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RE: OK, let's try a different angle. It's an AC circuit, right?.

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In Reply to: RE: OK, let's try a different angle. It's an AC circuit, right?. posted by Geoffkait on May 29, 2025 at 08:16:20

Hi
IF you were to measure a sealed box woofer that had the normal flat frequency response, or one in a vented box, or one in free air, you see the impedance curve is not anything like flat, like the SPL.

IT is that impedance that governs how much current is flowing and how much force the VC is producing.
What you can see clearly it the current flowing is nothing like "flat" magnitude BUT the input Voltage IS flat (same V at any frequency) and in the middle of it's range so is the sound pressure. The Voltage is the signal.

It is the Voltage (being flat vs frequency) that produces the flat SPL vs frequency while the current varies wildly vs frequency. Examine the impedance curve shape being upside down, now you have the shape of the current being applied.

The reasons are described earlier in the Back EMF explanation.

However, for an electrostatic speaker it is the Voltage it self and not current that is proportional to force on the radiator.

Follow Ups:

RE: OK, let's try a different angle. It's an AC circuit, right?. - Geoffkait 06:32:49 05/30/25 (2)
I've said repeatedly current doesn't flow, that's a mistaken way to look at this. Current is a calculated number. The only thing "flowing" is free electrons. Back to the drawing boards!
- RE: OK, let's try a different angle. It's an AC circuit, right?. - tomservo 07:09:50 05/30/25 (1)
  Repetition is not the same as validity, the only current I speak of is what one see's when one measures it. One has two tangible views of what the loudspeaker is doing, the aspects of the acoustic output and the impedance.
  
  Your free to see things any way you think makes sense but what i described is a view that lets you build new things, even invent and patent new types of transducers.
  
  If curious, find a copy of "Handbook for Audio Engineers" the 4th edition has some of my inventions but in the 5th edition I wrote the chapter on transducers and wrote it in plain English instead of heavy engineering and deals with all of this.
  - RE: OK, let's try a different angle. It's an AC circuit, right?. - Geoffkait 09:19:11 05/30/25 (0)
    We are definitely not on the same page. You can measure how tall an elephant is but that doesn't tell you anything else about the elephant. People believe what they want to believe about the elephant based on its height.
    
    Edits: 05/30/25 05/30/25

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