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gen0me View Drop Down
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Originally posted by Timebomb Timebomb wrote:

I dont understand what you mean by "Dont calculate crest factor of a bassline/peak. Calculate crest factor bassline/sineWink"
You set up soundsystem so rated power is your 0db level. So this is your level to which you compare. Not peak voltage level which is higher. It is a comparrison of power not voltage.

I wrote sine but in fact it is not exact sqrt(2) factor. You see on K10 spec(126V*sqrt(2)~=178V not 200V)
It will be more like undistored peak to rated power factor.
Originally posted by snowflake snowflake wrote:

"The problem is the more distored and less sine looking bass waveform is - the weaker it is percived on same output."

no, quite the opposite.
Make a track with sinusoidal bass on 0db. Distort it add some compression etc. You will have to bring the levels down so overally bass will be percived more silent.


Edited by gen0me - 12 June 2019 at 8:42pm
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Elliot Thompson View Drop Down
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Originally posted by Timebomb Timebomb wrote:

Originally posted by Tonskulus Tonskulus wrote:


Bass lines can be anything beetween the two. Sine wave is typical starting point but they usually add something to it, like some distortion, harmonics etc to make it sound better.



No,  Basslines in real music pretty much always have a higher crest factor than a sinewave, they are pretty much never between a sine and a square wave, always a high crest factor than a sine.

The tune mentioned that was described as having continual sine wave when actually analysed did not,  it has dynamic, like practically all music.

Can you point me to a tune that features these mythical long drawn out sinewaves?  Ive looked, but never found one..


The track offers a sine wave sweep ranging from 30 Hz to 40 Hz continuously for nearly 5 minutes. You need to use a Spectrum Analyser or a Spectrogram so you can view the frequencies offering the highest amplitude in real time. Opening up the file in Audacity is just  showing you the overall waveform.

Best Regards,




Edited by Elliot Thompson - 12 June 2019 at 9:04pm
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But in the real world no one does any of the above. 
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No RTA or spectrograph will show you if it is a sine wave or not. Again, the waveform used for the bass synth is NOT the output

Perhaps you should consider my history in this business and who I am friends with. It is fairly easy for me to verify this at source, as well as analysing the same way Timebomb is. No mastering engineer, let alone Beau, is going to put out a track with 0dB crest factor sine wave content.

In fact, if you run the same tests through WaveLab you can do both that test, and produce a spectrum plot to see the peaks. It’ll show the same damn thing.

Edited by toastyghost - 12 June 2019 at 10:13pm
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Originally posted by gen0me gen0me wrote:

Originally posted by Timebomb Timebomb wrote:

I dont understand what you mean by "Dont calculate crest factor of a bassline/peak. Calculate crest factor bassline/sineWink"
You set up soundsystem so rated power is your 0db level. So this is your level to which you compare. Not peak voltage level which is higher. It is a comparrison of power not voltage.

I wrote sine but in fact it is not exact sqrt(2) factor. You see on K10 spec(126V*sqrt(2)~=178V not 200V)
It will be more like undistored peak to rated power factor.
Originally posted by snowflake snowflake wrote:

"The problem is the more distored and less sine looking bass waveform is - the weaker it is percived on same output."

no, quite the opposite
Make a track with sinusoidal bass on 0db. Distort it add some compression etc. You will have to bring the levels down so overally bass will be percived more silent.

I am posting music signal crest factors so people can see that music has a higher crest factor than a sine wave,  to look at the crest factor you look at the ratio between peak and RMS voltage of the signal, how dynamic it is in the real world.    
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Timebomb View Drop Down
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Originally posted by Elliot Thompson Elliot Thompson wrote:

Originally posted by Timebomb Timebomb wrote:

Originally posted by Tonskulus Tonskulus wrote:


Bass lines can be anything beetween the two. Sine wave is typical starting point but they usually add something to it, like some distortion, harmonics etc to make it sound better.



No,  Basslines in real music pretty much always have a higher crest factor than a sinewave, they are pretty much never between a sine and a square wave, always a high crest factor than a sine.

The tune mentioned that was described as having continual sine wave when actually analysed did not,  it has dynamic, like practically all music.

Can you point me to a tune that features these mythical long drawn out sinewaves?  Ive looked, but never found one..


The track offers a sine wave sweep ranging from 30 Hz to 40 Hz continuously for nearly 5 minutes. You need to use a Spectrum Analyser or a Spectrogram so you can view the frequencies offering the highest amplitude in real time. Opening up the file in Audacity is just  showing you the overall waveform.

Best Regards,



The 30-40Hz content has a higher crest factor than a sine wave,  its not even close to a continual sine wave, it has dynamics, it is not continual like a sine wave, the level of the 30-40Hz content gos up and down,  it is not a continual sine wave, it has crest factor.

  If you look at it on a spectograh with a slow response time then you might not see the dynamics, you need to look at the actual waveform and analyse it.   
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Elliot Thompson View Drop Down
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Originally posted by toastyghost toastyghost wrote:

No RTA or spectrograph will show you if it is a sine wave or not. Again, the waveform used for the bass synth is NOT the output

Perhaps you should consider my history in this business and who I am friends with. It is fairly easy for me to verify this at source, as well as analysing the same way Timebomb is. No mastering engineer, let alone Beau, is going to put out a track with 0dB crest factor sine wave content.

In fact, if you run the same tests through WaveLab you can do both that test, and produce a spectrum plot to see the peaks. It’ll show the same damn thing.


