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3 way post #2 - the amp circuit

Posted 9th November 2009 at 08:59 PM by relder
Updated 9th November 2009 at 10:29 PM by relder (Update title)

Here is the basic circuit for the amps. Turn the pot in one direction and it acts like a current source. Turn it the other direction and it behaves like a voltage source -- almost, you still have that 0.5 ohm series resistor there, so output impedance will always be at least that.

It's stable on the bench with a fixed R and with real speakers.

The adjustability will allow me to:
  1. Tone things down at woofer resonance (you'd have a big peak at Fs if driven totally like a current source)
  2. Act somewhat like an adjustable Linkwitz transform for the woofer (around that resonance peak again)
  3. Control phase somewhat (if I recall right there is a 90deg phase change between current and voltage driven)
  4. Adjust frequency response somewhat, depending on the impedance plot
  5. Adjust distortion (less is better but compromises with the above must be made)
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