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Yamaha amps for my Shermann subs?


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I'm thinking of upgrading the amps powering the subs for my sound system.

I don't know what model they are but they're dual 15'' Shermanns loaded with Eminence Kappa Pro 15LF drivers.

1200 watts RMS per side, 4 ohms. At the moment I am powering them with 2 Numark Dimension 4 amps,

1900w each bridged @ 4 ohms.

And I find I'm always driving them as hard as I can without clipping and they get really hot.

Ive been reading posts on this site about how the amps should be about double the power of the speakers RMS rating?!

I have a Yamaha p7000s powering my 4 Shermann Cub tops.

Would I notice much of a difference if I upgraded my amps to Yamaha p5000s?


Thanks, Gethin.


I can't work out if the yamaha p series amps cam run bridged at 4 ohms either :s

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The problem here is the load you are given your amps to drive. 4ohm bridged is a bit of a rough job for any amp, and whilst some amps can handle it much better than others, its not going to be the coolest running setup. You'd probably find that amplifiers that give out the necessary power at 4ohms stereo would be a better bet, although I appreciate that these are big amps and often limited to more expensive manufacturers.
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The Yamaha will give a marked improvement over the Numark amp, that's for sure, but also if your budget will stretch a bit beyond the yamahas' CPC have got a rather good deal on QSC PLX2 amps at the moment. They're a better amp, will draw less juice and they're lightweight too, so you won't break your back carrying them about - PLX3102 is £550 and the PLX3602 is £640
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Hi Gethin


Sound's as though you're on a square wave trip driving cheap amps bridged into a nominal 4ohms.

Never mind the amps getting hot think about what you're doing to the windings of those poor drive units, they're only 75mm diam.


Good advice offered so far but whatever you do forget about bridging amps - go for something with reasonable balls and by that I mean an amp with decent sized transformers if such an animal is still available these days at the right price.

Alternatively, a s/h Amcron or Crest would probably be more cost effective and certainly last a lot longer then two new shoddy far eastern things used in bridge.


The Yamahas are excellent value for money and I've sold loads of them with our budget Bx Series boxes (oh, you probably have Shermann Bx215) BUT, when I've given even the P7000 some serious welly it will run out of road long before a more costly s/h unit.


You failed to mention what you're using between your mixer and the amps which will either help or hinder your sonic progress.

Are you using a decent crossover with an appropriately set H/P filter if not, forget the amps and get that bit sorted first.


Still stuck?

Give me a call - I'm usually here late!


Ken Hughes @ Shermann

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