NAT
VACUUM TUBE POWER AMPLIFIERS
Se1 GM70
Single Ended Mono Block Power Amplifier
New version already improve quality of previous model by set power to 25W with special single gain design. Single-Ended Mono Block Power Amplifier Se1 GM70 has very short signal path without main passive components - no coupling capacitors & no inter-stage transformers.
Input stage in Se1 GM70 form EC1010 (or equivalent) nuvistor tube capable to act as low distortion voltage stage, made by military standard, indicate as N.O.S. (new old stock) grade of the highest quality.
Driver stage form 3E29 (or equivalent) tube capable to act as low impedance stage. Made by military standard, it is indicated as N.O.S. grade of the highest quality as well as for the highier voltage operation.
Direct-heated triode (D.H.T) GM70 act as output stage, it is a high performance tube capable to dissipate up to 125W, made by military grade as well. Se1 GM70 represent a truly single-ended design without parallel connection of tubes.
Specially designed hand coiled output transformer support wide frequencytransfer.
Frequency response of Se1 GM70 is linear without any sub-resonance region.
Soft start improve reliability of entire amplifier by avoiding voltage stress during turn-on procedure.
Tonal quality is independent from line voltage fluctuation.
Se1 GM70 require higher sensitively loudspeaker to bring great sonic pleasure that only real D.H.T. virtues can do.
Quality of electronic components that is used inside Se1 GM70 are at high level - military grade and N.O.S. tubes, Caddock Vishay 0.1% resistors, electrolytic capacitors for 105C of operating temperature, last generation of IXYS semiconductors, Schutzinger laboratory grade connectors, silver-ofc input wiring...
Se1 GM70 works properly at world wide AC line voltage from 100-250 VAC, 50-60 Hz (set in factory only).
NOTE: -Standard version use pseudo-balanced input
-First step of upgrade : pure-balanced input realised with hand wound nano-crystalline core transformer
-Premium step of upgrade : pure-balanced input is realised with hand wound silver-ofc wired nano-crystalline core transformer
Design Features
- single-ended type - single stage (unique circuit by NAT)
- mono block pure class "A"
- triode direct heated (D.H.T.) output tube
- low feedback with absolute zero feedback as option
- all triode signal path configuration
- short signal path
- no coupling capacitor from input to output
- no inter-stage transformer from input to output
- high power GM70 triode output tube (military grade, and N.O.S.)
- hand coiled output transformer (custom design for NAT)
- regulated power supply for all stages
- soft start operate to improve long term stability
- hand assembled all modulated chassis
- aluminium front panel of 10mm thick (standard black finish, optional silver)
- high mass Shutzinger laboratory grade output connectors
- gold plated PTFE insulated RCA input connector custom ordered from NAT
- extensively used computer numeric control machines (CNC)
- cover cage (optional)
Specifications are subject of change without notice
| Technical Specification | |
| Name | Value |
| Type | Single Ended Class "A" |
| Power Output | 25 W @ 1 kHz, 8 ohms taps |
| THD | 0.95% @ 20 W @ 1 kHz, 8 ohms taps: less then 5% @ 28 W |
| Frequency Response | 10 Hz to 70 kHz |
| Input Impedance | 100 kohms parallel with 100pF |
| Input Sensitivity | 1 V RMS for 25 Watts Output @ zero feedback |
| Gain | 23 dB (x14) |
| Noise | 108 dB below rated output "A" weighted |
| Tube Complement | 1 x EC1010, 1 x 3E29 & 1 x GM70 (3 tubes/block, 2 tubes inside a chassis) |
| Power Requirement | 220 to 240 (110 to 120) VAC @ 50 to 60 Hz, 180 VA max. |
| Dimensions | 11.8" (300 mm) wide x 20.4" (520 mm) deep x 10.2" (260 mm) high |
| NET Weight | approx. 60 lbs. (25 kg) unpacked / monoblock |
| TOTAL Weight | approx. 133 lbs. (60 kg) packed in two polypropylene crate |