netto € 7.990,-


Balanced Dual Mono Zero Feedback Vacuum Tube Line Stage

NAT Audio introduced last version of tube balanced preamplifier as Symmetrical Vacuum model. New line stage is completely in dual mono configuration with zero feedback all triode vacuum tube design.

Total of fourteen (14) tubes that works in pure symmetry form both power supply and driver sections in Symmetrical Vacuum line stage .

Design is based on fact that line stage may work almost perfect in both type of operation (connection) as balanced (xlr) and (or) single ended (rca) mode.

Attenuation network as one of the most important part of any preamplifier is realized in Symmetrical Vacuum with 56 high reliability silver contact silent type relay. Only one resistor of high quality at any volume setting is on the signal path! Linearity of realized volume control is at high level – from DC to over 1MHz!

Symmetrical Vacuum may drive any type of power amplifier of any internal impedance (compatible with input impedance of 600ohms). It correlate to possibility of use high lenght of interconnect cable between pre and power amplifier.

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

Quality of electronic components that is used inside Symmetrical Vacuum are at high level – very high capacitance military grade capacitors, Caddock resistors, Vishay 0.1% resistors, electrolytic capacitors for 105C of operating temperature, last generation of IXYS semiconductors, pure silver input wiring …

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

Technical Specification
Name Value
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 15.5 dB (X 5.6 Phase status: non-inverted (0 degree)
THD & N < 0.03 % 20 Hz to 20kHz @ 1V rms
Input Impedance > 10 kohms single ended: >20 kohms balanced
Stereo Separation > 100 dB @ 1 kHz
Tube Complement 2 X EY500A, 4 X 6N1P-EV, 4 X 6N2P-EV & 4 X 6P30B-R(miniature)
Output Impedance < 200 ohms on single ended ; <400 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. 60 lb. (27 kg) unpacked
TOTAL Weight approx. 77 lb. (35 kg) packed in polypropylene crate

Design Features
– full dual mono construction realized with 14 tubes (7/channel)
– zero feedback design
– all triode pure class A configuration
– double regulated, hybrid output high precision power supply
– high current output tubes 6P30B-R(miniature) as N.O.S. & long life type
– vacuum tube power supply rectification with high voltage, high current EY500A booster diode type (N.O.S.)
– high quality 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
– soft start operate
– relay network attenuation (realised with 56 relays)
– gold plated PTFE insulated RCA jacks with gold plated XLR balanced connectors
– hand assembled all 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