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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => LAB Lounge => Topic started by: Dave Potter on September 06, 2017, 03:05:35 AM
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Its been years since I was here. Hi everyone.
I started playing Brazilian percussion and I've joined a community group which has its own rig for rehearsals. I'm just replacing tweeter coils!. Firstly, they have no audio knowledge so they treat their gear like trash. Over-driving everything. One thing that crossed my mind though:-.
They use these powered Mackie full range powered boxes, but they only use it for vocals and a ukelele - turned up to the limit. Are they putting all of their power through the tweeters? or does physics not work like that?
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Usually it's quite hard to destroy drivers in a powered cabinet. They have protection built-in. But it is not impossible. Most of the time a bad gain-structure is the cause.
Start with setting the gain-structure at reasonable levels, and check that the input on the box is set to line-level. Drive the boxes as hard so the limit-led will occasionally flash. That's the limit! If not loud enough, your boxes are not up to the task.
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They use these powered Mackie full range powered boxes, but they only use it for vocals and a ukelele - turned up to the limit. Are they putting all of their power through the tweeters? or does physics not work like that?
Are you asking if all the potential power of the cabinet is making it's way to the tweeter if the content is such that power is not eaten in the lower registers? Are these Mackie's biamped? Most (an awful lot of) powered boxes use separate amp modules for highs and lows.
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Good point, David.
Maybe Dave Potter can tell us what type of Mackie speaker we are talking about. Also: are the woofers still producing something resembling music?
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Usually it's quite hard to destroy drivers in a powered cabinet. They have protection built-in. But it is not impossible. Most of the time a bad gain-structure is the cause.
Baloney. In the right (wrong) hands, it's pretty easy to blow up any speaker. The built in protection only goes so far. People will find a way to make it do things that weren't supposed to happen.
I'm often surprised how bad people make speakers sound by over driving them, and then wonder why they always end up broken. It's shocking, really.
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Baloney. In the right (wrong) hands, it's pretty easy to blow up any speaker. The built in protection only goes so far. People will find a way to make it do things that weren't supposed to happen.
I'm often surprised how bad people make speakers sound by over driving them, and then wonder why they always end up broken. It's shocking, really.
These people are clueless. They all think they want "quality sound" and then drive the cheap-ass PA into sustained hard clipping until it dies. The don't recognize the distortion, particularly if alcohol is consumed by the operator, owner, DJ, band or audience. This is one reason genuine quality of sound is not seen as worth paying for - nobody (and usually the client) has a clue as to what "bad" is, let alone good.
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Baloney. In the right (wrong) hands, it's pretty easy to blow up any speaker. The built in protection only goes so far.
To Geert's point, in the right (good) hands they USUALLY are hard(er) to blow up. "Baloney" (or "bologna") is a bit harsh, akin to calling him a liar. Or at least what he said was a lie, which it certainly was not. :)
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This is one reason genuine quality of sound is not seen as worth paying for - nobody (and usually the client) has not a clue as to what "bad" is, let alone good.
And therefore easily satisfied by those that can do no better.
Some how, we (as audience) that find it supremely important that "it" sounds good, get so easily offended when "it" don't.
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They are Mackie SR1521s. I completely agree with all the comments about their use. Luckily these are only used for rehearsal, (they get proper rigs for shows) but that means that everyone starts messing with it. I aim to educate them, but I was wondering if a 15" plus horn box was the right choice in the first place. Hence the question about ONLY using the tweeter.
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They are Mackie SR1521s. I completely agree with all the comments about their use. Luckily these are only used for rehearsal, (they get proper rigs for shows) but that means that everyone starts messing with it. I aim to educate them, but I was wondering if a 15" plus horn box was the right choice in the first place. Hence the question about ONLY using the tweeter.
There are fundamental pitches that are 2+ octaves below the HF driver's electrical crossover so no, you do need a cone. Whether or not it should have been a different size is a red herring, it makes no difference for vocals or uke in regards to blowing up HF drivers.
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There are fundamental pitches that are 2+ octaves below the HF driver's electrical crossover so no, you do need a cone. Whether or not it should have been a different size is a red herring, it makes no difference for vocals or uke in regards to blowing up HF drivers.
Huh? I wasn't suggesting that there shouldn't be a cone. The original post was really asking if most of the energy was being directed through the tweeter. Actually I just found the manual online. 300W through the 15" and a separate 100W amp for the tweeter with a crossover at 1300Hz.
So Perhaps I should ask a slightly different question. Should they have bought something more HF capable, or with a slightly higher crossover point?
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Huh? I wasn't suggesting that there shouldn't be a cone. The original post was really asking if most of the energy was being directed through the tweeter. Actually I just found the manual online. 300W through the 15" and a separate 100W amp for the tweeter with a crossover at 1300Hz.
So Perhaps I should ask a slightly different question. Should they have bought something more HF capable, or with a slightly higher crossover point?
They should have bought a bigger better speaker. As an end user buying a powered speaker, you shouldn't care at all where the crossover point is.
Sent from my iPhone using Tapatalk Pro
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There's at least 3 to 4 octaves of content below 1300Hz with vocal material. Down to 80~120 Hz, depending on the voice & note. You certainly (should) be using the woofer almost as much as the tweeter, unless you enjoy overly bright sound... If you like your vocals to sound very warm and bass-heavy, you may even be putting more stress on the woofer than the tweeters.
All speakers should (and most do) sound relatively flat out of the box.
They should have as much headroom in the highs as they do in the lows.
