NAT Audio - Generator 90 W Class A

Main facts:

• One of the (if not) first high power coaxial triode cermic tube zero global feedback pure single-ended (realized with SINGLE triode tube) power amplifier.
• One of the (if not) most compact in the class of 100W single-ended (19"x19"x8.7").
• One of the (if not) most efficiency unit in the class (270W of power consumption for up to 100Wof tube single-ended pure class A output).

Generator CT gives an opportunity for listening the sound (music) with two different mode - as high power output setting up to 100W or moderate power output setting up to 40W. With power up to 100W in single - ended configuration there is a capability to drive almost any type of modern designed loudspeaker.

Military grade and N.O.S. (New Old Stock) GI-7B - output triode tube - represent high technology in vacuum tube manufacturing as coaxial ceramic based device. The anode is machined from pure solid copper - to insure best audio performance. Potential of output tube reach 350W of heat dissipation. Generator CT is used with not more than 60% of max. tube dissipation - that significantly decrease working temperature point for further improvement of reliability. Ceramic based transmitting tube construction gives an opportunity for ruggedness and freedom from microphonics. Special designed coaxial ceramic based tube has much lower mechanical impact than the standard - glass type of tube!

Tube that is used in Generator CT for driver purpose is 6S31B-V - SUPER tiny triode - made as long life tube and used as N.O.S. (New Old Stock) device.

High power of 600W, wide-bandwidth output transformer (custom designed by NAT) is used in Generator CT. Bandwidth reach 8Hz-70.000Hz. It is exceptional good flatness for single - ended zero global feedback type of amplifier. Output taps for 4 and 8 ohms speaker load are realized with highest quality laboratory grade connectors.
 

NOTE: Generator CT may drive almost any load from 2 ohms to over 16 ohms. Zero global feedback concept is the best known solution for purity of the sound reproduction. Generator CT may drive all type of speakers (electrostatic, magnetostatic, dynamic or other types).

Power supply section participate in sound quality almost as amplifiers main circuit. Silent power supply units is designed for double the power than Generator CT consume. There is separate voltage regulators in zero feedback manner for all amplifiers stages including the filaments (heaters). Polypropylene (MKP) type of capacitors is used in power supply, 0.1% resistors, electrolytic capacitors for 105C of operating temperature, last generation of semiconductors, laboratory grade connectors, silver-ofc internal wiring, etc..

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

NOTE:

- Standard version is used pseudo-balanced input (pin-3 connected to pin-1)

- First step of upgrade : pure-balanced input realized with hand coiled nano-crystalline core transformer

- Premium step of upgrade : pure-balanced input realized with hand cioled silver-ofc wired nano-crystalline core transformer


Design features:

• pure single-ended (realized with SINGLE triode tube) class A mono block power amplifier
• zero global feedback
• triode based configuration
• short signal path
• DC coupled all driver stages
• military specification power coaxial metal-ceramic type triode GI-7B (N.O.S.) output tube
• Hybrid Power Amplifier
• CE comfortable regarding maximum DC operating voltage
• input section use 6S31B-V tube (N.O.S.) as long life device
• output transformer custom designed for NAT - 600W of power
• silent power units - up to 500W of power
• high voltage (HV) air-core ckoke custom designed for NAT (hand coiled)
• polypropylene capacitors (MKP) in HV 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 up to 100W or 40W of power output (with switch position on rear panel)
• pure single-ended (realized with SINGLE triode tube) class A mono block power amplifier
• hand assembled non-magnetic entire modulated chassis
• high mass laboratory grade output connectors
• gold plated PTFE insulated RCA input connector custom ordered from NAT
• extensively used computer numeric control mashines (CNC)
• 0.8" (20mm) thick front panel

Technical Specifications:

• Type: Single-Ended (realized with SINGLE triode tube) pure Class A
• Power Output: up to 100 Watts @ 1 kHz, @ 4 ohms or @ 8 ohms
• Frequency Response: 8 Hz to 70 kHz -3dB
• Input impedance: 100 k ohms parallel with 200pF
• Input Sensitivity: 1.25 V RMS for 100 Watts
• Gain: 27 dB (x22.5)
• Noise: 110 dB below rated output "A" weighted
• Phase status: Regular ( 0 )
• Tube Complement: 6S31B-V & 1 x GI-7B both by military grade
• Power Requirement: 110 to 240 VAC @ 50 to 60 Hz, 270 VA max. (set in factory)
• Dimensions: 19" (483 mm) wide x 19" (480 mm) deep with connectors x 8.7" (222 mm) high
• NET Weight: approx. 95 lbs (43kg) unpacked / per block
• TOTAL Weight: approx. 254 lbs ( 115 kg) packed in "flight case" crate / per pair