DiyMobileAudio.com Car Stereo Forum banner

121 - 140 of 172 Posts

·
Registered
Joined
·
5,232 Posts
If the coil is truly pausing at each end of stroke, to produce the same number of cycles per second it's going to have to move quicker to afford the time to pause at the ends. I have no idea if the coil really pauses and I'm not going to guess. But if it does, this might support those that say clipping can mechanically damage a sub. Then again I can't imagine this being any harder mechanically or maybe even thermally on a sealed sub than a ported sub that has higher stress and nearly stops moving near tuning frequency with a clean signal.

I hope with my subs being in plain sight in the cabin I would hear some kind of distortion before it's too late. I don't know why but my amp has never shut down from long deep bass notes, it's the quick punch that has made them shut down for a few seconds.

This is probably a dumb question and not related but does clipping affect class D amps with feedback differently, will they go into protect when or before clipping occurs?
 

·
Banned
Joined
·
4,394 Posts
if I had to guess, I'd say that the dynamic pulse initiated by the quick punch, is going to put a condition on the circuit that if continued, would cause the amp to break.

so the person who engineered the protection circuit, programmed the response to that end, and the long bass notes do not engage the peak limiter, and so do not require the amp to shut down. In that case, the temperature protection circuit will have to suffice, because the amp isn't in a fail mode at any point until it reaches critical temps.

I know it seems like there's a mountain of evidence and people saying that clipping doesn't harm speakers, but I have personal observations and experience, backed up with the conjecture.

And if you go back to the old reviews in magazines, you see some magazines doing impulse testing of tweeters using over a thousand watts!

Clean, unsaturated, unclipped watts.

now, that's not "power over time" and something else, but it's also an indicator that if speakers fail when amps clip, it's not "power" itself that is the problem. It's something else.
 

·
Registered
Joined
·
4,941 Posts
It's common knowledge that a speaker can handle very high power input during short bursts, talking milliseconds here. Dynaudio even rates this in their specs.

Power is all that matters, if a speaker handles 100Wrms it shall handle 100Wrms of power CONTINUOUS. This is nothing but a thermal power rating and nothing about the waveform it's fed with. Clipped signals contain MORE POWER than a sine wave, a pure square wave contain 1,414x the power of a pure sinewave, i.e twice the voltage. U²/R=Power, this means that 1,414 times the voltage is twice the power...

ALSO, a severely clipped signal WILL CAUSE less cooling of the VC which means any speaker is likely to fail quicker if OVERPOWERED with a clipped signal than a sine wave.

Why Too Little Power will NOT blow Your Speakers
 

·
Banned
Joined
·
4,394 Posts
power ratings are variable, each manufacturer has a standard and then there's CEA 2006, I guess.

but speaker power ratings are still unreliable, Pioneer and JBL and JL all severely under-rate their speaker's ability to absorb short term, continuous power but then, they also add a dynamic rating that is closer to the signal that a musical input provides.

and I guess my inductor thing isn't going over too well, haha...

oh well.
 

·
Registered
Joined
·
4,941 Posts
but speaker power ratings are still unreliable, Pioneer and JBL and JL all severely under-rate their speaker's ability to absorb short term, continuous power but then, they also add a dynamic rating that is closer to the signal that a musical input provides.
Yeah... Manufacturers specs are severely off sometimes. I remember measuring a TangBand w3-871 8ohm speaker which was specced at 15Wrms continuous. Had it playing a 1kHz tone to calibrate SPL, when I fed it about 2,9-3 volts the VC started to give off that nasty white smoke. 3*3/8 ~ 1,1W. This was like 30sec after I applied the signal. Just like T/S parameters, I treat those specs as BS most of the time. Some manufacturers like Scan Speak, Seas and a few others are pretty reliable though.
 

·
Banned
Joined
·
4,394 Posts
Yeah... Manufacturers specs are severely off sometimes. I remember measuring a TangBand w3-871 8ohm speaker which was specced at 15Wrms continuous. Had it playing a 1kHz tone to calibrate SPL, when I fed it about 2,9-3 volts the VC started to give off that nasty white smoke. 3*3/8 ~ 1,1W. This was like 30sec after I applied the signal. Just like T/S parameters, I treat those specs as BS most of the time. Some manufacturers like Scan Speak, Seas and a few others are pretty reliable though.
HAHA..


so, those Scandinavian companies pass muster, heh..

:D

but that poor Taiwanese buildhouse can't make weight, hahaha...
 

