Using the Multi Segment Envelope Geneator

First Posted November 1, 2002


    Using the Multisegment board can be quite involved.  First, you need to construct a module out of it.  This is going to be a matter of deciding how much do you want, and how much room do you have.  In it's fully implemented form, this module could have 16 pots, 2 rotary switches, 8 Leds, and at least two jacks.  However, this module is designed for flexability.

    Sequence Lenth

    There are three inputs on JP7 (pins 2,4 and 6) that control the lenth of the sequence.  Or in other words, how many segments there are in the envelope.  These three lines make up an encoded binary number.  If the pin is grounded, this is equivelent to 0, and if higher than 5 volts, this is equivelent to 1.  It should be noted the the number of segments will be equal to the lenth + 1.  In other words, if LEN0 = 0, LEN1 = 0 and LEN2 = 1, which would be the binary number 100, or decimal number 4, there will be 5 segments.  The reason for this is the way the pipeline delays work in the logic.

    It should be noted, that the user can choose to make the lenth fixed.  This can be done by hard wiring the connector.  This is what I did on my first installation.

    Sustain Segment

    There are three inputs on JP7 (pins 12,14, and 16) that control the segment of the sequence that will be the sustain.  In an ADSR type envelope generator, when you hold the key down, the envelope generator will eventually go the a level set by the sustain control.  In this generator, since there are so many segments, there is a provision for selecting which segment will be the sustain level.  So, if you have 8 segments, and you pick segment number 4 to sustain, when you press the key down, the envelope generator will go through segments 1,2,3 and hold at 4 so long as the key is held down (or GATE is true).  When the key is released (GATE is false), the generator will finish up by going through segments 5,6,7 and 8.  It should be noted, that segment 8 (or the release segment), is actually segment 0, if you refer to the schematic.

    Again, the user can choose to fix the sustain segment by hard wiring the connector.  However, I find this to be a very useful thing to change.  It really changes the character of the envelope to be able to adjust this.

    Rage Voltage

    There are 8 inputs on JP3.  These inputs supply the voltage to control the RATE of attack or decay (depending on your point of veiw) of each segment.  You should note, that the input labled B0 is the release rate.  B1 is the Attack rate for the first segment (always), B2 is the rate for the next segment after that, and so on until B7, which would be the last rate before the release, assuming of course, that all 8 segments are in use.  If for instance, you have only 4 segments, you would only use B0, B1, B2 and B3, again, B0 is the release rate, and B3 would be the rate for the segment just before release, and B1 would be the attack rate.

    Level Voltage

    There are 8 inputs on JP1.  These inputs supply the voltage to set the level that each segment attacks to or decays to (depending on your point of veiw).  You should note that, the release level does not have to be zero volts.  This is traditional, but it does not have to be so.  Again, input A0 would be the release level.  A1 would be the Attack level, and so on and so forth.  If you have four segments, you would use A0, A1, A2 and A3.  Six segments would be A0, A1, A2, A3, A4 and A5, etc.

    It should be noted that the level voltages can range from -10 volts up to +10 volts.

    LED drivers

    There are 8 outputs on JP2 that can be used for driving an LED.  There are pairs of pins.  The Cathode of the LED goes to the odd pin , and the anode goes to the even pin.  The release driver is on pins 1 and 2 (LEDO0).  My personal preference is to use a RED led for the Release State (pins 1 and 2), A green LED for the Attack state (pins 3 and 4), and Yellow LEDs for the other states.

    Misc Inputs

    JP4 has all of the other inputs and outputs.  Pin 2 is the GATE input.  Any voltage below 1 volt is considered to be Low (Gate off).  Any voltage above 4 volts is considered to be High (Gate on).  Pin 16 is the output.  The voltage range can be from -10 to +10 volts coming out of here.

    Pins 12 (+10 volts) and 14 (-10 volts ) provide the voltages that are used to run the Pots.