This amp work with these speakers? - AVS Forum
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post #1 of 17 Old 01-05-2013, 08:26 PM - Thread Starter
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Hi, everyone. I just can't seem to wrap my head around all of this. I have a pair of JBL ND310 speakers, and they say to use an amp with a maximum of 250 watts of power.

Now, from some things I've read, you need to have MORE wattage from your amp so that it doesn't produce clipped signals that damage your speaker.

So with that being said, will this QSC GX3 (http://www.qscaudio.com/products/amps/GX/index.php) be okay to power those speakers or is it going to overload the speakers since it has 300 watts per channel at 8 ohms.

Thanks for any help, I just really don't understand all of this that well.
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post #2 of 17 Old 01-06-2013, 05:10 AM
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Wattage ratings in speakers are more for guidelines than absolutes and the difference between 250 watts and 300 watts is a fraction of a dB.

The BIG problem you have is a mismatch of equipment since the the amps you are looking at are designed for commercial use. Their SQ would be considered unacceptable for serious HT use. If going to use this in a commercial setting then the speakers are (likely) inappropriate for that task.
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post #3 of 17 Old 01-06-2013, 08:02 AM
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The power rating of a speaker is like the speed rating on a tire; it is the MAXIMUM safe operating power.

There is nothing wrong with having an amplifier with more or less of a power rating compared to the speakers, BUT if the amplifier can put out more than the speakers are rated for you have the capability to overdrive and damage the speakers.

This is almost never a real problem, however if you have ears and use them.

When the power level approaches a dangerous level, the speakers will almost certainly be deafeningly loud and they will distort.

If you ignore that, you can damage them, but a person has to be pretty dumb to let it get to that point.
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post #4 of 17 Old 01-06-2013, 09:56 AM
 
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Originally Posted by William View Post

The BIG problem you have is a mismatch of equipment since the the amps you are looking at are designed for commercial use. Their SQ would be considered unacceptable for serious HT use.
How did you figure that out?
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post #5 of 17 Old 01-06-2013, 09:59 AM
 
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Originally Posted by commsysman View Post

BUT if the amplifier can put out more than the speakers are rated for you have the capability to overdrive and damage the speakers.
Still safer for an amp to have more than speaker can handle because clipping from not having enough can cause serious damage to speaker drivers.
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post #6 of 17 Old 01-06-2013, 11:25 AM
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Still safer for an amp to have more than speaker can handle because clipping from not having enough can cause serious damage to speaker drivers.
Largely audiophile myth, actually. The real threat to speaker health is an idiot with a volume knob. the extra energy in clipped waveforms is generally marginal.

If you can't explain how it works, you can't say it doesn't.—The High-End Creed

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post #7 of 17 Old 01-06-2013, 11:28 AM
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Now, from some things I've read, you need to have MORE wattage from your amp so that it doesn't produce clipped signals that damage your speaker.
Not true. Clipping doesn't damage speakers; power does. (To be more precise, power in the hands of a nincompoop does.)

A basic 50 wpc receiver could probably drive your JBLs just fine.

If you can't explain how it works, you can't say it doesn't.—The High-End Creed

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post #8 of 17 Old 01-06-2013, 12:18 PM
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Originally Posted by diomania View Post

How did you figure that out?

There are several reasons but one is the amp uses Class B amplification. Class B is great for PA and very efficient but suffers from x-over distortion and is (almost) never used in HT amps.
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Not true. Clipping doesn't damage speakers....

Clipping can be very dangerous for speakers, especially tweeters. Here is a good easy explanation of why.
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post #9 of 17 Old 01-06-2013, 01:47 PM
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Quote:
Originally Posted by William View Post

Wattage ratings in speakers are more for guidelines than absolutes and the difference between 250 watts and 300 watts is a fraction of a dB.

Agreed.
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The BIG problem you have is a mismatch of equipment since the the amps you are looking at are designed for commercial use. Their SQ would be considered unacceptable for serious HT use. If going to use this in a commercial setting then the speakers are (likely) inappropriate for that task.

Please illustrate this claim with relevant measurements or reliable listening tests.
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post #10 of 17 Old 01-06-2013, 01:51 PM
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Quote:
Originally Posted by William View Post

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Originally Posted by diomania View Post

How did you figure that out?