·
Registered
Joined
·
5,232 Posts
It seems like most of the higher end speakers end up pretty close to TS specs and xmax while many of the lesser speakers outright lie about most parameters, especially xmax. That's not always the case obviously but more often than not.

I like the Dyn 10ms power rating. I think of this as the amount of power it takes to open a voice coil nearly instantly. I was going to say that I'm feeding my midbass a lot more power than they're rated for but with 300w available for each one I'm obviously below the short term power handling and I don't imagine I'm past the 180w long term by much if at all a d of course that's only at full tilt. I have had the bridged 600/4 shut off a few times on loud passages so assuming a good installation I dont know if that means I've tried to exceed the 600w continuous rating or if there's even more power getting to the midbass. Regardless I'll probably add more power in the future to the midbass and mids. Maybe a 750/1 on each midbass and bridge a 600/4 on the mids.
 

·
Registered
Joined
·
679 Posts
normalized power conditions.

when an amp is clipping, it's not just making square waves.

when the toroid saturates, it pushes a lot of nasty high frequency energy through the transistors, along with your solid square wave content.

this high frequency energy is not accounted for, when you've "normalized" the circuit for non-clipping operation.

that's one thing.
And that would apply additional POWER to the coil. That is not what you were discussing. You were talking about waveform.

the other thing, is that even if the coil "appears" to not be static, you don't have the quickness of eye, to determine if the coil is or isn't being static, or held over longer periods at that periodic interval of a square wave.

the straight across power delivery into the coil during the square wave, means over time there is uneven power distribution, that has to be perfectly clear...

you have to look past the acoustic time interval, and look at the electrical time interval.

overshoot and ringing THD should, actually help, if your position is that the coil is never in a static condition.

I believe that the coil may dwell longer in that static condition than what's intuitive, because you're getting a pseudo-sine wave output registering on a microphone, when the electrical input to the coil is actually a square wave.
And if this "dwell time" was enough to significantly affect cooling, then the squarewave would have caused the driver to fail sooner. It did not. Hypothesis disproven. Power, not waveform, is the culprit.
 

·
Banned
Joined
·
4,394 Posts
And that would apply additional POWER to the coil. That is not what you were discussing. You were talking about waveform.



And if this "dwell time" was enough to significantly affect cooling, then the squarewave would have caused the driver to fail sooner. It did not. Hypothesis disproven. Power, not waveform, is the culprit.
actually I was talking about clipping, and waveform was a result of that.

the square wave may not be damaging by itself, (although I can remember a while back in a magazine article long ago and far away, one testing lab stating this exact point, square waves are damaging in and of themselves) but when it's in the context of clipping, the combination of out-of-band energy in concert with the square wave's deleterious effects, is enough to create dead speaker syndrome.

Hypothesis still alive, and kicking...!
 

·
Registered
Joined
·
393 Posts
check this out:

I have recently been inducted into the queue of induction plate cooking.

(hah!)

so, let's remember that power in, doesn't equal acoustic power out.

and that a voice coil is an inductor that you put electricity into.

the efficiency of that coil to transfer the electrical energy to acoustic energy is somewhat less than 5% for even some of the best drivers.

that means that 95% of that energy is dissipated as heat.

now, let's enter the induction cooker theory.

that coil, is going to be releasing 95% of it's energy in some way, through heat.

I propose, that when a speaker is "stuck" in the clipped waveform, it's spending a lot more time in that one area at the top and the bottom of the waveform, and that's where the heat is being inductively coupled to the pole piece and top plate gap.

the coil is acting like an induction stove's coil, it's heating up the surrounding ferrous metal parts that are activated by the induction energy transfer.

so, when it's moving normally the coil distributes the inductive energy more or less, evenly.

when it's clipping, it's distributing the energy at the top and bottom of the coil's travel, over a longer time period, which leads to those places getting more energy than before, without clipping.


so, as the surrounding structures heat up, this also raises the temperature of the coil itself, causing the glues to soften, the former to warp, the copper itself to expand and delaminate from the former.

all signs of heat damage, that is the result of clipping energy being distributed unevenly by the induction process at the top and bottom of the waveform.

how's that for blow your mind?


haha.


that 95% of energy, in watts going someplace, means that it's no joke that a motor needs to dissipate heat, and motors that can't shed heat will fail.


maybe someone can disprove this hypothesis, but I think we're on a track now...
Wise words!
I believe this is the best and most likely explanation of why clipping hurts.
Cajunner I think your def. on the right track her!

