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Tuesday, September 19, 2017
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   Parallel Notch Circuit



A good way of looking at this intuitively, is to think of R as dropping the level, and L as shunting the LF's around the level pad, and C as shunting the HF's around the level pad.

These components, including the resistor, will need to be of the highest caliber, in order to not adversely impact the performance of the speaker system.

The resistor R will need to have a dissipation rating that is close to equal to the full rated power of the speaker system, or it could begin to limit dynamics due to heating effects, etc.
Use of less dissipation capacity here is not going to help things at all.

Like wise, the inductor L will need to have a low DCR, just as the normal series woofer inductor, to maintain a low DCR at LF's.
  • DCR = DC Resistant
  • LF = Low Frequency
  • HF = High Frequency
If your speaker is too loud at certain frequencies, this is regarded as irritating.

Therefore you have to use a Notchfilter removing a rise in the frequency response. In the following the frequencies and their damping in dB is indicated when the R-C-L crossover component is fitted.

Please enter the loudspeaker impedance (4, 8, 16 or even higher Ω) and the corresponding correction values (frequency fmax, damping dmax) and adjust the width of the lowered curve with the buttons   -> <-   or   <--->  

To calculate existing Filters, enter the Filter Values (R, C and L), to calculate the Level of damping (dB) from this Filters.

Attention: the calculated level reduction in the frequency response is only correct, if the entered loudspeaker impedance matches the measured value.

At the resonance frequency this is surely not the case; here, the level drop is a lot less severe, since the impedance of the speaker is higher.


It is difficult to establish hard and fast rules for these types of filters, so trial and error play an important part.

Find fmax, the midpoint of the peak, and its magnitude in dB. Also locate the -3dB frequencies f1 and f2

Increasing the value of R will increase the depth or Q of the notch. The L/C ratio creates a fairly narroe filter shape (hight Q) which should work for the most peak situations.

If a wider filter shape is desired use smaller values of C and proportionately langer values of L.
As long as the product of L x C is the same number, the circuit resonance will remain the same but the Bandwidth will change!



Components Parallel Notch Circuit (Dickason) Amplitude Parallel Notch Circuit Impedance Parallel Notch Circuit
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   Components Parallel Notch Circuit

 
Measured Loudspeaker's impedance [ Re ]:  Ω
Notch Filter Calculations:
R =  Ω
L =  mH
C =  µF
 
Bandwidth =  Hz
Resonant frequency =  Hz
Filter Impedanz [ Z ] =  Ω
max. Damping [ At ] =  dB
Phase at fmax =  °
Measured Frequency peak to to reduce [ fmax ]:  Hz
-3dB point below fmax [ f1 ]:  Hz
-3dB point above fmax [ f2 ]:  Hz

 



   Amplitude Parallel Notch Circuit

 
Measured Loudspeaker's impedance [ Re ]:  Ω
Measured Frequency peak to to reduce [ fmax ]:  Hz
Required max. damping [ dmax ]:  dB

 

reduce

expand
 
  calculated fmax Hz   Damping [ At ] :  dB  
 
 
Filter Values: 100 Hz 110 Hz 120 Hz 135 Hz 150 Hz 175 Hz 200 Hz 225 Hz 250 Hz 275 Hz 300 Hz 350 Hz
R: Ω
C: μF
L:  mH

dB dB dB dB dB dB dB dB dB dB dB dB  
400 Hz 450 Hz 500 Hz 550 Hz 600 Hz 650 Hz 700 Hz 750 Hz 800 Hz 850 Hz 900 Hz 950 Hz  
dB dB dB dB dB dB dB dB dB dB dB dB  
  1000 Hz 1100 Hz 1200 Hz 1350 Hz 1500 Hz 1750 Hz 2000 Hz 2250 Hz 2500 Hz 2750 Hz 3000 Hz 3500 Hz  
  dB dB dB dB dB dB dB dB dB dB dB dB  
  4 kHz 4.5 kHz 5 kHz 5.5 kHz 6 kHz 6.5 kHz 7 kHz 7.5 kHz 8 kHz 8.5 kHz 9 kHz 9.5 kHz  
  dB dB dB dB dB dB dB dB dB dB dB dB  
  10 kHz 11 kHz 12 kHz 13.5 kHz 15 kHz 17.5 kHz 20 kHz 22.5 kHz 25 kHz 27.5 kHz 30 kHz  
  dB dB dB dB dB dB dB dB dB dB dB  
   
  To narrow the filter make the coil smaller and increase the condenser with same factor.
To make the filter broader increase the coil and make the condenser smaller with the same factor.





 Impedance Parallel Notch Circuit

 
Values Impedance [Z] in Ω max. Z of  Ω at   Hz  
  calculated resonant frequency :  Hz  
 
 
R in Ω: 100 Hz 110 Hz 120 Hz 135 Hz 150 Hz 175 Hz 200 Hz 225 Hz 250 Hz 275 Hz 300 Hz 350 Hz  
 Ω  Ω  Ω  Ω  Ω  Ω  Ω  Ω  Ω  Ω  Ω  Ω  
  400 Hz 450 Hz 500 Hz 550 Hz 600 Hz 650 Hz 700 Hz 750 Hz 800 Hz 850 Hz 900 Hz 950 Hz  
C in µF:  Ω  Ω  Ω  Ω  Ω  Ω  Ω  Ω  Ω  Ω  Ω  Ω  
1000 Hz 1100 Hz 1200 Hz 1350 Hz 1500 Hz 1750 Hz 2000 Hz 2250 Hz 2500 Hz 2750 Hz 3000 Hz 3500 Hz  
   Ω  Ω  Ω  Ω  Ω  Ω  Ω  Ω  Ω  Ω  Ω  Ω  
L in mH 4 kHz 4.5 kHz 5 kHz 5.5 kHz 6 kHz 6.5 kHz 7 kHz 7.5 kHz 8 kHz 8.5 kHz 9 kHz 9.5 kHz  
   Ω  Ω  Ω  Ω  Ω  Ω  Ω  Ω  Ω  Ω  Ω  Ω  
  10 kHz 11 kHz 12 kHz 13.5 kHz 15 kHz 17.5 kHz 20 kHz 22.5 kHz 25 kHz 27.5 kHz 30 kHz    
 Ω  Ω  Ω  Ω  Ω  Ω  Ω  Ω  Ω  Ω  Ω    
 
  To narrow the filter make the coil smaller and increase the condenser with same factor.
To make the filter broader increase the coil and make the condenser smaller with the same factor.