[Sonido]

I was listening to Never Be The Same by Tritonal and at 1:10 to 1:20 there's an effect that sounds like bass rattling. I tried various headphones and sources and it's always there. With better sources and headphones it's more clear. It sounds like when teenagers blast their crappy car subwoofers and it starts rattling. I think that's clipping? Here's I guess it's digital, but could it damage drivers all the same?

 

[Lindholdt]

To me it sounds like a square wave synth, just a sound effect, that had nothing to do with clipping.
If you don't play it beyond the capabilities of your gear, so extremely loud, it cannot damage your gear.
Amplifier clipping can damage your gear, but that's when it is actually happening in you amp.

 

[gregorio]

I was listening to Never Be The Same by Tritonal and at 1:10 to 1:20 there's an effect that sounds like bass rattling.

Yes, it does sound a bit like that, I’ve heard similar when over-extending consumer subs/bass drivers.

I think that's clipping? Here's I guess it's digital, but could it damage drivers all the same?

No, it’s not digital or any sort of clipping. As @Lindholdt stated, it’s “just a sound effect” and digital clipping can’t damage your drivers anyway, unless you also over-drive your drivers (with your amp). BTW, I can’t tell how they’ve created that sound effect but it doesn’t appear to be a simple square wave.

G

 

[megabigeye]

Yes, it does sound a bit like that, I’ve heard similar when over-extending consumer subs/bass drivers.

No, it’s not digital or any sort of clipping. As @Lindholdt stated, it’s “just a sound effect” and digital clipping can’t damage your drivers anyway, unless you also over-drive your drivers (with your amp). BTW, I can’t tell how they’ve created that sound effect but it doesn’t appear to be a simple square wave.

G

I thought digital clipping could cause damage by asking the drivers to stop and start instantaneously (thus causing the voice coil to overheat, I guess)? Is that not true?

 

[VNandor]

I thought digital clipping could cause damage by asking the drivers to stop and start instantaneously (thus causing the voice coil to overheat, I guess)? Is that not true?

Technically, whenever a signal changes its slope from either positive to negative or from negative to positive, it asks the driver to stop and start immediately, digital clipping is not any different in that sense. This might sound unintuitive but this is how functions and their derivatives work.

The voice coil gets heated up by the electric power that is sent to it. If 1W is sent to the coil, it will ultimately have to dissipate that 1W as heat. It does not matter if this 1W is being delivered as DC, as a 100Hz square wave or as music. If the heat is not transferred, the voice coil will overheat at exactly the same time, no matter how the power is delivered. If the heat is transferred away, an equibrillium will happen at some point, when the generated heat matches the amount of heat being transferred.

The way the power gets delivered (DC/square waves/music) changes the heat transfer part of this equibrillium. If the voice coil is not moving (that is the DC case), the heat will get transferred quite inefficiently. So maybe the voice coil would not get overheated by "1W of music" but it would get overheated by 1W of DC eventually because there's no movement that could transfer some of the heat away. This is something that holds true in practice, voice coils get overheated with DC way more easily than with music.

You might think that the square wave case would be closer to the DC case than to the music, after all, if the square wave gets reproduced ideally, the voice coil will spend no time moving because it changes its position perfectly instantaneously so it would spend no time moving just like in the DC case. However, in practice this isn't really true. The square wave won't get reproduced perfectly and the coil will spend a "considerable" amount of time moving from one position to the other which will cool the coil quite well. The difference is very likely there between square waves and music but you would really have to push the drivers to its limits where it would start to matter. In general if the voice coil can take a certain Vrms music signal, it can also take the same amount of Vrms from a pure square wave. Again I'm not saying this doesn't matter at all, I'm saying that this effect is negligible unless your amp already pushes the limits of the driver.

BTW, I can’t tell how they’ve created that sound effect but it doesn’t appear to be a simple square wave.

To me, it sounds like multiple slightly different saw waves played together to get a unison/chorus effect, that's being filtered then heavily saturated. The unison makes it push the saturation in a rhythmically interesting way and the filtering controls which harmonics are being pushed into it more. Then there's a heavy multiband compressor added to bring back some of the harmonics lost to the unison and filtering so it doesn't feel as hollow.

I was completely blanking on speakers. Clipping caused by the amp can definitely blow the tweeters up because clipping creates plenty of higher harmonics that the tweeter tries (and fails) to reproduce. I don't think digital clipping is that different, except it can't create harmonics above half of the sampling rate so the really high frequencies get folded back below ~20kHz.

 

[gregorio]

I thought digital clipping could cause damage by asking the drivers to stop and start instantaneously (thus causing the voice coil to overheat, I guess)? Is that not true?

I’m not sure where you’re getting that “asking the drivers to stop and start instantaneously“ from. That would only be the case if you sent the drivers a sequence of separate Dirac pulses, not if you’re just clipping a digital audio (music or sound) file. What you get from digital clipping is a spray of harmonics, so an increase in higher frequency content. Theoretically, it would be most likely to damage a tweeter but again, that’s a function of how much you amplify the signal sent to the drivers, rather than digital clipping itself, even extreme digital clipping should have no effect. In fact I’ve done this deliberately, it used to be a common way of creating the sound effect of a rocket (a space craft type of rocket); just take noise (say pink noise) and absolutely jam it into the 0dBFS limit as hard as possible (Eg. Tens of dB over the limit). The result sounds like a sort of “tearing” sound and is virtually indistinguishable from actual recordings of large rockets (like the space shuttle, etc.) during lift-off. No damage at all to the drivers, although obviously the output level of this massively clipped file was reduced. Can’t do that as easily these days, as all DAWs are now floating point.

