G Pultec change low frequencies

[fatheaddrummer]

Hi Guys,

I would like to build a G Pultec with modified Bass Frequencies....instead of 20, 25, 30. 40, 60, 100 Hz, I would like to have 40, 60, 100, 150, 200, 250 Hz....

Can anyone tell me, which capacitor Values I have to use instead, of those from the G Schematic?

Another Question: Can I simply use 2 Mono Pultecs to drive Stereo? I have no experience with that...if not, what can I do, to make them Stereo? Excuse me, if this question belongs to another threat!


Thank you very much!
Best,
Christian

 

[ruffrecords]

You need to alter the values of the caps connected to S3a and S3b on the schematic shown below. To change the frequencies change the values by the ratio of the old frequency to the new one. So if the old frequency is 20Hz and the new one is 40Hxzthen change the capacitor by the ratio 20/40 or 0.5.

Cheers

Ian

 

[fatheaddrummer]

Hi Ian,

Thank you very much for your Reply!!

I am not sure if I got you right: In the case 20 and 40 Hz, I would have to take the caps value times 0.5? Is that right? Do I have to multiply both caps values?

Thank you very very much!

Best,
Christian

 

[ruffrecords]

Yes, you need to change both the boost and cut capacitors by the same ratio. Boost is S3a and cut is S3b.

Cheers

Ian

 

[fatheaddrummer]

So, if 2u2 and 100n are 20Hz, I have to take 2u2 x 0.5 and 100n x 0.5 to get 40Hz?

Have I got you right?

Thank you very much and excuse the (maybe) stupid question!

Best,
Chris

 

[ruffrecords]

That is right.

Cheers

Ian

 

[fatheaddrummer]

Thank you very much!

 

[Gustav]

Did you check the filters behavior without this modification?

I would recommend you do so, since the curve extends pretty high even at medium cuts/boosts, and you may not find the higher steps as useful as you may think.

Gustav

 

[fatheaddrummer]

No, I dind't have to chance to check it yet ;-/ Good to know, thank you!

chris