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Glossary
amplifying stages
Each EQ band contains an amplifying stage. The mic pre
contains two, as does the HPF. The original Neve BA338
amplifying stages have been tweaked to improve their
drive ability and stability versus temperature, resulting in
reduced distortion and approximately 9dB more dynamic
range. As a further improvement to the original designs,
each section of the 2081 channel module has its own
power supply filtering.
Channel Bin
Front on, the Channel Bins of the
Custom Series 75 are
almost indiscernible. However each group of eight 2081
channel modules are housed in an aluminum casing
known as a 'bin'. Beneath this are the individual Channel
Bin motherboards. From the rear, each bin can be seen
clearly. Depending on the chassis size, there may be up
to eight Channel Bins.
Current summing
Current Summing is a modern solution to the
'deficiencies' of Voltage Summing. No matter how many
signals you feed to the mix bus of a Current Summing
circuit, the voltage on the bus will remain at 0 Volts.
We call this a “Virtual Earth” - the inverted op-amp
output voltage is 'fed back' to the virtual earth point
via a feedback resistor, resulting in 0V at the op-amp
input. A more sophisticated variant of this circuit is used
to achieve balanced virtual earth mixing as used in
this console. Due to the virtual earth, this design does
not require an input or output transformer. A Current
Summing Mix Bus does not colour the audio.
Modern Output stage
The Modern Output Stage of the
Custom Series 75 has
been designed for sonic transparency and excellent
technical specification. It's a transformer-less balanced
floating output, that can drive balanced or unbalanced
professional grade studio equipment. All op amps are
LM4562 by National Semiconductor, generally regarded
as the best sounding opamp available.
All capacitors in the audio signal path (Modern & Retro)
are WIMA polypropylene film or Rubycon ZLH electrolytic
chosen for long life and superior sonic performance. All
relays, switches and connectors in the audio signal path
have gold plated contacts.
retro Output stage
The Classic Output Stage which was made famous by
the Neve 1073, 1272 and 2254 could be described using
words such as warm, defined and flattering. The only
way to truly know is to listen. Circuitry wise, the sound
is largely due to the BA283 output amplifier and L01166
output transformer. These two components, when used
together, have a significant sonic effect.
Care has been taken to recreate the renowned Classic
Output Stage for the
Series 75 Console. The BA283X
output stage, single ended, class A circuitry with a
gapped core transformer, and the L01166 output
transformer are as it was originally.
All capacitors in the audio signal path (Retro & Modern)
are WIMA polypropylene film or Rubycon ZLH electrolytic
chosen for long life and superior sonic performance. All
relays, switches and connectors in the audio signal path
have gold plated contacts.
stem Outputs
A Stem is a sub-mix output. In music mixing, stems are
more often stereo mixes of just the drums, guitars, or
vocals etc. These can then be subsequently re-mixed
together for a complete stereo mix. The
Series 75 Stem
Outputs are post-fader, and may be used to record just
the sub-grouped signals.
Voltage summing
In the 1970s Voltage Summing was the only way to
sum multiple signals onto a bus. Put simply, the signal
level on the mix bus drops as more signals are fed to
it, typically to around -30dbu. Further, the mix bus must
be designed from the outset to have a fixed number of
sources, and the impedance and bus level depends on
this not changing. The signal passes through an input
transformer and amplifying stage – the “mix amp”. This
input transformer will subtly colour the signal. Once
the signal passes through the mix amp it hits an output
transformer. The output transformer is where much of the
sonic colour comes from. In effect, a Voltage Summing
Mix Bus colours the audio in a way that is pleasing to our
ear.
