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Gasswolf

 

Silver Member
Username: Rosrock

Michigan

Post Number: 232
Registered: Mar-09
i was reading ur page on amp clipping. There are a LOT of causes to it. Now, my question is when the amp is clipping doesnt that mean that the sub will be clipping/distorting/ be damaged as well?( im reffering to the 1-7 on ur page).
 

Silver Member
Username: 813thumper

Tampa, FL United States

Post Number: 173
Registered: Sep-09
the sub at the point that the amp is clipping is no longer being sent a clean signal. so the sub becomes non linear and causes damage to the sub/coil and you will eventually blow the sub.
 

Platinum Member
Username: Glasswolf

Post Number: 13736
Registered: Dec-03
speakers don't clip. only amplifiers do that.
when the output of the amplifier is clipped, the peak and trough of the sine wave is cut flat. In severe clipping, the output is actually close to a square wave.
When this happens, the AC (alternating current) sine wave becomes direct current (DC) where the wave is clipped at the top and bottom of the waveform. When the signal is clipped like this, the voice coil gets the DC voltage, and the cone ceases to move back and forth, which stops airflow over the voice coil, and causes the coil to build heat in the windings. Enough heat, and the coil can become damaged.

Two ways to damage a voice coil. thermally, and mechanically.
 

Silver Member
Username: Rosrock

Michigan

Post Number: 239
Registered: Mar-09
OK , i just cut up my assassin and icon, now i see the the coil windings(THERE IS A LOT OF LINES/COILS!!! the icon has a lot more .. about 2 inches bigger diameter), the problem pretyy much has to be with the coils right? if not, wouldnt you say it normally is? is there any visible way to tell if it was thermally or mechancially overdone? Cause they both look fine to me... i dont smell any burning or anything either.

Also do u have a website that expalins how the coils make the motor work? cause i have no idea what goes on.
 

Silver Member
Username: Quirky

San Antonio, Texas

Post Number: 409
Registered: Feb-07
Sounds pretty hard to do actual damage to your sub from that form of clipping. Lots of music has square like waves but regardless your sub will still move enough to produce both sound and thermal cooling. I'm actually using a basic square wave right now and my speakers seem fine. Perhaps it would only do damage if it occurred for an extended amount of time (like a test tone) and no waves were completed.
 

Silver Member
Username: Quirky

San Antonio, Texas

Post Number: 410
Registered: Feb-07
From what I understand, distortion does not hurt speakers. It is just an indicator that the amp is turned to high. If the amp gain is turned too high, then the amp can produce more power than it was intended for and will also produce much more heat for your voice coils.
 

Silver Member
Username: Quirky

San Antonio, Texas

Post Number: 411
Registered: Feb-07
Also, the DC voltage theory is an seems to be an old myth... DC is different from a Square wave. If you look closely at any AC square wave, it is composed of fundamental frequency and an infinite number of harmonics/sine waves. The perfect square wave is only theory. How would AC current turn into DC current? There is no transformer making the conversion.
 

Silver Member
Username: Skdooley

Roanoke, VA Usa

Post Number: 776
Registered: Oct-09
Its also going to depend on how much power you're talking about. If you have a 1000 rms sub and you're running a 500 rms amp that is sending a clipped signal, it isnt going to do a lot of damage quickly. However if youre running a 500 rms sub on the same amp and sending it a clipped signal, it is going to be more likely to get damaged than the 1k sub. If you know better though, clipping should not be an issue. Clipping is going to be more of a problem for people who are new to car audio and think that their gain controls how much of the total rms the amp is putting out.
 

Gold Member
Username: Illuminator

USA

Post Number: 5178
Registered: Apr-05

quote:

Also, the DC voltage theory is an seems to be an old myth... DC is different from a Square wave. If you look closely at any AC square wave, it is composed of fundamental frequency and an infinite number of harmonics/sine waves. The perfect square wave is only theory. How would AC current turn into DC current? There is no transformer making the conversion.




DC is a square wave. Although DC doesn't carry any more RMS than a square of the same peak amplitude, the cone not moving, as Glasswolf said, is what damages the speaker more easily (aside from too much voltage, of course).
 

Silver Member
Username: Quirky

San Antonio, Texas

Post Number: 412
Registered: Feb-07
I understand that in theory if the sub were to not move it would overheat however I don't believe a square wave would prevent it from moving nor would it result in any damage. What does cause damage is the compressing of the wave when amp clipping takes place. Sign waves within the square wave will be compressed and rise to a higher average power level. This higher average power level is what causes the speaker to over heat. For example, one speaker may produce an average of 30 watts to a speaker. If you turn the gain up to where the amp starts clipping, within the peaks of the square wave the sign wave's amplitude rises (to a higher decibel output) but is also compressed and at a higher average power level of 100 watts to the speaker. Now at 100 watts vs the 30 watts to the speaker the coils will overheat.

Look at figure 13 and Figure 14 on this site to see the difference. It is also explained much better than what I can do if you want to read through the whole thing.

http://www.monstercable.com/mpc/stable/tech/A2420_Some_Facts.pdf
 

Silver Member
Username: Quirky

San Antonio, Texas

Post Number: 413
Registered: Feb-07
I just noticed Shawn's post... Shawn sry but I completely disagree with your example. In any sub amp combination, clipping will only occur when you have the gain too high or the bass boost too high. However if you are running a 500wrms amp for a 1000wrms sub, then you would be more inclined to push the amp to its limits and set the gain up too high where clipping damage may occur. So I would say if anything, it is more dangerous to run an insufficient amp (where amp's rms is lower than the rms of the sub) and safer to run an amp rated with a higher or equal rms than the sub.
 

