REDD Rumble Filter

[inf0]

I own a chandler redd47 preamp and there is something about the rumble filter that I can't get from other HP filters.
It sounds like it's somehow adding secondary harmonics to the signal while high passing ( maybe has to do with how it's integrated in the preamp? )
I am still not to the point where I can fully understand the technical aspect of it but I would love to know if there is anyone that knows more about it !

On a side note , having just the rumble filter as a 500 series unit would be perfection

 

[dmp]

I don't know what Chandler did, but the original schematic has the rumble filter before the input transformer. 1.8uF and 3k give a 3dB freq of 30 Hz. Changing the cap or the resistor with a switch would give you other frequencies.

 

[s2udio]

How about a simple parallel jack socket, to plug the filter into !
A whole rumble 500 unit seems a little OTT
Perfection is unobtainium