Audio Note M8 Phonosig - Manual (Page 7)

Technical overview
The M8 Phono Signature utilises simple but sonically effective circuitry using vacuum tube technology
rather than complex techniques using impure semi-conductor type devices, so common in the audio
industry.
This kind of circuit architecture is incredibly transparent and revealing. As a natural consequence, part
material plays an important role in the final sonic performance, so we use only the best possible
components and materials. Where components that meet our standards are not available - we make our
own.
The M8 Phono Signature's circuit arrangement is briefly described below.
Line inputs are routed from Audio Note non magnetic RCA connectors into ELMA, Swiss made gold
contact input selector. Volume and balance adjustments are made with Noble conductive plastic
potentiometers and this output signal drives the line stage. The phono input is directly routed to the phono
board with AN-V pure silver Litz interlink.
The input stage of the phono board uses a cascode connected 6072 General Electric dual triode
feeding a completely passive (zero feedback) RIAA EQ network. Final phono stage gain and buffering is
provided by a further 6072, connected as an anode follower. Tantalum resistors and Audio Note silver foil
capacitors are used throughout.
The line stage is of a direct coupled cascaded anode follower type. Two 5687 dual triodes are used for
both anode followers. The second stage is again pure class A, single ended and is transformer coupled
using a custom line level output transformer.
The use of transformer output coupling in the M8 allows the output power generated by the 5687 triodes
to be fully utilised to drive the power amplifier and cabling. This means that the M8 is capable of driving
low load impedances.
Also, this transformer design provides a true balanced output option, making the use of complex
differential circuitry used by other manufactures completely redundant.
Parts selection is of the highest order with an abundance of 2W Tantalum resistors, Audio Note silver foil
and Black Gate capacitors. The output transformers utilize the very best quality MBH double C cores and
have silver windings. The power supply incorporates vacuum tube rectification and choke input filtering
for each channel, and in addition, a new type of vacuum tube regulator ensures clean supply voltages
to the amplifier stages.
The best quality NOS valves are provided with the M8 for enhanced performance.
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