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Manny’s Modulation Manifesto: Bass Sounds

Written by Manny Fernandez on May 16, 2018. Posted in Synth Programming.

What do we need for a bass sound, and how do we break it down? In a typical application, the basic components we’re going to want are a sound that has a solid fundamental frequency and medium-to-quick envelopes with a moderate sustain useful for quarter, eighth and sixteenth note playing. The components will vary widely depending on the specific musical context or genre such plus the desired brightness and overall tone — is it a “harsh”, “smooth”, “analog” or “digital” timbre? And finally, how do we want to use velocity dynamics, and do we need monophonic mode for legato playing?

Now, time again for a little detour. In this article, I’m showing voices that use two new approaches in our series of FM programming – multiple stacked Modulators and Feedback Type. First let’s talk about multiple stacked Modulators — what are they? This is where the algorithm is set up so that Modulator operators are patched into other Modulator operators instead of the Carrier. So far, the example voices in this tutorial series have focused on the Algorithms that only have Modulator operators patched into the Carrier operator — Algorithms 5 and 8. With 4 total operators, the reface DX has algorithms with a 3-Operator stack like Algorithm 6 where Ops 2, 3 & 4 create a 3-Op stack:

and Algorithm 1, where Ops 1, 2, 3 and 4 create a 4-Op stack:

The main thing to understand in regards to stacking our Modulator operators two or three deep is that, in general, you get more brightness, harmonic variation, and dynamic harmonic behavior as you start stacking Modulators. Going back into the history of FM with only sine wave operators, the waveforms you could create with a single Carrier and Modulator were fairly simple. When Yamaha developed the DX7, their important expansions on John Chowning’s original FM implementation was having 6 operators, creating Modulator branches and stacks in their algorithms, and implementing Feedback. Stacking the Modulators allowed for the ability to modulate the Carrier with dynamic complex waveforms, instead of just a simple sine wave, and greatly expanded the array of sonic complexity available. Later on, Yamaha introduced complex waveforms directly available as operator waves in the TX81Z which allowed for a lot of harmonic complexity even though it had only 4 operators.

While the 4-Op FM engine in the reface DX only has sine wave operators, Yamaha has implemented Feedback on every operator. In addition, the Feedback Type can be either Sawtooth Type or Square Type. The difference in feedback types is as follows:

* Sawtooth Type adds in all the integer overtones, as in a sawtooth wave, as you increase the feedback setting.
* Square Type adds in only the odd-numbered overtones, as in a square wave, as you increase the feedback setting.

Combined with some new unique algorithms, this allows for a lot of complex harmonic capability in a 4-Op sine wave FM engine. And in my opinion, this makes the reface DX an extremely versatile and capable synth for Bass sounds that rivals even the TX81Z.

Back to our regularly scheduled program and time for an example… please reference the Voice “Synth Bass Example” along with the companion video on Soundmondo.

This example is a basic ‘single oscillator’ synth bass with a mixed sawtooth/pulse wave timbre. It has a fairly quick ‘filter’ attack and velocity control of the total brightness. So, as a ‘single oscillator’ sound, I’ve chosen a single Carrier algorithm, Algorithm 4:
bass sounds 3

I chose this particular algorithm, which is unique to reface DX, as I want to demonstrate later on some simple edits that drastically alter the sound and show how multiple stacked modulators work. Additionally, because this algorithm has both branched and multiple stacked Modulators and includes a ‘shared’ Modulator (Op 4), it can create unique characteristics in our sound, that we’ll dive into later. Let’s begin with the basic breakdown. In the Soundmondo editor, turn off all the Modulator Operators 2, 3 and 4.

I’m creating our fundamental tone by having a little Feedback set at 25 for our Carrier Op 1. Set the Feedback to Zero and back to 25 to hear the difference between a pure sine wave (Feedback = 0) to the subtle overtones with setting the Feedback to 25. Now, turn on Operator 2 and listen to the sound so far. I’m starting to build the sawtooth/pulse timbre structure using a Frequency Ratio of 1.00 for Op 2, Level set at 83, a Feedback set at 63, but using the ‘Square’ setting for Feedback Type. Then, change the Feedback Type for Op 2 back and forth from Square to Saw and listen to the difference in the sound. Using the Saw type creates a typical sawtooth wave timbre, whereas the Square type creates more of a mixed sawtooth/square wave timbre.

