Crossover question

[KJung]

Exactly.

They're manipulating/controlling distortion characteristics to give a pleasing sound. Even a so-called "clean" guitar tone has some degree of this going on. A truly clean guitar sound, like playing one through say a power amp and a 3-way PA type speaker would be pretty bland and lifeless....not musical.

And many would describe the impact of that type of rig on the tone of an EB the same. Just depends on the tone goal of the player.

 

[BurningSkies]

I totally agree.





So then overpowering a driver can clip-it which can harm/damage it so power (Watts) must matter to some degree. So this also means Eminence is right about overpowering, (distortion, clipping) can be harmful to drivers.

I wish an amp engineer “agedhorse” would join this discussion and help explain this amp power/driver relationship.

And I want to thank everyone here who have chipped-in so far, this is really cool.

I don't think that there's any debate that 'overpowering' either by exceeding xmax/xmech or by thermally exceeding the coil's abilities damages speakers. Its the 'underpowering' thing that makes no sense. Really exceeding xmax causes distortion (non-linearity), which may not damage the speaker, but if you exceed xmech you will damage your speakers.

 

[ulynch]

And I want to thank everyone here who have chipped-in so far, this is really cool.

Me too. This is the sort of awesome discussion I come here for. I really want to understand the finer points, and the input of Mr Skies, Mr FM, Mr Reaper and others is invaluable. Thanks all for addressing the issues yet again here. As a layman it's really useful to see it in slightly different contexts, and in response to the questions of other simple folk like me

- D

 

[Joe Louvar]

I don't think that there's any debate that 'overpowering' either by exceeding xmax/xmech or by thermally exceeding the coil's abilities damages speakers. Its the 'underpowering' thing that makes no sense. Really exceeding xmax causes distortion (non-linearity), which may not damage the speaker, but if you exceed xmech you will damage your speakers.

+1
Thanks BS, I agree.

 

[billfitzmaurice]

I don't think that there's any debate that 'overpowering' either by exceeding xmax/xmech or by thermally exceeding the coil's abilities damages speakers. Its the 'underpowering' thing that makes no sense. Really exceeding xmax causes distortion (non-linearity), which may not damage the speaker, but if you exceed xmech you will damage your speakers.

The only thing that can hurt a driver is overpowering. Tweeters can be easily overpowered by a clipped signal, because clipped signals have much higher power density in the highs than clean signals. Low frequencies do not have higher power density with clipped signals, so woofers are not affected by clipping. This is all explained in this JBL document, which is the source of the under-powering myth. As with any too many times in the retelling, which can be only once, the key phrase 'We occasionally hear of JBL owners who damage the high frequency componentsof their loudspeaker system' is ignored. Even people in the industry who should know better, such as Tony at Eminence, are not immune from this critical oversight, let alone the layman.

[Invalid or Expired Link Removed]

 

[KJung]

The only thing that can hurt a driver is overpowering. Tweeters can be easily overpowered by a clipped signal, because clipped signals have much higher power density in the highs than clean signals. Low frequencies do not have higher power density with clipped signals, so woofers are not affected by clipping. This is all explained in this JBL document, which is the source of the under-powering myth. As with any too many times in the retelling, which can be only once, the key phrase 'We occasionally hear of JBL owners who damage the high frequency componentsof their loudspeaker system' is ignored. Even people in the industry who should know better, such as Tony at Eminence, are not immune from this critical oversight, let alone the layman.

[Invalid or Expired Link Removed]

+1 The semantics of this get confusing, since you can blow a tweeter from overpowering it, which is most often due to running a head that does not have enough power for the gig or cab at overly high levels (which many consider 'underpowering' in the larger sense of the word... using not enough power for the context(.

So, with tweeters, it is kind of 'underpowered heads cause overpowering of tweeters' which is enough to make most players' heads explode!

 

[Joe Louvar]

Low frequencies do not have higher power density with clipped signals, so woofers are not affected by clipping

Just to be very clear - is this saying for example (1) or (2)?

1) A 3015lf absolutely can NOT be damaged by clipping or overpowering it with too much power.

2) A 3015lf CAN be harmed by clipping or overpowering it with too much power.

 

[KJung]

Just to be very clear - is this saying for example (1) or (2)?

1) A 3015lf absolutely can NOT be damaged by clipping or overpowering it with too much power.

2) A 3015lf CAN be harmed by clipping or overpowering it with too much power.