A Spectrum Analyzer will show you the frequency of the sine wave in the event it offers a continuous output at a particular dB range. Its like hum. The tone resides in the mix continuously in which the Spectrum Analyzer will show you at what frequency the hum is coming from. The FFT window should be no smaller than 32768 (Resolution 2.93 Hz) under 96 kHz or 16384(Resolution 2.93 Hz) if you are using a lower sample rate such as 48 kHz.


I've used Wavelab starting from version 2.0 and stopped at 6. Years ago I used to analyse tracks using Wavelab and, post the graph on Speakerplans when many wanted to view the lowest frequencies offered on a particular track.

Best Regards,  


Edited by Elliot Thompson - 12 June 2019 at 10:57pm
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Elliot Thompson View Drop Down
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Points: 5175 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Elliot Thompson Quote  Post ReplyReply Direct Link To This Post Posted: 12 June 2019 at 11:12pm
Originally posted by Timebomb Timebomb wrote:

Originally posted by Elliot Thompson Elliot Thompson wrote:

Originally posted by Timebomb Timebomb wrote:

Originally posted by Tonskulus Tonskulus wrote:


Bass lines can be anything beetween the two. Sine wave is typical starting point but they usually add something to it, like some distortion, harmonics etc to make it sound better.



No,  Basslines in real music pretty much always have a higher crest factor than a sinewave, they are pretty much never between a sine and a square wave, always a high crest factor than a sine.

The tune mentioned that was described as having continual sine wave when actually analysed did not,  it has dynamic, like practically all music.

Can you point me to a tune that features these mythical long drawn out sinewaves?  Ive looked, but never found one..


The track offers a sine wave sweep ranging from 30 Hz to 40 Hz continuously for nearly 5 minutes. You need to use a Spectrum Analyser or a Spectrogram so you can view the frequencies offering the highest amplitude in real time. Opening up the file in Audacity is just  showing you the overall waveform.

Best Regards,



The 30-40Hz content has a higher crest factor than a sine wave,  its not even close to a continual sine wave, it has dynamics, it is not continual like a sine wave, the level of the 30-40Hz content gos up and down,  it is not a continual sine wave, it has crest factor.

  If you look at it on a spectograh with a slow response time then you might not see the dynamics, you need to look at the actual waveform and analyse it.   


The loudspeaker will see such frequencies as a huge spike sweeping between 30 Hz - 40 Hz since the next octave above 30 - 40 Hz is significantly lower. The loudspeaker will bear the burden under the given scenario no matter how we look at.

Best Regards,

 
Elliot Thompson
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toastyghost View Drop Down
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Whether it’s a spike or not does not change the crest factor of the content. The crest factor of the octave above and up to the HF is closer to 10-15dB so will have a lower RMS voltage (RMS wattage does NOT EXIST) but a much higher peak voltage.

In fact, whilst we are at it, midrange is actually more responsible for voice coil heating than sub in most cases, so long as the DSP is developed correctly based on the cabinet’s impedance plot at small and large signal level.
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Tonskulus View Drop Down
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Originally posted by toastyghost toastyghost wrote:


In fact, whilst we are at it, midrange is actually more responsible for voice coil heating than sub in most cases, so long as the DSP is developed correctly based on the cabinet’s impedance plot at small and large signal level.

Yes, true.. and there is no such cooling effect in midrange speakers (not much cone movement). 

Last summer we had small outdoor (psy)music festival in a forrest. There was two stages and I equipped alternative music stage with two JBL SR4722's and two horn subs. Crossed around 110Hz.  Amplifier for them was 2x700Wrms and it was at full blast up to clipping, two days and 24/7!

I just kept my fingers crossed not to fry those 2206's. I knew they had really hard times keeping the crowd happy and keeping up with bass horns.  They survived and I'm still using them, for smaller gigs tho. Tough drivers those old JBL's indeed.  Enclosures could be better tho.. 









Edited by Tonskulus - 13 June 2019 at 6:42am
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gen0me View Drop Down
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When you calculate the crest factor of voltage, than you assume peak value as point 0db. Which on totally sinusoidal signal takes sqrt(2) surface of constant 0db lvl. Here escapes 3db. If you simplified change it into power P=Urms*Irms=sqrt(2)Upeak*sqrt(2)Ipeak you notice the power is 2 times lower than if you would take for reference voltage on rated power.
Taking peak voltage for reference level is not a reality because you set up amp on rated power. Good amp has peak voltage above the sqrt2 factor. So you always set it on power. Same with speakers. Long term you care only about power.
Originally posted by Timebomb Timebomb wrote:

I am posting music signal crest factors so people can see that music has a higher crest factor than a sine wave,  to look at the crest factor you look at the ratio between peak and RMS voltage of the signal, how dynamic it is in the real world.    
Wink Naturally, but add 3db to see what amp sees.


Edited by gen0me - 13 June 2019 at 10:22am
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The point i was trying to make is that the peak voltage capacity is normally the limiting factor, ie the clip point, so is normally the most important measure of an amplifier, how much voltage swing it can give, how far it can push my drivers, so i calculate from that.  With modern SMPS amps they are rated at max short term RMS voltage, but multiply that by 1.414, or multiply power by 2, it does not make any difference in the end, you can start with peak voltage and work from there, it makes no difference to working from RMS voltage.    

My point makes sense, for a 1700W AES rated driver on a modern SMPS amp i would look for a amp rating somewhere between 1700-3400W,  for old transformer amps they tend to be rated in continual sine, and have burst capacity (voltage headroom) above that,  though most dont tell you how much... Thats the point i was trying to make, that the max voltage is often the limiting factor when playing music not continual sine waves.   


Edited by Timebomb - 13 June 2019 at 10:51am
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