Next, turn on Op 4 (keep Op 3 off for now). Op 4 is set to a Frequency Ratio of 2.00, a Level of 55, and Saw Type Feedback set at 70. Now we have a three Op stack of Op 4 modulating Op 2, which then modulates our Carrier Op 1. Turn Op 4 off and back on and play notes to hear the harmonic richness and brightness added by Op 4. Let’s hear the difference multiple stacked modulators make in our sound so far. As I mentioned in our earlier detour, in general, you get more harmonic variation and brightness. To hear this, keep Ops 1, 2 & 4 turned on, and change the Algorithm setting back and forth between Algorithm 4 and 5, which results in changing the patching of Op 4 from being stacked behind Op 2 to being patched directly into the Carrier Op 1. Listen to the difference in the sound – pretty big difference!

Now, make sure you’re back on Algorithm 4, and Op 2 Feedback Type is set to Square and Op 4 Feedback Type is set to Saw. Turn on Op 3. I’m using Op 3 to add a touch of extra brightness and ‘snap’ in the attack at the highest velocities, using a Frequency Ratio of 1/00, and a Level of 75, Square Type feedback set at 70 and a Velocity Sensitivity of 90. If you want to intensify the bright ‘snap’ contribution of Op 3, gradually increase its Level from 75 up to about 90-110.

Again, go back and start switching the Feedback Type for Ops 2 and 4 and listen to the sound change, both with Op 3 Level at the original setting of 75 and set up higher in the 100 range. Play around, listen what happens as you start bringing up the Level of Op 4 to 70-85. Because Op 4 modulates both Ops 2 and 3 before they both combine back to each modulate our Carrier Op 1, and Op 3 has completely different Velocity and Envelope settings than Op 2. As I mentioned at the beginning of this article, choosing Algorithm 4 for this example allows for unique timbral changes by just switching the Feedback Types between Saw and Square for those three Ops and some minor Level tweaks. Make sure you watch the companion video for this Voice, as it will help keep things clear.

So, hopefully you’ve got some understanding how stacking modulators and the different Feedback Types can have a large influence in your sound. Apply these concepts when tweaking all your sounds, not just Bass sounds, to find some nice ‘haxidents.’ I’ll leave with one simple ‘haxident’ to try which drastically changes the sound because of those infamous quirks of FM math – take this original example Voice and just change the Frequency Ratio of Op 1 from 1.00 to 2.00 and be prepared for some big bottom end…!

For two examples of fully tweaked-out, in-your-(re)face synth Bass sounds, check out “Facely Bass 1” & “Facely Bass 2“. Some additional variations of synth Bass Voices on Soundmondo to expand your library are the “Yet Another FM Synth Bass” series: “YAFMSyBs1“, “YAFMSyBs2“, “YAFMSyBs3“, “YAFMSyBs4“, “YAFMSyBs5“, “YAFMSyBs6“, along with “Bass Byte.”

Finally, here are some bonus sounds, because you just never know when you need to have the ‘classics’ handy, check out: “That DX7 Bass 1“, “DX7 Slap Bass 1“, and “DX7 Slap Bass 2“,

Until next time – happy tweaking!

In the meantime, join us in the discussion about this lesson on the Forum here.

Not had a chance to experience the earlier lessons in Manny’s Modulation Manifesto? Catch up now:

Lesson 1 – Basics of FM Synthesiss
Lesson 2 – Solo Brass Voices
Lesson 3 – Ensemble Brass Voices
Lesson 4 – Synth Pads

A little bit about the Author:

Manny Fernandez has been involved with sound programming and synthesizer development for over 30 years. Initially self taught on an ARP Odyssey and Sequential Pro-One, he also studied academically on Buchla modular systems in the early 80’s. With a solid background in analog synthesis, he then dove into digital systems with release of the original DX7. Along with his aftermarket programming for Sound Source Unlimited, Manny is well known for his factory FM programming work on Yamaha’s DX7II, SY77, SY99, FS1R and DX200 as well as the VL1 and VL70 physical modeling synthesizers.

