I thought I would share a project I have been working on for a while. This is a tone control circuit based on the Baxandall circuit.
A few years ago I built a preamp without tone controls and I decided to build a stand alone tone control to go with it. Attached are some pictures.
The circuit uses both halfs of a 12AX7. B+ is about 260V and I used an elevated DC heater supply. Those are the biggest Hammond enclosures in that series, and space is limited. I ran some frequency plots on an old Sound Technology unit, but I have no way to export the data (and I have no time to manualy graph them in excel). Response is relatively flat when in the circuit and noise floor is low. Distortion is low with a standard 2 volt signal.
Attached are pictures of the insides and then a picture of the units in my system. The front left is the preamp, the right is the tone control and then the unit in the rear is a re-packaged Bottlehead Seduction phono preamp.
Dave