Neve 1084 Baxandall lo-hi EQ question

[Rogy]

Hi All,

I am playing around with a Neve 1084 clone.

The circuit works fine, but there is a slight gain difference between the lower frequencies and the higher frequencies running thru the lo-hi shelving EQ.

The lo-hi EQ section is Baxandall-style with a single makeup amp. I redrew the schematic, see link below:

https://rogy.spdns.eu/s/asAZ2gZSKzqdfky

All frequencies below say 500Hz come out about 1dB lower in amplitude than all frequencies above 500Hz. This happens with the bands active as well with the bands bypassed (freq switches in pos 1).

My question: Is there a way to manipulate the gain of the low and high section of the Baxandall independently?

Many thanks!

Best regards,

Rogy

 

[radardoug]

The amp of itself will probably be flat, so one of the frequency determining networks is not symetrical.

 

[Tekay]

My Neve 31102 behaved the same way also the old Vintagedesign CA73. Found an old sweep.
It was fixable but I can't remember how :

 

[Rogy]

Hi Tekay,

Yes your graph shows exactly what I am experiencing.

With some fiddling I got the difference as small as 0,5dB; that's about the difference shown in your graph.

Please think hard ;-)

Thanks,

Best Rogy

 

[RuudNL]

Did you try to change the value of the 12K resistor?