Forssell Technologies

The following schematics contain proprietary information that is the property of Forssell Technologies/Fred Forssell or the original designers as shown on the schematic pages. These schematics are presented here for the private use of viewers. For commercial use of these designs please contact Fred Forssell at fred@forsselltech.com or 208-263-0286, or the circuit designer listed with the schematic.

Forssell Technologies does not imply any level of performance with these circuits. Some circuits are incomplete or lack component values (hey, we can't do all the work for you, can we?). Therefore, you are on your own if choose to build any of these circuits. Have Fun!

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Summing Buss Schematics

- 8 Channel Passive Summing Busses (balanced and unbalanced input designs)

- 8 Channel Summing Buss with Level, Pan, and Master controls
Class A JFET Opamp Circuit (First Generation design... that means it is not our latest design.)
Single Amplifier 4 Band Passive EQ
Gyrator Filter Design Info for Single Amp EQ The gyrator is used in place of the inductor in a LC filter.
Opto Compressor/Limiter Side Chain with Gain Reduction Metering Opto Gerbers and LED Meter pcb schematics. Stereo Link schematic PDF link.
Tube Line Driver/Preamp (Published in Glass Audio #2/1993)
Vacuum Tube Opamp Circuit (Published In Glass Audio #3/1995)
JFET Double Balanced Mike Preamp (Based on a design by Graeme Cohen AES Preprint #2106)
Dual Transformerless Class A Discrete Mike Preamp (Uses JMP-1 Modules)
JFET Mike Preamp using Jensen JE16 Input Transformer
JFET992/3 Summing Amplifier Circuit (Summing buss and amplifier circuit for an Audio Console design)
Mike Preamp Power Supply with Phantom Power (Uses a single 48 VAC center-tapped transformer)
Dual Mike Preamp power supply Gerber
Balanced Floating Output Stage Circuit (A great output topology based on a design by George D Pontis)
JFET Jig1 Schematic of a Test Fixture for testing JFETs (PDF file)
Jitter Detector Input Part #1 of a 2 part schematic
Jitter Detector Output Part #2 of a 2 part schematic
Jitter Modulator
Dual JFET-992/993 PCB schematic PDF file or Dual Amp PCB.ZIP containing schematic and gerber files. For Use with Opto Compressor Project