Usage of impedance correction circuit:

Let's assume you have a loudspeaker with 8 Ohm, having its maximum impedance of 16 Ohm at 1000 Hz. The impedance rise is of no importance when a conventional amplifier is being used.

However, if you connect this speaker to a valve amplifier, then this impedance rise leads to an excessive level at 1 kHz. Therefore, this impedance rise should be compensated for in the crossover.

To achieve this a RLC element (pictured below left) should be connected in parallel to the crossover.
The components' values are calculated by entering by entering the following data:
- the nominal impedance of the loudspeaker
- the increased impedance that needs to be corrected
- the frequency where the maximum impedance occurs
- the neighbouring frequency where the impedance drops
exactly to half its value (see below)
 

Impedance correction for a valve amp Resistance to be entered with 2 decimals
Please enter decimal separators as "."
  Nominal
impedance
Maximum
impedance
at
frequency
half the
impedance
at
frequency
Components' values according to circuit diagram below left
   
Copyright © Iris Strassacker, 2003. All rights reserved - Warranty excluded

 
RLC Serial Resonant Circuit Calculator Resistance to be entered with 2 decimals
Please enter decimal separators as "."
Serienschwingkreis Values Impedance in Ohm Rmin of Ohm at Hz
R in Ohm: 100 Hz 120 Hz 150 Hz 200 Hz 250 Hz 300 Hz
  400 Hz 500 Hz 600 Hz 700 Hz 800 Hz 900 Hz
L in mH:
1000 Hz 1200 Hz 1500 Hz 2000 Hz 2500 Hz 3000 Hz
 
C in uF: 4 kHz 5 kHz 6 kHz 7 kHz 8 kHz 9 kHz
  10 kHz 12 kHz 15 kHz 20 kHz 25 kHz 30 kHz
  Note:
Copyright © Iris Strassacker, 2003. All rights reserved - Warranty excluded

Hint: please choose coil and resistance with adequate load-carrying ability.

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