Dattorro industry scheme

The Dattorro industry scheme is a digital system used to implement a wide range of delay-based audio effects for digital signals.

[1] The common nature of these effects allows to produce an output signal as the linear combination of (dynamically modulated) delayed replicas of the input signal.

The Dattorro industry scheme is based on digital delay lines and to ensure a proper resolution in the time domain, it leverages fractional delay lines, thus avoiding discontinuities.

The delay line can then be described in terms of the Z-transform of the discrete time signal as

When going back in the time domain exploiting the inverse Z-transform, this corresponds to

In this case, interpolation is required to reconstruct the value of the signal that lies between two samples.

is noted above and below as rarely it is taken from the last sample of the tap but instead it changes dynamically.

Setting the coefficients according to the desired effect results in a change of the filter topology.

[1] All the effects can be obtained by changing the parameters of the Dattorro system and by setting the delay ranges according to the following table.

[1] Vibrato is a small quasi-periodic change in pitch of a tone.

It's more of a technique than an effect per se but can be added to any audio signal.

[7] The delay is modulated with a low frequency sinusoidal function and no mix of the direct path of the signal is considered.

The chorus is an effect which tries to emulate multiple independent voices playing in unison.

[8] The flanging effect originated with tape machines.

This effect was created by mixing two tape machines set to play the same track but one of them is slowed down.

This produces a lowering in pitch and a delay of the slow track.

The process is then repeated with the other track reabsorbing the accumulated delay.

[9] This effect is very similar to chorus and the main difference is due to the delay range.

Chorus usually has longer delay, larger depth and lower modulating frequency.

[7] White chorus is a modification to the standard chorus effect aimed at reducing the aberrations introduced by the forward path.

The change consists in adding a negative feedback path with a different and fixed tap point in order to obtain an approximation of an all-pass configuration.

This effect is analogous to that of the Leslie speaker, a particular kind of speaker consisting of a rotating chamber in front of the bass loudspeaker and rotating cones above the treble loudspeakers .