Inovative Audio Manufacture

Single Ended Mono Block Power Amplifier - our newest flagship

NAT introduced the most powerfully and one of the most (if not) innovative single ended (with single tube) amplifier globally - called Magma Evo. Magma given name from the color of anode that is so real to volcano's magma.


Magma Evo is a newest refernce point power amplifier made by NAT as pure class A, single-ended triode type with zero global feedback configuration.

Magma Evo internally introduced driver circouit with path of no coupling capacitor or any other passive component (absolute DC coupling) as the newest NAT aproach. It means that not only on direct but on indirect driver signal path as well there is no exist capacitor or any inter stage transformer. Mention circuit configuration result on incredible speed of signal transfer that easily can hear!

Magma Evo gives an opportunity to amplify the signal by two different mode, as high power setting up to 170W or moderate setting up to 50W, both of pure direct heated triode (DHT) type. With mention power in single - ended configuraton there is a capability to drive any type of speaker.

Direct heated triode (DHT) type GM100 as output device represent the highest power vacuum tube manufacturing for audio. Potential of output tube reach 1.000W of heat dissipation! Magma Evo used operating point that significantly decrease working temperature for further reliability improvement. Construction of the output tube is robust in mechanical domain as well. Special design high mass laminated non magnetic cover cage additionally improved negative effect of vibration from the enviroment, correlate with better micro detail of sound reproduction. For the sensitive speaker Magma Evo offer low mode option to lower the output power. Further, it decreased power compsumption of entire device that resulting to significantly lower heat dissipation.

One of the most interesting MODE of operation due the fact of high power capability is higher damping factor option (for 8 ohms speaker only)! For higher damping factor mode simply put 8 ohms speaker into 4 ohms output tap! With special designed secondary section of output transformer, Magma Evo may reach this kind of operation with almost 100W of output pover! Even better, higher damping factor mode decrease THD with better frequency responde as well!

Input and driver circuit use double triode long life tube 6N6P-IR chosen as N.O.S. (new old stock) and military grade of the highest quality for the neutral sound. Wide-bandwidth output transformer of 1200W (custom designd by NAT) is used in Magma Evo. Bandwidth  reach 8Hz - 70.000Hz with exceptional good flatnes for high power single - ended amplifier. Output taps for 4 and 8 ohms speaker load are realized with high mass multi connection type laboratory grade connectors.

NOTE: Magma Evo may easily drive any load from 1.5 ohms to over 32 ohms.

By specific technical approach Magma Evo may drive all type (electrostatic, magnetostatic dynamic or other types) of speaker.

Power supply participate in sound quality almost as amplifier's main circuit. There is implemented AC conditioner as well! Soft start additionally improve Magma Evo reliability by avoiding high voltage and current stress during turn-on procedure. Quality of other than tube electronic components that is used inside Magma Evo are at the high level as well: aerospace grade foil resistors, military grade power graphite RF resistors, high energy electrolityic capacitors, power "in oil" capacitor, high mass laboratory grade output connectors, military grade PTFE silver - ofc input and other wiring...

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

NOTE: Pure-balanced input realized with hand cioled silver-ofc wired nano-crystalline core transformer as standard!    

NOTE: Protect covers should always be placed over output (big) tube due to safety!

Technical Specification
Name Value
Type Single Ended Class "A" Triode (D.H.T.)
Power Output max. 170 Watts @ 1 kHz
Frequency Response 8 Hz to 70 kHz -3dB
Input impedance 100 k ohms parallel with 200pF
Input Sensitivity 1.25 V RMS for full power
Gain 29 dB (x29)
Damping factor 10 ref. to 8 ohm load @8 ohm tap, 20 ref. to 8 ohm load @4 ohm tap (high damping factor mode), both @ zero global feedback
Noise 110 dB below rated output "A" weighted
Phase status Regular ( non-inverted )
Tube Complement 1x 6N6P-IR & 1 x GM100
Power Requirement 110 to 240 VAC @ 50 to 60 Hz, 650 VA max. (set in factory)
Dimensions 14.2" (360 mm) wide ´ 27.2" (690 mm) deep ´ 18.1" (460 mm) high
NET Weight approx. 133 lbs (60 kg) unpacked / per block
TOTAL Weight approx. 376 lbs ( 170 kg) packed in special crate / per pair


Design Features

- single-ended pure class A mono block power amplifier
- zero global feedback
- direct heated triode (DHT) output stage
- triode based configuration
- ultra short signal path
- no inter-stage transformer on signal path
- no coupling capacitor on entire driver path (absolute DC coupling) including cathode output stage
- output section - direct heated triode (D.H.T.) GM100 (N.O.S.) output tube
- driver section - double triode 6N6P-IR tube long life (N.O.S.)
- silent operation power supply unit (custom implemented for NAT)
- special audio output transformer of 1200W of power (custom designed by NAT)
- special audio choke of 600W of power (custom designed for NAT)
- hand coiled several air core chokes (custom designed by NAT)
- additional "in oil" capacitors for the output tube
- filament regulated power supply for driver as well as output tube
- regulated HV power supply for the output stage
- double regulated HV power supply for input stage
- over 1000J of energy storage in power supply
- soft start operate to improve reliability
- CE comfortable reference to max. high voltage level for domestic use
- hand assembled all modulated chassis
- high mass laboratory grade output connectors
- custom ordered gold plated PTFE insulated RCA input connector
- extensively used computer numeric control mashines (CNC)
- 4/5" (20mm) thick front panel
- aluminium pipe type cover cage (laminate type optional)

Specifications are subject of change without notice