Buffer and highpass combined

[mikee55]

Hi all,can anyone give me a circuit which combines a 12 db highpass at @7hz and acts as an input buffer.I need this as a first stage in a subwoofer circuit,my design uses 8 op-amps and I would like the unit to have a low power consumption and thought combining the above would reduce the demand by 1 op-amp.

 

[Russlk]

This may be what you want?

 

[mikee55]

Cheers Russlk

Thanks.mikee55

 

[Roff]

For 7Hz, you need to change the caps to 100nF.

 

[Nigel Goodwin]

Bear in mind though, this circuit really requires a buffer in front of it, to give it a low impedance feed - but as long as the circuit you feed it from has a low impedance output you should be OK.

 

[mikee55]

Thanks guys

Cheers for the answer

 

[Russlk]

I ran a simulation and the cap values in the circuit are correct. The design program was written 30+ years ago, so I am glad to know it has not had an error that long!

 

[Roff]

I ran a simulation and the cap values in the circuit are correct. The design program was written 30+ years ago, so I am glad to know it has not had an error that long!

What I was pointing out was that he was asking for 7 Hertz cutoff, not 72 Hertz. That's why I said change the caps to 100nF.

 

[mikee55]

Thanks guys

Your help is gratefully appreciated.So can I fabricate a PCB now?
Kind Regards mikee55

 

[Russlk]

Dang! I need new glasses, I could have sworn it was 72 Hz.