VC2 11
NOISE IN THE ENHANCER
Under many normal conditions of use, the enhancer has the effect of
amplifying selected narrow frequency bands in the upper mid range. The
danger is always to overuse the enhancer: This has the effect that any noise
sounds particularly 'scratchy'. The problem is that the existence of these
frequencies is common in quality
recording. The effect can be reduced to almost nothing with careful use of the drive and
enhance controls; but it does take practice.
THE TUBE (THE MAKE-UP AMPLIFIER)
The photoelectric compressor attenuates (reduces the volume of) the audio signal. This
gain loss has to be made up in an amplifier. Normally this amplifier is solid state and
adds no noise or distortion of any sort. In the JOEMEEK Tube Channel the amplifier
used is a thermionic tube. This old technology is used to produce a particular sort of
'warm' sound that is a product of the way thermionic tubes work.
TUBE DISTORTION
All amplifiers produce distortion of some sort. Modern solid state circuits have
effectively eliminated distortion down to such low levels that they are very difficult to
detect. However, such distortions that are left are basically 'third order', these are
distortions that impose microscopic additions to the sound in an unmusical way; that is
the distortion products are not musically related to the original audio signal.
Unfortunately for electronics designers, the human ear is extremely good at noticing
these very low levels of distortion and recognising them as ‘unpleasant'. This is why all
early 'transistor' radios had such a bad reputation for sounding nasty.
But not all audio distortion is unpleasant; the tiny distortions produced by thermionic
valves (or tubes) is basically second order distortion, harmonically related to the audio
signal and pleasant to listen to. So what little distortion is produced by a well designed
tube amplifier is good to listen to and actually enhances the 'quality' of the sound;
although when it is measured on sophisticated test equipment, it will actually show a
higher harmonic distortion figure!
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