CHAPTER 21. LIVE AUDIO EFFECT REFERENCE
293
21.7
Dynamic Tube
The Dynamic Tube
Effect.
The Dynamic Tube effect infuses sounds with the peculiarities of tube saturation. An in-
tegrated envelope follower generates dynamic tonal variations related to the level of the
input signal.
Three tube models, A, B and C, provide a range of distortion characteristics known from
real ampli er tubes. Tube A does not produce distortions if Bias is set low, but will kick in
whenever the input signal exceeds a certain threshold, creating bright harmonics. Tube C
is a very poor tube amp that produces distortions all the time. The qualities of Tube B lie
somewhere between these two extremes.
The Tone control sets the spectral distribution of the distortions, directing them into the
higher registers, or through the midrange and deeper.
The Drive control determines how much signal reaches the tube; greater Drive yields a
dirtier output. The intensity of the tube is controlled by the Bias dial, which pushes the
signal into the celebrated realms of nonlinear distortion. With very high amounts of Bias,
the signal will really start to break apart.
The Bias parameter can be positively or negatively modulated by an envelope follower,
which is controlled with the Envelope knob. The more deeply the envelope is applied, the
more the Bias point will be in uenced by the level of the input signal. Negative Envelope
values create expansion effects by reducing distortion on loud signals, while positive values
will make loud sounds dirtier.
Attack and Release are envelope characteristics that de ne how quickly the envelope reacts
