Is it damaging to clip an amp? - Page 3

Hi Wth,

To me, it appears to square fine with what Nick said. He does not say that all that "excess power" is going to the woofer or sub. Also, nobody is saying that a "clipped to death" 1000 watt amp into a 500 watt speaker is not going to "hurt", but is that a realistic scenario? and what exactly is going to be hurt? The tweeter maybe, but not likely the woofer. Keep in mind the context of the original post.

Understood. But the debate came about when N8 said he cooked 2 subs with a 1000 watt plate amp in a really small box. Sounds to me like the contention is that this can't happen due to clipping/the effect of increased power due to clipping. Perhaps I'm misreading that part.

But it seems plausible for that to be the culprit when you consider the conclusions from Ricci about it not being thermally limited in his testing, the small size of the box, the quote from Nick, PLUS the fact that the drivers crapped out during a couple minutes of music. The other options are amp defect or that the drivers really are thermally limited at 600 watts and 1000 will cook em in a matter of minutes. The latter being unlikely considering there are already members feeding them that kind of power now without issue.

Sigh...
Properly operating drivers fail for two reasons only. Mechanical damage and burning or overheating the voice coil.

You can cook any voice coil with far under rated power if you try. It is dependent on the signal, signal duration, box alignment, etc...I dont think there is a woofer out there that is impossible to cook with a real 1000w amp. Typical use and music signals are not going to cause it because the average power is far lower than the peaks and are usually not running the amp into heavy clipping (meaning not turned up all of the way effectively). Then there are 100% duty cycle signals like the 20+ second long sine sweeps I use for compression testing. These are 10x worse on the vc than anything that should typically be encountered in program material. Absolute worst case is you dump a pure sine tone into the system at a frequency corresponding to low impedance and minimal cone motion. It is only a matter of time for the heat to build up.

The SI I had survived one of the test sweeps at much more power than the Dayton amp can produce. This leads me to believe that either N8 was running a song with sine waves in it at full power for awhile while heat built up or there was something defective. (N8 I am labeling you a cranker from now on)

In any case this is the reason why generic power ratings are basically worthless because it varies so much. What might be safe on a 1500w amp for one person might get cooked on a 500w amp with another.

So are we saying that clipping won't cause a sub to heat up and burn the voice coils? I understand entirely on a loudspeaker that all that extra power when it goes through the crossover goes to the tweeter but I've personally burned up a few subs from trying to squeeze to much out of an amp before and the clipping/extra power takes them out.

Anything's possible. The third harmonic of a square wavre is about 10 dB down IIRC, about 1/10 the power of the fundamental. So there is additional in-band energy for a LF signal into a sub, but falling off rapidly. Most of the harmonics lie above the sub's range.

Running any speaker continuously at high power levels, clipped or not, could cause damage.

Here is my damage list thus far:

Drivers:
Velodyne CHT 10 and 15: overheated the amp inducing the protection circuits. Also bottomed the cones on may occasions. No longer use.
Velodyne HGS-10: Bottomed the cone on may occasions. Blew up the plate amp (manufacturers defect confirmed). No longer use.
SDX-15: Bottomed the cone on may occasions. Fried a voicecoil (manufacturers defect I ASSUME). The other one given the same signal continues to run flawlessly. Phasing out, but currently used for sub-duty.
TC Ultra: Bottomed the cone on one occasion causing the cone to dent outwards slightly (loud movie ULF). Otherwise flawless. Currently used for sub-duty.
Dayton 18: Detached one of the coils from the cone (manufacturers defect I ASSUME). The other 3 fed the same signal continue to run flawlessly. Self-repaired. Currently used for sub-duty.
Mal-21: Heat induced flux ring glue issue. Manufacturers defect confirmed. Self-repaired. Currently use for sub-duty.

Amps:
Velodyne A/B amps: Overheated the amp inducing the protection circuits. No longer use.
Velodyne 2150w plate amp: Got it really hot but it never went into protection (manufacturers defect confirmed). Mono 4-ohm stable. No longer use.
ED 1300: Clipped and Overheated on several occasions. Mono 2-ohm stable at low power. No longer use.
EP4000: Clipped and overheated, inducing the protection circuits. Dual 2-ohm stable at low power. No longer use for ULF-sub-duty.
Crown XTI-4000: Clipped and overheated, inducing the protection circuits. Dual 4-ohm stable. No longer use for sub-duty.
Crown iTech 8000: Clipped briefly, never overheated. Near flawless. Dual 1-ohm stable. Currently use for sub-duty.
10kQ clone: Clipped briefly, never overheated. Near flawless (thus far). Quad 4-ohm stable. Currently use for sub-duty.

I'm rather heavy handed with my equipment. I tend to break weak things.

Well, I'll admit, I am a cranker lol but in this case, it was the same test I've done 100 times before. Before I ship out any of the subs, I put them through the test to make sure I'm not getting any mechanical noises and to make sure everything seems good to go. I do about 30 mins of free air at close to xmax with a few selected songs to give the drivers some action. I try not to give them anymore than half their power rating during free air testing as well. These 2 sub went at the exact same time with the same amps. The daytons are my usual testing amps and the boxes were 3CF. They weren't making any mechanical noise before the went. On the build up to the big bass note they both just popped and stopped lol. Like I said, I did the same test with the Dayton 18's and they did start to make mechanical noise but I turned it down before any damage. 2 different things. It's likely they were just overpowered, I was not using sine waves or anything else. Thats why i was like "WTF???" It's entirely possible that they may have been defective, I don't know. After ripping it apart, the coil had become completely unwound and was a mess, there were burn marks but it was hard to see with the coil in such a mess. I took my mal-x 21 out and did the same test at 10dB's over what I tested the dayton and SI at and it show no signs of distress or any audible distortion. I know they are not exactly the same quality of driver but I generally only build with top tier drivers.


My 2 new SI's will be here next week and I plan on doing the exact same tests. Though after these 2 sIO's are done, my focus will be shifted to my Gjallarhorn project and my 86 Regal T-Type needs some m ore go fast parts so I can get into the 10's this year

Burnt speakers forensics
Does it fit N8D's description?

I should have taken a pic but at the time but it pretty much looked like this :
i've seen quite a few cooked coils but it was dark the whole way through, for sure burnt, just hard to see where it started on the coil (if that even matters)

Make sure to take pictures of the next pair you burn

Seriousely though, is not it unusual for the thermal failure to be so rapid? I mean normally it takes much longer for the heat to build up.

I have only cooked one driver in my life. It was an epic 12. The amp was playing along just fine and then the cone turned inside out, and the coil was cooked to death. It was the amp that was at fault they say, so it was repaired under warranty but the driver is still dead.

Keep cranking,


Robert

Sounds like dayton make **** amps. I just tested the scary xmas tune with a bridged ep2500 on 2 old shool aa atlas 15's . Very nice song btw, ty .