Bottoming out or just clipping the sh.t

[_dontaskwhy 10+ year member]

Like the title says. the flapping noise is it bottoming out or clipping bad. Been playing for about 30 minutes full tilt coming from work. Amp and sub were warm

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[gckless 5,000+ posts]

Lol, sounds like hard bottoming out.

Why are you playing it if it's doing that?????

 

[BoomBoxStereo 10+ year member]

it almost sounds like it's bottoming out, but at the same time it doesn't appear to be from the video. last time i heard that noise it was because of a dustcap issue on my 15, but clearly that isn't the case here.

 

[T3mpest 10+ year member]

Bottoming out. This forum and it's obsession with "clipping" is ridiculous. All clipping is, in a nutshell is an amp putting out maximum power over a longer period of time than intended by the source. The points that were already maximum end up creating higher order distortion at that point, which is just higher frequencies that didn't exist in the original source. So what used to be a pure 40hz wave for example will have 80hz, 160hz, 320hz content in it. Most subwoofers inductance will simply filter out the higher order harmonics so they wont' even be heard. The main damage it causes to a sub is simply by power over time as now when the amp might have only put out max power for 2 seconds before the signal fell, it'll hold max power, even on quiter passages, hence it fries coils.. Regardless clipping isn't inherently dangerous, you could clip the preamp all to hell for example and make the same signal you'd see out of the amp by clipping it all to hell. Only difference now is that waveform would exist at ALL volume levels and get worse if you then clipped the output side too. However, at low volume levels it wouldn't be any more harmful than anything else to a speaker. Again, tweets you'd want to watch it, since those higher order harmonics would add more POWER OVER TIME, which can fry a tweeter...

If you sub is making nasty mechanical noises, it's moving too far in most cases. Yeah, that COULD be clipping the amp, sending the sub moving too far too often, whereas if you weren't clipping you might only bottom out for a split second.. Also, check for air leaks on the box.. It really doesn't seem like the sub is moving all "that" far. Air leaks make nasty noises too or a loose dustcap if your sure it's coming from the subwoofer. Last option would be a broken tinsel lead. If none of those are present, your most likely bottoming out.. But in this case i don't think so for sure as it doesn't move very far, but I've never messed much with Type R's either. Some subs just have loud suspensions and sound like crap if you push the too far.. Somoene with specific type R experience can be more help here, I just wanted to give a brief summary of "clipping" and why it's not an applicable cause here.

 

[_dontaskwhy 10+ year member]

That's the first time I decided to record it playing lol but it's been playing like that for awhile I guess. But only certain songs

 

[Oraclem19]

Almost thought I saw your mounting ring move. Is there CCF or weatherstripping around the underside of the sub? Are all the screws tight? Box looks correctly tuned, in the 30s yes?

Noticed I hadn't looked at my sub for a while and it wasn't playing quite right, look at the thing when I remove it to paint the box and 2 screws had rattled themselves halfway out. Using Hurricane Nuts from now on and loc-tite.

 

[_dontaskwhy 10+ year member]

Naw their isn't a ring on the bottom just speaker and wood. The box more than likely flexing. I've had to add screws before

So what's gone happen eventually if I keep playing it like that

 

---------- Post added at 08:22 PM ---------- Previous post was at 08:22 PM ----------

 

Naw their isn't a ring on the bottom just speaker and wood. The box more than likely flexing. I've had to add screws before

So what's gone happen eventually if I keep playing it like that

 

[_dontaskwhy 10+ year member]

Yea tuned about 32 or close

 

[T3mpest 10+ year member]

Box will bust apart, may cause the sub to unload and damage/break it as well...

 

[_dontaskwhy 10+ year member]

Oh ****. Ill sell it soon to hopefully get a sundown x. Hope it lasts or I thought about sending it to spl

 

[bbeljefe]

Bottoming out. This forum and it's obsession with "clipping" is ridiculous. All clipping is, in a nutshell is an amp putting out maximum power over a longer period of time than intended by the source. The points that were already maximum end up creating higher order distortion at that point, which is just higher frequencies that didn't exist in the original source. So what used to be a pure 40hz wave for example will have 80hz, 160hz, 320hz content in it. Most subwoofers inductance will simply filter out the higher order harmonics so they wont' even be heard. The main damage it causes to a sub is simply by power over time as now when the amp might have only put out max power for 2 seconds before the signal fell, it'll hold max power, even on quiter passages, hence it fries coils.. Regardless clipping isn't inherently dangerous, you could clip the preamp all to hell for example and make the same signal you'd see out of the amp by clipping it all to hell. Only difference now is that waveform would exist at ALL volume levels and get worse if you then clipped the output side too. However, at low volume levels it wouldn't be any more harmful than anything else to a speaker. Again, tweets you'd want to watch it, since those higher order harmonics would add more POWER OVER TIME, which can fry a tweeter...

