Yamaha Tx81Z - Multi Timbral FM tone generator (1987)
A budget rack featuring a FM variation of traditional DX 6OP.
Budget spin-off from the famous DX-7 FM synthesis, however there are some interesting technical improvement.
RACK (weight: 3.4 kg)
Main panel features a 2 x 16 lines display and 11 push buttons.
Back panel terminal connectors:
- aux outputs
tape interface for data storage.
Front panel terminal connectors:
VOICE CPU is a HD63803XP Hitachi manages 8 digital voices.
The previous DX synthesis was based on a 6 operators system with just pure sinewave and 32 combinations algorithms. The internal TX81Z IC chip YM2414B has only 4 OP and 8 combinations, on the other hand if offers 8 different waveforms including the standard DX Sinusoidal plus 7 computer-generated harmonics variations with partials and fundamentals fixed settings.
are 4 sinewave operators organized as algorithms, assigned as carrier
or modulator, linked between them on different
pathways interacting on their harmonic contents depending on the
varable feedback strength.
- carrier: defines the amplitude and the spectral frequency
- modulator: sets the sound timbre and the relative harmonic contents.
Tx81Z offers 8 different combinations algorithms with frequency ratio or fixed frequency: the output is fed back to its input with 7 different levels feedback, as general rule, high values feedback results in richer harmonic contents.
PERFORMANCE system manages 8 parts each with independent settings:
- mix level
- effect amount
- pan position
- stack mode Eg: 4 voices or 8 monos
- portamento with glide time
- analog out assignment
The processor has some limits and cannot layer some particular algorithm combinations, and Midi response has some freezes with data flows (depends also on the OS EPROM official from 1.0 to 1.6)
LFO there are 2 delayed modulators (frequency range from 0.007Hz to 50Hz)
- LFO amplitude
The modulators can be set to retrigger mode and features 4 shapes: saw, square, triangle and sample & hold.
ENVELOPE there are 4 EG in total: each OP features 1 amplitude EG (4-segments) + a general shift. Very simple Key tracking scale less sophisticated than previous DX line.
EFFECTS not a real DSP but faked simulated by Midi notes tricks reducing the (tiny) polyphony.
There are 3 effect families:
-dDelay: with possible pitch shift and adjustable feedback
- pan moving: stereophonic path with follow velocity or LFO from left to right or vice versa
- chords mode: handles 4 notes
- 128 ROM payches
32 RAM patches
24 RAM performances.
No external storage but full Sysex dump and edit by Midi or tape dump; note that MIDI Sysex strings are NOT compatible with 6OP DX line.
battery soldered 3V Cr-2032
MICROTUNE the 4 OP structures has 13 different microtuning tables: 11 ROM preset + 2 users for non-standard intonation including Equal, pure, major-minor, Vallotti and Werckmeister.