If you blow the HF drivers, it means they're being driven hard (doesn't mean the woofer isn't being driven hard too) and you simply need a louder speaker. It doesn't matter whether that's a 15" or a 12" or a 10".
That being said, usually 15" speakers go slightly lower than other smaller sizes at the expense of beaming in the higher end of their frequency response. This is why higher end 15" 2-way cabs are usually paired with a 2" horn, that way the crossover point can be lowered and get more even response throughout the mid range area. It all depends on the actual woofer however, some high end 15" woofers may perform better in that regard than low-end 12" or smaller woofers.
Generally speaking, since you don't need low end extension down to 40Hz, a 12" speaker of the same series could - possibly - (again, it depends) improve the way vocals and ukeleles sound in the mids, but it's not related to your problem in any way.
What you need is a more powerful speaker, no matter the woofer's size.
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What you need is a more powerful speaker,
I'm asking the OP here... is that really the case? Do they really want it as loud as it is now at tweeter blowing SPLs or are they just totally clueless about systems operation and are happy with the SPLs after you tweak things and bring the levels under control?
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I'm asking the OP here... is that really the case? Do they really want it as loud as it is now at tweeter blowing SPLs or are they just totally clueless about systems operation and are happy with the SPLs after you tweak things and bring the levels under control?
How do I ask this?
The sound of distortion is not a distorted signal (necessarily). Correct?
If that signal (of the distortion sound) become distorted, is that signal clipped?
Can I swap distortion and Clipped? If that signal (of the distortion sound) become clipped, is that signal distorted?
Now, if a mic is clipped (distorted), will the main output be distorted, but not clipped?
Where in the chain does clipping directly affect the tweeter by introducing power above and harmonics (hz) below its capacity?
Channel pre?
Sub-mix bus?
Main bus?
Amp input?
Amp output?
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Where in the chain does clipping directly affect the tweeter by introducing power above and harmonics (hz) below its capacity?
Channel pre?
Sub-mix bus?
Main bus?
Amp input?
Amp output?
All of them.
Anywhere the distortion is created the signal then carries the resultant harmonics with it through all subsequent stages. You can add even more distortion in any of those stages by improper operation also. Nothing removes the clipping-type distortion from a signal and clipping a later stage adds new additional distortion (and does not remove the original clipping and "replace" it.)
And its not that any distortion will automatically result in a blown tweeter, like everything in audio its simply too much level of signal within the tweeter's range that burns it out.
You can blow that tweeter with pristine clear audio and amps not clipping too -if it's more than that tweeter can handle!
Likewise if the tweeter is robust enough you can send clipped audio to it all night long if the resultant audio still falls within it's thermal and mechanical limits.
Blowing tweeters at this level is generally not an inaudible process, You will hear the "magic" distortion-induced harmonics -it will sound louder (raspier and harsher) than normal. So at that point turn it down.
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H
So Perhaps I should ask a slightly different question. Should they have bought something more HF capable, or with a slightly higher crossover point?
Judging loudness by wattage is VERY OFTEN going to result in wrong answers.
Yes, wattage is ONE factor. But sensitivity is another VERY important factor in how loud things can get.
The crossover point of often not a matter of power capacity, but rather how well it mates to the next freq range, and the excursion capability of the driver.
Yes, as you narrow a passband, the power applied (and SPL) will be reduced, but often not as much as you would think.
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They should have bought a bigger better speaker. As an end user buying a powered speaker, you shouldn't care at all where the crossover point is.
Sent from my iPhone using Tapatalk Pro
Agreed.
The only "xover point" that should be of concern is the low freq response, which would give an indication of what the next lowest freq range should do.
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All of them.
Anywhere the distortion is created the signal then carries the resultant harmonics with it through all subsequent stages. You can add even more distortion in any of those stages by improper operation also. Nothing removes the clipping-type distortion from a signal and clipping a later stage adds new additional distortion (and does not remove the original clipping and "replace" it.)
And its not that any distortion will automatically result in a blown tweeter, like everything in audio its simply too much level of signal within the tweeter's range that burns it out.
You can blow that tweeter with pristine clear audio and amps not clipping too -if it's more than that tweeter can handle!
Likewise if the tweeter is robust enough you can send clipped audio to it all night long if the resultant audio still falls within it's thermal and mechanical limits.
Blowing tweeters at this level is generally not an inaudible process, You will hear the "magic" distortion-induced harmonics -it will sound louder (raspier and harsher) than normal. So at that point turn it down.
So a distortion effect on a guitar, not improperly driven, when sent to the powered speaker that is operating under normal (non limiting or clipping) conditions... the tweeter will still receive those lower added harmonics, even though they are well beyond the x-over's filtering, at their full (unfiltered) levels?
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So a distortion effect on a guitar, not improperly driven, when sent to the powered speaker that is operating under normal (non limiting or clipping) conditions... the tweeter will still receive those lower added harmonics, even though they are well beyond the x-over's filtering, at their full (unfiltered) levels?
If distortion, by and of itself, could blow speakers just think of where guitar amps would be today.... see where we're going here?
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If distortion, by and of itself, could blow speakers just think of where guitar amps would be today.... see where we're going here?
I was referring to Craig's response that no matter where distortion occurs, that it is bad for the tweeter. That the harmonics make it passed the x-over, regardless. It was contrary to what I thought, but was giving the opportunity to justify.
Do you want to take a stab at my list of possibilities above?
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I was referring to Craig's response that no matter where distortion occurs, that it is bad for the tweeter. That the harmonics make it passed the x-over, regardless. It was contrary to what I thought, but was giving the opportunity to justify.
Do you want to take a stab at my list of possibilities above?
