Behringer T1954 - Manual (Page 20)

20
TUBE ULTRAFEX T1954
you overdrive a transistor you get a sudden square deformation of the sine signal applied at the input, which
produces an extreme harmonic spectrum at the output.
Non-linear distortions are measured with a distortion factor that consists of the total harmonic distortion [k] and
partial harmonic distortions [k
n
]. The latter are defined as the ratio between the voltage of a single harmonic and
the voltage of the distorted overall signal. Thus, the content of even harmonics is expressed as k
2
, k
4
, ... and
that of odd harmonics as k
1
, k
3
, ... .
U
U
k n
n
=
Formula for calculating partial harmonic distortion
The total harmonic distortion is the root of all squared distortion factors of the second and third degrees. Since
the higher harmonics have only little impact on the measured results, they can be neglected.
k k k
= +
2
2
3
2
Formula for calculating total harmonic distortion
In tube circuits the distortion factor k
2
is used to describe an effect which the human ear classifies as “pleas-
ant”. Also the frequency bands in which distortion occurs play an important role because the human ear
differentiates very clearly, in particular, in the frequency range of human speech.
4.6.5 The best of both worlds
Despite many efforts neither manufacturers nor developers have succeeded so far in simulating these positive
properties of the tube by means of other devices. Additionally, the natural capabilities of the tube to act as a
soft limiter can only be mimicked with highly sophisticated circuitry. Today’s studio technology requirements
are therefore met by a combination of both high-grade semiconductor and tube technologies. In this context,
tubes no longer serve their original purpose as amplifiers, but are used for the detailed shaping of sound.
4.6.6 Studio applications
In a recording studio tubes do not perform the same task as they do in an overdriven guitar amp, where the
considerably higher saturation of the tube(s) leads to a full and often deliberate modification of the input signal
(in many cases combined with a heavy increase in noise floor levels). In the studio more subtle effects are
needed. Here, tube circuits add life to the signal’s tonal character and increase its power to make itself heard.
Often, tubes also increase the signal’s perceived loudness (in relation to the unprocessed signal), i.e. the
perceived loudness goes up although the volume level remains the same. This is because the dynamic range
of the applied audio signal is limited by the tube circuit, while the amplitude of the signal with the lowest
loudness is raised. Thus, increasing tube saturation produces a slight compression effect over the entire
dynamic range.
A similar effect can be perceived when analog tape is saturated. This saturation effect also compresses the
recorded audio material and produces additional harmonics.
5. INSTALLATION
Your BEHRINGER TUBE ULTRAFEX was carefully packed in the factory and the packaging was designed to
protect the unit from rough handling. Nevertheless, we recommend that you carefully examine the packaging
and its contents for any signs of physical damage, which may have occurred in transit.
+
If the unit is damaged, please do not return it to us, but notify your dealer and the shipping
company immediately, otherwise claims for damage or replacement may not be granted.
Shipping claims must be made by the consignee.
5. INSTALLATION