1. Early Japanese manufacture (approximately 1969–1971)
The combination of components is very characteristic of Japanese production:
-
Sanyo 2SB474 germanium output transistors
-
ELNA electrolytic capacitors
- Metric 50 kΩ potentiometers
- Single-sided phenolic PCB
- Japanese transformer construction
- Japanese fuse holder and indicator lamp
This is not an American-built chassis.
2. Extremely original
-
✔ Original PCB
-
✔ Original wiring
-
✔ Original solder joints
-
✔ Original ELNA filter capacitors
-
✔ Original transformer
-
✔ Original output transistors
-
✔ Original potentiometers
-
✔ No evidence of repair work
-
✔ No evidence of modification
From a collector's standpoint, this is an unusually untouched amplifier.
3. The transformer
The transformer is stamped:
TGA-2
with
- 117V primary
- 0–16V secondary
Unfortunately, "TGA-2" appears to be a transformer part number rather than a manufacturer's identifier, so it doesn't directly identify the builder.
4. The chassis stamp
The circular stamp with the K is intriguing. It appears to be a factory inspection or quality-control mark rather than a model designation. Because the front panel also carries a circled "K," it may represent the distributor's trademark rather than the actual manufacturer.
My current opinion
I believe this amplifier was built by a Japanese OEM around 1970 for a private-label importer. During that period, companies such as Shin-ei, Kawai, Guyatone, and Teisco often built nearly identical amplifiers that were sold under dozens of different house brands. Without factory documentation or a branded schematic, it's difficult to attribute it to a specific OEM with confidence.
Blue Note Authentication Assessment
Manufacturer: Unknown Japanese OEM
Brand: "K" (private label)
Estimated Year: 1969–1971
Country of Manufacture: Japan
Originality
- Chassis: Original
- Transformer: Original
- PCB: Original
- Output transistors: Original Sanyo 2SB474
- Capacitors: Appear original
- Wiring: Original
- Solder joints: Factory
Estimated originality: 98%
