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Author Topic: Underpowering Speakers  (Read 31132 times)

Rusty Irby

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Underpowering Speakers
« on: January 15, 2009, 05:27:09 pm »

Can anything happen to your speakers if you are underpowering them? I have done a test and the sound doesnt seem as full to me. Like its lacking the bottom end. The underpowered speakers will be used as monitors, with mainly vocal and guitar in them. Foresee any problems?
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Mike Caldwell

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Re: Underpowering Speakers
« Reply #1 on: January 15, 2009, 05:42:39 pm »

For simple terms if you speakers are rated for 1000 watts and you power them with a 500 amp. IF you have all the output you need, IF you are not clipping the amp then no it won't hurt the speakers. Headroom never hurts though!!! In looking at power ratings of speakers you also have to take into account the speakers efficiency.

Mike Caldwell

Andy Peters

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Re: Underpowering Speakers
« Reply #2 on: January 15, 2009, 05:50:16 pm »

Rusty Irby wrote on Thu, 15 January 2009 15:27

Can anything happen to your speakers if you are underpowering them? I have done a test and the sound doesnt seem as full to me. Like its lacking the bottom end. The underpowered speakers will be used as monitors, with mainly vocal and guitar in them. Foresee any problems?


Well, let's nip this notion of "underpowered" in the bud right now.

If you have a speaker that is rated at 500 W continuous, and you connect it to an amp that does 500 W, then is that speaker "underpowered?"

Answer: no.

Why?

Because it depends on the use. For example, if the system gets sufficiently loud with that combination, then it is correctly powered. If the system gets sufficiently loud with the drive level up only halfway, then it's probably overpowered.

Now if the system does NOT get loud enough, then some thought is required. Is it not loud enough because the amp cannot provide enough clean power to drive the speaker to its limits, then (and ONLY then) it is underpowered.

I suspect that your "doesn't sound as full to me" comment is borne out of simple lack of volume.

-a
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Bob Leonard

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Re: Underpowering Speakers
« Reply #3 on: January 15, 2009, 06:15:25 pm »

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Matt Vivlamore

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Re: Underpowering Speakers
« Reply #4 on: January 15, 2009, 07:28:26 pm »

If your amps are doing this...
http://www.youtube.com/watch?v=7_xRmfcX35M

So, if your rig is doing that its time to think about a restructuring plan.

That rig is: 8 EV T18 with 400 RMS being powered by a pair of QSC Model 1700 powering the woofers, 2 cabs per channel for a 4 ohm load.
Crowd Size = 250 people

* * I DO NOT OWN THAT RIG * *

It is an installed rig within Southern MD.  If you ever tour down to here, let me know.  

That Rig is "supposed" to be removed and new rig is "supposed" to be installed in there (a pair of KF850 and a pair of SB850s per side).  
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Find us on the web at: meerkatsound.com

I'm using: EV QRx212 over JBL SRX718s(2) with Crown IT's and MRX512m & MRX525 on monitors with XTi's; all controlled by Yamaha LS9-32.  I have a bunch of other stuff too.

Jack Gunn

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Re: Underpowering Speakers
« Reply #5 on: January 16, 2009, 01:41:22 am »

Real simple, direct answer to your question:  Can you damage speakers by under powering them?  YES.  In fact, it is more likely and EASIER to cause damage by too small an amp, than by too large an amp.

You should never push your amp to the point it is right up to the peak light and then peaks.  Stay away from way up there.  Because if that read clip/peak light comes on, that means your tweeter is being sent a SQUARE wave.  That's no longer audio signal... That's tweeter death signal.

It can't acoustically or physically recreate a perfect square wave with a magnet and moving coil.  But it sure tries.  Tries until it dies.

That's why that youtube video above is so horrifying to sound guys in the know... At the end of that night you will have smoke coming out of those tweeters.  Those lights should NEVER come on through the whole show if the system is designed and calibrated/configured right.  (GAIN STRUCTURE, people! Smile

That is why if you have a much larger amp than you need, you can bring that speaker up to it's maximum power and loudness, without ever getting near the peak light.  You're ALWAYS sending the speaker clean, pure, full signals.  

If your speaker is rated at 100/200/400W in the spec sheet, go for a 400W amp minimum assuming the program material you're playing isn't extremely compressed stuff like dance/techno.  If you're doing live mixing of most any sort, my personal rule of thumb is go with the highest of the three.