Diamond Member
Username: Wingmanalive

Www.stainles... .ecrater.com

Post Number: 22863
Registered: Jun-06
Your equipment is only as safe as the user's intentions and knowledge of its' limits. It's too late tonight to address all the other comments I disagree with inside this thread.

Bottom line is you can clip the hell out of one driver and see no damage. Clip another and see it fry within seconds. It all depends on the thermal/mechanical limitations (like Glass stated) of the driver and the power/clipped signal sent to it.

I always HATE hearing a dumbass crank is stock stereo thinking because it's loud.........its' cool.


All I hear is clipped signals and drivers screaming for mercy.



All static to me.
 

Diamond Member
Username: Wingmanalive

Www.stainles... .ecrater.com

Post Number: 22867
Registered: Jun-06
Oh crap lol. Am I the only one who sees the title of this thread as "gasswolf"???


Not funny.......but it is lol.





Ok.....sorry.
 

Platinum Member
Username: Glasswolf

Post Number: 13739
Registered: Dec-03
Ben has re-stated pretty much what I've already said in my articles, which I get the feeling he hasn't read, and to which this thread has been in regards.
 

Gold Member
Username: Wolf_hound

Phoenix, AZ

Post Number: 1205
Registered: Sep-05
glasswolf has alot of gas hahahaha maybe its funny cuz im drunk.
 

Silver Member
Username: 813thumper

Tampa, FL United States

Post Number: 175
Registered: Sep-09
lol @ Gasswolf



^^ i got you
 

Silver Member
Username: Rosrock

Michigan

Post Number: 247
Registered: Mar-09
i like to start conflictive type threads :D HAHA
 

Silver Member
Username: Quirky

San Antonio, Texas

Post Number: 414
Registered: Feb-07
Actually Glasswolf, I read your paper before I said anything and I did not agree with it. Hints why I spoke up and wrote what I thought was wrong about the paper and your previous explanation.

"In short, clipping is when the amplifier is unable to produce a clean sinusoidal waveform output, and instead produces a waveform with flat peaks, or in extreme conditions, square waveform output, which sends direct current to the speakers instead of the expected AC voltage, which in turn causes heat to build across the speakers' voice coils."-Glasswolf

First off, It does not produce pure direct current.. It produces square alternating current with DC components that may appear to look similar but they are not. It is easy to switch DC to AC but not so easy to create AC into DC.

"When the signal is clipped like this, the voice coil gets the DC voltage, and the cone ceases to move back and forth, which stops airflow over the voice coil, and causes the coil to build heat in the windings. Enough heat, and the coil can become damaged."-Glasswolf

Regardless of what you want to call the square wave, the main issue is how clipping damages the sub. I don't believe the lack of air flow is the cause of overheating the coils. What does overheat the coils is what I explained above; the compression of the sign wave at a higher average power level. Because the average power level is higher, regardless of cone movement, it will over heat the coils. The coils are designed for a specific average temperature (thermal power rating) but when the average power level is increased so does the average temperature. This is what burns up the coils. Has nothing to do with the cone not moving enough to cool it down. If that was the case, then compressing the waves at a lower level would still over heat the coils because of the lack of movement. It is only when the waves are compressed and the overall average level sits higher not giving as much rest to the coil.

Once again look at figure 13 and 14 to see the comparison of a compressed wave at a higher average power level and normal square wave.

http://www.monstercable.com/mpc/stable/tech/A2420_Some_Facts.pdf

That is not re-stating your article but disagreeing with certain components of it.

Glasswolf, I think you are a very knowledgeable man and I respect the advise and time you devote to helping people on ecoustics. I came across this thread and found interest in your theory so I explored more in depth from other sources and realized I found disagreement with your idea of amplifier clipping. I hope others do the same when they come across something that they disagree with rather than continue potential myths.
 

Platinum Member
Username: Glasswolf

Post Number: 13742
Registered: Dec-03
yeah heard the gasswolf jokes before.. It was funny the first few times, but after ten+ years, it loses the lol factor. sorry

while yes, overcurrent is also a factor in damaging coils, with which I do agree, and should update that page, since I wrote it at 3am and was doing it in a hurry, I would like to note, please, never ever use monstercable as a cited reference. Their products are so full of misinformation and toal BS marketing magic crap, it's laughable.

Yes, in a clipped signal, the waveform is compressed, but in severe clipping, the portion of the clipped waveform that is flat, for that period of time that it is flat, is direct current to the coil. The cone isn't moving, and there is no alternation in the waveform, again at that particular passage of time. Anyway yeah craeting AC from DC isn't easy which is why true sinewave output UPSs cost so much more than square wave or stepped wave output models. Rectification is of course much simpler.

actually I said articles, Ibelieve, as some of this was covered in other papers.

If you are interested in revising that page though, I'd be more than happy to replace it with the updated data.

Honestly, I just don't have the time to deal with a lot of this writing lately, and I added a lot of stuff just to gloss over answers to commonly asked questions without getting too overly complicated for the average Joe.

Right now 've been dealing with some sort of sinus infection, and trying to de-worm 17 cats, some of which are feral. It's not easy to catch them, pill them, and let them go without getting shredded. lol

This page should help clarify some of the information:
http://www.st-andrews.ac.uk/~www_pa/Scots_Guide/audio/clipping/page1.html
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