Above is a picture of an Oberheim OB-X 4 voice synthesizer

The OB-X came in 4, 6, and 8 voice configurations.

See sound examples below to see how fat 4 voices can be.

MIDI
This OB-X has the Encore Electronics MIDI kit installed.
http://www.encoreelectronics.com/cont_obxmk.html
This kit allows for MIDI notes as well as midi control of the filter cutoff, resonance and many more controls. It also increases the patch storage from just 32 to 120. Also, can send patch data over MIDI for backup. I had the Kenton MIDI kit initially but the Encore Electronics kit is much better.  The Oberheim OB-X never had MIDI when produced.

The left side of the controls of the Oberheim OBX.

The AUTO button on the left Auto Tunes the OB-X.

Let Unit warm up 5-10 minutes then press AUTO button so it's tuned to running temp.

The right side of the controls of the Oberheim OB-X.

The ABCD buttons select the group (bank) and the 1-8 select the Program (patch)

The right side wood panel of the Oberheim OB-X

The left side wood panel of the Oberheim OB-X

The left side on the back of the Oberheim OB-X

The middle on the back of the Oberheim OB-X

The right side on the back of the Oberheim OB-X

Close up left side of the OB-X

Close up of the OB-X showing the oscillators

Close up right side of the OB-X showing the filter on the left and the envelopes on the right

To ship an OB-X, use a Road case to ensure safe delivery

Four Sound examples (recorded 11/10/2012 directly from OB-X )

The first mp3 file is of the first preset A1 and shows how super fat 4 voices can be.

The OB-X is in Unison mode so all 4 voices are used for each key press.

OBxPresetA1 MP3 file

The second mp3 file is of the second preset A2 and shows how the Sample and Hold

can modulate the filter frequency to create some great sounding blurpy effects.

The OB-X is in Unison mode so all 4 voices are used for each key press.

OBxPresetA2 MP3 file

The third mp3 file is of the preset A3 and shows how 4 voices can be sounded.

Four octaves of the C key are played so you can hear each voice come in.

The OB-X is not in Unison mode so you get 4 single voices.

OBxPresetA3 MP3 file

The fourth mp3 file is of the preset B1 and shows how super fat "Rush" like

sounds can be made. The OB-X is in Unison mode so all 4 voices are used for each key press.

OBxPresetB1 MP3 file

Three Tips for the Oberheim OB-X

1. ALWAYS turn on the unit and let warm up for 5 -10 minutes, THEN press auto tune

(AUTO button on far left) The OB-X will drift until it reaches operating temperature.

It is best to just wait, let the Unit reach operating temperature, then press AUTO.

2. To EDIT a preset (have the knobs work) you need to press the EDIT button first.

The presets are selected by choosing 1 to 4 of the ABCD buttons, and then pressing a

number button on the right, then to change the frequency of the filter, or other control,

press the EDIT button then move the control.

3. To SAVE a preset, press the WRITE button on the far right and HOLD it for 2-3 seconds,

the light on the WRITE switch will come on and the next Preset selected will be written over

with the Preset you currently are playing. There are no "Are you sure you want to erase"

warnings it just does it. Hold the WRITE button until a number is pressed.

Open up and say AAAHHH

Look at the hinges at back in the above pictures.

4 screws and she is wide open.

Looking down the voice alley. In this case 4 voices. CPU at the end

In the middle is an Encore electronics midi kit.

Power enters on the left.

A closer look

This is a close up of the voice cards.

A look from above

And yet another look at a voice card.