I get that a clipped sine wave is no problem (electrically) for a preamp signal because the voltage and current in those signals is not moving a motor that generates heat and, consequently, impedance fluctuations. However, I'm a bit confused over your description of clipping as being no problem in the final amplification stage. As I've always understood it, a clipped sine wave becomes a long term DC signal and as such, causes the amplifier to have to stop and hold the coil at an extreme until the distorted portion of the sine wave falls below distortion. And I think it's pretty well accepted that DC current running through an AC motor tends only to dissipate it's energy as heat and thus, coil damage.

Can you help clear up my confusion?

 

[T3mpest 10+ year member]

I get that a clipped sine wave is no problem (electrically) for a preamp signal because the voltage and current in those signals is not moving a motor that generates heat and, consequently, impedance fluctuations. However, I'm a bit confused over your description of clipping as being no problem in the final amplification stage. As I've always understood it, a clipped sine wave becomes a long term DC signal and as such, causes the amplifier to have to stop and hold the coil at an extreme until the distorted portion of the sine wave falls below distortion. And I think it's pretty well accepted that DC current running through an AC motor tends only to dissipate it's energy as heat and thus, coil damage.
Can you help clear up my confusion?

Sure can.. First, don't think of the amplitude of a wave as cone position, think of it purely in terms of acceleration. If you've taken a physics class you know acceleration is velocity over time. It has a direction, so a car can be moving forwards (velocity) while accelerating backwards (slowing down) Speakers behave the same.. At the + peak of the sinewave, which way is the cone moving? Most people would say it's still... WRONG It's moving forward, because that's the direction it was moving a split second before max voltage. All the peak means is you aren't addding any new voltage and will be starting to add less. If you let off the gas does your car stop dead? It's going to continue moving that direction until the force of the suspension and the magnet pulling the other once the signal switches overcomes the speakers forward momentum.. Just after the peak on the way back down, which way is the cone moving.. Again, still forward, until opposing force can pull it the other way, however it is now accelerating backwards as it's moving forward, slower than before, like breaks on a car..... It's accelerating backwards, but moving forwards.. The cone is always moving.. Even if you apply DC, if your suspension was able to travel forever outwards, the cone would keep moving. So your cone is ALWAYS moving. Realize this all happens VERY quickly, 20-80 times per second it will do a full cycle so 40-160 times per second for each half of the wave.. Not alot of time factor at any point, but hopefully this sheds like on what the speaker is really doing with the signal it's given.

Now think of the sine wave signal again realizing the speaker is always moving. The x axis shows time, the Y axis is instantaneous voltage at any given point, right? CORRECT! haha. Anyways, if you want to calculate TOTAL power over time, you'd integrate, using calculus. If you've taken that you know it's simply area under the curve. So with 2 voltage charts, whichever area you could "shade in" more of with a pencil, has more total voltage over time and power applied.. That's where the clipped signal blows speakers. Where a non clipped signal wouldn't be putting out peak voltage, a clipped signal will be, so more power over time. That's not to say it's inherently any more dangeous than a clean signal at higher power however...

So if you clip the preamp signal and run it just under clipping at the output stage you can get the same cone movement by clipping the output stage and having a clean preamp signal.. Advantage would actually be to the clipped output here since it would have less power over time at lower volume levels, where it hasn't clipped yet.. If your going to clip, clip as late as possible in the gain stage. That way it's only amplified once and your not clipping an already clipped signal as that could sound bad at all volumes.

 

[_dontaskwhy 10+ year member]

Sure can.. First, don't think of the amplitude of a wave as cone position, think of it purely in terms of acceleration. If you've taken a physics class you know acceleration is velocity over time. It has a direction, so a car can be moving forwards (velocity) while accelerating backwards (slowing down) Speakers behave the same.. At the + peak of the sinewave, which way is the cone moving? Most people would say it's still... WRONG It's moving forward, because that's the direction it was moving a split second before max voltage. All the peak means is you aren't addding any new voltage and will be starting to add less. If you let off the gas does your car stop dead? It's going to continue moving that direction until the force of the suspension and the magnet pulling the other once the signal switches overcomes the speakers forward momentum.. Just after the peak on the way back down, which way is the cone moving.. Again, still forward, until opposing force can pull it the other way, however it is now accelerating backwards as it's moving forward, slower than before, like breaks on a car..... It's accelerating backwards, but moving forwards.. The cone is always moving.. Even if you apply DC, if your suspension was able to travel forever outwards, the cone would keep moving. So your cone is ALWAYS moving. Realize this all happens VERY quickly, 20-80 times per second it will do a full cycle so 40-160 times per second for each half of the wave.. Not alot of time factor at any point, but hopefully this sheds like on what the speaker is really doing with the signal it's given.
Now think of the sine wave signal again realizing the speaker is always moving. The x axis shows time, the Y axis is instantaneous voltage at any given point, right? CORRECT! haha. Anyways, if you want to calculate TOTAL power over time, you'd integrate, using calculus. If you've taken that you know it's simply area under the curve. So with 2 voltage charts, whichever area you could "shade in" more of with a pencil, has more total voltage over time and power applied.. That's where the clipped signal blows speakers. Where a non clipped signal wouldn't be putting out peak voltage, a clipped signal will be, so more power over time. That's not to say it's inherently any more dangeous than a clean signal at higher power however...

