The Yamaha TG55 Tone Generator represented a significant evolution in digital sound synthesis, moving beyond the limitations of simple sample playback by introducing a sophisticated voice architecture designed for extensive musical control. At the heart of the system was the second-generation 16-bit Advanced Wave Memory, or AWM2, which processed 16-bit wave data sampled at 32 or 48 kilohertz. This technology utilised 24-bit internal signal processing and high-resolution 22-bit digital-to-analogue converters, resulting in sound quality that rivaled the finest compact disc players of the era. The unit contained 2 megabytes of sampled waveform ROM, providing a library of 74 individual waveforms that served as the fundamental building blocks for sound creation.
Unlike earlier sampled-waveform instruments that offered limited post-processing, the Yamaha TG55 allowed users to shape sounds in real time through an advanced digital filter system. Each voice could be constructed from one, two, or four elements, with each element capable of being assigned a specific AWM2 waveform from the internal ROM or from external plug-in waveform cards. This multi-element structure enabled complex layering of different timbres, such as combining a piano attack with a synthesised brass sustain. Furthermore, the architecture supported split keyboard setups, where different elements could be assigned to distinct sections of the keyboard, allowing for exotic and versatile performance configurations.
The signal path for each AWM2 element followed a precise chain: the waveform passed through Filter 1, then Filter 2, followed by the amplitude envelope generator, before reaching the output. Additional control elements included a pitch envelope generator and two filter cutoff envelope generators. This structure provided deep control over the dynamic characteristics of the sound, allowing musicians to mould and shape the timbre to fit specific musical requirements with precision.
The digital filter system was a standout feature of the Yamaha TG55, offering two filters per voice element. One filter operated as a low-pass type, while the other was switchable between low-pass and high-pass responses. Each filter was equipped with its own 6-segment envelope generator, enabling a virtually unlimited range of dynamic filtering patterns. Users could combine low-pass and high-pass filters to create a bandpass response, or set both filters to low-pass operation to achieve a steep 24-dB/octave rolloff slope, with each individual filter providing a 12-dB/octave slope. To cater to those who preferred the character of analogue synthesisers, the filters included a resonance parameter that could boost the cutoff-frequency peak into oscillation. In a four-element voice, this meant eight filters were working simultaneously, providing immense textural depth.
Beyond filtering, the Yamaha TG55 offered extensive voice editing functions that granted total control over the sonic output. For each element within a voice, users could adjust volume, note shift, detuning, and high and low note limits. Velocity limits allowed for velocity-switched keyboard dynamics, where different elements could be triggered based on how hard the keys were played. Additional parameters included pan position, LFO modulation, and controller assignments. The unit came with 64 preset voices in ROM, but users could create their own from scratch using the bare waveforms or external cards. These custom creations could be stored in any of the 64 internal memory locations or on external voice cards, which held up to 64 voices each.
Expressive performance was facilitated by sophisticated control parameters that put the musician directly in touch with the sound. Standard pitch and modulation wheels performed their familiar functions, but the Yamaha TG55 allowed for the assignment of any MIDI controller to various parameters, including amplitude modulation, pitch modulation, filter cutoff modulation, direct filter cutoff control, envelope generator bias, and volume. After-touch pitch bias was also available, adding another layer of nuance. Velocity switching provided a unique type of expression, bringing different elements into play depending on the intensity of the key press.
The unit featured a built-in effects section that provided essential ambience, leveraging Yamaha’s expertise in digital signal processing. There were 34 programmable effect programs available, covering a wide range of sonic treatments including reverb, delay, early reflection, tone control, and distortion. Specific programs included variations of reverb such as Hall, Room, Plate, Church, Club, Stage, Bath Room, and Metal, as well as delay types like Single Delay, Stereo Delay, Stereo Echo, and Ping Pong Delay. Other effects included Doublers, Pan Reflections, Early Reflections, Gate Reverb, Reverse Gate, and various feedback and combination effects like Delay and Reverb, Tunnel Reverb, and Distortion and Reverb.
In addition to its normal voice play mode, the Yamaha TG55 featured a multi-timbre mode that allowed up to 16 different voices to be assigned to 16 different MIDI channels. This capability meant that the Yamaha TG55, a master keyboard, and a sequencer were sufficient for full-scale music production. Sixteen memory locations were provided for complete MULTI setups, which included voice-to-channel assignments, individual voice volume, note shift, tuning, panning, and effects. The unit also supplied a range of high-quality drum and percussion waveforms that could be assigned to different keys and handled as a single voice, eliminating the need for an external drum machine in many setups.
The Yamaha TG55 was designed for complete MIDI compatibility, featuring a full set of MIDI parameters to ensure versatility in any system. The receive channel and device number were programmable, and a range of bulk dump functions facilitated quick and easy data transfers to bulk storage devices. The stereo outputs were not merely for stereo effects; since each element in any voice could be panned to any position in the stereo sound field, users could create true stereo voices. Any of the 61 individual drum sounds in a drum voice could also be placed anywhere in the stereo field, as could individual voices in multi-timbre setups.
The physical design of the Yamaha TG55 was compact, fitting into a 1U rack-mount size. The front panel included a master volume control and a headphone jack for private monitoring. The display was a 16-character by 2-line backlit LCD, which was easy to read. Data entry was streamlined through a rotary DATA ENTRY control in addition to increment and decrement keys, allowing for fast and precise adjustments. Function groups were accessed via pages to keep the interface organised. The unit also included a built-in demo playback feature. For external storage, Yamaha offered MCD64 and MCD32 Memory Cards, which were light and compact, providing convenient storage for original TG55 voices.
Features
- Second-generation 16-bit AWM2 (Advanced Wave Memory) technology with 24-bit internal signal processing and 22-bit digital-to-analogue converters.
- Versatile 1, 2, or 4-element voice architecture with extensive sample layering and split keyboard capability.
- 74 preset waveforms in ROM, 64 preset voices and 64 internal user voice memory locations.
- Two digital filters per voice element, with low-pass and switchable low-pass/high-pass operation, resonance control and individual 6-segment cutoff envelope generators.
- Programmable 5-segment amplitude envelope generator, pitch envelope generator and extensive individual element editing functions.
- Velocity switching, MIDI controller assignments, modulation and after-touch control for expressive performance.
- 34 programmable digital effects including reverb, delay, early reflections, tone control and distortion.
- 16-part multi-timbre operation with 16 memory locations for MULTI setups, including voice-to-channel assignment, volume, note shift, tuning, panning and effects.
- Built-in drum and percussion waveforms, with 61 individual drum sounds assignable to different keys.
- Stereo positioning of individual voice elements, drum sounds and multi-timbre voices.