Reference Balanced Dual Mono Vacuum Tube Line Stage


Click here to see Symmetrical Dual Mono Line Stage photo gallery.

NAT Audio introduced tube balanced preamplifier called "Symmetrical". New line stage is completely in dual mono topology also with zero feedback all triode vacuum tube design.

There is twelve(12) tubes that works in perfect symmetry, means six(6) per each channel.

Design based on fact that preamplifier may work perfect in both type of operation - balanced (xlr) and single ended (rca).

Also, attenuation network is realized with 28 high reliability relay.

"Symmetrical" may drive any known power amplifier no matter of type or internal impedance (compatible with input impedance of 600ohms). It also means that interconnect length between pre and power amplifier may be of enormous value.

Remote control as standard option is made from solid block of aluminum.
 
Technical Specification

Frequency Response

0.07 Hz to 300 kHz – 3 dB ; 20 Hz to 20 kHz ± 0.01 dB

Noise

< -95 dB "A" weighted @ 1V rms

Gain

10 dB (X 3.16) Phase status: non-inverted (0 degree)

THD & N

< 0.03 %  20 Hz to 20kHz @ 1V rms

Input Impedance

> 47 kohms single ended: >94 kohms balanced

Stereo Separation

> 100 dB @ 1 kHz

Tube Complement

2 X 6N30P-DR, 2 X OA 2, 2 X EZ80, 2 X 6N1P-EV, 2 X 6N6P  & 2 X 6N2P-EV

Output Impedance

< 70 ohms on single ended ;  <140 ohms on balanced

Power Requirements

110 VAC or 220 VAC @ 50 to 60 Hz, max. 100 VA

Dimensions

19" (483 mm) wide ´ 18" (455 mm) deep ´ 6.5" (165 mm) high (max.dimensions)

NET Weight

approx. 38 lb. (17 kg) unpacked

TOTAL Weight

approx. 58,5 lb. (26,5 kg) packed in wooden box

Design Features

- full dual mono construction with 12 tubes (6 per each channel)
- zero feedback design
- all triode pure class A configuration
- double regulated, hybrid output high precision power supply
- high current output super tube 6N30P-DR double triode (military grade), long life over 10 000 hours
- plasma effect are used for stabilization in power supply realized with OA 2 tube (new old stock)
- vacuum tube power supply rectification with EZ80 tube
- high quality single audiophile grade capacitor of high capacitance on signal path
- polypropylene capacitors in high voltage power supply
- two low density silent power transformers each per channel for analog stages custom made for NAT
- separate low density silent power transformer for digital stages custom made for NAT
- soft start operate
- relay network attenuation
- gold plated teflon insulated RCA jacks with gold plated XLR balanced connectors
- hand assembled all aluminum modulated chassis
- laser engraved front panel made from triple separate aluminum block of 20mm thick
- laser engraved remote control made from solid block of aluminum
- extensively used computer numeric control machines (CNC)



 Specifications are subject of change without notice