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Will SS clipping damage speakers?


PaulyWally

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OK... someone just brought this up in another thread, and some sales guy at GC said the same thing to me a couple weeks ago (when he wanted me to buy an amp that put out more power than the speakers could handle).

 

What I've heard, is when you under power a speaker, you start sending square waves from the amp when you push it hard. The result can basically end up in you sending a DC current to the speakers, and thus damaging them.

 

In my limited experience, a power amp only amplifies whatever signal it's getting. So if you're running a distortion box... your power amp is amplifying a clipped sine wave (AKA square wave) and sending that to your speakers. But I've never heard of speakers dying because of a distortion pedal.

 

So? What's the deal?

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"This is because many solid state amplifiers are DC coupled, meaning that they can put out unchanging voltages like a battery. Such voltages are damaging to speakers. Manufacturers of solid state amplifiers often add DC fault detection circuits to their designs to prevent DC voltages from being impressed on the speakers.

 

When the solid state amplifier clips, the biasing of internal stages is disturbed, causing the average output voltage to move away from zero volts, resulting in some large low frequency currents flowing through the speaker. This causes heating, overexcursion, and eventual failure. Better solid state amplifiers prevent this, but less expensive ones do not.

 

Tube amplifiers are coupled through transformers which cannot pass very low frequency or DC currents and voltages, so clipping is not so dangerous. "

 

http://www.aqdi.com/pmfaq.htm

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I have never once heard of a speaker being blown by too little power.

 

 

Well... I've heard this off and on throughout the years and never gave it much credit. But I've been hearing it a lot more lately.

 

The general idea, is that you have speakers rated at 1000 watts. Power amp 'A' has 500 watts and power amp 'B' has 2000 watts.

 

With power amp 'B', You can use the full capacity of the speakers without pushing the amp to its fullest. Now here is where it gets sketchy... and this is how some people believe it:

 

"With power amp 'A', people think they can push all 500 watts out of the amp without hurting their speakers. But, pushing the amp to 100% will produce square waves which will hurt the speakers."

 

That's the explanation as I understand it.

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+10000


So does that mean if I have my amp turned down to 1 I'm going to blow the speaker.
:lol:

 

Yup...you can actually blow the speakers by having the amp turned off:eek::eek:..that is unless you have a Lava speaker cable connected which dispurses the dangerous electricity:thu:

 

 

 

Dan

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Yup...you can actually blow the speakers by having the amp turned off:eek:
:eek:
..that is unless you have a Lava speaker cable connected which dispurses the dangerous electricity:thu:


Dan

 

 

Oh noes! I forgot......I was playing bass earlier and I turned my amp off.... :eek:

 

Is it gonna blow? :cry:

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Yup...you can actually blow the speakers by having the amp turned off:eek:
:eek:
..that is unless you have a Lava speaker cable connected which dispurses the dangerous electricity:thu:

 

:D Dude!! I'm totally gonna give that to the next salesmen who says this {censored} to me.

 

"It's not good to under power your speakers because... bla bla bla..."

 

"OK... but it'll be OK if I use Monster Cables... right?"

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I don't have time for a full post, but I'll post again later.

 

Speaker failure occurs by overexcursion or over heating. Nothing else (I'm discarding floods, falling off trucks...). Clipping is no inherent danger.

 

Square waves are not DC. Square waves do no harm, otherwise synths would kill speakers. :)

 

It is a major (and rare) failure for any SS amp to put out DC.

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OK... someone just brought this up in another thread, and some sales guy at GC said the same thing to me a couple weeks ago (when he wanted me to buy an amp that put out more power than the speakers could handle).


What I've heard, is when you under power a speaker, you start sending square waves from the amp when you push it hard. The result can basically end up in you sending a DC current to the speakers, and thus damaging them.


In my limited experience, a power amp only amplifies whatever signal it's getting. So if you're running a distortion box... your power amp is amplifying a clipped sine wave (AKA square wave) and sending that to your speakers. But I've never heard of speakers dying because of a distortion pedal.


So? What's the deal?

 

 

Low power clipping isn't likely to hurt but high-power clipping can. The underpowered rap is BS. It takes underpowering along with overdriving to cause damage.

 

 

This JBL white paper has more on it.

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http://acapella.harmony-central.com/forums/showpost.php?p=24282459&postcount=6

 

Speakers (low frequency drivers for this discussion) fail for one reason and only one reason... excessive power. This damage can be either thermal or mechanical in nature.

