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DigiTech RDS 7.6 Time Machine Manual

Much of the following information regarding the DigiTech RDS 7.6 delay is reproduced in whole, or in part, from the DigiTech Digital Delay Systems Owners Manual. It is intended for personal use and educational purposes only. Any other use is expressly forbidden and subject to copyright protection by the actual owners(s) of the materials.
FLANGE 1.5 to 15 msec.
CHORUS 15 to 120 msec.
DOUBLE 120 to 950 msec.
ECHO 950 msec to 7.6 sec
REPEAT HOLD up to 7.6
SAMPLING up to 7.6 @ 15 kHz volatile memory

All of the DigiTech delays' front panels are divided up into four main functions areas: the LFO/VCO controls, the delay time range selection buttons and control, the signal manipulation controls, and, the input and output controls.


A bit of explanation of how the delays work at this time will help you understand the workings of the front panel controls.

The time delay produced by these units is a product of two things: the amount of memory available in the unit, and the frequency of the internal voltage controlled oscillator (VCO). The memory available is chosen by selecting one of four push buttons on the front panel, (or by the ARM/TRIGGER PULSE synchronization feature on the RDS 2001 and RDS 7.6). The VCO is set by one of three things:

(1) the TIME DELAY control on the front panel,

(2) the VCO CONTROL jack input, which allows remote control of the time delay with a foot pedal that delivers a control voltage of 0 to +5 volts, or

(3) the low frquency oscillator (LFO).

The LFO is active whenever the WIDTH control is turned clockwise from its "off" position. The LFO makes an automatic variation of time delay, which can be imitated by rotating the TIME DELAY knob back and forth, (or by using the VCO control jack). It is this low frequency oscillator that automatically makes the chorus effect and flanging effect sounds. In longer delay times such as the doubling and echo settings the LFO will make sounds that are not normally useful in music. The maximum amount of WIDTH or time change ratio is 9 to 1 (9:1) that can be controlled from the TIME DELAY control, the VCO CONTROL input jack, or automatically from the LFO.


The WIDTH and SPEED controls work together to form the LFO.

The WIDTH control set the amount of time delay variation by the LFO. When the WIDTH control is fully counterclockwise no variation is allowed, and when it is fully clockwise the variation of 9:1 is allowed.

The SPEED control adjusts the sweep speed of the LFO, which automatically changes the rate of time delay change. For the SPEED control to have an effect, the WIDTH control must be on any setting other than minimum.

The DELAY time control sets the amount of time delay when the WIDTH control is off. When the WIDTH control is on, it sets the center time setting, around which the delay will vary.


These buttons select specific rages of delay time by effectively changing the amount of memory used by the system. This allows for quick and easy selection and set-up.
FLANGE 14 msec. -- 512 bytes
CHORUS 119 msec. -- 4,096 bytes
DOUBLE 950 msec. -- 32,768 bytes
FLANGE 7600 msec. -- 262, 144 bytes

An LED under the button will light when that range has been selected.

When the ECHO time range button is pushed, the LED underneath will flash on-and-off four times during each cycle of the memory. The RDS 7.6 flashes eight times. This can be used as a metronome to help time your playing to the sample length (See the section on sampling).

Memory size is also set with the ARM/TRIGGER PULSE memory reset function on the RDS 2001, and 7.6. This feature is explained in more detail in the REAR PANEL section of this manual.

NOTE: When powering up or changing the delay time range on any of the units, the output is muted to allow the machine to clear any random data from the memory. The mute time may last as long as 10 seconds depending upon the delay time you have selected.

The REPEAT HOLD button stops anything else from being "recorded"in the memory of the delay unit and endlessly repeats whatever was last put in just before the button was pressed. While the REPEAT HOLD function is activated, a lead line may be played over the top of a repeating riff and mixed via the mix output control. This function can also be activated through the REPEAT HOLD input jack on the rear panel.