Bill can correct me if I'm wrong, but here goes.

Any speaker can be damaged by TOO MUCH POWER if you greatly exceed its thermal power rating over a reasonable period of time.

Clipping has nothing to do with it. 1000 watts of clean power cranked to the max for an hour, clean or not, and you will be in trouble. Of course, all you will hear most likely is a farting mess long before you do the driver any thermal damage, even with the good specs of that LF driver

 

[BurningSkies]

Bill can correct me if I'm wrong, but here goes.

Any speaker can be damaged by TOO MUCH POWER if you greatly exceed its thermal power rating over a reasonable period of time.

Clipping has nothing to do with it. 1000 watts of clean power cranked to the max for an hour, clean or not, and you will be in trouble. Of course, all you will hear most likely is a farting mess long before you do the driver any thermal damage, even with the good specs of that LF driver

Its probably important to note that since the 3015LF has such a large x-max, it makes the difference between xmax and xmech a much smaller thing. Thus if you DO exceed xmax, you're very likely to endanger your speaker. Unlike most speakers where if you're you're exceeding xmax, you've still got 'dirty headroom' before you hit mechanical failure. So, really you're not getting a farting mess 'long before' you do damage.

Most likely, you're not going to harm a 3015LF with clipping because it's not a full range speaker, most people use it crossed over, and the extra energy in the upper ranges will be hitting your high pass and your mid and tweeter.

 

[rpsands]

The 3015lf actually has quite a high xlim iirc. The risk with the 3015lf is more to do with thermal and excursion being do close. But that has been grossly overblown as well

 

[billfitzmaurice]

Bill can correct me if I'm wrong, but here goes.

Any speaker can be damaged by TOO MUCH POWER if you greatly exceed its thermal power rating over a reasonable period of time.

You can toast a driver at considerably less than its thermal rating under the right circumstances, as heat build up in the motor over a long enough period can be just as injurious as a short pulse that's four times the rated maximum. But that scenario tends to apply more to DJ playback systems than musical instrument speakers.

Most likely, you're not going to harm a 3015LF with clipping because it's not a full range speaker, most people use it crossed over, and the extra energy in the upper ranges will be hitting your high pass and your mid and tweeter.

You won't harm a 3015LF or any other woofer with clipped waveforms, and that includes full range guitar drivers that are sent heavily clipped waveforms on a regular basis. Problems occur in the range where tweeters operate, above 4kHz. Normally a tweeter only receives perhaps 5 watts of program in a 100 watt signal. Boost the harmonic content by 10dB, the tweeter gets 50 watts and the tweeter is toast. Send that same 50 watts of harmonic content into a woofer and it's like rain off a duck's back, because the woofer is able to handle 100 watts anyway.

 

[KJung]

You can toast a driver at considerably less than its thermal rating under the right circumstances, as heat build up in the motor over a long enough period can be just as injurious as a short pulse that's four times the rated maximum. But that scenario tends to apply more to DJ playback systems than musical instrument speakers.

That makes sense. I guess that is due to the 'compressed/programmed' nature of that sound source, which doesn't have the 'rests' in it that a live instrument does.

 

[will33]

That makes sense. I guess that is due to the 'compressed/programmed' nature of that sound source, which doesn't have the 'rests' in it that a live instrument does.

Makes sense. Most "finished product" recorded music levels don't stray by more than about 3db where an instrument being played is all over the map. Some exceptions would be movie soundtracks, maybe classical music with all it's dynamics.

 

[Joe Louvar]

Cool - so the following statement is a true and acceptable statement!!!

“A woofer CAN be damaged by overdriving it with too much power.”

Here's another question - if clipping and distortion don’t mean the same thing what is the difference? I’m asking for explained definitions if any?

EDIT:
For simplicity I’m only asking about a 3015lf and not a 15/T (no tweeter) - think basic 101 for dummies and this is in the context of overdriving a woofer (not a fuzz box vs. input clipping).

 

[agedhorse]

Cool - so the following statement is a true and acceptable statement!!!

“A woofer CAN be damaged by overdriving it with too much power.”

Absolutely true.

Here's another question - if clipping and distortion don’t mean the same thing what is the difference? I’m asking for explained definitions if any?

EDIT:
For simplicity I’m only asking about a 3015lf and not a 15/T (no tweeter) - think basic 101 for dummies and this is in the context of overdriving a woofer (not a fuzz box vs. input clipping).

