To Much Power?
09-17-2008, 10:13 PM
#11
The results I have had in the last 20 years that I have been in this industry is at the exact opposite end of the spectrum to you. I am going to find a link for the op to have a look at where this topic was discussed in depth.
<edit>
Here is the link from what I remember.
http://www.the12volt.com/installbay/forum_posts.asp~TID~74226~PN~1
<edit>
Here is the link from what I remember.
http://www.the12volt.com/installbay/forum_posts.asp~TID~74226~PN~1
09-17-2008, 10:28 PM
#12
50 Watt CAFz'r
Join Date: Aug 2008
Posts: 61
We used to get guys bring subs in with unwound voice coils all the time. It happened when they were running 300 watts mono to 2 x 12", and it didn't happen when they went to larger amplifiers.
I used to see lots of suspension damage, especially with ported boxes.
Quote from Manville Smith of JL:
The fact that a signal is clipped does not make it inherently damaging... if the average power of the clipped signal is low it won't ever damage a speaker. At higher power levels, the fact that a clipped signal carries more average power over time can result in damage.
The fact that tweeters have low inductance, do not employ low-pass filters and have small, delicate voice coils makes them more susceptible to damage from a clipped signal than a woofer or mid.
Does that make sense?
It just points out that the old statement of an amp that is too small will damage speakers more than a more powerful amp is entirely dependent on the use of each amp... if you clip both amps to the same extent, the more powerful one will blow speakers faster.... but it is possible to make a small amp operated into clipping produce as much average power as an unclipped larger amp (even though the peak power is greater on the big amp).
When you clip an amp you not only increase distortion, you also compress the dynamic range of the signal... the distortion isn't what kills the speakers (except tweeters in some cases)... it's the dynamic range compression that really does it.
Halo1...
Do you mean an inductor? An inductor will make the impedance rise at higher frequencies (reducing power at higher freq's). You can achieve the same result by filtering the amp's input signal via a low-pass active crossover. The latter is more desirable because it does not introduce resistance like the inductor and is much more precise.
Best regards,
Manville Smith
JL Audio, Inc.
I used to see lots of suspension damage, especially with ported boxes.
Quote from Manville Smith of JL:
The fact that a signal is clipped does not make it inherently damaging... if the average power of the clipped signal is low it won't ever damage a speaker. At higher power levels, the fact that a clipped signal carries more average power over time can result in damage.
The fact that tweeters have low inductance, do not employ low-pass filters and have small, delicate voice coils makes them more susceptible to damage from a clipped signal than a woofer or mid.
Does that make sense?
It just points out that the old statement of an amp that is too small will damage speakers more than a more powerful amp is entirely dependent on the use of each amp... if you clip both amps to the same extent, the more powerful one will blow speakers faster.... but it is possible to make a small amp operated into clipping produce as much average power as an unclipped larger amp (even though the peak power is greater on the big amp).
When you clip an amp you not only increase distortion, you also compress the dynamic range of the signal... the distortion isn't what kills the speakers (except tweeters in some cases)... it's the dynamic range compression that really does it.
Halo1...
Do you mean an inductor? An inductor will make the impedance rise at higher frequencies (reducing power at higher freq's). You can achieve the same result by filtering the amp's input signal via a low-pass active crossover. The latter is more desirable because it does not introduce resistance like the inductor and is much more precise.
Best regards,
Manville Smith
JL Audio, Inc.
Last edited by macguyver; 09-17-2008 at 10:35 PM.
09-18-2008, 07:41 PM
#14
Yankee
Join Date: Oct 2003
Posts: 3,599
Energy to a sub is far more transient in level and duration than any other speaker.
Heat damage to the coil with clean power is not very likely
Unjustified theory- speakers used to get loud due to efficiency, NOW they get loud due to good heat sinking and driver inefficiency allowing MANY KW to be used
but suspension damage from over-excursion (sub in improper box, or playing music with significant energy below the tuning frequency of a ported box for example) is much more of an issue.
Last edited by JohnVroom; 09-18-2008 at 07:45 PM.
09-18-2008, 09:22 PM
#15
50 Watt CAFz'r
Join Date: Aug 2008
Posts: 61
Well, we all know a sub has a larger voice coil. More copper is going to be less I squared R losses than what you'll find in a smaller driver. You might find a 1000W rating on a sub with a 3" voice coil, but you'll not find it on a tweeter with a 3/8" voice coil if that. Plus a sub has forced air cooling, and will radiate thermal energy to the basket, poles, etc.
