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Author Topic: Underpowering a speaker causes damage, I think not!!
mdee2004
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Icon 2 posted June 28, 2004 03:12      Profile for mdee2004     Send New Private Message       Edit/Delete Post   Reply With Quote 
I was in Best Buy and I saw this speaker which had lost it's dust cap. This over eager clerk comes up to me and my buddy and says "Yeah that was broken by under powering" He looks at me in a matter-of-fact kind of way and says "You know it's possible to damage speakers by giving them too little power." At that point I looked at my buddy and said "Maybe I can get a job working for them." The store clerk was like "Oh well we have applications at the front." And I pointed at the name on the speakers and said "No, work for them, I'm trying to get a job with my degree in electrical engineering" at that point the guy melted into the back ground, in shame. Bwa ha ha!!

Let's examine this one. "Underpowering a speaker can cause damage." Given that audio electronics are my passion I will explain this one for anyone that has been told this bogus crap. If the audio wave coming from the amplifier is a replica of the input (which is what you would think it would be anyway) this is theory is total crap. A small perfectly reproduced audio signal is never going to hurt a speaker, ever.

However, if the amplifier experiences something known as saturation, where the peaks of the audio signal which is essentially several super imposed sine waves gets clipped (you remeber sine waves don't you). When this happens you end up with something that looks like a bunch of superimposed square waves which can be painful for a transducer such as a speaker.

This theory of underpowering is actually a case of shotty amplifiers and should be viewed as such.

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Bass lines are at their best when they are played by a bass.

Posts: 26 | From: Maryland | Registered: Jun 2004  |  IP: Logged
Alan!
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Icon 1 posted June 28, 2004 03:17      Profile for Alan!     Send New Private Message       Edit/Delete Post   Reply With Quote 
"underpowering a speaker can cause damage to the amplifier"

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Alan!

Two rabbis, a priest, and an awkward silence after there's no intelligible punch line to this joke, walk into a bar.

Posts: 219 | From: Perth, Western Australia | Registered: Apr 2002  |  IP: Logged
csk

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Icon 1 posted June 28, 2004 06:26      Profile for csk     Send New Private Message       Edit/Delete Post   Reply With Quote 
It may be sort of what you said, mdee, but isn't clipping more likely to happen when an amp is pushed beyond its limits volume wise? Which can happen more easily with a low power amp, hence the low power amp and big speakers connection the guy thought was there.

Or to put it another way, the two guidelines would be:

1. Don't push your amp beyond it's limits (speaker polyswitches can help to prevent damage in this case, no?)

2. Don't push more power through your speakers than they can take (particularly if the amp is rated for higher power than the speakers)

Yes?

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6 weeks to go!

Posts: 4455 | From: Sydney, Australia | Registered: Jan 2003  |  IP: Logged
Cap'n Vic

Member # 1477

Icon 1 posted June 28, 2004 09:50      Profile for Cap'n Vic     Send New Private Message       Edit/Delete Post   Reply With Quote 
quote:
Originally posted by mdee2004:
I was in Best Buy and I saw this speaker which had lost it's dust cap. This over eager clerk comes up to me and my buddy and says "Yeah that was broken by under powering" He looks at me in a matter-of-fact kind of way and says "You know it's possible to damage speakers by giving them too little power." At that point I looked at my buddy and said "Maybe I can get a job working for them." The store clerk was like "Oh well we have applications at the front." And I pointed at the name on the speakers and said "No, work for them, I'm trying to get a job with my degree in electrical engineering" at that point the guy melted into the back ground, in shame. Bwa ha ha!!

Let's examine this one. "Underpowering a speaker can cause damage." Given that audio electronics are my passion I will explain this one for anyone that has been told this bogus crap. If the audio wave coming from the amplifier is a replica of the input (which is what you would think it would be anyway) this is theory is total crap. A small perfectly reproduced audio signal is never going to hurt a speaker, ever.

However, if the amplifier experiences something known as saturation, where the peaks of the audio signal which is essentially several super imposed sine waves gets clipped (you remeber sine waves don't you). When this happens you end up with something that looks like a bunch of superimposed square waves which can be painful for a transducer such as a speaker.

This theory of underpowering is actually a case of shotty amplifiers and should be viewed as such.

Are all your posts gonna be about the fact you think you are smarter than a retail clerk?

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(!) (T) = 8-D

Posts: 5471 | From: One of the drones from sector 7G | Registered: Jun 2002  |  IP: Logged
ooby
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Icon 1 posted June 28, 2004 10:10      Profile for ooby     Send New Private Message       Edit/Delete Post   Reply With Quote 
To elaborate on what Csk is saying:

Generally, amplifiers use the formula V1=G*V2. To power the amplifying device, you usually need two reference points, +Vcc and -Vcc. For symetrical reasons, they usually have the same absolute value. If these values are not high enough, the amplified peak value may exceed +-Vcc, causing clipping.

