Single Ended Mono Block Power Amplifier

Transmitter is a new reference point power amplifier made by NAT standards – pure class A, single – ended type and zero global feedback circuit configuration.

Transmitter gives an opportunity to listen favorite music on three different mode. In fact it represents three types of amplifier in one unit – pure direct heated triode, ultra-linear or tetrode mode. With power approx. 120W in single – ended technique there is a capability to drive almost any type of  loudspeaker.

Industrial type QB5/1750 –  output tube -  represents high technology in vacuum manufacturing. Potential of output tube is 565W of heat dissipation while we use only 55%-60% of that decreases working temperature point – means further improvement of amplifiers reliability. Construction of output tube QB5/1750 is very robust also in mechanical domain – means there is no high level of micro-phonic effect for negative influence to the sound reproduction. Special designed “heavy weight” pure non magnetic inox tube cover cage additionally improving negative vibration effect from reflection in listening room that also positive increase quality of sound reproduction. For the audiophiles with very sensitive loudspeaker there is low mode option (position on front panel) to lower the output power from 100W (in standard mode) to 30W, also to decrease power consumption of output tube – means no need for extra heat dissipation in that situation.

Input and driver tubes 6N1P-VI and 6N6P/6N30P are made by military standard also indicated like N.O.S. (new old stock)  grade.

Hand crafted wide-bandwidth output transformer (custom designed for NAT ) is used in this unit. Output transformer contains no less then 61 separated different material layers. Bandwidth is from 8Hz – 100.000Hz. That is extremly good result for single - ended operation mode. Output has separate taps for 4 ohms and 8 ohms speaker load (may drive any load from 1.5 ohms to over 32 ohms). By specific technical approach mention output transformer in combination with output tube QB5/1750 may drive easy any type of loudspeaker with damping factor equaly with push-pull tube configuration. Zero global feedback concept is well known also as the best solution for purity of sound reproduction without negative influence from wide variety speaker impedance – means good for driving all type of speaker equally (electrostatic, dynamic or other types).

Power supply section also speaks for itself. Main transformer is designed for double power then Transmitter consume (over 1000W) with totally silent operation. There is separate voltage regulators also in zero feedback manner for all amplifier stages including the output one. On such a way sound quality is totally independent from line voltage instability. Equivalent energy from power supply is huge, example for bass response down to 20Hz, it is equal to no less then 8000 Joules (8kJ) of related capacitor type energy. Soft start additionally improving reliability of entire amplifier by avoiding voltage stress during turn-on procedure.

There is no need for any adjustment from time to time of output tubes standing current. Electronic circuit automatically adjust current through mighty QB5/1750 type no matter of tube duration – means constant current in time domain –  from the brand new to the end point of tube life.

Quality of electronic material that is used inside Transmitter is impressive -  teflon military grade capacitors, 0.1% Vishay’s resistors, electrolytic capacitors for 105C of working temperature, last generation of  IXYS semiconductors WBT connectors, pure silver input wiring…

Amplifier works properly at all world wide AC line voltage from 100 – 250 VAC, 50-60Hz (different transformers are used).

Technical Specification
Name Value
Type Single Ended Class "A" Triode, Ultra-linear or Tetrode connection
Power Output 120 Watts @ 1 kHz
Frequency Response 8 Hz to 100 kHz -3dB
Input impedance 100 k ohms parallel with 100pF
Input Sensitivity 1.5 V RMS for 100 Watts
Gain 25.50 dB (x18.8)
Rise Time 3.0 microsecond
Noise 110 dB below rated output "A" weighted
Tube Complement 1 x 6N1P-EV, 1 x 6N6P/6N30P, 1 x QB5/1750
Power Requirement 110 to 240 VAC @ 50 to 60 Hz, 450 VA max. (set in factory)
Dimensions 11.8" (300 mm) wide ´ 20.9" (530 mm) deep ´ 10.2" (260 mm) high
NET Weight approx. 77 lbs (40 kg) unpacked / per piece
TOTAL Weight approx. 212 lbs (96 kg) packed in wooden box

Design Features

- Single Ended pure class A mono block power amplifier
- zero global feedback
- all triode configuration (ultra-linear and tetrode output mode available) – three mode in one unit
- short signal path
- no inter-stage transformer
- direct heated industrial type QB5/1750 (N.O.S.) output tube - long life grade
- driver section use 6N1P-EV & 6N6P/6N30P input tube (N.O.S.) - long life grade
- hand wound output transformer (custom designed for NAT)
- hand wound power transformer (custom designed for NAT)
- polypropylene capacitors in power supply for QB5/1750 (N.O.S.) output tube
- regulated power supply for all stages (including the output)
- automatic bias current control for the output tube with long term stability
- soft start operate to improve reliability
- hand assembled all aluminum modulated chassis
- WBT output connectors
- extensively used computer numeric control machines (CNC)
- 4/5" (20mm) thick double aluminum front panel
- cover cage (optional)

Specifications are subject of change without notice


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