Author Topic: Choosing constant reactance values for LC resonant filter  (Read 860 times)

DAN_000

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Choosing constant reactance values for LC resonant filter
« on: March 01, 2009, 11:44:38 PM »
Like in Pultec or any other LC type filter, there are a constant value of reactance in the resonant frecuency.

Now the question :
If I choose a reactance value of 2500 and F=1KHz , how can I calculate gain(dB) and bandwidht of this filter at this frecuency ?

Thanks !


DAN_000

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Re: Choosing constant reactance values for LC resonant filter
« Reply #1 on: March 02, 2009, 10:30:09 PM »
Bump!

CJ

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Re: Choosing constant reactance values for LC resonant filter
« Reply #2 on: March 03, 2009, 01:58:13 AM »
Just compare the reactance with the other resistive elements that force the signal thru the filter.
If you have a 10K pot and a series reactance of 2500 and 2500, the you have a 5k to 10k ratio.

Bandwidth is just the series resistance of the inductor plus the resistor and or Q pot that is in the circuit.
If I can't fix it, I can fix it so nobody else can!
Frank's- www.mif.pg.gda.pl/homepages/frank/vs.html
Guitar- http://tdsl.duncanamps.com/schematics.php

DAN_000

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Re: Choosing constant reactance values for LC resonant filter
« Reply #3 on: March 03, 2009, 10:51:08 PM »
OK, thanks CJ.   
I made my math with Pultec EQP-1A schemo and got around 10dB in filters. That's ok!.  In this case there is 3.333K to 10K ratio.

But, why around 2000 to 3000 of reactance in Pultec was choosed ? and not lower or higher value ?  ie: xl=25000+xc=25000  and 100K pot (10dB gain too)

Thanks!

CJ

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Re: Choosing constant reactance values for LC resonant filter
« Reply #4 on: March 04, 2009, 12:11:44 AM »
This is where a simulator is a lot of fun.

Do you have one?
If I can't fix it, I can fix it so nobody else can!
Frank's- www.mif.pg.gda.pl/homepages/frank/vs.html
Guitar- http://tdsl.duncanamps.com/schematics.php

DAN_000

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  • Posts: 102
  • Ganimedes
Re: Choosing constant reactance values for LC resonant filter
« Reply #5 on: March 04, 2009, 04:02:23 PM »
No, but I will donwload one simulator tonight and check this.
Thanks CJ !!



 

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