There are several reasons but one is the amp uses Class B amplification.

http://www.qscaudio.com/products/amps/gx/gx_faq.php#q8

QSC says that the GX3 uses a revolutionary biasing scheme that allows a near-perfect implementation of class B which eliminates the historical problems of Class B operation with crossover notches. That is not the same as a traditional class B output stage.

This is relatively unique among pro audio amps, so nothing about pro audio amps should be extrapolated from the GX3,
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post #11 of 17 Old 01-06-2013, 04:08 PM
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Clipping can be very dangerous for speakers, especially tweeters. Here is a good easy explanation of why.
No, it really can't, except in rare circumstances that don't generally apply to home audio. If you have a driver connected directly to an amplifier, as you might in a pro setup (and note that you linked to a pro audio site), then yes, that could happen. But a passive crossover will prevent that extra energy from reaching the tweeter—except for the extra harmonics produced by the clipped waveform as it starts to resemble a square wave. Often these extra harmonics are blamed for the damage, but they just don't account for enough energy to do the trick.

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post #12 of 17 Old 01-06-2013, 07:10 PM
 
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Originally Posted by mcnarus View Post

No, it really can't, except in rare circumstances that don't generally apply to home audio.
Not that rare, at least the group that I'm familiar with. Many of them use "full range" speakers (Fostex, Lowther) with no passive crossover.
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post #13 of 17 Old 01-06-2013, 07:39 PM
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Not that rare, at least the group that I'm familiar with. Many of them use "full range" speakers (Fostex, Lowther) with no passive crossover.
Then you travel in very rarified circles. wink.gif

Please note that the OP does not use such a speaker.

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post #14 of 17 Old 01-06-2013, 08:06 PM - Thread Starter
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Thanks for the replies everyone. I have an Audiosource Amp 102 (http://www.audiosource.net/products/electronics/amplifiers/amp-102/overview/), I haven't had a chance to test it, but will that work ok with my speakers? I run them at high volume in a dance studio.
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post #15 of 17 Old 01-06-2013, 08:28 PM
 
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Originally Posted by phatcorns View Post

I run them at high volume in a dance studio.
That could mean many different things. One person's high volume may mean medium volume for perception of someone else. To get some bearing, you will need to come up with decibel numbers.

If you mean dance studio as in commercial setting, I'll be more concerned with the durability of the speakers and amp. How often, how long of use and what db level are you dealing with?
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post #16 of 17 Old 01-07-2013, 06:34 AM
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Quote:
Originally Posted by diomania View Post

Quote:
Originally Posted by phatcorns View Post

I run them at high volume in a dance studio.
That could mean many different things. One person's high volume may mean medium volume for perception of someone else. To get some bearing, you will need to come up with decibel numbers.

If you mean dance studio as in commercial setting, I'll be more concerned with the durability of the speakers and amp. How often, how long of use and what db level are you dealing with?
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Originally Posted by phatcorns View Post

Thanks for the replies everyone. I have an Audiosource Amp 102 (http://www.audiosource.net/products/electronics/amplifiers/amp-102/overview/), I haven't had a chance to test it, but will that work ok with my speakers? I run them at high volume in a dance studio.

If I were trying to present high volumes in a dance studio, and we mean truly high volumes well in excess of 110 dB SPL, I would not look at hifi gear, but start looking at the world of professional audio.

On balance a pair of ND310s driven by a 300 wpc QSC power amp have a lot of pro audio DNA, and may exactly what you are looking for.

I think that they are worth giving a chance. If they come up a little light you have some logical paths for upgrades that would preserve the value of your initial investment - get another pair of ND310s and/or get a subwoofer.

Note that ND310 have not been made for about 4 years and are valued at about $2-300 each in the used equipment market. I don't know what you are being asked to pay for them.

Like other insightful posters. I also don't really know what you are trying to do - size of room, actual SPLs, room acoustics, etc. However if you are currently using a boom box or something like it, this is going to be one heck of a good upgrade!
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post #17 of 17 Old 01-07-2013, 09:34 AM
 
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Originally Posted by mcnarus View Post

Please note that the OP does not use such a speaker.
But it's still better to have some headroom than not. Plus, clipping doesn't sound good.
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