Marc Marc
TD Cross Generator

  full panel

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The TD Cross Generator is a modular analog device based on classical synthesizer techniques and featuring 'rare' options which intend to stimulate the joy for exploring experimental concepts in electronically generated music. This application is fully hand made (BTW: a XX Cross Generator also can be made with dull colors ;-).

How the TD fits into a 19 Inch rack

Thanks for background photography to Dijkman Musical Store (Amsterdam).

third generation, 5U high. third generation, 8u high. third generation. 12 High.

Some picture of the third generation 5, 8 and 12 u high pre-design. The third generation combines the originality of the Cross Generating concept with the full compatibilty with musical oriented analog synthesizers.

f generators
The TD counts two voltage controlled function generators - with both FM and AM controls. Theķ can be used as audio wave form generators, low frequency modulation generators and as Ring modulation effects on audio signals. They can generate sinusoidal, triangle, Saw Tooth, Ramp, Square and pulse wave forms. Hard and Soft Synchronization is possible to create complex wave forms and sounds. Each generator is connected to a Balance control and a wave form selector. These Balance controls provide a signal for an internal patched cross feedback loop to create complex feedback controlled sound patterns which you never thought of would be possible.

A modulation VCO generates aņ adjustable wave form to be use for modulation purposes. This may be either a Low frequency or an audio frequency. The wave form is tunable between Saw Tooth, Triangle and Ramp and also a Square/Pulse is available (Pulse width tunable). By using the FM input you can control the frequency by an external voltage. The MVCO is very useful in many different patches as being a third hand (the other two are the main fGenerators)

The Preset Unit is a touch controlled device that lets you change a control voltage manually. It may function as a small keyboard to play in real time with the parameters you have connected the Sequencer voltage output to. With the 8 pot controls you can set a voltage for each position. It is a very playful extension to the TD.

The PSU unit can be switched from manual control to sequencer control. You then have an 8-step analogue sequencer available with extra HOLD and RESET options. With this sequencer you also can generate complex patterns (random or pseudo random) by using the HOLD and RESET features (which can be controlled externally by other internal generators or foot switch control). With this sequencer you only compose a small amount of notes and then let a certain patch do the rest for you - creating interesting patterns based on your base notes. Both HOLD and RESET are synchronized with the adjustable beat rate. In combination with one of the internal Quantizer unit the sequencer can provide you a tuned melody pattern when used in combination with the fGenerators.

The Sample and Hold unit provides you random or pseudo random based voltage patterns which you can use to control parameters of other modules. Melody, amplitude timbre patterns. Actually anything you can control with a voltage (or MIDI through a converter) becomes very playful when using a Sample & Hold unit.
With the Clock generator you can set the speed (rate) of sampling the patchable input signal. The input really can be anything you like to apply (other control voltages or any audio). At the command of the Clock pulse, the S&H unit store the momentary amplitude of the input signal (voltage) and this level (amplitude) becomes available at the output until the next sample command. In combination with one of the internal Quantizer unit the S&H can provide you a tuned melody pattern when used in combination with the fGenerators.

Noise & Low Pass
The TD also is equipped with an analogue Noise generator providing White and Coloured Noise far more better then any digital noise (components are especially selected to generate a perfect analogue noise) . This Noise can be used to feed external filters to create any Rain, sea, storm etc. effects. Also the Coloured Noise is fed to a LP (extreme Low Pass filter) to create a Random voltage. With the SLOPE control you can adjust the speed of the Random voltage. This random voltage is internally used to feed the S&H unit to create full random patterns but can be used to control any voltage controlled input to add life to a sound.

The TD also is equipped with a combination of a Pre amplifier and an Envelope Follower. The Pre-AMP is meant to amplify external signals such as from a microphone, pickup element or standard audio sources. It brings the signal to a level that it becomes useful to function as a voltage for further treatment and to control the voltage controlled inputs of the TD. The Pre-AMP can both deal with DC and AC voltage and has a gain range from 2 times to 2200 times - also can be used to overdrive any input signal (distortioner).
The Envelope follower normally is connected to the Pre-Amp to convert microphone or pickup signals into control voltages which are useful to control the other units of the TD. manipulating Voice effects or creating a Synthi-drum is the main goal but the ENV unit may be patch in many ways to manipulate any signal.

The TD also is equipped with two Quantizers. They round up any incoming analogue voltage to a value which correspond to the nearest tuneā note - based on a 12 notes per Octave system. Standard the Quantizers are connected to the sequencer output and the S&H output but 1 of the Quantizers can be fully patched.
This is not visible yet at the front panel design because it was a later extension which still need to be implemented in the existing design.

LOG converters
The TD also is equipped with two Linear to Logarithmic converters. They provide a control voltage that is based on the musical ratio between linear control voltage and the final musical result. In context to the fGenerators they provide a voltage which makes the fGenerators be playable with a keyboard. But, they also may serve a wave form shapers or converting any voltages from other units to sound in their effect more natural.


New window: Read comprehensive manual . View Block Diagram . View third generation

More details about the roots of a device such as the TD Cross Generator,
you can find at the Sonic Laboratory

Back to MAIN Index - Back to ELECTRONICS Index

Also view the GEAR catalog which contains many informative chapters on analog musical devices and fundamental issues on electronic music.

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This page and all contents: (C)2002 by Marc Marc Amsterdam