What it Does!
The Bell Tone Synth Works EML-101/100 1V/Octave Mod provides the offset and voltage scaling adjustment needed to be able to control Oscillators 3 and 4 of an ElectroComp EML-101 or EML-100 with conventional 1/V Octave control voltage from an external keyboard, sequencer, or other synth. When a cable carrying your 1V/octave CV is plugged in, the CV will be scaled up to EML standard and then sent to replace what is known throughout the synth control panel and schematics as “KB2”. When generated by the
keyboard, KB2 is the upper voice CV so when an external CV is plugged in, the keyboard’s upper voice is disabled. Then, anywhere KB2 can be sent via the panel controls, your new CV will go. When nothing is plugged into the jack you are using for the new CV, the synth will function completely normally.
Building the mod board
The PCB for the mod is a leaded, through-hole PCB intended to be used with lead-based solder (60/40 or 63/37).
Parts list / Bill of Materials (pdf)
Installation Instructions
EML-100: EML 100 Mod Installation
EML-101: There are 2 versions of the EML-101, and each has different installation instructions. Determine which version you have and download the correct instructions!
The first version of the EML-101 has a brushed aluminum front panel with black labels and all black knobs. There is no “Sequencer” jack like the later version has.
The second version of the EML-101 has a jack on the upper left of the panel labeled “SEQ”, the black knobs may or may not have aluminum caps, and the panel is coated with white or light grey enamel instead of being bare metal.
Version 1 Installation Instructions (pdf)
Version 2 Installation Instructions (pdf)
You may also want to refer to the original schematics and service manual, which are hosted at Synthfool here: http://www.synthfool.com/docs/EML/100_series/
Notes on Using your EML with the Mod Installed
When the 1V/Octave Mod for the ElectroComp EML-100 and EML-101 is installed, the control voltage you plug into the modified jack, scaled up so that the EML oscillators can track it musically, becomes what is designated as KB2 on the panel and goes everywhere KB2 goes. That means you can use it to control both the “upper” voice (Oscillators 3 and/or 4) and the filter. When a cable is plugged into this jack, the KB2 control voltage generated by the EML’s own keyboard is bypassed, but when nothing is plugged in, KB2, and its control over Oscillators 3 and 4 and the filter, work the same way that they used to.