Manny’s Modulation Manifesto: Synth Pads

Written by Manny Fernandez on May 16, 2018. Posted in Synth Programming.

The first thing I consider is how I want to divide my Operator resources to be either Carriers or Modulators.

The Reface DX is a 4-Operator FM engine. In general, using more Modulators gives the possibility to have more widely varied, complex timbres and harmonic (overtone) control.

Using more Carriers gives the possibility of thicker, detuned sounds or the ability to have multiple pitches played for each key, such as octaves or fifths. Compare the Voices “Detuned Saws” referenced in our prior article with Peter Jung’s “Fat Analog Sawtooth Pad“. For the Voice Detuned Saws, it uses two 2-Operator stacks for an emulation of an analog two-oscillator synth sound, then uses the effects to enhance the ‘thickness’. Because it uses Modulators to create the sawtooth wave harmonics, the brightness can be controlled with velocity dynamics and the Modulator Envelope for ‘filter’ sweeps and decays, etc., by changing the EG’s Rate and Level values.

In contrast, Peter’s Fat Analog Sawtooth Pad uses all four Operators as Carriers, having to rely on the Carrier Feedback to create the sawtooth wave harmonics. This allows for a much thicker and fat detuned four-oscillator analog sawtooth synth sound and doesn’t need the effects to thicken the sound. In addition, you can re-tune some of the ‘oscillators’ (Carriers) to octaves, fifths or other intervals. However, with no Modulators the only harmonics available are simple sawtooth or square waves depending on the feedback setting. More importantly, without any Modulators you lose the ability to create complex or unique waveform harmonics as well as losing any behavior or dynamic change in the harmonics with either velocity or the EGs for ‘filter’ sweeps, etc. You have to consider this trade-off when envisioning the type of pad sound you want to create; when choosing the Algorithm – a complex & dynamic pad needs more Modulators.

So, it’s example time — reference the Voice “Complex Pad Example” on Soundmondo and the linked video. This is a soft-attack sawtooth sound that sustains as a square wave pad, which then gradually evolves into a LFO controlled harmonic ‘shimmer’ effect. Play and hold notes or chords for 10-12 seconds to hear the entire sound. To allow for the independent control of these different components of the timbre, I’m using Algorithm 5 which has Operator 1 as the single Carrier, and Operators 2, 3, and 4 and the modulators:

Operator 2 creates the initial sawtooth harmonics of the timbre with a 1.00 Ratio Frequency setting in combination with Carrier Operator 1’s Frequency setting of 1.00. The Envelope shape for Op 2 is a medium rate decay to a level of zero, so the sawtooth harmonics starts the initial first second or so of the sound. Operator 3 creates the square wave harmonics of the timbre with its 2.00 Ratio Frequency and the Op 1 setting of 1.00. The Envelope for Op 3 is set to slowly fade in over 3-4 seconds or so as you hold sustained notes. Operator 4 creates the repeating harmonic ‘shimmer’ harmonics of the timbre with its 4.66 Frequency setting and the LFO Pitch Modulation Depth setting. The Envelope for Op 4 is set to a very slow fade-in of about six seconds, so you have to hold notes for 7-8 seconds before this portion of the timbre comes in. The repeating effect is created by setting the LFO Amplitude Modulation Depth (AMD) for Operator 4 to 43 to emulate a repeating, or gated, Envelope. As you continue to hold notes past 10 seconds, Op 1 will fade back in to add additional harmonics to the shimmer. Finally, to thicken up this one-Carrier sound, I’m using both the Flanger and Chorus effects.

OK, time for a quick quiz question: Where have you seen the core structural components of this sound before?

