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Old 23rd February 2009, 10:29 PM   #1
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Default Power amp suggestions

Hi - looking for some advice...
We have a rock band that plans to start playing some gigs at small neighborhood bars. I want to upgrade our crappy power amp. It's used just for vocals - no mics on the instruments.

We have a pair of 150 watt unpowered JBLs, I think it has a 15 inch speaker with a horn. And some various crappy speakers for monitors. We have an unpowered mixer with a reverb unit.

Option 1: What would be a good power amp for this setup. Powering the board, JBLs and 2 monitors.
Option 2: Would you suggest upgrading to some better speakers and using the JBLs as monitors? What speakers and power amp would you suggest.

As you guessed, yes our budget is tight. I would appreciate any comments. Thanks!
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Old 23rd February 2009, 10:56 PM   #2
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Personally I dont think 150WRMS speakers are any good for a band.

You need to ramp this up a bit to at least 400WRMS.
Then buy a cheap amp to match the speaker power rating.
There are loads on ebay.

I have designed and built my own speakers and amp for my disco but it is a major undertaking.
I couldnt make a speaker or an amp for what I can buy one for.
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Old 24th February 2009, 04:03 AM   #3
Leolabs is offline Leolabs  Malaysia
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Yes!A second hand high power amp will fit the bill.
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Old 24th February 2009, 01:26 PM   #4
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What model are the JBLs?

What are the part numbers on the woofer and horn and
compression driver?

"Personally I dont think 150WRMS speakers are any good for a band"

A JBL 130A is about 6dB more efficent than most PA drivers, and for mids will play louder with 150W than newer drivers will with 400W.
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Old 24th February 2009, 11:03 PM   #5
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Quote:
Originally posted by djk
What model are the JBLs?

What are the part numbers on the woofer and horn and
compression driver?

"Personally I dont think 150WRMS speakers are any good for a band"

A JBL 130A is about 6dB more efficent than most PA drivers, and for mids will play louder with 150W than newer drivers will with 400W.

I use a 200WRMS amp with high efficiency speakers for my disco (99dB sensitivity) and that struggles in a large room.
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Old 24th February 2009, 11:21 PM   #6
wg_ski is offline wg_ski  United States
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Quote:
Originally posted by nigelwright7557

I use a 200WRMS amp with high efficiency speakers for my disco (99dB sensitivity) and that struggles in a large room.

Are you trying to get bass out of it? 200W isn't enough to produce ba-hass. Drumstruck want to use this for voice. 99dB speakers work pretty well for that. Although, even with 150W speakers he needs 400-600 watts of amp (and a limiter). Vocals need a lot of headroom and sound particularly bad when clipped.
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Old 25th February 2009, 12:37 AM   #7
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Hey thanks for the replies.
I was really hoping you guys might have some more specific ideas. Brands and specs of some budget priced gear that gives you some bang for the buck. I'm sure there are power amps that are just garbage and others that are way too expensive for a bar setting.
Also, maybe a rule of thumb on the amp's wattage/ohms? What specs are most important when powering two speakers and two monitors for vocals?

Thanks.
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Old 25th February 2009, 02:04 AM   #8
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"I was really hoping you guys might have some more specific ideas. Brands and specs of some budget priced gear that gives you some bang for the buck."

What kind of tires shoul I buy?

Can't answer that, can you?

No one can give intelligent advise without knowing exactly what you have.
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Old 25th February 2009, 01:09 PM   #9
Xoc1 is offline Xoc1  United Kingdom
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An RMS rated Speaker will usually handle double that amount on peaks.
So 150w RMS speaker = 300w peak
A 1000 w amp 500w per channel into 4ohm will provide 300w into a 8ohm speaker per channel.
If Budgets are tight then run the speakers in mono on one channel 250w per cabinet. Use the other channel to run 2 monitors.
This way you can run different Levels and EQ for the PA and monitors.
As mentioned above You are going to need a Compressor limiter to manage this properly. Epecially if no-one is going to manage the levels continuously during your gig.
If the speakers blow you can allways cheaply re-cone them with new drivers with an higher power rating.
A 1000w amp and a compressor will always be useful in the future for any expansion of your PA.
If this all works OK I would then look at a pair of bass bins on a 2400w amp and a 2 way electronic crossover.
Is hard to be specific with equipment recomendations as I have no idea what is available in your part of the world and your budget.
Have Fun!
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Old 25th February 2009, 02:03 PM   #10
wg_ski is offline wg_ski  United States
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Quote:
Originally posted by drumstruck
Hey thanks for the replies.
I was really hoping you guys might have some more specific ideas. Brands and specs of some budget priced gear that gives you some bang for the buck. I'm sure there are power amps that are just garbage and others that are way too expensive for a bar setting.
Thanks.
RMX2450 is the right amplifier to use for this type situation. Mains on one channel, mons on the other. Get another when there's money. Has built in limiters and low cut so you don't have to buy more processing right away. QSC does make the cheaper GX series, but I'm not sure I'd want to push them very hard or go below 8 ohms load. Probably ok for just monitors, but may struggle with the higher average power in the mains. Ditto for the Crown XLS - they just look cheaply built (I have a pair of the XS1200 and they're way better amps). The EP2500 or one of the other direct RMX2450 clones (Tapco, Mackie, etc) will probably be just fine if you need a lower price tag. If you can find older QSC's like the USA1310 or older Crowns like the Micro/MacroTech 2400 they would work as well. But those older designs do run hotter and it might be good to have a backup, or split the mains/monitors to separate amps. If you go with older used amps, I would try to get two.
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