IGS AUDIO ALTER 500 – mono FET Limiting Amplifier
The ALTER 500 is a FET compressor built is the 500 standard. The FET-type solution was used
for the first its application in the legendary UREI 1176 compressor from the 70s.
The ALTER is a single-channel unit with stepped input and output controls. The Ratio switch has
six positions, including two additional to the original 1176 1:1 and 2:1 settings. Slam Mode can
be turned on with a separate switch, working regardless of the Ratio settings. Attack and
release times can be set to Fast / Mid / Slow with 3-pole switches. The compressor is equipped
with a relay bypass, achieved on the front panel. The input is balanced with a modern, low-noise
op amp and the output with a Carnhill transformer. The circuit has two amp stages, between
which is the output control. The stage amps are based on the discreet API2520 circuit. The level
of gain reduction is shown by a 20 point led bar.
Typical usage:
✔
Good for compressing instruments (guitar, bass, mono synth)
✔
Great vocal compressor
✔
Work well with single drum tracks and samples
Till this day no better vocal compressor has been designed! This is a professional device. Best
results are achieved when recordings are made with a good microphone and low noise preamp.
Notice
Block diagram
