Pultec EQ1PA 40HZ filter

[muffy1975]

Hi there,

does anyone know how to implement a 40hz filter on the classic pultec circuit? And a good place to put it in the circuit. There must be a number of places.

I was looking at the helios eq which has a 40hz filter but it's a different kind of amp.

I've included the filter and amp schematics if anyone would be kind enough to point out where a cap/resistor combo might go?

regards

Michael

 

[muffy1975]

the filter section.....

 

[ruffrecords]

What sort of 40Hz filter do you want - high pass??

Cheers

Ian

 

[ruffrecords]

Hi Michael,

I cannot seem to find the retro on the net. Can you post a link? - might give me an idea of how they did it.


And, yes thanks, I am fully recovered from my skin caner operations!!

Cheers

Ian

 

[emrr]

6dB? 12dB? 18dB? etc

 

[emrr]

I don't see a hpf option on that piece.

 

[kosi]

Right in the middle above the power switch, you see it in the 4th detail pic.

Subsonic Filter, Off, 40Hz and 90Hz

 

[emrr]

So it is....

 

[ruffrecords]

The only clue I can find to the way it works is in this snippet from their web page:

"Utilizing the interstage transformer, the filter not only reduces the subsonic energy but also provides distinct transformer tonal characteristics for tracking and mixing. The filter has settings of 40 and 90 Hz with a peaking response and sharp cutoff."

Cheers

ian