Distortion is not necessarily clipping, which is a square wave. Realize that clipping the output of a power amp occurs at FULL TILT BOOGIE, while distortion can be at any measurable level.
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Many people do not understand what "distortion" actually is-or what it "adds" to the sound/signal.
Basically distortion is simply added harmonics. Meaning more freq.
It is NOT the additional freq that cause problem.
If that was the case, then you could say that classical music is more damaging than simple rock-because there are more freq there.
Distortion is NOT a knife that cuts through devices, just more freq.
If distortion itself would kill speakers, then just about any guitar or keyboard that is run through a sound system would kill the HF.
How distortion CAN kill speakers is the additional freq "piling up" and causing a higher average voltage applied to the driver-causing it to heat up more.
Of course, simply turning up the level will ALSO apply additional heating to the driver.
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I was referring to Craig's response that no matter where distortion occurs, that it is bad for the tweeter. That the harmonics make it passed the x-over, regardless.
The two things you need to understand is that crossover filters operate on frequency only, the type of signal doesn't matter.
The other thing is that speakers are blown by being overpowering... Period. They also don't care what type of signal you feed them, clean, heavily distorted.. doesn't matter they will try to reproduce all of it and will do it indefinitely as long as the thermal power handling or mechanical excursion limits are not exceeded.
But these two properties(distortion and harmonics) can combine to cause a driver to fail. A distorted signal or clipped amplifier stage will produce a lot more sustained hi frequency content than a high frequency driver would normally see with a clean music signal.. which is fairly dynamic with a relatively low average level, and that is how it ends up being overpowered and that is why overdriving a mixer or amplifier is bad.
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I'm asking the OP here... is that really the case? Do they really want it as loud as it is now at tweeter blowing SPLs or are they just totally clueless about systems operation and are happy with the SPLs after you tweak things and bring the levels under control?
Both! I won't kid you. Its ugly. More education/rule/limits need to be applied.
I personally have been a bass player used to playing with amplified musicians since the late 70s. What I've been doing sounds reasonably right even if I didn't know the precise science (you don't need to know the exact nature of distortion damage if you have headroom and don't allow distortion!).
Its a 20 - 40 piece Rio style samba band even at rehearsals. They are primarily dancers and drummers and top notch at what they do, BUT For these guys, its the first reason they had to be amplified. There was no core knowledge and they've been used to doing it badly for a long time. Fingers everywhere.
"Use the 58."
"What's a 58?"
So the original question wasn't about how to avoid distortion or run clean sound. Just really if there was something fundamentally wrong with the type of equipment for the application. I've been with them for a year or so. Earning a certain amount of respect, so it time to start influencing some changes.
Thanks for all of the replies. Wish me luck. :-\
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The two things you need to understand is that crossover filters operate on frequency only, the type of signal doesn't matter.
The other thing is that speakers are blown by being overpowering... Period. They also don't care what type of signal you feed them, clean, heavily distorted.. doesn't matter they will try to reproduce all of it and will do it indefinitely as long as the thermal power handling or mechanical excursion limits are not exceeded.
But these two properties(distortion and harmonics) can combine to cause a driver to fail. A distorted signal or clipped amplifier stage will produce a lot more sustained hi frequency content than a high frequency driver would normally see with a clean music signal.. which is fairly dynamic with a relatively low average level, and that is how it ends up being overpowered and that is why overdriving a mixer or amplifier is bad.
I will give one more stab at this.
If a guitar pedal adds distortion to the direct channel sound of the guitar, and the output from the mixer is set at a specific amplitude, and the wave form is captured, then sent to the amp and speaker. The affect on the tweeter is "X".
If a guitar (less pedal) is plugged into a channel, can the channel or main bus be over-driven to match the waveform (previously) going to the amp?. Did the affect to the tweeter change? And if it can't duplicate, pretend that it could.
What if the matching waveform is only achieved in the amp's input circuit or the output circuit due to clipping?
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I will give one more stab at this.
If a guitar pedal adds distortion to the direct channel sound of the guitar, and the output from the mixer is set at a specific amplitude, and the wave form is captured, then sent to the amp and speaker. The affect on the tweeter is "X".
If a guitar (less pedal) is plugged into a channel, can the channel or main bus be over-driven to match the waveform (previously) going to the amp?. Did the affect to the tweeter change? And if it can't duplicate, pretend that it could.
What if the matching waveform is only achieved in the amp's input circuit or the output circuit due to clipping?
ANY DIFFERENCE BETWEEN THE INPUT WAVEFORM AND OUTPUT WAVEFORM IS DISTORTION.
Clipping is a form of distortion but not the only form of it, but SUSTAINED AMPLIFIER OUTPUT CLIPPING is bad for speakers because it's happening at the FULL OUTPUT CAPABILITY OF THE AMP.
I don't think I can make that any clearer.
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ANY DIFFERENCE BETWEEN THE INPUT WAVEFORM AND OUTPUT WAVEFORM IS DISTORTION.
And just to add, even a tonal difference or compression or gating or "whatever plug in" IS adding distortion to the original signal.
Because the signal that comes out IS NOT the same as what went in. Therefore it is "distorted" and unlike the original. Hence the name "distortion".
Once again, a term that is commonly used, yet used incorrectly most of the time.
Of course a "clipped signal" (which is what most people refer to as distortion) IS distortion. But you can have distortion with a non clipped signal as well.
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Every answer given has definitely been an answer, and all correct to my understanding. However not an answer to my question.
Maybe this will trigger what I want to know.
Identical systems in identical condition.