I do think however, that a better term than underpowering should be used to describe the problem.

Another possible cause for this "underpowering" might be poor impedance matching.

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"haven't you ever wondered if there's more to life than being really, really, rediculously good looking?"

Posts: 680 | From: South Jersey | Registered: Feb 2004  |  IP: Logged
Cap'n Vic

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Icon 1 posted June 28, 2004 10:40      Profile for Cap'n Vic     Send New Private Message       Edit/Delete Post   Reply With Quote 
quote:
Originally posted by ooby:
To elaborate on what Csk is saying:

Generally, amplifiers use the formula V1=G*V2. To power the amplifying device, you usually need two reference points, +Vcc and -Vcc. For symetrical reasons, they usually have the same absolute value. If these values are not high enough, the amplified peak value may exceed +-Vcc, causing clipping.

I do think however, that a better term than underpowering should be used to describe the problem.

Another possible cause for this "underpowering" might be poor impedance matching.

Amplifiers are using formulae now? [Roll Eyes]

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(!) (T) = 8-D

Posts: 5471 | From: One of the drones from sector 7G | Registered: Jun 2002  |  IP: Logged
mdee2004
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Icon 1 posted June 28, 2004 20:33      Profile for mdee2004     Send New Private Message       Edit/Delete Post   Reply With Quote 
No not all my posts are about store clerks, just the last two.

Saturation is the same thing as pushing an amplifier beyond its limit/ having its output go beyond Vcc and Vdd. Polyswitches probably wouldn't prevent damage caused by a clipped sine wave coming off the amplifier since they only open when they experience too much power and the point is that the clipped signals max and min values are not beyond vcc and vdd which is within the power handling capability of the speaker. It's the motion that a square wave would have the speaker perform is what would damage it in time.

Additionally your gain formula is normally written Av = Vout/Vin.

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Bass lines are at their best when they are played by a bass.

Posts: 26 | From: Maryland | Registered: Jun 2004  |  IP: Logged
Cap'n Vic

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Icon 2 posted June 29, 2004 00:32      Profile for Cap'n Vic     Send New Private Message       Edit/Delete Post   Reply With Quote 
[Roll Eyes]

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(!) (T) = 8-D

Posts: 5471 | From: One of the drones from sector 7G | Registered: Jun 2002  |  IP: Logged
ooby
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Icon 1 posted June 29, 2004 05:36      Profile for ooby     Send New Private Message       Edit/Delete Post   Reply With Quote 
Speakers that have circuit breakers are a very good idea.

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"haven't you ever wondered if there's more to life than being really, really, rediculously good looking?"

Posts: 680 | From: South Jersey | Registered: Feb 2004  |  IP: Logged
ooby
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Icon 1 posted June 29, 2004 06:44      Profile for ooby     Send New Private Message       Edit/Delete Post   Reply With Quote 
quote:
Originally posted by mdee2004:


Additionally your gain formula is normally written Av = Vout/Vin.

I was just thinking from a control systems flow diagram model-type standpoint. In simultaneous linear systems, you can't really divide, per se. You have to multiply by the inverse.

Even though we aren't using matrices here, I've just gotten used writing it Vout=Av*Vin. You say toe-may-toe; I say toe-mah-toe.

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"haven't you ever wondered if there's more to life than being really, really, rediculously good looking?"

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TheMoMan
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Icon 1 posted June 29, 2004 09:14      Profile for TheMoMan         Edit/Delete Post   Reply With Quote 
If speakers can be damaged by under powering them what happens when the power is turned off? Do they go up in flames?
Posts: 5454 | From: Just South of the Huron National Forest, in the water shed of the Rifle River | Registered: Sep 2002  |  IP: Logged
drunkennewfiemidget
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Icon 1 posted June 29, 2004 09:43      Profile for drunkennewfiemidget     Send New Private Message       Edit/Delete Post   Reply With Quote 
quote:
Originally posted by TheMoMan:
If speakers can be damaged by under powering them what happens when the power is turned off? Do they go up in flames?

HAHA. That's hilarious!

I remember installing speakers in my car once, and I wanted to intentionally blow up the factory ones (it was in my old 1988 Pontiac Tempest, speakers were worthless.) So I hooked my amp up to a factory speaker, and cranked it. The speaker lasted approximately 30 seconds before it made a loud pop, let the magical smoke out, and smelled *REALLY* *REALLY* awful.

... I'm too easily amused.

Posts: 4894 | From: Kitchener, ON, Canada | Registered: Jun 2004  |  IP: Logged


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