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Consequences of speaker EQing on amp power needed

RayDunzl

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#41
Thank you but I don't understand what you did.
I played a signal consisting of three pure (undistorted) sine wave tones from the PC through the audio gear and JBL speakers and monitored the in-room sound at the listening position with a UMIK-1 microphone and REW software's Real Time Analysis (RTA) display at two different SPL levels, the first is not loud enough to excite much distortion in the speakers, the second, though not excessively loud, is too much for the little LBLs to handle cleanly, in response to your question above.

Where is the signal?
In Audacity.

Three pure tones of increasing frequency, combined into a single signal comprising three pure tones of increasing frequency.

I played the three tracks at the top simultaneously.

I could have played the mix track, just created now so you can see the combined signal.


1557434966852.png


What are the red curve?
Peak SPL (Sound Pressure Level) the microphone received and the RTA displayed for the displayed frequency band.

The current SPL for all frequencies in the band monitored.

In the first video, you see (and hear) three tones, increasing in frequency. Along the bottom is the Noise Floor of the room/measurement system. The Red is a history of the Peak SPL by Frequency for that test sweep.

In the second video, you see (and hear) three tones, along with the smaller tones of Harmonic and Intermodulation Distortion Products the speaker is producing as it exceeds its comfort level, as the three Tones slowly increase in frequency. Again, the Red is a history of the Peak SPL by Frequency of that test sweep.

The Audio portion should enable you to heard the undistorted, and the distorted output of the speakers.
 

daftcombo

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#42
OK I think I understand.

In the second vid, when the 2nd peak (the one in the middle) reaches 300 Hz, there are extra peaks from 400 Hz to 1kHz.
Those are not present in the first video.

Which means that when played at 80 to 90 dB, other frequencies are impacted (400 to 1k, and even a bit under 200 Hz) but not higher. Right?
And no problem at 60 to 70 dB.
 

LTig

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#43
I have a question about distortion.

If I play music loud enough so that a speaker starts to distort at one frequency (let's say 60 Hz), do the other frequencies played at the same time distort as well?
All frequencies transmitted by the distorting chassis will also distort.
Isn't that more likely to happen at the impedance peaks?
Have to think about ......... it may depend on the cause of the distortion:
  • If it's a clipping amplifier then I guess that it is not likely to happen at the impedance peak because here the amplifier sees a lighter load then elsewhere in the frequency range.
  • If the cause is too much excursion then it is possible that it occurs more likely at the impedance peak created by the chassis resonance because the chassis needs less power to create high excursion.
 

daftcombo

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#44
All frequencies transmitted by the distorting chassis will also distort.

Have to think about ......... it may depend on the cause of the distortion:
  • If it's a clipping amplifier then I guess that it is not likely to happen at the impedance peak because here the amplifier sees a lighter load then elsewhere in the frequency range.
  • If the cause is too much excursion then it is possible that it occurs more likely at the impedance peak created by the chassis resonance because the chassis needs less power to create high excursion.
Thanks. Tough one I guess. :)
Experiments would have to be made but your hypothesis seem legit.
 

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