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Single Ended Integrated Amplifier

For the first time NAT introduce real high-end integrated amplifier. NAT Single is tube based pure dual mono device.

As an integrated amplifier, there is no extra interconnect cable between pre. and power section – one of the positive aspect from integrated amplifier as a single unit.

Single operates in single-ended, zero global feedback, pure class A manner. Power output is set to max. 50W into 8 ohms. Recommendation for the best sound reproduction is to have medium to high sensitivity loudspeaker with stable impedance from 4 ohms to 16 ohms.

Driver stage form E88CC (or equivalent) tube capable to act as low distortion stage made by military standard, indicate as N.O.S. (new old stock) grade of the highest quality.

Output stage form military grade direct-heated triode GM70, high performance tube capable to dissipate up to 125W of  power. Single represent a truly single-ended design without parallel connection of  tubes, yet moderate 50W of power output.

Hand connected wide bandwidth output transformer (custom designed for NAT ) is used in this unit.

Single's bandwidth from 10Hz – 60.000Hz has exceptional good flatness for single-ended zero feedback unit!

By specific connection output transformer with power tube type may drive any type of moderate sensitivity loudspeaker with dumping factor equal to push-pull design.

Soft start  improve reliability of entire integrated amplifier by avoiding voltage stress during turn-on procedure. Standby function additionally improve reliability by setting amplifiers internal voltage at minimum tension.

No adjustment from time to time of output tubes standing current is necessary. Single has automatically adjust current capability for GM70 tube no matter of tube duration – constant current in time domain –  from the brand new to the end point of tube lifespan.

To avoid unnecessary heat Single has possibility to be selected to low mode - 15W of output power with significantly reducing of power consumption (select on front panel).

Power supply section participate in sound quality almost as amplifiers main circuit. Silent power transformer of 1.000W is designed for multiple power than Single consume.

Separate power supply (conditioner) unit additionally improve sound quality by removing magnetic leakage flux inside the main chassis!

For the highest "purity" of power supply voltage a special designed separate regulators (in zero feedback manner) for all amplifier stages are used. Tonal quality is independent from line voltage fluctuation. Single is equipped with multi function remote control unit made from solid block of aluminum. Front panel is made from solid block of aluminum as well! Indication of all amplifiers function is shown by blue led's with additional  universal display .

Attenuation network as one of the most important part of any integrated amplifier is realized in Single with 56 high reliability silver contact silent type relay. Only one resistor of high quality at any volume setting is on the signal path! Volume control linearity is at high level - from DC to over 1MHz!

Quality of electronic components that is used inside Single are at high level - military grade and N.O.S. tubes, PTFE and "in-oil" military grade capacitors, Caddock and Vishay 0.1% resistors, electrolytic capacitors for 105C of operating temperature, last generation of IXYS semiconductors, Schutzinger laboratory grade connectors, pure silver input wiring…

Single works properly at world wide AC line voltage from 100 – 250 VAC, 50-60Hz (different voltages set in factory only).

NOTE:
          -Standard version use pseudo-balanced input
          -First step of upgrade : pure-balanced input realised with hand wound nano-crystalline core transformer
          -Premium step of upgrade : pure-balanced input realised with hand wound silver-ofc wired nano-crystalline core transformer

Technical Specification
Name Value
Type Single Ended Tube Base Zero Global Feedback
Power 50 W @ 8 ohms
Frequency Response 10 to 60 kHz, -3 dB; 20Hz to 20kHz, +/-0,5dB
Noise 90 dB IHF  reference to 1W
Gain 35 dB (X 55)   Phase status: non-inverted (0 degree)
THD & N < 0.1 %
Input Impedance >15 kohms
Output Impedance <1.6 ohms (damping factor >10 reference to 16ohms load @zero feedback)
Stereo Separation >95 dB @ 10 kHz
Tube Complement 2 x 6N23P (E88CC) & 2 x GM70  per unit
Power Requirements 100VAC to 240VAC (50 to 60 Hz), max. 370 VA
Dimensions 19" (483 mm) wide ´ 15.7" (400 mm) deep ´ 10.2" (260 mm) high
NETWeight (Control Unit) approx. 112 lbs (51 kg) unpacked
TOTAL Weight approx. 145 lbs ( 66kg) packed in polypropylene crate

 

Design Features

- single-ended type - integrated amplifier
- zero global feedback design
- triode direct-heated output type
- short signal path
- full dual mono construction
- 50W of pure class A
- output section - GM70 tube by military grade and N.O.S.
- driver section - 6N23P (E88CC) tubes by military grade and N.O.S.
- hand wound output transformer (custom designed for NAT)
- hand wound - silent operation power transformer (custom designed for NAT)
- separate transformer-conditioner power supply unit
- regulated power supply for all stages (including the output one)
- universal (12 leds) display
- soft start operate to improve entire reliability
- remote control made from solid block of aluminum
- automatic bias current control with long term stability
- standby function
- relay (silent type) attenuation network
- hand assembled all modulated chassis
- high mass Schutzinger laboratory grade output connectors
- gold plated PTFE insulated RCA input connector custom ordered from NAT
- extensively used computer numeric control machines (CNC)
- 5/8" (15mm) thick aluminium front panel
- cover cage (optional)
  

Specifications are subject of change without notice