Overpowering Speakers

Thanks Al,
I was trying to make very general terms understandable and as much as you are generally correct. Crossovers do see DC as High frequency and do route 1st to the tweeter. This DC is raw current. Crossovers do not block DC. In fact, Through the years, I have used circuit breakers to protect against current and have even put small light bulbs on 6x9's in cars. The kids used to think it was very cool to see them flash with the music. The sole purpose of these bulbs was to filter off DC. It worked very well.

This is from Club knowledge, an article about clipping distortion. I hope this makes sense. Tim

Glad you asked! The amp will try to meet the power demand placed upon it, but it cannot exceed its design capabilities. This in turn, produces the deadly "square wave" output to the speaker. The speaker sees this severely clipped signal as DC current. Speakers cannot deal well with DC inputs. The cone goes in or out and stays there. No motivation to cool the voilce coil and sooner or later, the speaker will fail.

YEAH... YEAH... SO WHAT CAN I DO TO PREVENT THIS?

Alright, we know what clipping is, how it affects amps and speakers. What do we do to keep this problem from destroying our expensive drivers? Easy deal:

1. Use amps that closely match or modestly exceed the power rating of the speaker. A 100 watt speaker will love getting 125 watts of "clean power" vs a 100 watt speaker getting 25 watts of badly clipped (distorted) power.

2. Know what distortion sounds like and prevent it by proper amp setup procedures. (HU/amp gain matching, limited bass boost usage)

3. If you are not sure your system is clipping, best thing to do is get out
of the vehicle, open the doors and step to the rear of the vehicle about 10 feet and listen...

a. Are the highs and mids clear and natural sounding or harsh, shrill and very poor SQ? You are clipping the amp if you hear the latter!

b. Does the bass sound full, tight, have a definite thump and smooth transitions from one note to another? If not, good chance the sub amp is clipping or your enclosure design is not optimal for the subs.

OK, that's about all I can do for now on this topic... Class dismissed and PLEASE... NO CLIPPING ALLOWED !!! 15 yard penalty and you will pay the piper eventually.

Sorry everyone if I have put you through all of this, I hope it has been beneficial, but I think that I'm going to leave this one alone, I didn't sign on to argue or prove anything, only to help, I'm a big stickler on seperating fact from opinion. I need to learn when to quit, I'm not trying to hurt feelings.
See you on the next thread,
Tim

Don't worry about your 300wpc amp powering your 100wpc speakers. You do not have to match the numbers. As stated above, it is much more likely to overdrive a low powered amp to clipping and damage a tweeter. You will hear the strain when over driving your speakers with clean power, so back off when they sound like they might explode!
By the way, an amp has to malfunction to "send DC" to your speaker. That is not what "clipping" is.

Tim, I sincerely appreciate your gentlemanly responses and your good intentions. However, I too feel a responsibility to separate fact from mis-information.

As someone with multiple electrical engineering degrees, and multiple decades of experience in electronics design, I can tell you that DC is not "seen as high frequency"; that a clipped audio waveform is not DC and is not seen as DC (as Blkadr correctly indicated, and contrary to what is stated in the article you quoted); and that the portion of a crossover network that is between the speaker terminals and the tweeter (which is designed to pass high frequencies and to block low frequencies, and may be simply a capacitor in series, or something that is similar at a simplified conceptual level but more elaborate) will block DC. DC is actually the LOWEST possible frequency, zero Hertz. Capacitors block DC, and impede low frequencies.

If DC is ABRUPTLY applied to a circuit, high frequency components may be briefly present, corresponding to the abruptness of the change in voltage. Those are referred to as transients. Similarly, the abrupt waveform changes I referred to in my earlier post, that occur when a LOW frequency waveform is clipped, contain HIGH frequency spectral components.

Which leads me to simply reiterate that my earlier post correctly explains why tweeters are commonly damaged by the clipped waveforms that can be generated by underpowered amps.

Best regards,
-- Al