#1 - mic preamp overdriven to making the vocal sound fuzzy, bad, distorted, no good, output to amp and speaker where the total energy (adjusted for harmonics and power) to the tweeter is "X".
#2 Mic preamp is clean, output to amp and speaker where the total energy (adjusted for harmonics and power) to the tweeter is also the same as "X" in #1.
Is the distorted signal tweeter stressed more than the other?
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Every answer given has definitely been an answer, and all correct to my understanding. However not an answer to my question.
Maybe this will trigger what I want to know.
Identical systems in identical condition.
#1 - mic preamp overdriven to making the vocal sound fuzzy, bad, distorted, no good, output to amp and speaker where the total energy (adjusted for harmonics and power) to the tweeter is "X".
#2 Mic preamp is clean, output to amp and speaker where the total energy (adjusted for harmonics and power) to the tweeter is also the same as "X" in #1.
Is the distorted signal tweeter stressed more than the other?
This is the best I've seen this question asked. It deserves a thread of its own.
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Is the distorted signal tweeter stressed more than the other?
If both setups were driving the speakers within their RMS & peak power limits there wouldn't be a problem with either.
But if you're "on the edge" I'd say it depends on how you measure "X".
Clean vocals have a good deal of dynamics, distorted vocals have less dynamics.
If "X" is peak power then undistorted vocals would be "safer" material, as their RMS power would be lower than that of distorted vocals.
If "X" is RMS power, then distorted vocals would be "safer" material, as their dynamics are much less than the dynamics of clean vocals and thus their peak power would be lower.
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If both setups were driving the speakers within their RMS & peak power limits there wouldn't be a problem with either.
But if you're "on the edge" I'd say it depends on how you measure "X".
Clean vocals have a good deal of dynamics, distorted vocals have less dynamics.
If "X" is peak power then undistorted vocals would be "safer" material, as their RMS power would be lower than that of distorted vocals.
If "X" is RMS power, then distorted vocals would be "safer" material, as their dynamics are much less than the dynamics of clean vocals and thus their peak power would be lower.
My "equal total energy" requirement eliminates fluctuations and what-ifs (I think) regarding RMS vs peak vs a male or female voice. Lets say the mic is picking up a 5khz sine tone.
One mic is over-driven. The distorted signal gains harmonics, but level is reduced to have equal "energy". Same as the undistorted mic.
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ANY DIFFERENCE BETWEEN THE INPUT WAVEFORM AND OUTPUT WAVEFORM IS DISTORTION.
Clipping is a form of distortion but not the only form of it, but SUSTAINED AMPLIFIER OUTPUT CLIPPING is bad for speakers because it's happening at the FULL OUTPUT CAPABILITY OF THE AMP.
I don't think I can make that any clearer.
Correct on all counts as usual.
Dave,
Those compression drivers are failing because they are being driven past there electrical capabilities, not because of the distortion.
ANY amplifier driven to clipping can and will generate as much as 10x the rated output of the amplifier. And even though this power is generated for moments in time the end result is a destroyed driver in every case. You need to look at the voice coil as if it were a FUSE. The capability of that FUSE is measured by the amount of voltage/current it will handle. Too much generated current and the FUSE faults. Bye, bye voice coil.
Want the speakers to last. Stop driving them into clipping.
From the Mackie manual;
6. LIMIT Indicator
The SR1521z has a built-in limiter that prevents the amplifier outputs from clipping or overdriving the transducers. The LIMIT indicator lights when the limiter is activated. It's okay for the LIMIT indicator to blink occasionally, but if it blinks frequently or lights continuously, turn down the level control until the LIMIT indicator only blinks occasionally.
Max SPL for the cabinet is 127db. Don't expect miracles.
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My "equal total energy" requirement eliminates fluctuations and what-ifs (I think) regarding RMS vs peak vs a male or female voice. Lets say the mic is picking up a 5khz sine tone.
One mic is over-driven. The distorted signal gains harmonics, but level is reduced to have equal "energy". Same as the undistorted mic.
In that case, as long as the "X" is within the speaker's power limits it'll be no problem with either. You could feed pink noise into it and it would be exactly the same.
Think of it this way; The tweeter's diaphragm is just making a movement that corresponds to what sort of signal you feed it.
It doesn't matter what that movement looks like, as long as short & long term power as well as frequency content (high-pass) are kept within certain limits to prevent over-excursion, over-heating and long-term fatigue.
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Here is a good way to think about it.
Speakers die from 2 causes, to much heat over time and overexcursion.
I won't talk about the excursion issue here.
It is ALL about the time AND the level.
Think of it this way. What if I asked you what the maximum temp your body could withstand. Let's call it a "rating"-a nice simple number. You know what happens with "simple numbers".
Most people would say around 120*Fahrenheit. But what if I told you I could easily withstand 1500*F. I can, and can easily prove it any time.
All you have to do is to run your finger through a candle flame.
If you do it fast, you won't burn.
So put a candle on the ground. Hold your hand above it about 6' off of the ground. How long can you hold it without pain?
Now lower it to 3' and the time becomes much shorter.
And so forth.
So it is not just the "power" but ALSO the time the power is applied that is the problem for most loudspeakers.
Peaks are fine, as long as the average level is well below the peak.
When an amplifier is clipped, the peaks are not any higher, but the AVERAGE LEVEL goes up quite a bit, and causes the burning.
