Passive EQ to active EQ

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I want to convert the passive EQ that I am using for my OB speakers to active.

This is the current passive arrangement.

An externally hosted image should be here but it was not working when we last tested it.


Can I just split this into a low pass and high pass filter using the circuits below?

An externally hosted image should be here but it was not working when we last tested it.


An externally hosted image should be here but it was not working when we last tested it.


Or is it more complicated than that?

Also what sets the input impedance of the above circuits and what controls the level of cut?
 
Cascading the two lower circuits will not give the same result as the upper circuit. It will remove low and high frequencies, whereas the upper circuit attenuates a band in mid frequencies.

The simple solution is just to take the first circuit and a buffer on its output.

Why do you want to make it active?
 
Why do you want to make it active?

Mainly to do with impedance matching through the 'chain'.

My new DacKit needs to see a load of at least 10K, then Iwould like to lower mthe values in my attenuator to feed into the buffers (22K input impedance) that preceed the GC amp.

I had a feeling this wasn't as simple as I had hoped :(

Is there an active circuit that does do the same as the passive circuit?
 
Nuuk said:


Mainly to do with impedance matching through the 'chain'.

My new DacKit needs to see a load of at least 10K, then Iwould like to lower mthe values in my attenuator to feed into the buffers (22K input impedance) that preceed the GC amp.

I had a feeling this wasn't as simple as I had hoped :(

Is there an active circuit that does do the same as the passive circuit?


I thought a bit, and came up with this. The upper can be made to have the same response as your circuit (apart from being inverting), but the lower one seems simpler and the component values would be the same as you have now.
 

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What exactly does your current PLLXO do, (asking is easier than getting my brain in gear to calculate frequencies)? :)

Btw, I am hoping, (that in that other project we have already discussed), to do something similar if I can get away with low order crossovers. I see no reason why it should not work, especially with the OPA chips that are designed to work exactly like opamps.
 
Nuuk said:
I had another think about this and wondered about including the EQ, or at least the bass 'lift' in the feedback loop of the inverted Gainclone circuit.

This would save including more opamps in the signal path. Any ideas or comments on this?

Given that you find the right circuit, it would be cheaper, better, simpler. Actually I cannot see any reason not to do it, if you are building the power amp anyway.
 
What exactly does your current PLLXO do, (asking is easier than getting my brain in gear to calculate frequencies)

I know that feeling well Al! I provides a bit of lift at the low end (60 Hz up) to counteract a slightly rising response) and a bit of lift at the top end.

BTW -what is PLLXO?


I hope you realise that there should be a resistor to gnd on the first opamp, and decoupling capacitors for the power etc. You probaly knew this, but just in case...

Yes thanks, I did but it never hurts to make sure. ;)

Given that you find the right circuit, it would be cheaper, better, simpler. Actually I cannot see any reason not to do it, if you are building the power amp anyway.

Thanks again. It always helps to know what the the correct question should be in order to get the correct answer! ;)

I don't know exactly how to do this but I think that I know a man who can :cool:
 
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