Now this should be a relatively common amp:
NEW US AMPS 4000 WATT MONO CAR STEREO SUB AMPLIFIER AMP - eBay (item 350096784756 end time Sep-18-08 18:36:32 PDT)
1500W, 4000 peak? If you notice, there are 75A worth of fusing on that amp. If it really did big power for long durations, the most that amp could make at fuse rating is 15V (maybe) x 75A = 1125W. Maybe the fuses are a subject to tolerances, and maybe you might squeeze 1200W out of it, but not for long. But the commonly accepted fact is that this energy doesn't last in durations long enough to blow those fuses, unless you are listening to Bass Mechanix or something like that. And most music does not contain notes like that.
Yes, the subwoofer requires and uses more power than any other driver in a system (typically). But you must feed it clean power, like any other driver. The fact that humans can't discern distortion below 10% doesn't mean it isn't there and isn't troublesome. And it's much tougher to detect at bass frequencies, in fact I'd say damn near impossible even for trained ears. This is also what makes this an issue. You can hear it quite easily at midrange or treble frequencies, and adjust your system accordingly.
It's pretty easy these days to know the mechanical limits of your speakers, as big power (cough!) is relatively cheap (clean is another matter entirely). Once you can reach those, it's easy to control. But when you underpower a speaker, you may never reach the mechanical limits, but instead bombard it with useless and wasted energy that must go somewhere, and is manifested as heat. Heat kills, speakers are only 1 item in a long list. Clean power also must go somewhere, and can also be manifested as heat, but we equate loudness with distortion (6x9's off deck power anyone?), and when we detect loudness (distortion in many cases), we tend to want more, becoming immune. Or the sane folks adjust levels to avoid those scenarios.
When I did car audio as a living (the 1990's), big amps didn't really exist, or were affordable. Folks wanted 150dB on 1000 watts, but the amp was $3K. So, lower power and multiple drivers was the norm. And we had lots of warranty claims back then, on all sorts of drivers, but mostly subs.
I'm sure subs have become "better" and amps "bigger", but too little power and an itchy "volume-up" finger is as much a problem today as it ever was back then.
Now this should be a relatively common amp:
NEW US AMPS 4000 WATT MONO CAR STEREO SUB AMPLIFIER AMP - eBay (item 350096784756 end time Sep-18-08 18:36:32 PDT)
1500W, 4000 peak? If you notice, there are 75A worth of fusing on that amp. If it really did big power for long durations, the most that amp could make at fuse rating is 15V (maybe) x 75A = 1125W. Maybe the fuses are a subject to tolerances, and maybe you might squeeze 1200W out of it, but not for long. But the commonly accepted fact is that this energy doesn't last in durations long enough to blow those fuses, unless you are listening to Bass Mechanix or something like that. And most music does not contain notes like that.
Yes, the subwoofer requires and uses more power than any other driver in a system (typically). But you must feed it clean power, like any other driver. The fact that humans can't discern distortion below 10% doesn't mean it isn't there and isn't troublesome. And it's much tougher to detect at bass frequencies, in fact I'd say damn near impossible even for trained ears. This is also what makes this an issue. You can hear it quite easily at midrange or treble frequencies, and adjust your system accordingly.
It's pretty easy these days to know the mechanical limits of your speakers, as big power (cough!) is relatively cheap (clean is another matter entirely). Once you can reach those, it's easy to control. But when you underpower a speaker, you may never reach the mechanical limits, but instead bombard it with useless and wasted energy that must go somewhere, and is manifested as heat. Heat kills, speakers are only 1 item in a long list. Clean power also must go somewhere, and can also be manifested as heat, but we equate loudness with distortion (6x9's off deck power anyone?), and when we detect loudness (distortion in many cases), we tend to want more, becoming immune. Or the sane folks adjust levels to avoid those scenarios.
When I did car audio as a living (the 1990's), big amps didn't really exist, or were affordable. Folks wanted 150dB on 1000 watts, but the amp was $3K. So, lower power and multiple drivers was the norm. And we had lots of warranty claims back then, on all sorts of drivers, but mostly subs.
I'm sure subs have become "better" and amps "bigger", but too little power and an itchy "volume-up" finger is as much a problem today as it ever was back then.
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