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David A. Parker

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Re: Underpowering Speakers
« Reply #6 on: January 16, 2009, 07:52:49 am »

you can't hurt a speaker by underpowering it, if you could, then every time you turned them on and turned the volume down they would blow! You can only hurt a speaker by overpowering it. Very simply, if you have an amp that is less than the speakers are rated for, and you overdrive the amp, the amp will clip. When an amp clips, the power output is greatly increased. That overpowers the speaker and cooks it. You can do the same thing with an amp that IS the proper size for the speakers. I have blown speakers both ways, with too small an amp, and with too large an amp. Distortion in an of itself will not hurt a speaker, or every time a guitarist plugged in a fuzz box it would blow his guitar amp AND the PA. If the distorted signal does not exceed the capacity of the speaker, then all survives. The danger is that when an amp is distorted by being overdriven, the output of the amp increases way beyond it's rated output. Crown gives distorted output ratings for it's MA series amps. An MA 3600 will easily put out 6000 watts with very mild distortion. If you can get the volume you need with an amp that is half the rated capacity of a speaker, then that's all the power you need. Generally it is suggested to get an amp that matches the program rating of the speaker so that you can get the full potential of the speaker. If the full potential of the speaker is more volume than you need, then you don't need a bigger amp. It's all about making sure you aren't overdriving your amp.
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David Parker
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Brad Weber

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Re: Underpowering Speakers
« Reply #7 on: January 16, 2009, 08:19:58 am »

Jack Gunn wrote on Fri, 16 January 2009 01:41

Real simple, direct answer to your question:  Can you damage speakers by under powering them?  YES.  In fact, it is more likely and EASIER to cause damage by too small an amp, than by too large an amp.

A case of missing one critical element - a speaker cannot be 'underpowered', it is the system that can be underpowered for the application.

A simple example, say you have a situation where you are just clipping the amp inputs.  Now keep everything the same but change the speaker to one with the same power rating but 3dB higher sensitivity.  Hmmm, the power rating didn't change and the amp didn't change but the system is no longer 'underpowered'.  Even better, move from outdoors to indoors without changing the system at all and you may suddenly find yourself with more than enough output without clipping.

Or from a different view, if clipping is the problem, does it matter where that occurs?  What if the clipping occurs prior to the amplifier, isn't the result the same?  Do you say a processor is 'underpowered' because it is clipping or do you say that is improper operation?  If you do clip prior to the amp, would you rather that went through a 500W amp or a 1,000W amp?  A bigger amp doesn't seem to help if the clipping is occurring elsewhere.

The issue is providing sufficient output and headroom for the application and that is dependent upon the overall system and its operation, things like poor gain structure or trying to get more than the system can give or the infamous 'not enough rig for the gig', that actually makes any system 'underpowered' and not the components.  The bottom line is that a speaker cannot be underpowered by itself but you can always operate any system such that it is underpowered.


Rusty Irby wrote on Thu, 15 January 2009 17:27

I have done a test and the sound doesnt seem as full to me. Like its lacking the bottom end. The underpowered speakers will be used as monitors, with mainly vocal and guitar in them. Foresee any problems?

To clarify, how did you test them?  Did the output level change?  If so, then what you heard may be a result of human response (http://en.wikipedia.org/wiki/Equal-loudness_contour).
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Brad Weber
muse Audio Video

Rusty Irby

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Re: Underpowering Speakers
« Reply #8 on: January 16, 2009, 09:46:19 am »

Matt Vivlamore wrote on Thu, 15 January 2009 18:28

If your amps are doing this...
http://www.youtube.com/watch?v=7_xRmfcX35M

So, if your rig is doing that its time to think about a restructuring plan.

That rig is: 8 EV T18 with 400 RMS being powered by a pair of QSC Model 1700 powering the woofers, 2 cabs per channel for a 4 ohm load.
Crowd Size = 250 people

* * I DO NOT OWN THAT RIG * *

It is an installed rig within Southern MD.  If you ever tour down to here, let me know.  

That Rig is "supposed" to be removed and new rig is "supposed" to be installed in there (a pair of KF850 and a pair of SB850s per side).  


This is only just for one gig that I will need an extra monitor. My main rig is sufficient, its just that on the amp I use for my third monitor mix, I bridge it which puts out 500 watts at 8 ohms. But when ran in stereo it puts out 125 watts at 8 ohms. Program power of speaker is 500 watts.
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Steve Oldridge

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Re: Underpowering Speakers
« Reply #9 on: January 16, 2009, 10:41:48 am »

Rusty,

in short.. as long as you don't clip the amp, you should be be fine.

If you clip the amp, you can fry your speaker very quickly. Think speaker coils looking like the heating element on your electric cook-top. If you then back off and normal operation continues,  presto.. melted wax, coils busted and cone extruded from core. Not pretty. Been there done that.

Let us know how it goes..

-Steve
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