Like we did with the 100, we can set up an old school patch on the Doepfer. Here we’ve got a VCO going to a VCF, LPF, or low pass filter.
Then we can go from the LPF to the VCA
We’re going to use MIDI in this example, so we’re going from the MIDI to CV converter gate output to the ADSR envelope generator. We’ve also plugged the VCA output into the mixer.
We can use the CV output to control both the VCO and the VCF
If you want to use a keyboard or other MIDI device, you can use a MIDI cable. If you’re just using a laptop or a computer, you can also plug in a USB cable.
You can use the Doepfer to filter and process other sounds by going into the Ext Input module. You could plug in the DtoA converter of a computer to do things to a sound or could could come out of the Roland 100M’s mixer.
That module also does envelope following so if you want to use the Doepfer to do FM with a recorded sound, for example, you can follow the envelope, so the loudness of the source sound can be sent to the CV input to a VCA. This way, you have the sample amplitude profile as the source sound.
It’s ok to plug mixer output of the 100M into the Doepfer, but the CVs may have different ranges.
The typical way people historically played these in bands was with keyboards. The keyboard outputs two control voltages. One is the gate, which is open when a key is pressed and closed when one isn’t, and the other is a CV which corresponds to the frequency associated with the particular key.
You would send the gate to an envelope generator. This is a module that makes a nicer shape than on or off, For instance, the Roland 100 has an ADSR envelope – Attack, Decay, Sustain, Release which vaguely corresponds to the amplitude profile of striking a piano key. It’s really loud, then it gets quieter and then it sustains for a while until you let go of the key, then when you release they key it goes to nothing. You can see in the photo that we have fast attacks and decays, and an almost instant release. The sustain level is quiet.
You’d send the CV to a VCO – a voltage controlled oscillator. It controls the pitch of the oscillator. You also want to turn up that control input – in the picture, it’s turned down.
It’s also possible to plug in the keyboard so it’s output goes to all the modules on a row. This is by plugging in at the right hand side of the bottom section of any row.
The control inputs of the VCOs are at the bottom and the audio output is at the top of the module. Modern synthesisers usually do this the other way around.
You need to tune your oscillators. You’ve plugged in your keyboard which tells the oscillator how to move the pitch up and down, but you haven’t set the base frequency. Use the tuning knobs to get the frequency to match the keyboard key.
In traditional synthesising, you would probably plug the out put of your oscillator into a votlage controlled filter, or VCF, which I’ve done there with the grey wire.
I’ve plugged the output of the filter into the input of the VCA. The voltage controlled amplifier lets us change how loud the sound is.
The I plug the envelope output to the control voltage input of the VCA. That’s using the red wire in the photo. The colours of the wires correspond only to how long they are. Otherwise, they’re identical.
I’ve sent the VCA output to a mixer and the mixer is plugged into the amp.
This patch is quite boring. I could send the gate to a second envelope generator to control the filter. Or I could send the VC to a bunch of slightly detune oscillators. This can sound very nice with sawtooth waves.
There’s also the option to use one oscillator to modify another, which is FM or I could use an oscillator to modify an VCA, which is AM. Those make more complicated spectra for sounds.
Putting a complicated spectra or noise through a filter is called subtractive synthesis. People used to put synthesisers based on what their filters sounded like so they could do this kind of synthesis. Low pass filters were an especially popular way of doing this, but people also used other shapes like high pass, band pass and band reject.
The Roland has a lot of oscillators, so you can also do some additive synthesis where you take a bunch of waves (like detuned saws) and add them together, but sending them all to a module that takes multiple inputs, like a filter, mixer or VCA.
You can send any kind of audio into a filter, VCA, or mod input to an oscillator, if you want to change the spectrum of a recording using the synthesiser.
A word of warning on this particular synthesiser is that the arpeggiator on the keyboard is broken and it will sound weird if you try to use it. You’ll have to turn off the keyboard and let it cool down.