The ARM/TRIGGER button switch appears only on the RDS 2001 and the RDS 7.6, and will be discussed in more detail in the section on sampling.

The DELAY/SAMPLE MODE switch appears on the RDS 2001 and the RDS 7.6, and selects the operating mode of the delay. This switch should be put into the "NORMAL" position when no sampling functions are wanted. Always put the unit in "NORMAL" position when first turning on the unit. Putting the DELAY/SAMPLE MODE switch in either the "SAMPLE" or "TRIGGER" positions, automatically sets the delay time to the ECHO range. (For a discussion of the function of this switch, see the section on sampling.)

The feedback INVERSION switch inverts the phase of the delayed signal as it is fed back into the delay. When the switch is out, the phase is normal. Pushing the switch in lights the INVERT PHASE LED, indicating that the phase is inverted. Inverted phase changes the character of the flanging and chorusing sounds.

The FEEDBACK contol adjusts the amount of delayed signal that is fedback through the delay unit again. By turning the FEEDBACK control up, more echoes are heard. Increased feedback will also make the flange sound more pronounced. With the FEEDBACK control fully clockwise, the feedback is set at 100%, allowing for sound-on-sound layering, using the INFINITE REPEAT function of the delay.

The MIX control adjusts the proportion of the original (dry) signal to the delayed (wet) signal that is sent to the MIX OUTput and PHASE OUTput. When the mix control is fully counterclockwise, only the dry signal is sent to the outputs, and in the fully clockwise position, only the wet signal is sent to the outputs.

The OUTPUT control sets the level of the output signals sent to the MIX OUTput and PHASE OUTput, but does not change the level of the DRY OUpt signal.

The INPUT control sets the signal level that is fed into the delay unit.

The LED bar graph indicates the strength of the input signal level. The input signal should be as high as possible with lighting the red (+3) LED. Signals greater than this will distort the unit.

The EFFECT switch inserts the delay effect into the signal path or removes it.

The POWER switch turns on the power to the unit.
The INPUT LEVEL SENSITIVITY SWITCH lets you select the input level which will allow the greatest dynamic range with the least noise from the digital delay. The -30 position is used for the direct input from an instrument or guitar. The -10 position is used when the delay is used as part of an effects loop from a guitar amplifier or as an outboard unit from a mixer when the signal strengths are closer to line level. This switch, when used with the INPUT and OUTPUT controls of the digital delay, can optimize the dynamic range and signal-to-noise performance of the unit.

The INPUT to all models of delays is a 1/4-inch mono phone jack, which accepts unbalanced inputs and has an input impedance of 470K ohms. The units will accept a maximum input level of +18 dBv (ref.:0.775 V rms).

The DRY OUTput is a loop-through connection, so the signal may be daisy-chained on to other effects. The connector is a 1/4-inch mono phone jack with an output impedance of 470 ohms and is unaffected by the INPUT and OUTPUT LEVEL controls.

The MIX OUTput connector is a 1/4-inch mono phone jack with an output impedance of 470 ohms. The signal from this output is a proportion of the dry and wet signals as adjusted by the OUTPUT mix control and its strength is adjusted by the OUTPUT LEVEL control. The maximum output level is +18 dBv (ref.:0.775 V rms) into a load of 10K ohms or higher, or is +14 dBv (ref.:0.775 V rms) into a load of 600 ohms.

The PHASE OUTput is a phase inverted (180°) output of the MIX OUTput signal. This is useful for a stereo amplifier set-up and creates a psuedo-stereo effect. Send the MIX OUTput to one amp and the PHASE OUTput to the other to create the stereo ambience.

The DELAY KILL is a 1/4-inch phone jackwhich can be used to mute the delayed signal, allowing the dry signal to pass. A foot switch will mute the delayed signal when the tip conductor is connected to ground. When the delayed signal is muted (foot switch is activated), the dry signal is allowed to pass to both the MIX OUTput and the PHASE OUTput (180 ° out of phase).

