Pultec filter LF variation

[simonsez]

Hello guys, I'm just finished my pultec eq with slow blowie preamp make up gain. It's works good. But now i thing i need some more range for LF freq. boost/cut (still with 4 pos rotary sw). My idea is adding switch and few relays to multiply LF freq. by 3. So 20Hz became 60Hz, 30Hz ==>90Hz, and so on. My first (raw?)thought is just dividing all cap in the LF freq. by 3 like in the pic below. But I need confirmation, Is it can work? Thank you ....

 

[abbey road d enfer]

I've done a quick sim of your mods, it seems to work ok. Now I don't know about the interaction between LF when the highest frequency is selected and the midrange control. Should be interesting...
I suggest you get LTSpice from the Linear Technology website. It is free and very good.

 

[simonsez]

Thanks Abbey, I've done adding "3x" LF toggle switch. It's work, but i don't know the exact freq multiplying by that mod. It's ok for now...And thanks for the suggestion too, I will get it...now