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OP/ interested others,
Please take the time to read the documents at the links below;
http://www.jblpro.com/ProductAttachments/spkpwfaq.pdf
http://www.jblpro.com/ProductAttachments/lowpower.pdf
http://www.jblpro.com/ProductAttachments/pssdm_1.pdf
http://www.jblpro.com/ProductAttachments/pssdm_2.pdf
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If a guitar pedal adds distortion to the direct channel sound of the guitar, and the output from the mixer is set at a specific amplitude, and the wave form is captured, then sent to the amp and speaker. The affect on the tweeter is "X".
X = Higher average power dissipation.
If a guitar (less pedal) is plugged into a channel, can the channel or main bus be over-driven to match the waveform (previously) going to the amp?.
Exactly match it? Probably not but will it be close enough to produce a similar result.. yes.
Did the affect to the tweeter change?
Not appreciably.
What if the matching waveform is only achieved in the amp's input circuit or the output circuit due to clipping?
Now you are getting into very dangerous territory. Overdriving an upstream preamp stage can be done without over powering a speaker because there is always another gain control downstream that can adjust for the increased signal level.. this is how guitar amps live to see another day. But over driving a power amp is almost always a guaranteed path to blown speakers because you have no control over the output.
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Now you are getting into very dangerous territory. Overdriving an upstream preamp stage can be done without over powering a speaker because there is always another gain control downstream that can adjust for the increased signal level.. this is how guitar amps live to see another day. But over driving a power amp is almost always a guaranteed path to blown speakers because you have no control over the output.
Actually a lot of guitar amps get their sound from overdriving the output stage, and the compression that comes along with it.
Especially for the LOUD players.
The speakers survive because they are typically only reproducing one instrument-NOT a whole band.
With a full band, there is a lot more energy, even though the peak levels between a guitar and a full band are the same, the average levels would be higher with a full band.
It is the "total power under the curve" that does the heating/damage
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My "equal total energy" requirement eliminates fluctuations and what-ifs (I think) regarding RMS vs peak vs a male or female voice. Lets say the mic is picking up a 5khz sine tone.
One mic is over-driven. The distorted signal gains harmonics, but level is reduced to have equal "energy". Same as the undistorted mic.
Problem is speakers can be blown by any one of several different methods so you can't distill several different scenarios down to one common denominator. Your typical 1" exit compression driver may have a peak power rating of 100w but only a 25w rms rating. A powered speaker like this Mackie has a 100w amplifier feeding the CD, that means this amp has 4 times more power than than this driver can handle in certain situations. That may sound stupid but providing less would really hurt output potential. This works fine with all kinds of music but a sustained tone at the right frequency could melt the driver. People blow tweeters with mic feedback all the time.
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Actually a lot of guitar amps get their sound from overdriving the output stage, and the compression that comes along with it.
OK.. but in that case it is a 15w or 25w amp driving a 50w or 75w driver, and the manufacturer has designed the device to operate this way so maybe it wasn't a good example as it's pretty much the opposite amp/speaker relationship that a PA speaker has.
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Every answer given has definitely been an answer, and all correct to my understanding. However not an answer to my question.
Maybe this will trigger what I want to know.
Identical systems in identical condition.
#1 - mic preamp overdriven to making the vocal sound fuzzy, bad, distorted, no good, output to amp and speaker where the total energy (adjusted for harmonics and power) to the tweeter is "X".
#2 Mic preamp is clean, output to amp and speaker where the total energy (adjusted for harmonics and power) to the tweeter is also the same as "X" in #1.
Is the distorted signal tweeter stressed more than the other?
If they both have the same average power as you imply, they'll be under equal thermal stress. One of the drivers will be producing more frequencies than the other, but with the level adjustments you're making, it'll level out.
Making that level adjustment would be seriously difficult, since the impedance of a speaker varies hugely with frequency. 1w of heating power might be 2.83v at one frequency, and 10v at another. Not impossible, but certainly non-trivial.
ANY amplifier driven to clipping can and will generate as much as 10x the rated output of the amplifier.
Not even close.
The power difference between a pure sine wave and a square wave of the same peak voltage is a factor of two. 3dB.
That assumes, of course, that the power supply can source the extra current required and the rails won't sag.
Chris
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Something else to remember.
The power rating is for a SPECIFIC TIME, with a SPECIFIC WAVEFORM.
As soon as either of these are different, the rating will be different (it could be higher or lower).
It is NOT for 24/7 with any signal you want.
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Not even close.
The power difference between a pure sine wave and a square wave of the same peak voltage is a factor of two. 3dB.
That assumes, of course, that the power supply can source the extra current required and the rails won't sag.
Chris
I know the textbook Chris. I didn't say "does" I said can and will, which can and will be the case in many instances.
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I know the textbook Chris. I didn't say "does" I said can and will, which can and will be the case in many instances.
"Will" sounds pretty "does" to me.
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I think the OP wants to know if all else is equal, will one wave form cause more damage than the other. The answer is, if you add DC content, which some forms of distortion do, then YES. However, when you say "...total energy would be the same", then the same amount of heat and damage to both drivers should occur. You would have to reduce the overdriven signal, (or signal with higher DC content) though, to have the "total energy" equal on both signals.
An audio signal with DC, or direct current, causes a higher amount of heat on drivers (tweeters, woofers, and sub-woofers).
I hope this answers your question.
Sent from my iPad using Tapatalk
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Not even close.
The power difference between a pure sine wave and a square wave of the same peak voltage is a factor of two. 3dB.
That assumes, of course, that the power supply can source the extra current required and the rails won't sag.
Chris
But that is not what bob was talking about.
Yes, you are correct, if the actual signal was a steady state sine wave.
But with clean musical signal, the peaks will be WELL above the average )think 10-20dB).