Regarding manf. specs:
Some manf. simply dont public any specs, some lie and overrate their products and some underate. Personally I prefer to deal with the underrating manufacturers!
 

·
Registered
Joined
·
17 Posts
Bottom line... why would you want to send a clipped signal into a speaker??? I do agree that you should set a system and get every drop of power... I do agree that clipping won't lead to global warming... its not that big of deal, to most of us that really understand what we are doing.... BUT to the below average person in car audio that isn't educated that turns it up all the way, just cause he can.... Will torch more speaker due to lower power higher distortion..... So is it the distortion or clipped brain cells... I personaly have NEVER blown a speaker or even a fuse in one of my systems....
 

·
Registered
Joined
·
393 Posts
Well honestly I do not understand the "max it until it clips or overheat" mentality that seems to rule here on diymobile...
Personally I prefer a lot of headroom, what ever happened to the old "never above 12 a clock" (50%) volume on the amps mentality??
The power specs of amps makes it quite clear that amps have more distortion when they are loaded down to maximize power output, so for SQ I think its better to get a "overpowered" amp instead of "trying to utilize 100%" of a smaller amp.
Am I missing something here??
 

·
Registered
Joined
·
2,230 Posts
Well honestly I do not understand the "max it until it clips or overheat" mentality that seems to rule here on diymobile...
Personally I prefer a lot of headroom, what ever happened to the old "never above 12 a clock" (50%) volume on the amps mentality??
The power specs of amps makes it quite clear that amps have more distortion when they are loaded down to maximize power output, so for SQ I think its better to get a "overpowered" amp instead of "trying to utilize 100%" of a smaller amp.
Am I missing something here??
To me it seems like more people agree with you than disagree. Just read some of the build logs and you'll see people putting 200+ watts to tweeters. I, on the other hand, would rather save some money and only spend on an amp that puts out the power that I'm going to use rather than power that will forever sit there untapped.
 

·
Banned
Joined
·
4,394 Posts
Well honestly I do not understand the "max it until it clips or overheat" mentality that seems to rule here on diymobile...
Personally I prefer a lot of headroom, what ever happened to the old "never above 12 a clock" (50%) volume on the amps mentality??
The power specs of amps makes it quite clear that amps have more distortion when they are loaded down to maximize power output, so for SQ I think its better to get a "overpowered" amp instead of "trying to utilize 100%" of a smaller amp.
Am I missing something here??
it's because there is no old "never above 12 o'clock" analogous to gain, as each amplifier has a different ratio of min to max gain.

one amp could adjust from 250mV to 3V, and another amp could adjust from 100mV to 1V, and another amp could go from 2V to 16V.

in home audio, there are common standards that cap the line level voltages and input/output impedances, to ensure most consumer product is able to work with each other.

in car audio, the gain at 12 o'clock could be 500mV on one amp, and 2V on another. That's a huge swing.

and on source units, the same problem exists!


so it's important to remember that a system that is maximized for gain, will have the source unit push as much undistorted voltage to the next component in line to meet it's S/N ratio specs.

an issue of late, is overdriving the inputs to digital processing units. Another wrinkle the home audio industry has seemingly ironed out, because of their adoption of standards.


If a deck can put 3V undistorted into an amp designed to max out at 2V, (like most old school amps) then you will certainly be able to drive that amp into clipping on occasion. Drive a DSP with that 3V, one that only takes 2V, and you can cause some serious issues with your system.

Anyways, I remember my old Technics receiver from 1982 or so having the ability to only use 50% of it's volume knob's range, (tone controls set to flat) and when I connected an equalizer to it with the smiley face curves, it would go about 4 detents to listening level, and 6 detents to distorted output, on a 32 click knob?
 

·
Registered
Joined
·
393 Posts
Regarding S/N and amp gains...
I have been thinking about adjusting my gains.
Before I reconfigured the amps my system would play "very loud" when the 80prs was only at 30 so I never had any need or desire to turn it up more than about 35 or so...
After I reconfigured the amps I need to turn the volume a little higher to like max 40 to match the previous volume at 35.
But the 80-prs goes to like 62 (or is it only 52?) so I realise i'm not getting anywhere near 5v on the rca outputs does this hurt the SQ of my system?
I don't wanna turn the dial 4 turns just to reach normal volume if I don't have to. normal volume at 25 would suit me best.

Do you think I would improve the sound if I lower my gains to get higher voltage from the RCAs?
 

