Synth Notes: DX11, DX7II and TX802
2024-10-01
More notes about synthesizers, and pretty pictures from Yamaha Black Boxes.
Yamaha DX11
Image source: Yamaha Black Boxes
A few months ago I wrote about the Yamaha TX81Z. I liked this rackmount synthesizer so much that I ended up also buying the keyboard version, the DX11.
Side tour: Yamaha's FM synthesizer line-up
Yamaha's breakthrough FM synthesizer product was the DX7. This musical instrument was powered by two custom Yamaha IC's called the YM2128 and YM2129. Together these IC's could produce 16 voices with 6 oscillators ("operators") each, so 96 oscillators in total.
In parallel with the YM2128/YM2129 Yamaha started developing simplified FM IC's for use in arcade games and home computers. IC's such as the YM2151 had fewer oscillators (8x4 instead of 16x6) and fewer parameters. Eventually Yamaha started developing keyboards for the (home) musical instrument market powered by descendants of the YM2151. First came the 1985 YM2164 used in the DX100 and its siblings, followed one year later by the YM2414 used in the TX81Z and the DX11. It seems Yamaha was iterating up from the low-cost YM2151 towards the market segment of the DX7.
The DX7 itself got a refresh in 1986 with two new IC's (YM2604 and YM3609) which were used in products like the DX7II ("DX7 mark 2") and the TX802 rack module. The YM2604/YM3609 was supposed to have improved sound quality compared to the original YM2128/YM2129 while still sounding essentially the same.
I find it amazing that Yamaha made so many variations of the same thing. You can read more about all the various IC's here.
Back to the DX11
I love the sound and the ease of use of the simplified synthesis engine of the TX81Z. I only feel that it is held back by its spartan user interface. Because of this I kept an eye out for an opportunity to buy a DX11: that synth would give me the same sound with a better interface. Now that I have a DX11 I can report that is indeed much nicer to use. It also looks very sleek. You can navigate to synthesis parameters much quicker because it has more buttons.
I ultimately prefer keyboard synthesizers over rackmount units. I need a keyboard to play on as I program. The way I play is a reaction to the sound I programmed, and then I change the programming in reaction to how it sounds when I play it. It's a kind of feedback cycle. I know that some people like programming a synth while a sequencer or arpeggiator plays notes into it on repeat but that does not work for me. I get tired from hearing the same notes over and over again and the notes I want to hear depend on the timbre of the sound.
This way of doing sound design works best if the keyboard and the programming interface are integrated. I can put a keyboard next to a rack module and sort of use the same process, but my hands constantly have to move from the keyboard to the rack module and back. It's just more ergonomic to have the programming controls built into the keyboard. Now that I write this, I think this also explains why I don't get along with computer editing software for synthesizers: alternating between playing the piano keyboard and using the computer keyboard and mouse is a pain in the neck.
The DX11 is living up to my expectations: a more ergonomic way to explore the sonic possibilities of the TX81Z.
Yamaha DX7II/TX802
Image source: Yamaha Black Boxes
The DX7II was my first FM synthesizer. I had a false start where I bought a broken one, hoping I could fix it. After a month or so I gave up and I bought a working one, keeping the broken one for parts.
Image source: Yamaha Black Boxes
Several years after my adventure with the broken DX7II I couldn't help myself and I bought a broken TX802. It sounded like it was broken in a different way from the DX7II I was unable to fix before. The seller said it made sound but the sound was "distorted". I soon found out this meant "overmodulated". The machine was almost working correctly but not quite.
I tried disassembling the firmware and I used a logic analyzer to spy on the digital signals exchanged between the TX802 CPU and the Yamaha IC's. In the end I got it working again by replacing the YM3609 in the TX802 with one I salvaged from my broken DX7II. The story of how I got it working again deserves its own blog post perhaps. In the mean time, if you're interested you can look at these notes.
Like with the TX81Z/DX11, I here again own two versions of more or less the same synthesizer. I mostly end up using the DX7II because I am more familiar with it and because it is a keyboard instrument. But the differences between TX802 and DX7II are actually greater than those between TX81Z and DX11 and I keep wanting to better understand the strengths of the TX802 and where I might be able to use them.
The DX7II can be used in 3 different ways: one synth with 16-note polyphony, one synth with 4-note polyphony where each keypress plays 4 slightly detuned voices at once ("unison mode"), or two synths with 8-note polyphony each (the "split" and "layer" modes). The original DX7 could only be used in the first mode: one synth with 16 voices.
The TX802 has "802" in its name because it is structured as 8 independent synthesizers that can each play 2 notes at a time. Because you can link 2 or more of the constituent synths, you can recreate all the modes of the DX7II on the TX802.
One stand-out feature that separates the TX802 from the DX7II is that you can also have it alternate between its 8 constituent synths. If you program the 8 synths with subtly different versions of the same sound, the end result is similar to what you get with old analog polysynths: the timbre of each note you play is the same but not quite. Digital synthesizers like the DX7 can sometimes sound too perfect and the TX802 lets you introduce some quasi-analog liveliness through inter-voice variability. The TX81Z/DX11 can also do the voice alternation trick.
Or you can choose to not be subtle and create an automatic hocket effect.
Hocketing
"Magic Marimba" uses 4 different voice patches: B17, B18, B19 and B20.
This is the TX802 "Magic Marimba" preset which demonstrates automatic hocketing. I start off pressing the same key on the keyboard 11 times in a row. The timbre, octave and left/right/center stereo position changes from note to note. Then you hear me improvise a bit. I'm playing the black keys across 3 octaves. The improvisation sounds more "interesting" because of all the timbral variety and the sudden jumps in octave.
Micro-tuning
Another unusual way to add variation between notes through the alternating mechanism is to use tunings other than equal temperament ("micro tuning"). The intended use is probably to tune the whole synthesizer in one tuning but because the TX802 is 8 independent synthesizers in a box, you can give each of the 8 its own micro tuning scale. Like with the timbral variations, the effects can be subtle or extreme, like in the "Inside the VLSI" factory preset.
"Inside the VLSI" uses 8 instances of the same voice patch: B57 "GlassTines". The little arrows to the left indicate that voice alternation is active.
Each voice in "Inside the VLSI" is transposed down by a different number of semitones.
What's worse, the tunings are a mix of equal-tempered (P01), quarter-tone (P10) and eight-tone (P11).
"Inside the VLSI" uses 8 instances of the same sound "GlassTine". In the first 24 seconds you hear me play a single GlassTine using normal tuning; the notes are C-G-A#-C#. Then I switch over to "Inside the VLSI" and I play the same 4 notes twice in a row. The melody is unrecognizable because each note is played by a synth with a different tuning and transposition.
You could do something like "Inside the VLSI" on the TX81Z/DX11 but it won't let you have both quarter-tone and eigth-tone tuning. You can have at most one non-equal temperate tuning in a multi patch. The TX802 is clearly more flexible here. I think "Inside the VLSI" is beautiful but it's so unpredictable that I don't know if I'll ever use it in a song.
Weirdly enough I find the TX802 almost easier to navigate and program than the DX7II. In spite of being 8 synths in one box it feels less complicated than the DX7II and the numeric keypad on the TX802 works fine as a replacement for the data input slider of the DX7II. Ultimately the DX7II wins out for me though because it is a keyboard instrument.