If you squash that (the peak will stay the same, but the average level will go up), then the actual heating effect to the voice coil could easily be 10-20dB higher than the "clean" average.
I love it when people say "but my amp never peaked", yet they were hitting 20dB of compression the whole time-------------
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I think the OP wants to know if all else is equal, will one wave form cause more damage than the other. The answer is, if you add DC content, which some forms of distortion do, then YES. However, when you say "...total energy would be the same", then the same amount of heat and damage to both drivers should occur. You would have to reduce the overdriven signal, (or signal with higher DC content) though, to have the "total energy" equal on both signals.
An audio signal with DC, or direct current, causes a higher amount of heat on drivers (tweeters, woofers, and sub-woofers).
I hope this answers your question.
Sent from my iPad using Tapatalk
Thank you. You understood the question. It seemed that most had a preconceived question in mind, or just an answer they wanted to give.
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DC content is (usually) filtered out anyway. Well, it's certainly filtered out of the tweeter with a 1300Hz high-pass, it (should) be filtered out of the woofers on a properly designed active cab.
Nobody had a preconceived question in mind, it's just the fact that your question depends on a lot of factors. You first mentioned vocals, then a 5kHz sine wave. It's all VERY different.
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DC content is (usually) filtered out anyway. Well, it's certainly filtered out of the tweeter with a 1300Hz high-pass, it (should) be filtered out of the woofers on a properly designed active cab.
Nobody had a preconceived question in mind, it's just the fact that your question depends on a lot of factors. You first mentioned vocals, then a 5kHz sine wave. It's all VERY different.
DC content is not filtered out quite the way you are visualizing. You must define DC as an unchanging current regardless if it is above or below the 0Volt line. An overdriven guitar signal can have plenty of DC content, because of that unchanging current, specially in square waves, or waves with flat tops, and yet guitar solos are not filtered out by the tweeter's crossover capacitor.
You may have what is called Capacitive Reactance, or Xc, but that does not mean it "filters" the whole wave out.
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But that is not what bob was talking about.
Yes, you are correct, if the actual signal was a steady state sine wave.
But with clean musical signal, the peaks will be WELL above the average )think 10-20dB).
If you squash that (the peak will stay the same, but the average level will go up), then the actual heating effect to the voice coil could easily be 10-20dB higher than the "clean" average.
I love it when people say "but my amp never peaked", yet they were hitting 20dB of compression the whole time-------------
Ivan, I'd invite you to look at the quote again.
ANY amplifier driven to clipping can and will generate as much as 10x the rated output of the amplifier.
If you take the sine wave rating of an amplifier, lets say 500w @8ohm, that's 63v RMS or 89v peak. If you push that up to full square wave clipping, the peak voltage output is the same as the RMS voltage output (by definition of a square wave), resulting in 1000w output into 8ohm.
That is the maximum possible power output from the amplifier. Ever. It's only a factor of two.
Program material and peak-to-average ratios don't come into it - the statement is patently false, and that's the bit I took issue with.
When it comes to the thermal ratings of a speaker, they're usually rated with pink noise clipped to a 6dB peak-to-average ratio, per AES standards. So, a 1000w AES rated driver (6dB p/a) would burn with 500w of sine waves (3dB p/a) or 250w of square waves (0dB p/a). Each signal has the same heating power, but different peak voltages. In theory, you could burn a 1000w rated driver with a 250w amplifier run completely into square waves. That's not the product of an amplifier putting out 4x power, but a result of the test signals used to define a speaker's thermal characteristics.
With regards to DC content, remember we're talking about speakers where each amplifier is assigned to a frequency range and drive unit. If the amplifier is allowed/made to clip, the short-term DC (if you believe in oxymorons) will be delivered to the drivers.
Chris
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Theory is a wonderful thing Chris. Especially Canadian theory based on tiny gigs and home brew cabinets.
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Ivan, I'd invite you to look at the quote again.
If you take the sine wave rating of an amplifier, lets say 500w @8ohm, that's 63v RMS or 89v peak. If you push that up to full square wave clipping, the peak voltage output is the same as the RMS voltage output (by definition of a square wave), resulting in 1000w output into 8ohm.
That is the maximum possible power output from the amplifier. Ever. It's only a factor of two.
Program material and peak-to-average ratios don't come into it - the statement is patently false, and that's the bit I took issue with.
When it comes to the thermal ratings of a speaker, they're usually rated with pink noise clipped to a 6dB peak-to-average ratio, per AES standards. So, a 1000w AES rated driver (6dB p/a) would burn with 500w of sine waves (3dB p/a) or 250w of square waves (0dB p/a). Each signal has the same heating power, but different peak voltages. In theory, you could burn a 1000w rated driver with a 250w amplifier run completely into square waves. That's not the product of an amplifier putting out 4x power, but a result of the test signals used to define a speaker's thermal characteristics.
With regards to DC content, remember we're talking about speakers where each amplifier is assigned to a frequency range and drive unit. If the amplifier is allowed/made to clip, the short-term DC (if you believe in oxymorons) will be delivered to the drivers.
Chris
I think it is a matter of "details" here.
You are correct, the actual power could only go up by a maximum of 3dB . It could be less, due to current limiting.
But will stand my my statement and "assuming" Bobs intention in which the power delivered to the load could go up 10dB (or more) by a musical signal when driven into hard clipping.
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But will stand my my statement and "assuming" Bobs intention in which the power delivered to the load could go up 10dB (or more) by a musical signal when driven into hard clipping.
Fair enough, I'll agree with you on that.
Bob, it's a good job I'm not Canadian then, eh?
Chris
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Canadian logic direct from England. It's an inside joke here in Boston.
