Orban 422 Compressor/Limiter De-Esser Front & Back Views

Here's an Orban 422 Compressor/Limiter DeEsser. It used to be half of one of my 424 dual units,
but the other circuit board, front panel and chassis met with an untimely end under a big bad road case.

It a totally analog unit, works perfectly, and gives extremely smooth "pump free" compression and
"thump free" limiting for a variety of inputs. It works best with voice, but is great with an instrument or
any kind of program material you've got. The De-Essing (or sibilance) function really cleans up harsh
vocals or recorded material.

A good deal with the Alembic box at $250, buyer pays half shipping and insurance from Santa Rosa CA.

The box is an original 1970s 9 ply birch single rack space cabinet. These were very expensive back then
and I wouldn't mind keeping it if you don't need it.

Without the Alembic box $175, shipping included.

MSRP was almost $500 in the mid 1980s, but of course Orban was folded into AKG in the late 1980s
and the Pro-Audio product line changed significantly.

Without the Alembic Box

Build, or buy your own box to put it in. It's a normal single space 19"rack mount. The circuit
board layout is so well done that unless you are in a high RF or EMF environment serious shielding
is not really necessary. The Timing and D Ess modules (black rectangles) are already shielded.
All the inputs, outputs and AC connections have ferrite beads attached.

The Control Panel & Output Terminal Strip


These came stock with terminal strip connectors. The connector is labeled for + - and the chassis
and circuit ground symbols. As shown in the above Front & Back Views picture, I added XLR and
1/4 Phone jack input and outputs to the back panel. The other two holes are explained in the
paragraph following the Meter pictures below.

The controls are labeled on the Alembic box and are thoroughly explained in the manual. The Output
Level control has been moved from the back panel to the front.

There is a Red Power On indicator LED, a Yellow and Red LED for the amount of De-Essing (when
De-Essing is on) and a Green LED to indicate the Gating status.

Gain Reduction (left side) & VCA Level (right side) Meters


These are the meters that came originally with this circuit board and were calibrated to it. The meters
can be connected via leads soldered to the circuit board and attached to the meters by mini alligator
clips. Yes, they are included, but not shown in the pictures. You may find that seeing the meters in
action will help you "hear" the circuit, but after a while you will know how to set the controls for the
input source being used and the effect desired.

You can make a new front panel with spaces for the meters (like the 424 picture below), or mount them
in a separate box or rack space. I stopped using them long ago.

What a 424 Looks Like

Yes, blue panel is cooler than black panel, but the original panel and bottom circuit board were trashed.
The Red knobs are the Output Level controls that I moved from the back panel, the switch is for Independent
or Coupled Channel operations.

The Owner's Manual Front & Table of Contents


I have another 424 and will be keeping the manual. I will make a photocopy or scan and send
you jpg pages in email; your choice. It has 50 plus pages covering everything from Installation,
Calibration and Usage to circuit schematics, geographic and parts BOMs (Bill of Materials).

The Owner's Manual Schematic & Geographic