To me, it sounds like like multiple slightly different saw waves played together to get a unison/chorus effect, that's being filtered then heavily saturated. The unison makes it push the saturation in a rhythmically interesting way and the filtering controls which harmonics are being pushed into it more. Then there's a heavy multiband compressor added to bring back some of the harmonics lost to the unison and filtering so it doesn't feel as hollow.

That’s certainly a possibility but there are numerous ways it could have been done. For example, it could just be a very over-driven resonant filter, post EQ’ed with a side-chained (ducking) compressor. There’s lots of ways this cat could have been skinned and there’s no way to be sure without actually asking the engineers/creators.

G

 

[megabigeye]

I’m not sure where you’re getting that “asking the drivers to stop and start instantaneously“ from. That would only be the case if you sent the drivers a sequence of separate Dirac pulses, not if you’re just clipping a digital audio (music or sound) file. What you get from digital clipping is a spray of harmonics, so an increase in higher frequency content. Theoretically, it would be most likely to damage a tweeter but again, that’s a function of how much you amplify the signal sent to the drivers, rather than digital clipping itself, even extreme digital clipping should have no effect. In fact I’ve done this deliberately, it used to be a common way of creating the sound effect of a rocket (a space craft type of rocket); just take noise (say pink noise) and absolutely jam it into the 0dBFS limit as hard as possible (Eg. Tens of dB over the limit). The result sounds like a sort of “tearing” sound and is virtually indistinguishable from actual recordings of large rockets (like the space shuttle, etc.) during lift-off. No damage at all to the drivers, although obviously the output level of this massively clipped file was reduced. Can’t do that as easily these days, as all DAWs are now floating point.

That’s certainly a possibility but there are numerous ways it could have been done. For example, it could just be a very over-driven resonant filter, post EQ’ed with a side-chained (ducking) compressor. There’s lots of ways this cat could have been skinned and there’s no way to be sure without actually asking the engineers/creators.

G

I'm not sure where I got that idea from either, to be honest. Maybe from reading something about either using Audacity or EQ, neither of which I've used or read about even remotely extensively. Or possibly/probably just my misunderstanding something. Or maybe some nonsense I read here on Head-Fi!

Thanks to both you and @VNandor for explaining it to me. I won't say that I totally understand it, but it's beginning to make some sense to me.

 

[VNandor]

Theoretically, it would be most likely to damage a tweeter but again, that’s a function of how much you amplify the signal sent to the drivers, rather than digital clipping itself, even extreme digital clipping should have no effect. In fact I’ve done this deliberately, it used to be a common way of creating the sound effect of a rocket (a space craft type of rocket); just take noise (say pink noise) and absolutely jam it into the 0dBFS limit as hard as possible (Eg. Tens of dB over the limit). The result sounds like a sort of “tearing” sound and is virtually indistinguishable from actual recordings of large rockets (like the space shuttle, etc.) during lift-off. No damage at all to the drivers, although obviously the output level of this massively clipped file was reduced.

I brought up speakers getting blown by clipping because my father have a pair of old passive 3-way speakers with some old amp as well. The speaker's nominal power handling is 80Wrms and the amp was supposed to output 50Wrms max according to their specs. Despite this, the tweeter consistently got blown out by the amplifier when listening to regular music at not even the max, only near max of the amplifier's output. We eventually replaced the amp that claimed higher output power instead of replacing the tweeters and the new amp never killed the tweeters again. We used the same music with the same output voltage. This happened like 15 years ago, and the speaker is from the early '80s.

If you ever looked at standard home use multi-way floorstanding speakers, it's clear that the tweeter's power handling is not anywhere as high as the woofer's power handling. So while the speaker could very likely take 80Wrms when the signal got played by the woofer, 80Wrms would blow the tweeter in probably mere seconds (I've never actually tried this obviously). When looking for replacement tweeters, the forums recommended 4 to 10W tweeters (for a 80W speaker). The 4W ones were a controversial pick because some people reported that they got blown out while they worked fine for others. We never found out how much the original one was supposed to take but we've found that the crossover had a 4.5kHz cutoff frequency. If I've ever tried to send pink noise with the same average power as with music, it would most definitely kill these speakers' tweeter. The spectrum balance plays a very important role in determining how dangerous a signal is to a multi-way speaker because what matters in this case is the amount of power that the tweeter (as that is the weakest link) has to take which depends both on the overall output level and the spectrum of the signal.

With that said, I tried to both hard and soft clip some music to see how much it affects the frequency balance but I've found that it's basically insignificant so now I'm not sure if it was actually the clipping amplifier that blowed the tweeters.

 

[gregorio]

If you ever looked at standard home use multi-way floorstanding speakers, it's clear that the tweeter's power handling is not anywhere as high as the woofer's power handling.

That’s a general truism of pretty much all speaker systems, not just home use. Live sound systems and cinema sound systems typically have tens or many tens of kilowatts of output power, the vast majority of which is dedicated to the woofers and subs, even though they use horns and the crossovers are much lower than with tweeters.

G