and found it was just too small and clipping at relatively low volumes.

[agedhorse]

I would start with 2 of the MRX boxes on one channel and 2 if the cheapo monitors on the other, be careful with your monitors but if you do damage them by having an accident it's not the end of the world as they should be the next thing to replace before your board.

[Over the Hill]

Aged, with your configuration in mind, what size amp would you recommend? Can we say for arguements sake the the yamaha board will most likely be out of the picture?

[335BoB]

 

Aged, with your configuration in mind, what size amp would you recommend? Can we say for arguements sake the the yamaha board will most likely be out of the picture?

 

 

With all the "hoopla" on the other thread about blowing speakers, I would be interested in the answer to this question also.

[agedhorse]

 

Aged, with your configuration in mind, what size amp would you recommend? Can we say for arguements sake the the yamaha board will most likely be out of the picture?

 

 

Start out with the amps in the Yamaha board. If that gets you sufficient volume without hitting the amp's limiter too hard, you are good to go.