The Yamaha YDD-2600 utilises 16-bit linear sampling at a nominal 50 kHz rate to support a full 20 kHz bandwidth and provide dynamic range of greater than 90 dB. Careful attention to both Analog-to-Digital (AID) and Digital-to-Analog (DIA) conversion, and to anti-aliasing filter circuitry keep the distortion below 0.03% at maximum output level (1 kHz reference). The sophisticated audio processing and control functions of the YDD-2600 are made possible by advanced LSI chips (Large Scale Integrated circuits).
The back lit LCD display on the main unit can be set to display the delay times of all 8 outputs simultaneously, with a cursor showing the “selected” output which is currently being programmed. Alternately, the display can show the physical air-transmission “distance” represented by the delays, or the number of “samples” represented by the delays.
The sample time, normally 1/50,000 of a second (20 microseconds), can be altered for precise synchronisation. In addition, once all 8 outputs have been set for the desired delay times, the entire unit can be offset in delay time, so you don’t have to reprogram 8 outputs.
In the near future there will be a digital signal input (to avoid unnecessary D/A and A/D conversion when working with an already digitised audio signal). An RS-232 computer interface, and separate serial 110 (Input/Output) connections permit the Yamaha YDD-2600 to be remotely controlled by a computer.
User memories may be recalled, or entire panel settings changed via the digital control interface. An external clock input permits exact synchronisation with other digital processors, as well as other special effects. Additionally, a parallel digital I/O connector mates to an optional expansion unit for longer delay times.
Individual outputs can be bypassed (input connected directly to output) or all 8 outputs can be bypassed at the press of a button; the bypass status is indicated on the LCD panel. the unit can be placed in a “LOCK” mode so that inadvertent pressing of various buttons will not change the mode or delay times.
The Delay for Large Sound Reinforcement Systems
In large concert halls, theatres, amphitheatres, and so forth, it is not often possible to cover the audience from the main stage “speaker cluster” because sound levels would have to be too high in the front in order to reach the rear with adequate level.
In such cases, the audience may be divided into “zones,” each of which is fed by different power amps and loudspeakers. By using the Yamaha YDD-2600 to obtain the appropriate delay times for the various zones, the sound that anyone in the audience hears will be synchronised with the on-stage cluster.
While we often tend to think of a delay system as a means to create echoes, in this case the Yamaha YDD-2600 actually avoids echoes. With a monaural sound system, up to 8 different zones can be selected; with a stereo system, up to 4 different zones can be selected for each side of the house.
A “distance” mode for the Yamaha YDD-2600 display makes it easy to select the proper time delay; you can directly enter the distance to the speakers instead of having to calculate the number of milliseconds delay based on the speed of sound. Or you can directly enter the number of milliseconds (up to 2.66 seconds maximum delay in the 1 in mode).
A Sophisticated Signal Processor for the Studio
Whether the task is making records, producing radio shows or mixing film/video soundtracks, the Yamaha YDD-2600 offers exciting possibilities. For example, using just a single input signal and setting the unit to its 1-IN mode permits the sound to seemingly “bounce off the walls” as it emerges from the 8 outputs at different times. These 8 outputs can then be mixed into a mono, stereo or multichannel soundtrack to achieve incredible depth.
A stereo sound can be delayed with 4 discretely set outputs for each input. In fact, because the Yamaha YDD-2600 can accommodate 2 stereo inputs the unit can take the place of 2 conventional stereo delay systems (or 4 mono delays) – a tremendous savings in rack space and money for the sophisticated production facility.
A Necessary Tool for Satellite/Microwave Audio Links
When you’re trying to get the audio to sync with the picture on a satellite up/down link, the Yamaha YDD-2600 becomes an absolute necessity. The Yamaha YDD-2600 basic delayed output can be set with a very high degree of precision – within one sample time.