The RECORD CANCEL is a 1/4-inch mono phone jack which appears on the RDS 2001 and RDS 7.6 delays, and can be used to cut off the input to the delay section of the units. This allows editing of the delayed or sampled signal on-the-fly to precisely get the desired line or lick into the delay. This function is most easily used with a momentary foot switch.

The BYPASS is a 1/4-inch mono phone jack that allows foot switch control of the EFFECT button on the front panel of the delay. Activation of the BYPASS shuts off the input and output of the delay section of the unit. The DRY OUTput, the MIX OUTput, and the PHASE OUTput continue to produce the original signal unaffected by the delay. This function is best used a push-on/push-off type foot switch. The EFFECT in/out switch on the front panel must be in the out position to give control to the BYPASS foot switch.

The REPEAT HOLD is a 1/4-inch mono phone jack that allows foot switch control of the REPEAT HOLD feature of the delay. Use a switch that connects the tip conductor to ground when activated.

The VCO CONTROL VOLTAGE input is a 1/4-inch mono phone jack, which allows control of the delay time with a volume type pedal. Use a pedal that provides a control voltage of 0 to +5 volts. Plug the output of the pedal into the VCO VOLTAGE CONTROL jack.

The RDS 2001 and RDS 7.6 are equipped with a ARM/TRIGGER PULSE input. a 1/4-inch mono phone jack, which is designed to be connected to a synchronous +5 volt pulse generator, like a drum machine. When the RDS 2001's or RDS 7.6's DELAY/SAMPLE MODE switch is in the NORMAL position and a pulse is received at the ARM/TRIGGER PULSE jack; the memory is reset, thus adjusting the number of bytes of memory to be used by the delay section. This feature allows synchronizing of the memory-length time with an interval determined by the device generating the sunc pulse. When used for sync, the time between the pulses must be less than the delay time of the unit.

When the RDS 2001 or RDS 7.6 is in the trigger position, the recorde sample stored in memory can be started by a synchronizing pulse. The time between pulses may be any length of time, however, if it is shorter than the sample length, only part of the sample will be heard before it repeats again.

A pulse fed to the ARM/TRIGGER PULSE input jack will also arm the record sample function when the DELAY/SAMPLE MODE switch is in the SAMPLE position (see the section on sample recording).

The RDS 2001 and RDS 7.6 are equipped with an ARM/TRIGGER FOOT SWITCH jack which allows you to execute the ARM/TRIGGER button functions remotely with a foot switch.

A FUSE is provide to prevent damage to the delay unit by excess current. To replace a blown fuse, push a small tool, like a small screwdriver into the hole on the bottom of the fuse holder. This will release the catch and allow the fuse and holder cap to pop out. Replace the fuse with a .25 amp slow blow fuse to prevent possible damage to the delay unit.

REMEMBER: When powering up or changing the delay time range on any of the units, the output is muted to allow the machine to clear any random data from the memory. The mute time may last as long as 10 seconds depending upon the delay time you have selected.

Most of the musical effects produced by the digital delays are a function of one of three variables: the DELAY TIME length, the amount of delay time length variation (WIDTH), and the SPEED at which the delay time length varies. The intensity of the effect is changed by the FEEDBACK control and the MIX control.

Flanging uses very short delay times (1 to 12 ms.) and usually a lot of width at a slow speed. Width refers to the ratio of the longest to shortest delay time; the more width the higher the ratio. Speed refers to hw fast the delay time changes. A fast speed is used for vibrato and shimmer type sounds, while a slow speed is used for smooth sweeping type sounds. The flanger's characteristic sound comes from mixing the dry and delayed signal together. At some frequencies the signals combine, and at others they cancel, creating a series of peaks and valleys in the frequency response. These peaks and valleys are commonly referred to as a comb filter. Regeneration makes the comb filter effect more pronounced, adding a resonant flavor to the sound.

