I haven't DIY'ed for a long time, so to kickstart this hobby again, I decided
I'm going to build an 1176 Compressor.
The 1176 is one of the classic compressors in used by almost every recording
studio out there. (The other classic compressor is the LA-2A). Bill Putnam designed
the 1176, based on the 1108 preamp. Back in 1966, the Field Effect Transistor
(FET) was just developed and he's experimenting with the properties of this new
device. Basically, think of an FET as a "voltage controlled variable resistor." The
FET has three terminals. Drain, Source, and Gate. The resistance between the
Drain and Source can be varied/controlled by the Gate voltage. So what
Mr. Putnam was doing with the FET is using it as a variable resistor to contorl
the gain reduction in the circuit.
The output stage of the 1176 is a Class A line level amp, feeding a load of 600
ohms. It's got an output transformer which converts the output from unbalanced
to balanced, and also do impedance matching.
If you don't know or don't want to DIY, you can buy an 1176LN (for Low Noise)
compressor for about $1800. Or, you can purchae "virtual" 1176 plugins from $130
to $225 price range.
Click
here for software plugin versions of the 1176.
