out a vocal or snare crack while compressing. There can be a slight pop
when switching between states.
Bypass/Link
To bypass compression or to link another D864 in stereo operation, flip the
Bypass/Link switch down.
Dim Switch
The "dim" switch is located at the bottom of the switch matrix next to the
meter. It cuts the maximum gain to 25dB, but does this by padding the output
signal down (kind of like the EMI RS124 does). It’s useful for reducing signal
level from hotter sources. Flip the switch down to engage it.
Meter Switch
The Meter Switch allows a user to switch between compression mode and
output level mode. In compression mode (switch up) the meter will show the
approximate amount of compression. In output mode (switch down) the
meter will show the approximate amount of output signal.
It’s worth noting that the meter circuit is an exact copy of the original--which
means it behaves exactly like and old school meter behaves. The original
AM864 compression meter circuit simply measures the amount of current
passing into the input stage tubes as it relates to the level detector. That
means certain changes to attack or ratio can affect the meter’s behavior.
Its behavior isn’t 100% accurate, but it’s close enough to do the job.
Compression Features and Behavior
The compression circuit is based around a half-wave rectifier (6SQ7 tube,just
like the Federal). It's not a very efficient circuit, which means the response
can be a little slow and unusual compared to modern designs. But it's part of
the Federal's unique soft-knee sound. It also means that the compression