Chorusing uses longer delay times, (4 to 50 ms.), less width, and no regeneration. When using delay times in this range varying the delay time will cause the pitch of the delayed signal to be changed, Mixing the delayed signal with the dry signal also causes notches and peaks in the frequency response. However, in this range of delay times the notches and peaks are close enough together that any coloration is very subtle. Varing the delay time causes the notches and peaks to slide up and down in frequency. This, combined with the mild pitch shift, is what gives chorusing its characteristic sound. Personal preference plays a big part in setting up a chorus, as there are many different settigs that sound good. To set up a chorus: first set the TIME RANGE SWITCH to 56 msec and DELAY TIME to a medium setting, or to 225 msec and a short setting; and the width control to a medium setting. Set the SPEED control to the desired sweep rate and then re-adjust both the DELAY TIME and WIDTH controls to achieve the desired chorus sound. Balance the SPEED setting against the WIDTH setting to avoid and "out of tune" sound. Slower SPEED settings (sweep rate) require wider WIDTH settings (delay time variation), and faster SPEED setting require narrower WIDTH settings. Longer TIME DELAY settings create a thicker sound and shorter TIME DELAY settings create a more colored sound in a chorus effect.


Doubling uses slightly longer delay times than chorusing, (40 to 80 msec.) and no width or speed. Rather than sounding like two diffeent players playing the same line as in chorusing, doubling does what it sounds like - the same line played just slightly behind the original. The signal is delayed enough to be heard as two signals, but with little comb filtering effect. For doubling, set the TIME RANGE SWITCH to the 225 msec position, the DELAY TIME control to medium low, and the MIX and FEEDBACK controls as desired.

Slap back uses a longer delay time than doubling (50 to 100 msec.). Slap back sounds like a very quick, single echo, something like the bounce off of the back wall of a small, absorbent concert hall. Set the TIME RANGE SWITCH to the 225 msec position, DELAY TIME low, FEEDBACK low and MIX control as desired.

Echo can use almost any of the delay time settings of the digital delays from 250 msec to full delay time available. Adjust the DELAY TIME for longer or shorter echoes. Add FEEDBACK for more than one repeat to smooth out the sound.

INFINITE REPEAT is the ability of the DigiTech digital delays to record a sound up to 1.9 or 7.6 seconds in length and continually play it back like a tape loop. To use the INFINITE REPEAT, set the MEMORY LENGTH SELECTION switch to ECHO, DELAY TIME control to the amount of delay time desired, and MIX as desired. The ARM/TRIGGER PULSE input on the back of the RDS 2001 and RDS 7.6 may instead be used to set the amount of delay time in order to synchronize it with a drum machine. (See the section on SYNC input). Play a riff in time with the delay, press the INFINITE REPEAT button, or the foot switch if one is connected. The rhythm will now be stored in memory and will continue to repeat until the INFINITE REPEAT switch is pressed again. While the INFINITE REPEAT switch is depressed, anything that is played into the unit comes out as a dry signal mixed with the repeating rhythm. Note that the EFFECT switch may be pressed without erasing the memory. Another touch of the EFFECT switch will bring the rhythm riff back.

SOUND ON SOUND is achieved with the INFINITE REPEAT foot swith. Put down a rhythm riff as explained above. Turn the FEEDBACK control all the way up. Press the INFINITE REPEAT foot switch, play a lick that fits the rhythm, and press the INFINITE REPEAT foot switch again. With this method, several tracks may be stored in memory, however, the earlier tracks will be attenuated (reduced) slightly.


The RDS 2001 and the RDS 7.6 are the only models [at this time] capable of sampling sound. Sampling is the recording of a sound in the memory of the unit so that it may be played from the beginning whenever you want. The sound will remain in memory until it is erased, replaced, or the power is turned off.

To sample a sound: push the ECHO delay time range button (note that the LED underneath the button will begin to flash), turn the DELAY TIME control to the desired amount of delay time (or set the pulse time from a drum machine) and place the DELAY/SAMPLE MODE switch in the "SAMPLE" position. Make sure that the level control is up, and delay is receiving the proper level.

