JFET Treble Booster


This treble booster is simply the Two-Stage JFET Preamp/Booster circuit with a tone control placed between the two JFET stages. The values for Rd and Rs for both stages are based on the characteristics of the 2N5457 JFET model I used in Multisim, and the values you should use for real JFETS will depend on each individual JFET. C2, R8, and C1 form a high-pass filter. C6 provides a way to bypass this filter. R9 allows one to adjust the amount of bass cut. 

With maximum cut, this circuit in simulation had the following frequency response: (23.4 dB at about 4.8 kHz and -4.5 dB at about 32 Hz)


And with no bass cut, we actually have a bit of a bass boost:


The output voltage of this circuit should be about 16 Vpp, which might be a bit much for boosting solid state amplifiers or pedals, but it's great in front of my little Valve King Royal 8.



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