【Serviced】1960s Columbia Vacuum Tube Amplifier Unit (12AX7 / 50EH5)

This is a vacuum tube amplifier unit extracted from a 1960s Nippon Columbia record player with a built-in reel-to-reel tape deck. It utilizes the luxurious circuit design of the era and has undergone practical maintenance to be enjoyed in modern audio environments.

[Circuit Configuration & Vacuum Tubes Used]
First Stage Amplification: Toshiba 12AX7 (Dual Triode)
Output Stage: Toshiba 50EH5 x 2 (Stereo Configuration)
Features a punchy, high-sensitivity design typical of the era. The vacuum tubes themselves are in good condition with low hours of use.

[Maintenance & Customization Details]
Part Replacement: Aging resistors and capacitors have been replaced with modern, reliable components at key points. While respecting the original design's strengths, safety has been enhanced.

Wiring: BELDEN, a trusted brand, is used for additional wiring.

Input/Output Terminals: Versatile RCA input terminals and speaker output terminals have been added (currently for operational checks, please replace them according to your preference).

Input Systems:
TAPE Input (Monaural): Enjoy a raw, punchy sound with high sound pressure. *A stereo-to-monaural conversion adapter is attached to allow connection with modern portable music players, CDPs, etc.

PHONO Input (Stereo): Enables delicate and calm playback, even at low volumes.

[Sound Impression]
Tested with YAMAHA NS-1000M (90dB efficiency) and small speakers.

When connected to NS-1000M: As a low-output amplifier with a few watts, it naturally reaches its limit at high volumes, but at appropriate listening levels, it delivers a surprisingly raw sound. The monitor-like resolution of the NS-1000M combined with the density of the vacuum tubes creates a compelling listening experience.

When connected to small speakers: When connected to small DSA-421 units from the same era, the sound transformed into a warm, comfortable, lo-fi sound reminiscent of a vacuum tube radio.

[Condition]
There is a slight crackle in the volume control, but it is within a range that does not interfere with playback and is in good condition for a component of that era.

[Notes]
This unit is a chassis-bare model extracted from an antique radiogram. Due to the high voltages and transformerless structure characteristic of vacuum tube amplifiers, we are looking to sell this to DIY enthusiasts and experienced individuals with knowledge of electronics.

Please consider it for various applications, such as incorporating it into your preferred cabinet, or integrating it with DIY speakers and a Bluetooth module.