Clipping is one leading form of distortion... they can mean the same thing. Distortion is anything that makes the output waveform different from the input waveform (other than amplitude which is generally accepted as not distortion). There are different kinds of distortion, clipping being perhaps the most common.

 

[Joe Louvar]

Now we’re cooking with gas - thank you agedhorse. So this brings me back to the original question I asked Eminence (questions tie together).

Here is a message I wrote to Eminence about the following -

In your “Understanding Loudspeaker Data” under “Power Handling”
[Invalid or Expired Link Removed] it states “Obviously, you need to choose a loudspeaker that is capable of handling the input power you are going to provide. By the same token, you can destroy a loudspeaker by using too little power.”

Question - is this a writers error? If not please explain how “using too little power can destroy a loudspeaker”? Thank you very much. Joe
---------------------------------
Hi Joe,
This is mostly a statement for pro audio applications. The idea is to provide adequate amp headroom so that you avoid clipping the amp and sending a distorted signal to your speaker. Low power doesn't really harm speakers, but distorted signals will.
Regards

Anthony Lucas | Sr. Lab Tech
Eminence Speaker LLC
P.O. Box 360
838 Mulberry Pike
Eminence, KY 40019

So my question is - are the distorted signals that Anthony from Eminence is referring to above the same as the clipping that BFM is referring to - are they one and the same or different?

EDIT: Oh, and everyone reading this pay no attention to the “too little power” statement thingy - it’s already agreed that is bogus.

 

[billfitzmaurice]

Absolutely true.



Clipping is one leading form of distortion... they can mean the same thing. Distortion is anything that makes the output waveform different from the input waveform (other than amplitude which is generally accepted as not distortion). There are different kinds of distortion, clipping being perhaps the most common.

+1. The most commonly referenced distortion is harmonic distortion, which means the harmonics of the reproduced signal are different than those of the original signal. 1% THD (Total Harmonic Distortion) is considered quite high with an amp, although 10% is considered tolerable with a speaker. A clipped signal in theory can result in 100% THD, though that would be more of a laboratory than real world result.

 

[agedhorse]

Now we’re cooking with gas - thank you agedhorse. So this brings me back to the original question I asked Eminence (questions tie together).

Here is a message I wrote to Eminence about the following -



So my question is - are the distorted signals that Anthony from Eminence is referring to above the same as the clipping that BFM is referring to - are they one and the same or different?

EDIT: Oh, and everyone reading this pay no attention to the “too little power” statement thingy - it’s already agreed that is bogus.

What Anthony is alluding to is the fact that when say a 1000 watt ("RMS") amp is driven hard into clipping, it can deliver as much as 2000 watts in thermal energy (minus power supply sag) as the area under the power curve for a square wave (very hard clipping looks very much like a square wave) is twice that for a sine wave of identical peak amplitude. He just didn't go into the necessary detail required to understand this.

 

[agedhorse]

+1. The most commonly referenced distortion is harmonic distortion, which means the harmonics of the reproduced signal are different than those of the original signal. 1% THD (Total Harmonic Distortion) is considered quite high with an amp, although 10% is considered tolerable with a speaker. A clipped signal in theory can result in 100% THD, though that would be more of a laboratory than real world result.

A signal with 1% THD will contain added harmonics (2nd + 3rd, etc.) that is 1% of the total signal.

Depending on the application, for a pure power amp that is designed for low distortion, 1% wouold be considered "high"... BUT for an amp that's part of a musical instrument amplification system, there may be additional circuitry that intentionally increases or generates musically related harmonics as part of the tonal design goal. Many tube bass and guitar amps and some hybrids fall into this catagory.

I would also like to mention that a very low THD is not always desireable even in a raw power amp. Often, in order to obtain VERY low THD measurements, the circuit topology will contain elements that allow for very high global feedback which "corrects" for non-linearities that result in THD. In many listening tests, the artyifacts from very high global feedback begin to degenerate to response of the amp in ways that are considerably worse than the original distortion components. High feedback also degrades the way an amp sounds and recovers when being driven very hard into and out of clipping and some high feedback amps sound positively awful under these conditions.

 

[walterw]

Unlike most speakers where if you're you're exceeding xmax, you've still got 'dirty headroom' before you hit mechanical failure.

aha!

so "Xmax" is how far the cone can be thrown and still sound clean, and "Xmech" is where it starts to get physically torn apart. is that the same as "Xlim"?