Marshall 2203 SS PreAmp

This is a modified Marshall 2203 circuit designed as a Solid-State Preamp, replacing the vacuum-tubes with JFet transistors.I have included footprints for your choice of SMD JFets or Thru-hole JFets. I suggest the #MMBFJ202 SMD JFets!

Some component values have been changed to incorporate these lower voltage JFets, otherwise, it is essentially the same circuit as the 2203.

There are 3 Trimmer Resistors that need to be adjusted; initial voltage on the JFet Drains (Q1, Q2, Q3) should be 4.5volts, then each trimmer adjusted for best sound.

Use this as a "Set Top" guitar effect!

Connect your guitar to the Hi or Low Input, then the Output to a Guitar Amplifier of your choice.

Controls are GAIN, VOLUME, TREBLE, MIDS and BASS.

Required a +12vDC power supply.

Unverfied.