Three opamp 24db/oct crossover? - Page 2

vacuphile · 6th February 2012, 08:41 PM

Add a rail splitter and you can do it with quad opamp without getting into complications.

AndrewT · 6th February 2012, 09:11 PM

S3,
I don't need the answers I need the method to determine the answers.

Can you talk me through the 2pole High Pass shown?
C7, C8, R11, R17, R18.

How do you correct the component values for the non zero source impedance and the non infinity load impedance?
How do you arrange for the Q to come out at the desired value?

gruni · 7th February 2012, 08:36 AM

alright i think there is no real solution to this so i will just go with a dedicated rail splitter opamp and leave the quad opamp for crossover

s3tup · 8th February 2012, 08:53 AM

AndrewT, I've spent 2 evenings on the matter

First time i've managed to get the calculations work, but when i've dialed-in the 2nd stage, i always got -6db at filter's Fo. Filter's Q didn't vary much, something between 0.5 and 0.707, maybe 1.

Second time i calculated the transfer function for the circuit, simplified it to the
(s+1)/(s^2+s+1)
form, and then again i've got stuck

I tried to solve the equation for H=2, but got some unrealistic numbers.

I think it's the right time to google for help

6th February 2012, 08:41 PM	#11
vacuphile diyAudio Member Join Date: Apr 2011 Location: Seaside	Add a rail splitter and you can do it with quad opamp without getting into complications. __________________ If my 15 V DC were the radius of the Earth, Mount Everest would be 1 meter tall.

6th February 2012, 09:11 PM	#12
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	S3, I don't need the answers I need the method to determine the answers. Can you talk me through the 2pole High Pass shown? C7, C8, R11, R17, R18. How do you correct the component values for the non zero source impedance and the non infinity load impedance? How do you arrange for the Q to come out at the desired value? __________________ regards Andrew T.

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7th February 2012, 08:36 AM	#13
gruni diyAudio Member Join Date: Feb 2008	alright i think there is no real solution to this so i will just go with a dedicated rail splitter opamp and leave the quad opamp for crossover

8th February 2012, 08:53 AM	#14
s3tup diyAudio Member Join Date: Dec 2004 Location: Israel	AndrewT, I've spent 2 evenings on the matter First time i've managed to get the calculations work, but when i've dialed-in the 2nd stage, i always got -6db at filter's Fo. Filter's Q didn't vary much, something between 0.5 and 0.707, maybe 1. Second time i calculated the transfer function for the circuit, simplified it to the (s+1)/(s^2+s+1) form, and then again i've got stuck I tried to solve the equation for H=2, but got some unrealistic numbers. I think it's the right time to google for help

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