I’m covering this as (as when I first started out in SynthEdit there are a few little “gotchas” that can leave you scratching your head.
I’m getting no audio out, what’s “broken”?
It’s tempting to jump straight and in leave out the VCA and ADSR… if you do you may well not get any audio out of it, just a low frequency buzzing. Synthedit expects the VCA to be there, and to be connected to the Trigger and Gate plugs.
The ADSR isn’t triggering properly when I play quickly.
You must have both the Trigger, and the Gate connected for the ADSR to work correctly, these two signals work as follows;
Trigger: This is a short pulse received every time a key on the keyboard is depressed. This initiates the ADSR cycle.
Gate: This is necessary for the sustain portion of the ADSR envelope to be present. If it’s not connected then at best you’ll just get the Attack and Decay cycle, or it will just fail to work correctly .
The Tuner (AKA Detuner).
I recommend connecting this module up, and having a look at what goes on inside it, as it will give you an insight into how the 1 volt/Octave pitch to voltage works in SynthEdit. The octaves are just steps of one volt, and the fine tune knob is set with a maximum value of 0.083 V so that you can fine tune against other instruments, or if you have two oscillators you can vary the pitch of one to get a (very) basic chorus effect.
I have added a Level Adjust module on the output and fed this to the Pitch plug on the VCF, that gives us the classic “Moog” filter sweep sound especially with the Resonance or “Q” turned up to about 8 Volts.
I’m getting a pronounced click at the start of the note, why?
This often occurs when you have a very short (or zero) attack time set, it’s unavoidable, just set the attack time so the click disappears.
Measuring Pitch voltage.
I tried to measure the voltage on the Pitch plug on the MIDI-CV2 module and the readings don’t match what I would expect. Why is this?
Because of the way SynthEdit works you’ll just keep getting voltages coming and going as keys are depressed your Synth will work out what’s going on, but the voltmeter can’t make sense of it.
Likewise if you hook up the ‘scope to the VCO while you’re playing you will see multiple signals instead of one composite audio signal. This is normal, and is due to the way SynthEdit handles Polyphonic operation. You’ll only see a single signal if you force the Synth to operate as “Monophonic” i.e. one note at a time.