 

Thermal failure is the result of too much power causing excessive temperature rise in the voice coil and bobbin assembly, causing a softening of the adhesives, blistering of the former and a breakdown of the wire insulation. Thermal failure can occur when the speaker is used with an amplifier that is rated to large for the duty cycle the speaker sees. If the signal is heavily compressed, the duty cycle increases and the speaker power rating (thus amp size) must be decreased. Another cause ofthermal failure is using an amp that is too small for the job at hand, that amp being driven heavily into clipping. When an amp is driven heavily into clipping, the power delivered to the speaker can be as much as twice the RMS rating of the amp. This is, IMO, the primary reason behind the myth that underpowering a speaker can blow it. The failure mode is still too much power.

 

The second failure mechanism of a speaker is due to mechanical damage. This is always caused by too much power. It's pretty simple for a manufacturer to determine how much power causes mechanical damage. The problem is putting it into a specification that is useful to the average musician. The mechanical power handling of a speaker is not a fixed number, but varies greatly by decreasing as the frequency decreases. This is due to the mechanical loading that the air mass creates to the drivers and below some point the driver is no longer adequately loaded and flops around like an undamped spring. It's not uncommon for a speaker to show a power rating of 1/4 the original mid-band rating when you approach 25-40Hz. Combine this with a grossly large power amp and you have the single most common cause for bass driver failure.

 

Also note that an amplifier rated at say 1200 watts "RMS" by definition produces a peak 2400 watt rating because of the conversion factor for a sine wave between RMS values and peak values.

 

I have attached a good overview of loudspeaker power ratings from my good friends over at Harman. Note their discussion relating to derating for musical applications and their references to such in examples 2 & 3.

 

http://www.jblpro.com/pub/technote/spkpwfaq.pdf

 

Hope this helps.

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http://acapella.harmony-central.com/forums/showpost.php?p=24282459&postcount=6


Speakers (low frequency drivers for this discussion) fail for one reason and only one reason... excessive power. This damage can be either thermal or mechanical in nature.


Thermal failure is the result of too much power causing excessive temperature rise in the voice coil and bobbin assembly, causing a softening of the adhesives, blistering of the former and a breakdown of the wire insulation. Thermal failure can occur when the speaker is used with an amplifier that is rated to large for the duty cycle the speaker sees. If the signal is heavily compressed, the duty cycle increases and the speaker power rating (thus amp size) must be decreased. Another cause ofthermal failure is using an amp that is too small for the job at hand, that amp being driven heavily into clipping. When an amp is driven heavily into clipping, the power delivered to the speaker can be as much as twice the RMS rating of the amp. This is, IMO, the primary reason behind the myth that underpowering a speaker can blow it. The failure mode is still too much power.


The second failure mechanism of a speaker is due to mechanical damage. This is always caused by too much power. It's pretty simple for a manufacturer to determine how much power causes mechanical damage. The problem is putting it into a specification that is useful to the average musician. The mechanical power handling of a speaker is not a fixed number, but varies greatly by decreasing as the frequency decreases. This is due to the mechanical loading that the air mass creates to the drivers and below some point the driver is no longer adequately loaded and flops around like an undamped spring. It's not uncommon for a speaker to show a power rating of 1/4 the original mid-band rating when you approach 25-40Hz. Combine this with a grossly large power amp and you have the single most common cause for bass driver failure.


Also note that an amplifier rated at say 1200 watts "RMS" by definition produces a peak 2400 watt rating because of the conversion factor for a sine wave between RMS values and peak values.


I have attached a good overview of loudspeaker power ratings from my good friends over at Harman. Note their discussion relating to derating for musical applications and their references to such in examples 2 & 3.


http://www.jblpro.com/pub/technote/spkpwfaq.pdf


Hope this helps.

 

Thank God. You saved me a pile of typing. :D

 

The crux of the biscuit is that when an amp clips, it produces more than its rated power, so while you might think you're safe to drive a 500W amp super hard if you have a (say) 600W rated cabinet, if you're driving it way into clipping, you could be developing enough power to damage the speaker.

 

That doesn't even get into speaker power ratings and how little they really mean..... A driver rated at X amount of power might only be able to handle 1/4 of that in a cabinet at low frequency....

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Thank God. You saved me a pile of typing.
:D

The crux of the biscuit is that when an amp clips, it produces more than its rated power, so while you might think you're safe to drive a 500W amp super hard if you have a (say) 600W rated cabinet, if you're driving it way into clipping, you could be developing enough power to damage the speaker.


That doesn't even get into speaker power ratings and how little they really mean..... A driver rated at X amount of power might only be able to handle 1/4 of that in a cabinet at low frequency....

 

We definitely need to keep a copy of this post so I never need to type this again.

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