Inovative Audio Manufacture

Single Ended Mono Block Ceramic Tube Power Amplifier

Microwave is a new mono power amplifier made by NAT, based on military grade tubes in pure class A, single – ended mode with zero global feedback operation.

Main facts:

  • First high power coaxial metal-ceramic tube zero-feedback single-ended power amplifier globally - unique device
  • Most compact in the class (19"x19"x6.5")
  • Most efficiency in the class (280W of power consumption for 80W of all tube single-ended class A)

Microwave gives an opportunity to listening the sound on two different mode as high power setting to 80W or moderate setting to 40W, both of pure coaxial-ceramic triode type. With power of 80W in single – ended configuration there is a capability to drive almost any type of  loudspeaker.

Military  grade(N.O.S - new old sock) GI-7B - output triode tube - represent high technology in vacuum tube manufacturing as coaxial metal-ceramic device. The anode is machined from pure solid copper, to insure best audio performance. Potential of output tube reach 350W of heat dissipation. Microwave is used 60% of max. dissipation that significantly decrease working temperature point for further reliability improvement. Ceramic-metal transmitting-tube construction gives the GI-7B extreme ruggedness and freedom from microphonics. Special designed coaxial metal-ceramic tube has much lower mechanical impact of reflected vibration from the environment then standard glass tube!

Input tubes ECC85 is also made by military standard (N.O.S.).

Hand crafted wide-bandwidth output transformer (custom designed for NAT ) is used in Microwave. Output transformer is constructed with no less then 56 separated layers. Bandwidth reach 6Hz – 70.000Hz. as exceptional good flatness for single – ended zero feedback amplifier. Output taps for 4 and 8 ohms speaker load are realized with laboratory grade connectors

NOTE: Microwave may drive any load from 2 ohms to over 16 ohms. By specific technical approach output transformer in combination with output tube may drive easy any type of loudspeaker with damping factor equally as in push-pull configuration. Zero global feedback concept is the best solution for purity of sound reproduction without negative influence from wide variety of speaker impedance. Microwave may drive all type of speaker equally (electrostatic, magnetostatic, dynamic or other types).

Power supply section participate in sound quallity almost as amplifiers main circuit. Silent power transformer is designed for double the power then Microwave. There is a separate voltage regulators in zero feedback manner for all amplifier stages including the output one. Tonal quality is independent from line voltage fluctation. Equivalent available energy from power supply is huge, equal to no less then 8000 Joules (8kJ) of energy. Soft start additionaly improve Microwave reliability by avoiding high voltage stress during turn-on procedure. Polypropilene-in-oil type of capacitors is sed additionaly for the single output tube's high voltage supply.

Special high voltage (HV) air-core choke is used in Microwave as the best high frequency reduced element in power supply section!

No any adjustment of output tube's standing current is necessary. Automatic electronic circuit  adjust tube's current no matter of tube duration – means constant current in time domain –  from the brand new to the near end point of tube life.

Quality of electronic components that is used inside Microwave are at high level – polypropilene-in-oil capacitors, Caddock resistors, Vishay 0.1% resistors, electrolytic capacitors for 105C of operating temperature, last generation of  IXYS semiconductors, Schutzinger laboratory grade connectors, pure silver input wiring…

Microwave work properly at worldwide AC line voltage from 100 – 250 VAC, 50-60Hz (different voltages set in factory only).

NOTE:Last generation, high tech. FAN is used inside a chassis with noisless operation.

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 Class "A" Triode (coaxial metal-ceramic type)
Power Output 80 Watts @ 1 kHz
Frequency Response 6 Hz to 70 kHz -3dB
Input impedance 100 k ohms parallel with 100pF
Input Sensitivity 1.5V RMS for 80 Watts
Gain 24.5 dB (x17)
Noise 110 dB below rated output "A" weighted
Tube Complement ECC85 & 1 x GI-7B, all by military grade
Power Requirement 110 to 240 VAC @ 50 to 60 Hz, 280 VA max. (set in factory)
Dimensions 19" (483 mm) wide ´ 19" (483 mm) deep ´ 6.5" (165 mm) high
NET Weight approx. 86 lbs (39 kg) unpacked / per piece
TOTAL Weight approx. 110 lbs (50 kg) packed in wooden box / per piece

Design Features

- single - ended pure class A mono block power amplifier
- zero global feedback
- based on triode configuration
- short signal path
- DC coupled circuit (only output transformer on signal path)
- military specification power coaxial metal-ceramic type triode GI-7B (N.O.S.) output tube
- CE comfortable regarding maximum DC operating voltage
- input section - ECC85 tubes (N.O.S.) military grade
- output transformer custom designed for NAT – 1000W of power
- power transformer custom designed for NAT – 600W of power
- high voltage (HV) air-core choke custom designed for NAT
- polypropylene-in-oil capacitors in HV power supply for GI-7B output tube
- regulated power supply for all stages (for the output stage as well)
- automatic bias current control for the output tube with long term stability
- switch selector for 40W & 80W of power output
- soft start operate to improve entire unit's reliability
- hand assembled all modulated chassis
- high mass Schutzinger laboratory grade output connector
- gold plated PTFE insulated RCA input connector custom ordered from NAT
- extensively used computer numeric control machines (CNC)
- 0.6" (15mm) thick double aluminum front panel

Specifications are subject of change without notice