11.0

560 EFFECTS MENU
With the de-emphasis circuit the pre-filter can be undone by an inverse characteristics
curve on playback. However, distortion caused by tape saturation might shift the spectral
balance.
As a result of the enormous complexity of the process of magnetic recording, additional
factors also influence the acoustic result, like, for example, pre-magnetization (bias). This
relates to high-frequency voltage swing (usually in sine form at 150 - 200 kHz) which is then
applied to the tape via the erase head before the same part passes by the recording head
a few centimeters later. This erasure current ensures the equal orientation of the magnetic
particles, keeps the hysterisis loop intact, which is important for the magnetization process,
and functions qualitatively. Low currents do have a brighter sound picture as a result, but
magnetization is inefficient and the maximum recording level is therefore quite low. On the
other hand, a bias current which is too high is associated with losses in highs, but does
allow for higher levels with less distortion.
In addition, memory effects when recording tapes are responsible for a part of the
characteristic sound as time-dependent factors play a role in the feeding of the tape reel
along the heads, for example, mutual inductance and self-erasure.
Regarding the simulation of these processes, we have concentrated on some aspects of
the "real world" and have created a virtual "machine" in am-track, which permits the
following interventions by using the controllers on the interface:
• Level: Sets the input level. You determine when the "tape" is saturated and how great
the effect of the coloring/soiling is. You simultaneously gain more "loudness".
• EQ Low/Hi: Adjust the frequency response (spectral balance controller). You can
choose whether you would like to have an output signal of high bass level or whether it
should have more highs. This alters the pre-emphasis at the "recording end" as well as
playback equalization. In "Expert" mode you can vary the employed frequencies for lows
and highs for distortion and equalization. However, please note that the frequency
response of the simulation will not be neutral even if the "EQ Low/Hi" controller is dead
center. There will always be some slight frequency-selective amplification, but that can
be referred to as a machine's "sound".
• Bias: Moving the operation point (bias adjust). Increasing the bias will result in a higher
"recording level", "magnetic flow" but tape saturation will occur sooner. You will also
increase the above mentioned loss effects, and the result will be a (dynamic) reduction of
the highs. Turning the bias controller to the left results in the opposite effect: the highs
are not reduced, but the signal level stays lower.
• Tape mix (in the "expert" section): Anything that applies to a parallel compression can
also be applied to the tape section. Non-edited transients in particular are responsible
for perceiving "speed", "liveliness" and "freedom", but may be lost in the event of too