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speaker 'program watts' question

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Postby RayR » September 5th, 2009, 6:07 am

HI - When matching a power amp to a speaker - would I go by the 'program watts' rating as the most power a speaker can continuosly handle?


I was looking at a pair of used Yamaha sv 112 12" mains and did some checking.They were rated as follows:

175wts noise/350wts program/700 peak (no ohms was given but I figure these ratings are for 8ohms?)

Would I go by the 175 or 350?

I understand peak is the most a speaker can handle with a short/transcient 'burst'.I've also read where you want to have a little bit more power than the speaker is rated for,but how much do you want to go over? 25wts,50wts?
I also understand that driving an under-powered amp to clipping will trash the speakers.

Basically - I guess I'm asking what size power amp would be suffient to power the sv112's (for a small blues band,a few vocals & a couple of guitars mic'd,drums & bass wouln't be mic'd).
Set-up for now might be 2 mains on one side of the amp (daisied @ 4ohms) and 1 montitor (8ohms)running off the other side.
Would this be feasable with a stereo power amp or would a dual-mono be needed?

THANKS for any answers (and your time :D )

Ray

WES - what is the name of your band? It's been a while since I've been up thru Torrington - used to go up that way to go to Lime Rock races or trout fishing up by Winsted.
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Postby Ricochet » September 5th, 2009, 8:40 am

Program watts would be appropriate. I'm unfamiliar with that "noise watts" rating. Peak is NOT what you want to match with the amp power rating.
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Postby RayR » September 5th, 2009, 11:10 am

'RIC' - Thanks for the reply.

So then - I could use an amp at 350wts per chnl @ 8ohms and still be 'safe' without over-powering the speakers as long as I'm careful with the volume controls at the mixer?

Thanks again -
Ray
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Postby RayR » September 5th, 2009, 11:15 am

'175 wts noise'...I know it's a strange rating. I Haven't seen speakers rated for that before either but that's what was listed on the Yamaha site and on some of the music store sites.

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Ray
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Postby Diceman » September 5th, 2009, 2:19 pm

It is recommended that a power amp be rated at twice the power as the RMS rating of the speaker . This ensures that the amp doesn't clip when peaks occur in the music .
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Postby Ricochet » September 5th, 2009, 6:02 pm

That's fine as long as you know how to keep the amp turned down to not exceed the RMS power of the speaker, or you're using an amp driven so only brief transient peaks run above that. If you're talking about a guitar amp, though, playing distorted rock music, that amp's going to be running well above that power level and you KNOW it's going to be clipping. If the RMS rating of the speaker doesn't match the output of the amp, pretty soon you're going to have a damaged speaker, maybe a smoking one.
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Postby greybeard » September 6th, 2009, 12:07 am

After a few minutes googling, I found that JBL use a "Pink noise rating", which appears to correspond to the noise rating of your speaker.

Quote: "Continuous Pink Noise rating is IEC-shaped pink noise with a 6 dB crest factor for 100 hours continuously.
Continuous program power is a conservative expression of the system's ability to handle normal speech and music
program material and is defined as 3 dB above the Continuous Pink Noise Rating."

In the meantime, I've found further references to "pink noise rating" (e.g. in the Pioneer forum), so I'm assuming that that is what it is
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Postby Diceman » September 8th, 2009, 5:21 pm

Ricochet wrote:That's fine as long as you know how to keep the amp turned down to not exceed the RMS power of the speaker, or you're using an amp driven so only brief transient peaks run above that. If you're talking about a guitar amp, though, playing distorted rock music, that amp's going to be running well above that power level and you KNOW it's going to be clipping. If the RMS rating of the speaker doesn't match the output of the amp, pretty soon you're going to have a damaged speaker, maybe a smoking one.


The originator of this post was talking about a PA speaker . Below is a quote from the Musician's Friend website :



"The power amp boosts low-level signals coming from the mixer to a level required by the speakers. A power amp consists of a line-level input and a high-level output and possibly a power switch, volume control, and meters. A stereo power amp provides two channels, each able to drive its own speaker load.

Make sure to buy an amp with plenty of power for your speakers plus enough headroom. Many speakers are damaged by getting too little power, causing clipped waveforms that will ruin your gear. You will probably want an amp with twice the wattage of your speaker's rated power handling to ensure clean power gets to them. "
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Postby Ricochet » September 9th, 2009, 11:13 am

OK, that's right. I've seen tweeters smoked by running an amp rated way below the speakers' rated power, but turned up into clipping.
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