posted
I know Tech man said if the voltage passes over + to - it is AC, but it would seem a square wave would be + and - pulsed DC..JMO
Posts: 5348 | From: Nash-Vegas, TN | Registered: May 1999
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posted
Exactly. The flat spots are basically DC bursts that change from full positive to full negative phase almost instantaneously. Very hard on woofers.
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And that's the bottom line, cuz: LORD DUKK SAYS SO!
The Big Show The Dukk says: Know your bass: PORT your damn box!! Have HoleSaw, Will Travel!
posted
I agree with your analogy, but if it was an AC wave to begin with, there is still a slope on the waveform, therefore it is still AC. The lower the frequency, the longer the sub is at it's max. excursion, the quicker you burn the voice coil...............Forget it, lets just call it Alternating Direct Current! AAARRRGGGHHH, that term just doesn't jive for me. That's like saying motionless motion, or.....you get what I mean.
------------------ inno73@hotmail.com
Posts: 490 | From: Fort Frances, Ontario, Canada | Registered: May 1999
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posted
Agreed, Inno! I was referencing true square waves in my last post, but I agree with your assertion that the flat momentary DC areas riding on the AC waveform are bad for the subbies...
Posts: 5348 | From: Nash-Vegas, TN | Registered: May 1999
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posted
I'm still not convinced that a square wave at 20Hz can hold a woofer at x-max long enough to overheat the voice coil. It is still going to be changing direction 20 times a second... I'm really not trying to be argumentative here... I like the idea of cycling DC!!!
------------------ STILL waiting to hear a GOOD pair of HLCD's!!
If it dont fit, force it... if it breaks, it needed to be replaced anyway...
posted
heres my two cents, since nowbody explained this I will and hope I clear up the confusion between ac and dc with respect to square waves. when I think of square waves, yes I think of them as pulsed dc, but this is actually wrong. It really is ac. If you were to look at a square wave on a spectrum analyzer you would not see a line at 0hz(DC) you would see a whole bunch of lines over the entire frequency spectrum. a perfect square wave is the sum of an infinite number of sin waves. thus you will never see a perfect square wave. under real conditions you see the non-perfect square wave which is made up of sinwaves that are within the amps bandwidth. It's kinda wierd but if you add up a bunch of sin waves (ac waves with different frequency's, amplitudes, and phases) you get any thing from square waves to tiangular waves. the fallowing formula is for a square wave. f(t) = (4A/pi)sum[(1/n)(sin nwt)] f(t) is the square wave A = amplitude of square wave sum is from n=1,3,5... to infinity (ideally) w = 2*pi*f f = 1/T T =period of squarewave. I hope I didnt make this to complicated and bore you. I know most people hate math. what im trying to say though is in the real wourld, real things see square waves as a bunch of sin waves (different ac signals). but you could pulse a dc voltage and get a square wave.
[This message has been edited by mr.dank (edited 01-04-2000).]
Posts: 1259 | From: Fullerton. CA ,USA | Registered: Oct 1999
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posted
I think weather power can be called DC or AC; it has to be referred to a pacific time frame. If you look at the whole passage of a typically clipped signal over a few seconds, the charge cycles from positive to negative regardless of clipping; hence making it AC. If you were to analyze a small time frame of a part of a wave (any ware from 0 deg. to 180 deg. -OR- from 180 to 360) that bit of information in itself would only be directly positive or directly negative, again regardless of clipping; hence DC.
[This message has been edited by LOTSAWATTS (edited 01-06-2000).]
Posts: 140 | From: TEAM HERTZ C A N A D A | Registered: Oct 1999
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posted
My post was strictly technically speaking. If the current changes direction during the the waveform then it is AC. AC can have a DC component but this would be AC + xdc volts. If the waveform does not cross 0 volts, or change current flow direction then it's pulse DC. An amp that is clipped to the point that you have a square wave coming out is still producing AC. The fact that the waveform lingers at xpeak and -xpeak volts during portions of the cycle doesn't change that. I do understand the thought that it's like DC for those milliseconds.
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