Modular synthesis in Reason part 2: Detuning and Vibrato

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Last time we built a basic monosynth using modular synthesis in Reason. What we have so far is pretty simple; a single oscillator sawtooth wave triggered by an envelope generator. So far it’s nothing fancy so this time I’m going to be building it up by adding a second oscillator and showing you how to apply vibrato using the mod wheel.

To follow along you will need AMMO 100LA (€15), Charlotte Envelope Generator (€19) and Propellerhead’s Pulsar (€39). We will be following on directly from last week’s tutorial, so if you’re following along you might want to check out part 1 first.


Adding and detuning a second oscillator.

  1. Right click on AMMO and select ‘Duplicate Devices and Tracks’. A new instance of AMMO should appear below the original one. All of the settings on the front panel have been copied across to the new instance so we don’t need to dial them in again.

Duplicating the device will also copy any settings from the original.


  1. All of the settings on the front are the same but no CV or audio cables will be attached so let’s flip around to the back and sort that out. Attach the EG, Gate and Note cables from voice 2 of Charlotte to the Env, Gate and CV inputs of AMMO 2. Now let’s connect audio out 1 of AMMO 2 to the second mixer channel. If you get confused with the routing please refer to the image below.

Hook up AMMO 2 in the same way as we did with AMMO 1 in the previous article.


  1. Now we have two oscillators that play the exact same thing. Let’s make things more interesting by detuning the second oscillator. Click the range button on AMMO 2 so that it’s in ‘Cent’ mode and adjust the rate to 8 cents. This should give your patch a nice thick detuned character.

Detuning AMMO 2 will give our patch a nice full sound.


Adding vibrato and mapping it to the mod wheel

Let’s make our patch more expressive by adding vibrato using an LFO. We’ll create this vibrato effect by using Propellerhead’s own pulsar Rack Extension to modulate the pitch of both oscillators. Well also do some routing inside the Combinator’s modulation matrix so that the mod wheel controls the vibrato amount.

  1. At the moment the mod wheel controls the level of AMMO 1 & 2. Let’s disable this by clicking the ‘Show Programmer’ button on the Combinator, selecting AMMO 1 from the Key Mapping section and un-check the ‘Mod.W.’ box. Do the same thing for AMMO 2, now the mod wheel should do nothing to the patch.

Make sure you disable the mod wheel for both AMMO 1 & 2.


  1. Insert an instance of Pulsar from the utilities menu and flip the rack around to the back. Now we’re going to connect CV out 1 from LFO 1 of Pulsar to the rate CV input of AMMO 1 and CV out 2 to the Rate CV input of AMMO 2 (Refer to the image below if you get stuck).

As there’s no trim knob for AMMO’s Rate CV input we’ll adjust the amount on the front of Pusar.

  1. We now have some crazy pitch modulation going on so let’s dial it back a little bit. Flip back to the front and increase the LFO 1 rate to 1/16, now bring the LFO 1 level all the way down to 0%.

Feel free to experiment with the rate setting. I feel that 1/16 works best for most situations though.


  1. Now let’s assign the mod wheel to increase the vibrato level. Select pulsar in the Key Mapping section and then select ‘Mod Wheel’ as a source in the Modulation Routing section. Set the target to LFO1 level and decrease the Max value to 30%.

Use an empty slot for the mod wheel modulation. This keeps everything organised in case we want to use the other parameters later.


That’s it. Now when you engage the mod wheel the amount of vibrato will increase. Even though this effect is pretty basic is adds a certain level of expression to an otherwise static patch.


Notable mentions:

–    4 Phase LFO (€7.50) – A nice alternative to Propellerhead’s Pulsar if you’re just looking for a CV LFO. 4Phase LFO is limited compared to Pulsar but if you’re on a budget it’s worth checking out.

–    AdditiveOscillator (€29) – This one’s worth checking out if you’re looking to expand beyond subtractive synthesis. AdditiveOscillator opens you up to a whole other kind of synthesis, create your own waveforms using additive synthesis and expand your modular possibilities.

–    CV Mutant (€12) – One of my personal favourites. CV mutant let’s you shape and mutate your CV signals; you can also get some pretty crazy results when you modulate the Big Knob inside a Combinator. I like to use it as a custom LFO that I can use when I need some really precise modulation.

–    CV tuner (€7.50) – This thing is like auto tune for your CV signals, try hooking it up between a sample and hold LFO and the pitch input to a synth. You can produce endless sequences that will always be in tune with the rest of your project.

–    AS-16 Analog Sequencer (€35) – A great way to sequence your modular creations. There’s lots of options for those who favour the look and functionality of an old school analog sequencer. Flip to the back of the rack and you’ll find more CV connections than you can handle.

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Freelancer and sound designer from the UK. Interested in all things music tech.