Pultec EQP-1S3 filter section

[mg73]

Couldn't find this in any old thread but sure it must been covered before?

Anyone know how the filter section is designed to get that shelving  5k and 10k?

 

[audiogeeks1]

Probably removing the inductor will cause a shelf instead of a bell type boost.

 

[ruffrecords]

Basically the hi boost uses a series LC circuit for the regular boost frequencies. In the two shelf positions I expect they simply switch in a C or RC circuit.

Cheers

Ian