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The two things you need to understand is that crossover filters operate on frequency only, the type of signal doesn't matter.
The other thing is that speakers are blown by being overpowering... Period. They also don't care what type of signal you feed them, clean, heavily distorted.. doesn't matter they will try to reproduce all of it and will do it indefinitely as long as the thermal power handling or mechanical excursion limits are not exceeded.
But these two properties(distortion and harmonics) can combine to cause a driver to fail. A distorted signal or clipped amplifier stage will produce a lot more sustained hi frequency content than a high frequency driver would normally see with a clean music signal.. which is fairly dynamic with a relatively low average level, and that is how it ends up being overpowered and that is why overdriving a mixer or amplifier is bad.
I didn't read all the way through the thread (way too long) but this is the correct view to take.
In Most cases distortion is caused by over driving something in the circuit path. When this is done, it tries to go beyond the maximum voltage available to that circuit. The end result is a "clipping" off of he top of the waveform. When this occurs you deliver more average current to the next circuit in the chain and it acts like an ugly compressor or limiter. If it's on the output stage (power amp) of your audio chain, it can "in effect" deliver more average wattage to the speaker driver and cause damage. For instance a 100 watt power amplifier can deliver well over 100 average watts for a while to it's connected load (speaker). If the speaker isn't rated to handle this higher average wattage it can fail. Simple as that. If you're driving a 500 watt rated speaker with an over driven 100 watt amplifier, odds are the amplifier's output stage will fail first.
Simple Rule of thumb. When you see red blinking lights, try and rectify the situation :).
Yes powered speakers are harder to blow up because they have limiters on the power amp's output and the speaker drivers are usually over rated for the amplifiers wattage BUT not impossible. A well designed SR system has amplifier & speaker power ratings matched and limiters in place (either within the amplifier or in a DSP unit). Powered speakers are kinda like SR for dummies BUT if you're dumb enough....... Anything is possible :).
Just my .02
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Canadian logic direct from England. It's an inside joke here in Boston.
Well, in that case, thanks for sharing. I would hate to have missed that.
I gather that you've taken my response to your post personally in some way - certainly from the following quote, which appears to be derogatory towards my business:
Theory is a wonderful thing Chris. Especially Canadian theory based on tiny gigs and home brew cabinets.
Let me assure you that it's not personal. This forum is, in my opinion, one of the best audio-related ones on the internet. In order to maintain that, if I see something that I believe to be false based on my experience and knowledge, I'll pull it up. In a few years, someone that's new to audio might read this and I want to make sure what they read is factual and informative.
However, taking shots at my business isn't acceptable. We all have to start somewhere - I'm in my first year of business (having done freelance work for some years prior), and I've got enough to worry about without someone from Boston making snide comments.
So, I'd kindly invite you to back off and keep the discussion useful and preferably factual. If you've got anything useful to contribute, please do. If you'd like to debate the point, again, please do. Debate is good. Comments like those, not so much.
Chris
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Point being you were given useful information then proceeded to spout theory. You've probably learned quite a bit building your own cabinets and from what I saw you've done a good job. The book does not often contain the real world or complete answer. The complete, or rest of the answer will more likely be passed through experience or the word of others. I'm done, nice job on the cabinets, have fun, play nice.
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Point being you were given useful information then proceeded to spout theory. You've probably learned quite a bit building your own cabinets and from what I saw you've done a good job. The book does not often contain the real world or complete answer. The complete, or rest of the answer will more likely be passed through experience or the word of others. I'm done, nice job on the cabinets, have fun, play nice.
Okay, in that case could you explain how an amplifier will put out 10x it's power ratings when driven to clipping?
The theory says it can't happen, and I've never seen it in practice. Is there something I've missed?
Chris
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Okay, in that case could you explain how an amplifier will put out 10x it's power ratings when driven to clipping?
The theory says it can't happen, and I've never seen it in practice. Is there something I've missed?
Chris
A direct lightning strike to the amp?
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Clipping is loosely defined as the point where the amplifier/power supply can no longer produce output voltage and the resulting signal "clips". In some cases the amplifier power supply will respond with very large voltage spikes prior to "clipping". This is not a common problem with most of todays better made amplifiers, but it can still occur. Another factor is the effect the abuse will have in the production of heat within the circuit. Components fail often with the result of large electrical discharges that are not controlled by any means of protection. This is quite easy to demonstrate in a tube amplifier when plate voltages of 400 or more DC volts are let loose within the circuit destroying components including transformers and speakers. So although it's safe to assume the textbook definition of clipping to be correct, there are many other factors which come to play other than a power supply that runs out of gas.
And I have repaired amplifiers that have taken a direct lightening strike. We won't categorize that as clipping.
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Clipping is loosely defined as the point where the amplifier/power supply can no longer produce output voltage and the resulting signal "clips". In some cases the amplifier power supply will respond with very large voltage spikes prior to "clipping". This is not a common problem with most of todays better made amplifiers, but it can still occur. Another factor is the effect the abuse will have in the production of heat within the circuit. Components fail often with the result of large electrical discharges that are not controlled by any means of protection. This is quite easy to demonstrate in a tube amplifier when plate voltages of 400 or more DC volts are let loose within the circuit destroying components including transformers and speakers. So although it's safe to assume the textbook definition of clipping to be correct, there are many other factors which come to play other than a power supply that runs out of gas.
And I have repaired amplifiers that have taken a direct lightening strike. We won't categorize that as clipping.
Actually clipping is any time the output of any amplifier or device in the signal chain can no longer produce a sinusoidal waveform and the rounded edge of the waveform is "clipped" off and replaced with a square wave.