Press the ARM/TRIGGER button to arm the sampling function. The sampling function may also be armed by a foot switch connected to the ARM/TRIGGER FOOT SWITCH jack on the rear of the delay panel, or a pulse fed to the ARM/TRIGGER PULSE input jack on the rear of the delay. As soon as you play a sound into the unit, the REPEAT HOLD LED goes off, indicating that the unit is recording a sample. The REPEAT HOLD LED comes on when the sample memory is full and the unit stops recording. There is no other way to begin the sampling other than to play into the unit. The RDS 2001 has a maximum sampling time of 1.9 seconds, and the RDS 7.6 has a maximum sampling time of 7.6 seconds. The sampling time may be shortened with the DELAY TIME control, or a pulse into the ARM/TRIGGER PULSE input jack. The flashing LED under the ECHO delay time range button is useful in timing your playing to the sample time length. The LED flashes on-and-off four times per sample time length on the RDS 2001 and it flases eight times on the RDS 7.6. This metronome-like flashing automatically resets when you begin the sample recording or when you press the ARM/TRIGGER button in the sample TRIGGER mode. So it automatically synchronizes to beat out its four (or eight) flashes for each memory cycle.

Playback of the sample may be done in three different ways: place the DELAY/SAMPLE MODE in the TRIGGER position, and (1) push the ARM/TRIGGER button on the front panel, or (2) depress a foot switch connected to the ARM/TRIGGER FOOT SWITCH jack on the rear panel, or (3) trigger the playback with a pulse wih another device, like a drum machine, into the ARM/TRIGGER PULSE jack.

Sound-On-Sound recording is easy to do with the RDS 2001 or RDS 7.6 in the sample mode. Set the delay to the same settings as when making a sample recording: turn the DELAY TIME control to the desired amount of delay time, be sure the WIDTH and SPEED controls are off, place the DELAY/SAMPLE MODE switch to the "SAMPLE" position, make sure that the level control is up, and delay is receiving the proper level, and turn the FEEDBACK control all the way up. This way, whatever is recorded in the memory will be re-recorded at the same time the new signal is layered with it as you play. To record the Sound-On-Sound sample: be sure the unit is in the SAMPLE MODE, arm the system by pushing the ARM/TRIGGER button (or depressing a foot switch connected to the ARM/TRIGGER PULSE input jack) and begin to play. The unit will immediately begin the recording process and also play back the signal that is stored in memory. Use of the RECORD CANCEL, BYPASS, and DELAY KILL foot switches will allow you to edit the material recorded in the sample recording.

The ability of the RDS 2001 and RDS 7.6 to delay, repeat infinitely, sample, record sound-on-sound, and edit makes for an infinite number of creative possibilities.


DigiTech digital delays give you features, the flexibility, and the possibilities for superior music effects. All of the settings and set-ups possible with these units is far beyond the capacity of this manual, therefore, the only way to realize the full potential of these capabilities is to experiment with the unit.


Frequency Response: Wet - 20 Hz to 15K Hz, +/-1dB (RDS 3.6: 20 Hz to 7.5K Hz, +/-1dB) Dry - 20 Hz to 20K Hz, +/-0.5 dB.

Signal to Noise Ratio: Wet - greater than 85 dB. Dry - greater than 90 dB.

Maximum Input Level: +18 dBv (ref.: 0.775 V rms).

Input Impedance: 470K ohms.

Maximum Output Level: +18 dBv into 10K ohms or higher. +14dBv into 600 ohms.

Output Impedance: 470 ohms.

Maximum Overall Gain: 20 dB

Trigger Pulse Input: Accepts +5 volt control voltage.

VCO Control Voltage: Accepts 0 to +5 volt control voltage.

Dimensions (all units): 1.75" H. x 19" W. x 8.5" D. (45 mm H. x 479 mm W. x 214 mm D.)

Weight (all units): 5.5 lbs (2.5 kg.)

Specifications are subject to change without notice.

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