Answer: The example Voice “Wave Example” from our first tutorial article! The important tweaks I made to create the significant differences between the basic “Wave Example” Voice and this polished and finessed “Complex Pad Example” Voice are as follows:

* changing the Envelope values for Operator 1 for a sustaining pad sound;
* tweaking the Modulator Ops 2, 3 & 4 Level and Feedback values;
* using the Level Key Scaling to even out the volume and brightness across the keyboard range;
* adding velocity sensitivity to control volume and brightness with playing dynamics;
* using the LFO to control the PMD and AMD of Operator 4 for the repeating ‘shimmer’; and,
* then using Flanger and Chorus Effects for final polish.

The core components – the Algorithm and all Operator Ratio Frequency settings – are the same in both Voices.

Again, I encourage you to play around with changing the Level, Feedback and Frequency settings for the Modulator Ops 2, 3 & 4 and listen to how they change the sound.

To hear a subtle variation of this example Voice using different Frequency settings and faster LFO shimmer effect, check out the Voice “Evo Example” on Soundmondo. For an example of a more complex variation check out the Voice “Complex Bell Pad” which has edits to the Op 1 & Op 4 Envelopes to add the bell tone in the attack, along with adding Pitch EG to Op 4 to accentuate the percussive strike for the bell tone. Also, the Frequency settings for Ops 1 and 3 have been changed for a more ‘digital’ timbre. This shows how much complexity and control can be achieved with three Modulators.

Next let’s see and hear the advantages versus trade-offs in creating a similar type of pad using more Carriers for a ‘lush’ or ‘thick’ type of sound with a little less harmonic complexity as discussed earlier. Reference the Voice “Lush Pad Example” on Soundmondo along with the linked video. For this example, I’m using algorithm 8:

By detuning the two separate Operator stacks, we can create a lusher, thicker sound. However, there will be less opportunity for creating timbral complexity and behavior as there is only one Modulator Operator in each of the Operator stacks to create and control the harmonics. One way that I compensated for some of the loss of complexity is by mixing up the Ratio Frequencies for the Operators in the different stacks, so that in effect we’re mixing two different sounding waveforms with our “two oscillators.” In the first stack, the Frequency for Carrier Op 1 is set to 2.00 and the Frequency for Modulator Op 2 is set to 1.00, which along with the Feedback settings for both Operators and the Op 2 Level create a pulse wave timbre with a soft filter sweep type behavior.

In the second stack, the Frequency for Carrier Op 3 is set to 1.00 and the Frequency for Modulator Op 4 is set to 2.00, which along with the Feedback setting for those two Operators and the Level setting for Op 4 gives a square wave timbre, again with a soft filter sweep type behavior. Note that the Envelope Level and Rate settings are different for Op 2 & 4. The values for Op 4 are set to make the square wave timbre (from the Op 3 & 4 stack) fade-in slower and fade-out faster compared to the Op 1 & 2 stack pulse wave sound. In addition, the Envelope Level 3 and Rate 3 settings for Op 2 and Op 4 have them eventually fade back in with longer held notes. So overall, the Op 1 & 2 stack pulse wave timbre will fade back in sooner than Op 3 & 4 stack square wave timbre. All these variations in the Envelope Level and Rate setting mixes up the harmonic behavior over time to also help compensate for the diminished complexity and control available because there are fewer Modulators as compared to the “Complex Pad Example” Voice. For another example of this approach for creating lusher pad sounds check out the Voice “Subtle Evolution Pad” on Soundmondo.

So there you have it – two different approaches to pad sounds. As always, take some time to tweak the Frequency, Level, Feedback and Envelope values and listen what happens to the sound. Also play around with the Effects. Modulation effects like the Chorus, Flanger and Phaser mixed with lots of Reverb or longer Delays can be very effective enhancements to the final sound. Finally, some additional pad Voices to check out on Soundmondo: “Aetherium“, “Seraphine 1“, “Seraphine 2“, “Mobius Trip“, “Neeto Repeeto“, “Digi Repeeto” and “Evolviane“.

So have fun – and when you are ready, the next lesson is now available: Lesson 5 – Bass Sounds.

Want to discuss this lesson? Join us for a discussion on the Forum here.

Not had a chance to experience the earlier lessons in Manny’s Modulation Manifesto? Catch up now:

A little bit about the Author: