Helmuth,
It took over 300 posts to get Charly off the 18" OB crack pipe and go to a ported 15".
Only 3 or 4 posts explaining why his port is too small, give him time
!Art
Helmuth,
It took over 300 posts to get Charly off the 18" OB crack pipe and go to a ported 15".
Only 3 or 4 posts explaining why his port is too small, give him time
Art
Charly try 3 or 4 of that ports in your speaker. They will become a bit longer there for they will do their job better then a to small port.
haha, very funny .
Yep, I knew the port was a bit small but it was the cheap pipe available at the store. So I plan to change that soon.
Sadly, that TAD driver is rattling, so I think there is a problem with the voice coils.I just stopped using it. When I gently push the cone, I feel how the coil is scratching something inside. I should start with another 15in woofer soon.
I was sanding and repairing the big horns during the weekend, so I expect to pait them white soon.
Also waiting for a passive crossover for the Mid-Highs.
Hope to get back with news soon.
best,
C.
.Yep, I knew the port was a bit small but it was the cheap pipe available at the store. So I plan to change that soon.
Sadly, that TAD driver is rattling, so I think there is a problem with the voice coils.I just stopped using it. When I gently push the cone, I feel how the coil is scratching something inside. I should start with another 15in woofer soon.
I was sanding and repairing the big horns during the weekend, so I expect to pait them white soon.
Also waiting for a passive crossover for the Mid-Highs.
Hope to get back with news soon.
best,
C.
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Clipping does not burn voice coils, too much average power does.
An "underpowered" 10 watt amp if driven to full square wave clip could possibly put out as much as 20 watts, which the TAD woofer could easily handle.
Generally when one gets a driver for free, there is a reason
, in this case it probably was previously overheated.I'd suggest cutting the dust cap off carefully, it is possible the former warped or blistered when the voice coil was overheated.
If that is the case, putting a piece of emery cloth in the gap, running a LF sine wave while vacuuming the debris could cure the problem.
I got luck fixing one 15 that way, after I'd completely cut off the cone on another, suspecting sloughed coil wires when it was blistered Kapton
.Art
Art, I have to disagree here. Not for a home system, but for pro ones, clipping can be a real problem. I saw this in spades when I made speakers that went into clubs.
There is usually not much attenuation of the signal to a speaker at and above 10 kHz, because most are having trouble in this range anyways. When the amp is clipped the harmonics move ever higher in frequency and get into this region where all they do is heat the Voice coil.
When we put in a LP filter at about 18 kHz, the burnouts stopped. Most club mixing guys have no idea that they are clipping virtually 100% of the time.
Yes, voicecoils don't seem to like a nice square wave when an amplifier is driven into clipping, not something that takes long to take out a voicecoil. Go talk to anybody who manufactures speakers and I bet this is the majority of all warranty problems with any type of speaker. A burned voice-coil and not from to much power but from to little and clipping of the amplifier.
Originally Posted by weltersys
Clipping does not burn voice coils, too much average power does.
Art
The reason the tweeters burned out was not from the clipping, but from the additional average power the contained in clipped harmonics . This is often a problem with club DJs, who generally are behind the speakers and don't hear all the extra HF energy that clipping is causing the tweeters to endure.
The 18 kHz LP reduced the average UHF power the tweeter received when subjected to amp clipping.
At any rate, what cooked Charly's woofer was not his 10 watt amp, regardless of how clipped it was, and his coax mid/hi driver is not connected to the same amp, so he doesn't have to worry about excessive upper harmonics generated by LF clipping burning them out.
Clipping does not burn voice coils, too much average power does.
Art
Earl,
The reason the tweeters burned out was not from the clipping, but from the additional average power the contained in clipped harmonics . This is often a problem with club DJs, who generally are behind the speakers and don't hear all the extra HF energy that clipping is causing the tweeters to endure.
The 18 kHz LP reduced the average UHF power the tweeter received when subjected to amp clipping.
At any rate, what cooked Charly's woofer was not his 10 watt amp, regardless of how clipped it was, and his coax mid/hi driver is not connected to the same amp, so he doesn't have to worry about excessive upper harmonics generated by LF clipping burning them out.
H. L. Menchen
There is so much wrong with this post, that it is hard to know where to begin.
Sound system engineering; you're doing it wrong.
"Most of the club owners have no idea that the sound systems I sold them are inadequate 100% of the time." Fixed that part for you.
An engineer, a mathematician, and a physicist are each sentenced to die by the guillotine. As the physicist is led to the guillotine, she decides that she'd like to observe the blade as it falls, perhaps to verify v=at, and she requests to be strapped in face up. The executioner agrees (why not? it all pays the same...), and straps her in. As the blade falls, it sticks about two thirds of the way down. Seeing this, the crowd cheers - the physicist must be innocent! So the exectuioner unstraps her and sets her free. The mathematician is next. Being well versed in matters statistical (perhaps she is an actuary), she quickly asks to be placed face up as well - after all, the odds of it happening again are pretty good, especially if the initial conditions are similar. So the excutioner obliges, and once again, the blade sticks about two thirds of the way down. Again the crowd cheers, and the mathematician is also set free.
Finally, the engineer. Not willing to do anything in public that is different from her peers, she, too, requests to be placed face up. As the executioner is strapping her in, she's looking up at the blade and studying the track in which it slides. As she does so, she notices something. "Do you see that?", she asks. "About one third the way up? If you fixed that there..."
See, to fix the problem, most people would adjust their behavior before hand, so as not to get in this position. Instead of fixing the problem, you just facilitated the lopping off of the head. There is still the situation of being in clipping 100% of the time.
So far, all of this has nothing to do with the matter at hand. That of the blown speaker. But I now have reason to view everything you write with suspicion, as you have mucked up this situation so bad, and seem to have no real world experience in applying otherwise well thought out principles.
So getting back to the problem at hand. Average heat is the problem. And the more clipping there is, the more heat there is. This is because the duty cycle goes up. So in your scenario, you have made a huge problem by not only generating more heat, but by generating this heat in a an area where it can't be heard. All you did was filter off some of the heat. The average power was reduced. Not the clipping. If anything, the board is now being pushed harder to try and get back that signal that is now going no where.
A pretty heavy handed and arrogant pointless response.
I did not cause the clipping, the user did. I only needed to try and protect him from himself, but alas, you "cannot fix stupid".
And your last sentence is a classic. The board is "pushed harder" to increase the lost sound that was inaudible?
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Originally Posted by weltersys
Clipping does not burn voice coils, too much average power does.
The reason the tweeters burned out was not from the clipping, but from the additional average power the contained in clipped harmonics .
Semantics or clipping don't burn voice coils, too much average power burns voice coils.
Voice coils don't care what the waveform shape was that burnt them, or how the power was generated.
We are in agreement on three points:
1) Clipped amps can generate more than their rated power.
2) Amp clipping generates additional high frequency harmonics which can contain enough average (or even peak) power to burn a relatively low power high frequency driver while the higher power woofer may easily survive.
3) You "cannot fix stupid", but if your passive HP keeps "stupid" from burning up more tweeters, problem solved.
Clipping does not burn voice coils, too much average power does.
The reason the tweeters burned out was not from the clipping, but from the additional average power the contained in clipped harmonics .
Earl,
Semantics or clipping don't burn voice coils, too much average power burns voice coils
.Voice coils don't care what the waveform shape was that burnt them, or how the power was generated.
We are in agreement on three points:
1) Clipped amps can generate more than their rated power.
2) Amp clipping generates additional high frequency harmonics which can contain enough average (or even peak) power to burn a relatively low power high frequency driver while the higher power woofer may easily survive.
3) You "cannot fix stupid", but if your passive HP keeps "stupid" from burning up more tweeters, problem solved.
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You got to the point more succinctly, and politely than I did, and got it posted whilst I was constructing my rant.
The point is, you did not reduce the clipping in the system. Only the power/heat. By reducing the output of the system, it could be argued that the sound man is now pushing the system farther into clipping to try and get back the power that you are filtering off.
So, there is more clipping, less power. Which is even more to Art's point. Heat burns voice coils, not clipping.
Your little example proves his point, and you call it semantics?
I'll cop to two out of three. Sorry for heavy handed/arrogant.
But, if you have sold a system that is in clipping 100% of the time, you do not understand the needs of your client. Even remotely.
Yes, there are a ton of bad sound men out there. But, there are even more bad sound systems. I am sensitive to this and overreacted.
To solve the problem, you removed heat/power, not clipping.
The system is still clipping 100% of the time.
So in effect save a few drivers in the high end while guaranteeing that the system is running in a distortion mode? There is a reason that most good PA systems have a minimum of 3db of headroom over the highest power rating of the speaker system and generally even more than that and it is to stay out of this situation.
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