So if you clip the preamp signal and run it just under clipping at the output stage you can get the same cone movement by clipping the output stage and having a clean preamp signal.. Advantage would actually be to the clipped output here since it would have less power over time at lower volume levels, where it hasn't clipped yet.. If your going to clip, clip as late as possible in the gain stage. That way it's only amplified once and your not clipping an already clipped signal as that could sound bad at all volumes.

some good sh.t there

 

[bbeljefe]

I'm not sure why you'd suggest that the sine wave isn't representative of cone position. The principle of loudspeakers is that the cone mimics (as close to exactly as possible) the movement of air which creates a sound wave, so it is indeed representative of cone position. Granted, a driver won't always be in the exact position it's supposed to be but to be sure, that's what we're attempting when we build a sound system.

And again, the peak of a clipped sine forces the amplifier to attempt to hold the speaker cone at an extreme position for an extended period of time, thus creating a dc voltage across the coil and resulting in poor sound quality and excessive wear and tear on the coil and the amplifier. That said, I don't know how you've come to the conclusion that clipping isn't harmful in certain situations. At the very least it is unpleasant to the ear.

I'm also confused here:

"So if you clip the preamp signal and run it just under clipping at the output stage you can get the same cone movement by clipping the output stage and having a clean preamp signal."

Driving a clipped preamp signal at low gain simply means distortion with no damage. When we clip a any signal in the final amplification stage, especially an already dirty one, that's when we do real damage because we're asking the amplifier to produce more power than it's capable of or, perhaps, give the loudspeaker more power than it is capable of handling. So I disagree, you don't get the same cone movement. You get similar cone movement but to an extreme that causes damage to the speaker and or amplifier.

 

[T3mpest 10+ year member]

The waveform off an amp is voltage in respect to time.. If the waveform is tracked exactly in the way your claiming, then displacement of the cone is related DIRECTLY to voltage input as that's what "tracking the waveform" actually mean. Trust me, I believed this too until I really thought about it and confirmed my thoughts, by some very smart people... Anway to disprove that common idea, remember, by doubling frequency and holding voltage at each peak constant we find excursion is lowered by 4x at each peak which throws that right out the window as a 2v peak at 80hz won't drive a speaker as far as a 2v .peak at 40hz. If cone displacement is what your measuring then 4 volts any frequency should produce the same excursion, thankfully for the worlds tweeters, that's NOT what we see in the real world.. In the real world, another basic rule of speakers, just as if you go up an octave (double frequency) your excursion drops by a factor of 4. Thats's why it's acceleration that voltage governs. If you go up in frequency and keep voltage constant, you'd have the same magnitude of acceleration, but over a much shorter time interval for each direction, which reduces cone movement. Cone acceleration is directly related to input voltage however. Acceleration being the key factor explains why these relationships exist as they are offshoots of basic kinematic equations. Lastly, realize that if the waveform tracked like that, you'd have NO ouput at the peak of clipping if the wave was square. Even an approximation would be lowered pressure since the cone would barely move at all at peaks.

Also I've never said clipping is good.. I've only tried to say minor clipping is not bad; a position I stand by 100%. Clipping is hard to hear, especially on a subwoofer for reasons I already explained... The highest even order distortion is filtered by coil inductance in the first place. Combine that with a sheer lack of hearing sensativity at low frequencies. You can clip an amp by several DB, especially if it's only for brief periods in time, and have it be a non issue, both is SQ and speaker reliability.

In the vast majority of setups most arent.using an amp that can overdrive a woofer say 50% above rms.. Most people match power to RMS fairly closely.. In these case minor clipping will sound louder to the ear without damaging anything ib most cases if you have a equally matched sub and amp.. Its all about moderation and the no clipping anywhere philosophy just leads to very quiet soundsystems without extreme amplification or effeciency.

Just for final proof now that I'm off work, HERE is the kinematic equation, as I was blanking earlier lol, hence my edit

D=1/2at^2. That works for all moving objects not approaching the speed of light lol. Distance travelled is 1/2a (where a is acceleration) multiplied by the t^2 (where t is time) Looking at this, if we cut voltage in half (in my world I decided voltage is proportional to acceleration remember) we find the distance also gets cut in half, GREAT works out so far. If you cut voltage in half keeping the signal constant in both frequency, you cut excursion of the cone in half, we all know that. However that also would be true if displacement was all about voltage. Now the "proof" is the other half, if we cut the time in half, which in the world of speakers means doubling frequency (you have to move back and forth 2x as fast, OR another way to say it, MOVE IN HALF THE TIME) we find distance get's cut now by a factor of 4 as the value is squared. Proof that not only do they not pull the old "doubling frequency cuts cone movemenent in half" out of this air, but that the formula that proves it ALSO proved voltage=acceleration.. Not displacement or velocity or any other value that people like to quote..

As an example a=10 t=50

1/2 (10)=5x 50^2 (2500) so 5*2500=12500

now let's cut time in half, so use t=25

5*25^2*25^2=3125.. Care to tell me what 3125x4 is?