"Clipping, by producing harmonic distortion and/or DC, blows woofers."

The idea behind this that a clipped signal contains a heavy harmonic distortion component which can be damaging to voice coils. The problem with this idea is that it's wrong. The harmonic content of the clipped signal is not the culprit at all (the inductance of the woofer pretty much kills any high frequency energy).
DC (direct current) is not to blame either. Modern amplifiers do not produce significant DC when clipped. Even the cheesiest amplifiers to be found at the flea market will not produce a lot of DC.

You may think you can prove this wrong by connecting a multimeter set to DC voltage mode to an amplifier's outputs and measuring "DC voltage" of some value, but the only thing you've proved is that music signals and output stages are not always symmetrical and these asymmetries are misread by the meter as a fluctuating DC value. You're not actually reading DC.

The real villan is dynamic range compression, which refers to an increase in the amount of average energy vs. peak energyof the amplifier's output. signal when it is overdriven (clipped).
When an amplifier clips, the short-duration peaks of the music are "chopped off", but the average level of the signal is allowed to run higher than it would if the amplifier was not clipping. The short duration peaks don't last long enough to worry about in most cases, but the increase in average energy can heat up a voice coil very quickly and are the direct cause of burnt voice coils. A amplifier driven into severe clipping will produce average energy like an amp twice it's rating (a 250 Watt amp like a 500 Watt amp). It's not the clipping that is blowing speakers, it's the old story of too much power.

If you look at the graph imagine the top and bottom lines represent the maximum output of the amp. Note how long the unclipped sinwave spends on the maximum line. The clipped sinewave spends alot more time along that maximum line. There is a lot more average energy being produced on the right.

 

Ummm? im not as smart as you, can you explain that in english?

 

I take it you went to school for this... :D

-THE DON

 

or he pasted it from the web.

 

I was hoping the image (which is from the web) would help clear things up. Hopefully, the text will be up on the internet soon. It would be alot easier to post a link rather than typing this all out!

The cliff notes:
Amplifiers producing distortion and DC current doesn't blow woofers, excessive average power over time does.

P.S.
I did not go to school for this, I stayed at a Holiday Inn Express last nite. :D

 

they told my physics would come in at some point in life, too bad i didn't pay any attention. but my system still thumps

 

he wrote it in english and provided a graph it makes sense
to me but i have automotive electrical exp

 

Holiday Inn Express. Awesome. :D

 

I should stay at this Holiday Inn you speak of. ;)

 

yep this is what I was talking about in myth #1 thread... but why bother I mean as you can see most people do not understand or want to be bothered.... Go get some rest..find a hobbby

 

i think this is his hobby/job.. He's definely a dedicated SLer... goes to a holiday inn still thinking of us =)

btw this definetely refreshed my memory... good work again

 

I do belive he works for JL Audioand drives a TC from what steve at JL told me i think his name is. I wont tell his name you might call him at work. Hope to sdee you at ces
JLTD i will be in on sat due to work overload.

 

Please stop making these threads. You are at best, twisting words and concepts to try and diffuse a "myth".

 

I disagree. Please keep spreading the knowledge.
If you aren't into learning, why are you reading this thread in the first place? Don't knock the guy for helping.

 

hmmm...sounds like someone has been reading the MECP study guide....i remember seeing that when i was studying for the basic installer cert. Good stuff,

 

See what happens. No good deed goes unpunished. You try to teach them and what do they do they eat the teacher

 

Just playing devil's advocate here but "DC (direct current) is not to blame either." can be argued. As you can see, per the graph, when the amplifier clips the signal level/power output is constant until the signal drops below the maximum level again. In effect that duration is direct current since it doesn't vary. So in essence the theory that direct current will blow a woofer is accurate. It's just a different more simplified interpretation. It is direct current that does it but since the power does change with the signal it is technically the average energy that will overheat the coil.

 

I degress i think dumbass people who dont understand how to use there equipment
is what clipps destroys or other wise blows stuff up. We can argue for years about this but it comes down to just plain old common sense if it sounds like ___ when you go past a point on your volume control turn it down or have it tuned. The graphs are great but too many people have been tought to many different theroy's (sp).
for all of us to agree to one. This is not a flame it is kinda funny tho.

 

I find one of the biggest problems is current. We see in the audio world now some big amps in cars with 60 amp alternators. By the time they get their system up and running they can pull a smooth 120 amps. Then they want driving lights, neon, leds, video, etc.. Now there all out of power and they starve the amps and make them run hot .... Dont get me started.

 

this statement is true... however i think it confuses more people then it helped... you really have to break it down to really understand it...

usdmbb, you are right... with people over gaining/boosting there amps, they definetely push there amps into clipping which sounds like poop and destroys speakers... most shops/installers kept those terms so that 95 percent of the people purchasing the products will understand...

but the real science is stated above...

so most people don't get confused and start playing tons of distortion thinking your speakers won't blow... make sure your system is tuned right... if it sounds like butt... turn it down...