Four matched FETs for direct stereo operation.
The FET compressor uses a pair of 2N5457 Field Effect Transistors. One is used to attenuate (compress) the signal, and the other is used for VU meter tracking. Having the transfer characteristics of the two GR FETs closely matched will allow for direct stereo connection. Having the transfer characteristics of the two meter FETs (Q11) closely match to the GR FETs will help to guarantee that your VU meter accurately displays what is happening to the signal.
These Fairchild 2N5457 FET's are matched using Vgs values from 0V to -3V in 0.25V increments. All corresponding Vds values for the GR FETs (Q1) are matched +/- 1%. The corresponding Vds values for the meter FETs (Q11) are matched +/- 5% relative to the GR FETs.
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