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A clipped waveform has a higher duty cycle than an unclipped one. Meaning the voice coil is dissipating current for a longer period of time even though the voltage is within the limits expected for a sine wave of X "watts" (the rating of the amp or speaker). Which can burn it out.
FWIW, a guitar speaker has pretty significant mechanical inductance (stiff suspension) as well as pretty decent electrical inductance (large voice coil on some) and so it doesn't do the upper harmonics of a clipping tube guitar amplifier. And thus can tolerate that overdriven sound much more than a HF driver attempting to do it. Hook a tweeter up to something with a basic hard clipping fuzz tone and it will burn out at pretty moderate volumes. Learned the hard way not to play my guitar though the stereo using my tape deck as a fuzz tone. It worked for Richie Blackmore because he was plugged into things with limited HF response.
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Actually clipping is any time the output of any amplifier or device in the signal chain can no longer produce a sinusoidal waveform and the rounded edge of the waveform is "clipped" off and replaced with a square wave.
Most understand that a clipped sign wave has similar properties to a square wave, but is actually not an actual square wave, because of the ramps being sinusoidal. Does this hybrid wave have a technical name?
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Most understand that a clipped sign wave has similar properties to a square wave, but is actually not an actual square wave, because of the ramps being sinusoidal. Does this hybrid wave have a technical name?
Ummmm. Distortion ?
Chris.
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Ummmm. Distortion ?
Chris.
I found this.
"Distortion Wave is a Quantum power that becomes available at Level 22. Release a wave of chronal distortion to damage your enemies. "
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One thing that seems to be missing from this discussion is the relationship between limiting and rated (RMS) power.
Today's amps, and any relatively recent amps, all seem to have rated power that pushes right up against where limiting occurs.
All the spec sheets ive read typically show only a db or so between rated power and power at limiting.
Rating wars I take it.
So definitionally, I'm with Chris...no way an amp can make 10x rated power.
If you want to call rated power something other than RMS, like program or music power, typically at 1/8 rated rms, then sure, 10x works.
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Most understand that a clipped sign wave has similar properties to a square wave, but is actually not an actual square wave, because of the ramps being sinusoidal. Does this hybrid wave have a technical name?
It's just a clipped sine wave.
The more you push it into clipping, the closer it gets to being a square wave.
Chris
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I found this.
"Distortion Wave is a Quantum power that becomes available at Level 22. Release a wave of chronal distortion to damage your enemies. "
Well, it wouldn't mean shit if it only went to 11...........
Prelude to a Klingon Disruptor ?
Chris.
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They are Mackie SR1521s. I completely agree with all the comments about their use. Luckily these are only used for rehearsal
These cabs blow their HF drivers so easily. Mackie used the same HF driver they put in the 450, and crossed them over 300hz lower.
Just look at them funny and they're gone. Mic feedback will take them out every time, and in a rehearsal space ::)
If it's for rehearsal, I'd replace them with a more robust driver and be done with it.
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"Distortion Wave is a Quantum power that becomes available at Level 22. Release a wave of chronal distortion to damage your enemies. "
Sounds plausible.
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So definitionally, I'm with Chris...no way an amp can make 10x rated power.
If you want to call rated power something other than RMS, like program or music power, typically at 1/8 rated rms, then sure, 10x works.
Most amps are spec'd at a given easy frequency like 1kHz and at some percent THD. Typically fractions of a percent. Power is the integration of the area under that waveform. When you try to increase the voltage swing the top of that waveform is constrained by the limits of the amp, but the shape below that broadens out until you have something sorta resembling a square wave. Now the area under the waveform, where the amp is sourcing current and the driver is dissipating it, becomes much larger. Thus the "power" is much greater. Even though the peak voltage hasn't gotten any greater. At some point, something usually gives. Either the amp can't continue to deliver that much power (current over the duration of that waveform) or the speaker's voice coil burns out.
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Most amps are spec'd at a given easy frequency like 1kHz and at some percent THD. Typically fractions of a percent. Power is the integration of the area under that waveform. When you try to increase the voltage swing the top of that waveform is constrained by the limits of the amp, but the shape below that broadens out until you have something sorta resembling a square wave. Now the area under the waveform, where the amp is sourcing current and the driver is dissipating it, becomes much larger. Thus the "power" is much greater. Even though the peak voltage hasn't gotten any greater. At some point, something usually gives. Either the amp can't continue to deliver that much power (current over the duration of that waveform) or the speaker's voice coil burns out.
I dunno Stephen, I really think all the crest factor and waveform shape talk over complicates.
IMO, simple RMS is the integration of power you mention...it's heating power....whatever the waveform.
So it's all the power the amp can potentially output, .....with music, music clipped, sine, or square...doesn't matter.
And specs tell me clipping generally occurs right on top of that rated power.
So for short term, heck even for near instantaneous term, there's not 10x available...
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Most understand that a clipped sign wave has similar properties to a square wave, but is actually not an actual square wave, because of the ramps being sinusoidal. Does this hybrid wave have a technical name?
I'd call it a complex wave form. If the "clipping of a sine wave is severe enough, for most practical purposes it's a square wave (not exactly but the distinction can be a fine one). Sometimes there's a tiny spike at the leading edge of a clipped waveform before the total current draw pulls the voltage back down a bit (depends on circuit design).
Whoever mentioned duty cycle should get kudos. that's exactly what happens. A clipped sinusoidal wave has a longer duty cycle at full available voltage/current making the average MORE than RMS which is derived from a sine wave.