·
Registered
Joined
·
4,941 Posts
Gains should be set correctly. There's no golden "only use half of the output" rule. You'll have headroom by having enough power output from the amplifier at the level you like listening at. Reducing gains to the point where's there no clipping at all will only reduce the output capability of the system, if you don't have enough power and don't wanna allow any clipping the system will most likely not be especially loud. No music is recorded at 0dBFS anyway so it's simply redundant to be so conservatory with the gain knob. Use a -10dB sine tone together with a scope or use your ears.
 

·
Registered
Joined
·
4,941 Posts
Regarding S/N and amp gains...
I have been thinking about adjusting my gains.
Before I reconfigured the amps my system would play "very loud" when the 80prs was only at 30 so I never had any need or desire to turn it up more than about 35 or so...
After I reconfigured the amps I need to turn the volume a little higher to like max 40 to match the previous volume at 35.
But the 80-prs goes to like 62 (or is it only 52?) so I realise i'm not getting anywhere near 5v on the rca outputs does this hurt the SQ of my system?
I don't wanna turn the dial 4 turns just to reach normal volume if I don't have to. normal volume at 25 would suit me best.

Do you think I would improve the sound if I lower my gains to get higher voltage from the RCAs?
I tend to lower the gains on my tweeter/midranges amp so my headunit outputs higher voltage to the DSP. I only do so because I have enough power AND because of the improved SNR (outside noise).

62 is max at my p99rs. Very loud usually lies around 50-55 in my setup, whilst normal listening volume usually lies around 40-45. I don't think the volume knob/preout voltage got "linear" increments either. It feels like it boosts the signal more around 58-62. Unless you running sine tones at 0dBFS and have the volume knob at maximum, most headunits outputs much less voltage than the specced one on a average/continuous basis.
 

·
Registered
Joined
·
393 Posts
To me it seems like more people agree with you than disagree. Just read some of the build logs and you'll see people putting 200+ watts to tweeters. I, on the other hand, would rather save some money and only spend on an amp that puts out the power that I'm going to use rather than power that will forever sit there untapped.
I guess thats the difference between SQ and SPL...
But your nick is golden ear? If you use all the power from you amp it will have lots of distortion, how can someone with a golden ear stand that?
I would rather listen at half the volume with near zero distortion and no power compression etc. than have my hearing damaged from the high spl and distortion from an amp at full power...
And these days you can get great amps dirt cheap, just find the old proven sq amps used!
I have just sold a Ground Zero titanium 1200w amp...
[email protected] 10% distortion!! It may be 1200w and 1 ohm stable but the distortion is 10%!! No thank you not for me!
@1000w the distortion is "only" 1%! Would you also try to max your amp if you knew for sure it behaved the same way?
And how different do your amp behave at full power??

Maybe I'm just old...
 

·
Registered
Joined
·
393 Posts
Gains should be set correctly. There's no golden "only use half of the output" rule. You'll have headroom by having enough power output from the amplifier at the level you like listening at. Reducing gains to the point where's there no clipping at all will only reduce the output capability of the system, if you don't have enough power and don't wanna allow any clipping the system will most likely not be especially loud. No music is recorded at 0dBFS anyway so it's simply redundant to be so conservatory with the gain knob. Use a -10dB sine tone together with a scope or use your ears.
The part about: "No music is recorded at 0dBFS anyway" is becoming outdated. Try google the loudness war :)

I really don't care horseshit if my system clips above 45 because I nor anyone I know will never play it that loud. So if i'm not losing real world SQ (volume corrected blind test anyone?) I will keep my gains so that I do not have to turn the knob 2-3 turns just for normal volume.
 

·
Registered
Joined
·
393 Posts
I tend to lower the gains on my tweeter/midranges amp so my headunit outputs higher voltage to the DSP. I only do so because I have enough power AND because of the improved SNR (outside noise).

62 is max at my p99rs. Very loud usually lies around 50-55 in my setup, whilst normal listening volume usually lies around 40-45. I don't think the volume knob/preout voltage got "linear" increments either. It feels like it boosts the signal more around 58-62. Unless you running sine tones at 0dBFS and have the volume knob at maximum, most headunits outputs much less voltage than the specced one on a average/continuous basis.
I think a linear volume knob would be awkward to operate...

But can you actually hear any difference in sq due to the higher SNR at the lower gain setting? Isnt SNR so high on modern hifi that its way below what a human can actually hear anyway??
 
121 - 140 of 172 Posts
Top