Audio Note M8 RIAA - Manual (Page 6)

Congratulations on your purchase of the Audio Note (UK) M8 RIAA phono stage.
It has been specifically engineered for sonic performance rather than technical
specification, and fulfills all Audio Note (UK) Level 5 criteria: -
Pure Class A operation
Zero negative feedback
Single Ended circuit topology
Valve rectification
Materials and component quality
It is well known that the accurate reproduction of music, not just sound, requires the
purity of the incoming signal to be preserved. It is therefore not difficult to conclude
that, in order to achieve this goal and to retain the musicality of the original
performance, the complexity of the circuitry itself must be kept to a minimum.
In response to this, the M8 RIAA phono stage uses a single-ended, zero feedback
circuit topology. This is simply the most linear design possible, demanding pure
Class A valve operation and removing the need for a phase splitter, which introduces
unnecessary crossover distortion.
In contrast to the majority of the audio industry, we design our circuits with the aim of
minimising non-harmonic and time base anomalies, rather than producing
vanishingly small harmonic or low intermodulation distortion measurements. These
non-harmonic amplitude and time base distortions have a highly perceptible and
adverse affect on the signal waveform, and it is far more important to address these
factors than participate in the increasingly irrelevant numbers game that chases
‘perfect measured response’.
As a result, the M8 RIAA phono stage was designed for maximum linearity and
minimum transient distortion, and avoids the need for detrimental ‘corrective’
measures, such as inherently error-prone feedback loops.
At the heart of the M8 RIAA is an exceptionally fine Moving Magnet phonostage
which uses three CV4068 / 13D3 valves. This is followed by an ECC82 and 6463 line
stage, and both sections are powered by their own dedicated 6X5 valve rectified
power supply based on the M10’s Galahad PSU. These power supplies also
incorporate an ECL82 for voltage regulation and an OB2 as a voltage stabilizer.
Audio Note (UK) Silver wiring, Tantalum resistors, Black Gate capacitors and Audio
Note (UK) Silver foil signal capacitors are used in critical areas, along with in-house
designed and manufactured, custom Audio Note (UK) output transformers which
feature MBH double c-cores and Silver windings. The M8 RIAA also has a correctly
designed and implemented balanced output circuit.
M8 RIAA PHONO STAGE