EQ order

[bruno2000]

Most EQ section schematics that I have studied have the HPF last in the chain.  Is there a reason for this?
Thanks!
Best,
Bruno2000

 

[gyraf]

No.

HPF (and LPF) usually comes first, in order not to overload following circuit unnecessarily....

Jakob E.

 

[bruno2000]

No.

HPF (and LPF) usually comes first, in order not to overload following circuit unnecessarily....

Jakob E.

Thanks Jacob, that's what I thought, too, but the Harrison, SSL, Neve, all seem to have the filters after the EQ section.  I'd like to see the filters right after the mic pre.
Best,
Bruno2000

 

[sahib]

On our EQ ONE the filters are before the eq.

 

[JohnRoberts]

Most EQ section schematics that I have studied have the HPF last in the chain.  Is there a reason for this?
Thanks!
Best,
Bruno2000

Perhaps to scrub off any accumulated DC errors? Old op amps used to have pretty poor DC performance.

I find it valuable to bandpass the audio path in the front end. Most importantly a LPF to keep out above-band interference that could rectify through slower circuits introducing audible artifacts. An early HPF may improve headroom (if close miking cannon fire or explosions). 

For premium audio paths I generally performed the defining HPF pole with film caps, and made all the other poles using electrolytic caps octaves lower.  I didn't generally put this defining HPF at the last stage, but it didn't go at the very front end either. Somewhere after the signal was already boosted up to line level so I could made this HPF using modest sized film caps and R values.

JR 

 

[L´Andratté]

I think some Audio Developments schematics have the HP-filter even before the transformer to minimize low freq distortion

 

[JohnRoberts]

I think some Audio Developments schematics have the HP-filter even before the transformer to minimize low freq distortion

Transformers are more sensitive to saturation from loud LF content. 



JR

 

[ruffrecords]

The Helio69 EQ has its HPF first.

Cheers

Ian