Grateful Dead Music Forum

Hey folks!
I blew up my old PA poweramp - used to run our mains. I'm gonna get a new one but wanted to see what you all had to say.
Our speakers are Mackie S500 (passive) - rated at 250w @ 8ohms

First question is how big of a power amp to get? I've always thought it should be about twice the rating of the speaker - so a 500w per side? Anyone have better info?

Second is brand - I'm not gonna spend too much but have been looking at a QSC RMX1450 which is around $500 or Crown XLS 2500 which is about $100 more. Is the Crown worth it?

The blown amp is a Crest which, not that it was a bad amp but I think I'm gonna not get another Crest.

I would go with the QSC I have yet to hear better. Granted we are using their powered speakers, but the class D amps sound awesome for vocals and micd instrument fill. the amp handles all the frequencies perfectly even when there are 2 instruments 2 drum mics and 3 vocals coming through. I have nothing but great things to say about my QSCs. You have a great set of speakers, now you need a great amp to have a great set up... yes, I think you will want something 2x the power of the RMS of the speaker... With low and highs coming from the PA you need the power to push them at a pure clean level, gain around 3 or 4.

Good Luck tcsned, I think the crown is marked higher for no reason worth noting other than they did that. Find out the equivalent amps they put into the K series powered speakers, they are class D 1000 watt. Best sound we ever had, especially for vocals.

tcsned wrote:First question is how big of a power amp to get? I've always thought it should be about twice the rating of the speaker - so a 500w per side? Anyone have better info?

Double is what most used to say. 1.5x is what I heard recently by a guy who really knows his stuff! Reason is that the speaker will clip before the poweramp will clip. If a speaker clips a little, it's ok as you can quickly turn down. But the signal a clipping poweramp can send can trash the cab. His advice.

I think the QSC GX3 is worth your consideration.:
http://www.guitarcenter.com/QSC-GX3-Ste ... ifications

Thanks guys! I'm thinking of getting a QSC GX5 - if I have time to stop by Stage Sound in Roanoke before the gig tonight. My Crest amp that blew was about 1,000w @ 4ohms I think the GX5 is just under that. We rarely pushed the Crest very hard so I'm thinking I don't need extra power. The GX7 looks really cool but I want to make sure I have enough $$ left over to get a Mesa 50/50. I'm hoping to snipe one of those for around $400. My new guitar is being wired up today - too bad my gig is early 'cause I won't have time to pick it up before I have to leave. Getting damn close to getting the whole new rig up and running.

The QSC GX3 is a ideal amp for the Mackies. 300watts is plenty for those. Good warranty and cheap.

After its all said and done, you prolly won't use the 300 to the clip point most of the time especially using it for mostly vocals, but you do play some bigger events now and then that may require more speakers, or other uses like multiple monitors and crap. It doesn't hurt to get more umph just in case.

Thanks for the advice everyone. I would up going with the GX5 - used it last night at a club in Roanoke - it worked great! I was a little concerned it would be underpowered - but we had a packed house of pretty loud folks and we hardly pushed it at all. I think it'll be fine for a larger venue (of course if the venue is too big we get someone else to do sound). WOOT!

Congrats , The GX stuff is good equipment IME. Id think about a cheap limiter to throw in the amp rack with the speaker/power ratio you have. Dimming the sensitivity on the amp doesn't change the power output. Someone knocks over a mic or the key player hits a patch that is beyond crazy and poof your getting your speakers re-coned.

Side note- I recently mixed monitors that consisted of bi-amped JBL Srx's with GX-5's. Rip your face off loud.... Great amps.