Hi, I would value some help I have a few questions relating to setting up our Pa system for my band, first some info about gear etc.

we play punk music, using Alesis multimix mixer, Yamaha p3500s amp, sending one side of amp to JBL JRX118S (for kick, and bass guitar) - filter set to sub woofer, frequency set to 125Hz. Other side going to Wharfdale 12 cabs (8 ohm 150W each).for vox, snare - filter set to low cut, frequency 125Hz. Then daisy chaining JBL- JBL and Wharfdale to Wharfdale.

Q1. Is it ok to set the amp up in this way?

Q2. JBL's are 4 Ohms, tops are 8 ohms is this Ok?

Q3. Are we in any danger of overdriving the tops?

Q4. What would be the ideal way to set up, using what we have with as little expenditure as posible.

many thanks

Mike

Well one side of the amp would be seeing a 2ohm load and the other side would be seeing a 4ohm load which is not a problem. The subs would be seeing 500w per cab and the tops would be 225w per cab. The tops are about right on power however the subs are being a bit under powered. Also I don’t tend to recommend running an amp on a 2 ohm load for a few reason, mainly the extra heat and the fact that if something does go wrong you have no safety margin.



I think your best bet would be to get another amp and use the existing P3500 on the tops or subs.



The other thing is the tops are a bit underpowered to get even the vocals over the top of a punk band so they would be next on my list of things to upgrade



The other option is to keep the setup you have if it works for you and hire in bigger kit for bigger shows

Thanks kevin, thats great. with another amp what would be the pathway of connection from the mixer to amp to speakers? Is there anything else we can do with the curent set up to help with the safety margin of the bass bins?

You would go from the mixer into ideally a crossover, from the crossover you would take the high outputs and plug that into the high amp and the low output and plug that into the low amp. Each amp would then run 2 subs each and 2 high cabs



In the absence of a crossover I’m assuming that the speakers have one built in. If so then the easiest way to hook thinks up without any Y cables would be for each amp the power one sub and one mid/high. You would route the L output into the first amp and run that amp in dual mono mode. This amp would then power the left side of the rig I.e. sub on channel 1 top on channel 2. Repeat the same for the other side.



The second option will not be as efficient as using an external crossover as the amp will be amplifying parts of the signal that the speaker would then just “throw away” at its internal crossover.



With the price of a cheep crossover on ebay at something like £40 I would say that your best bet would be to get another amp and an external crossover and go from there.



I don’t think there is any way to optimise your existing setup without buying new equipment, except maybe looking at speaker placement and maybe clustering the subs together to benefit from the coupling effect to gain a few extra dB



Give me a shout if you are in my neck of the woods and want to try this type of setup out

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Thanks a lot for that, really useful. I'm up in manchester, but if you don't mind I might get in touch again in a couple of months when we're ready to upgrade.

Mike