Given its 50 kHz sampling rate, that means you can set the delay to 20 millionths of a second resolution. You won’t see the smoke before you hear the crack of the bullet – nor will you hear it before you see it. What’s more, with the increasing trend toward stereo TV soundtracks, particularly in cable/satellite systems, the YamahaYDD-2600’s double stereo program capability makes good economic sense.
A Tremendous Asset for Disc Mastering
Until recently, the only way to optimise cutting pitch (groove spacing) and cutting depth when making master lacquers was to use a specially modified tape reproducer with two playback heads. The first head in the tape path was the “preview” head, and it sent the signal to the cutting computer which adjusted the lead screw and cutter head height in anticipation of the audio which was about to arrive at the cutting head.
The audio was delayed before it went to the cutting amplifier and head by means of a zig-zag tape path on the way to the main playback head. With the Yamaha YDD-2600, a conventional tape reproducer may be used for disc mastering. The signal from the tape head is split; it goes directly to the cutting computer for “preview” purposes, and to the YDD-2600, which delays the stereo signal an appropriate time and then feeds the cutting amp and head.
Because the YDD-2600 signal quality is superb, there is no audible degradation of the sound, and the flutter-inducing guides of a long tape path are eliminated along with the extra maintenance for a second head. A further advantage is that the Yamaha YDD-2600 can be used in live “direct to disc” sessions, enabling the cutting computer to function where it could not previously be utilised.
This relieves the burden on the mastering and mixing engineers by automatically preventing over-cutting, shallow grooves, excess land width and groove kissing. Similarly, any digital recorder now may be used. The Yamaha YDD-2600 delivers precision, flexibility, and a broad range of control features that were previously unavailable in a compact digital delay system. It represents the current state of the art in digital signal processing technology.
The Rear Panel
The Yamaha YDD-2600 rear panel features electronically balanced XLR type inputs and outputs matched to a +4 dB line level. An RS232C “TO COMPUTER” connector is provided for easy interfacing to a computer system which will be used to control the YDD-2600. A REMICOMP switch selects control from either the standard remote-control unit (connected to the REMOTE connector) or the computer.
A parallel DIGITAL I/O connector is provided for connection to a delay extension unit, and a serial 4-in/4-out DIGITAL I/O port is provided for direct processing of already digitised signals. An external word clock input is provided permitting the sampling clock to be derived from an external function generator or other digital equipment. An INTIEXT switch selects either the internal clock or an external clock when the EXT. W, CLK input is used.
Extensive Control and Multi-M0de Versatility
The Yamaha YDD-2600 consists of two units: a main rack-mountable chassis with local control of many parameters, and a small hand-held remote-control unit with still greater control capability.
The remote unit has an alphanumeric LCD (Liquid Crystal Display), and the main unit has a back-lit LCD. These displays indicate the selected delay times, whether a given output is bypassed, and other important data. There are four balanced XLR inputs, each with ns own recessed, detented level control and 4 16-LED level meters.
A Stereo headphone monitor output facilitates setup and testing; it may be set for MONO monitoring (the output of the selected channel only fed to both ears) Or for INPUT/OUTPUT (the selected output to one ear, and the corresponding input to the other). The delayed audio outputs are accessed by 8 balanced XLR connectors (+ 4 dBm nominal).
The YDD-2600 has 3 modes of operation:
- 1 IN MODE
1 input x 8 discrete outputs: up to 2,621 milliseconds delay each output - 2 IN MODE
2 x (1 input x 4 discrete Outputs up to 1,310 milliseconds delay each output - 4 IN MODE
4 x (1 input x 2 discrete Outputs up to 655 milliseconds delay each output
Red LEDs above each of the 4 INPUT LEVEL controls turn ON to indicate the active inputs (and hence the selected mode of operation).
You can store entire setups in any of 12 user-programmable memories (4 memories for each of the 3 operating modes). In addition, provisions are made for an additional 10 read only memories (ROM) which may be useful in custom installations where system requirements are regularly changed between several “fixed” configurations.
