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Voice Crystal - Merger Plus Manual

Merger Plus Manual

Merger Plus

The Voice Crystal Merger Plus Ver. 2.0 allows two MIDI signals to be 'merged' together into one output. Power for the Merger Plus is supplied by a MIDI device (midi-out) plugged into the 'IN1' input.


  • Powerful new firmware using Hi-speed Lo-power microprocessor.
  • No batteries required.
  • Dual feature RESET 'PANIC' button resets the processor and sends a series of All-Notes-Off commands to each of 16 MIDI channels.
  • LED provides 'Power ON' status and MIDI signal indication.
  • Supports full MIDI protocal. New version 2.0 also fully supports SMPTE.
  • High performance slip-resistant rubber feet included.


A typical MIDI output supplies 114 mw (milliwatts) of power to the MIDI line. MIDI inputs require a maximum of 57 mw, but typically respond to less than 10mw. The MERGER PLUS uses only 20 mw which leaves 37 mw to spare - enough to power some other midi-line powered devices.

When connecting the MERGER PLUS output in series with other midi line-powered devices such as thru-boxes, midi filters, etc., correct operation is not guaranteed. It is therefore not recommended, because the combination of devices may use more power from the line. This can result in a weaker signal, however, it won't damage your equipment to try it, and if it works, it works!


Stuck MIDI notes can occur under certain conditions. If you are using a master-keyboard controller to select different programs on a module or synth and you hold a note down while switching from one program to another, the first program will not receive a MIDI note-off command. This may cause it to continue to sound indefinitely. If this happens, simply press the RESET button. The micro-processor will re-initialize, then send four different MIDI data streams to each of all 16 channels to remedy stuck notes, as follows:

  • All-Notes-Off (global)
  • Sustain-Off (global)
  • Mod & Pitch Wheel centering - New withVers. 2.0
  • Individual Note-Offs for each note C0 thru C127
Note: Some synths do not respond to the global All-Notes-Off message. This is why the individual Note-Off messages are sent.

LED (Light-Emitting Diode)

When power is first applied to the input 'IN1' of the MERGER PLUS or the RESET/All-Notes-Off button is pressed, the LED will flash four (4) times indicating reset of the micro-processor and All-Notes-Off messages being sent. After Reset, the LED will remain lit indicating 'Power ON' status, but will turn off whenever a MIDI Note, Controller, MIDI-Time-Clock or System Exclusive message appears at either input of the MERGER PLUS.

MIDI-Clock and Active Sensing signals are sent straight thru to the output bypassing the LED indicator, This makes it easier to determine what type of data is passing thru the unit.


You may send bulk sys-ex dumps thru either input. When a sys-ex dump is received by an input on the MERGER PLUS, any data received by the other input is held in a buffer memory until the sys-ex dump is complete. When the buffer is full, the processor will begin to throw its data away to make room for more. Buffer time varies depending on how much data it's receiving. When the sys-ex dump is complete, all remaining buffer data is sent to the output. This procedure protects the sys-ex dump from being corrupted by data received at the other input (like accidentally hitting a note or something). If the sys-ex dump is short, the data on the other input will not be affected.

If a sequence is running on one input and a sys-ex dump is sent thru the other input, the sequence data will likewise be held in the buffer until the sys-ex dump is complete. If the sys-ex dump is small (i.e. one program dump) the hold time may not even be noticed. Though it is best to implement sys-ex dumps between songs, the MERGER PLUS is designed to handle this jamming-the-inputs scenario.


MERGER PLUS is designed to comply with MIDI spec. 1.0 document version 4.1.1

Optoisolator Isolation:

3KV A.C. rms, If(max)=60ma

Input 'IN1' MIDI current source load:

Static(LED On)=20mw,5.2ma (typ)
Active(LED Off)=16mw,4.5ma (typ)

Voice Crystal firmware: Version MP2.0


EYE & I Productions warrants this product to be free from manufacturer's defects for a period of ONE year from the date of purchase. Remember, though, that we try to keep a perfect record of satisfied customers...even after the warranty runs out!

MERGER PLUS is a trademark of EYE & I Productions.

FCC COMPLIANCE: This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generates, uses and can radiate radio frequency energy and, if not used in accordance with the instructions, may cause harmful interference to radio communications. However, there is no guarantee that interference will not occur in a particular installation. If this equipment does cause harmful interference to radio or television reception, which can be determined by disconnecting the powered input, The user is encouraged to try to correct the interference by one or more of the following measures:
-Reorient or relocate the receiving antenna and/or the MIDI cables connected to this device.
-Increase the separation between equipment and receiver.
-Connect the equipment this product is powered by, into an outlet on a circuit different from that to which the receiver is connected.
-Consult the dealer or an experienced radio/TV technician for help.


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Voice Crystal® is a registered trademark of Eye and I Productions