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GemTune GS-02 Vacuum Tube Audio Amplifier
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Audiophiles rejoice: What's old is new again! If you have been longing for the fabled tones that, according to the Apollonic faithful, only a vacuum tube amplifier can produce, then the GemTune GS-02 might be what you have been seeking. Of course you could buy a vintage tube amp off of eBay or at a Hamfest, but maybe you don't have time or knowledge or desire to recondition it. One nice feature of the GemTune GS-02 is that the five vacuum tubes it uses, one (1) each 5Z3PA and two (2) each KT88 (matched pair) and 12AX7, are readily available, whereas you could have trouble locating some of the tubes a vintage amplifier might have. The painted chassis with natural finish wood panels provides a nice mix of classical and modern styling, and the open design makes it a real showpiece!

Over the last few years I have noticed many new vacuum tube products coming on the market. Maybe that is due at least in part, according to societal and style experts as prominent as The Old Farmer's Almanac, to people tending to crave reminders of 'the good old days' in times like these when everything seems to be turned upside down.

GemTune GS-02 KT88 Hi-Fi Tube Amplifier (front) - RF Cafe

GemTune GS-02 Hi-Fi Tube Amplifier - Chassis Front

GemTune GS-02 KT88 Hi-Fi Tube Amplifier (front) - RF Cafe

GemTune GS-02 Hi-Fi Tube Amplifier-  Chassis Rear

GemTune GS-02 Rear Panel Connections - RF Cafe

GemTune GS-02 Rear Panel Connections

Unlike when I did the write-up on the Tesslor R601S vacuum tube AM/FM radio, I do not own one of these GemTune GS-02 audio amplifiers. If I had one (donations gratefully accepted), I would be glad to open it up and provide photos and a circuit description.

Here are the specifications from the website:

GemTune GS-02 Tube Amplifier, Hi-Fi, 100% Handmade

  • Output Power: 13 W (x 2 channels)
  • Frequency Response: 20 Hz - 25 kHz
  • Single Ended Class A Amplifier to reduce distortion
  • Distortion: <1 % (1 kHz)
  • Input impedance: 100 kΩ
  • Output impedance: 8 Ω or 4 Ω
  • Signal/Noise Ratio: 90 dB
  • Dimension: 390 mm x 245 mm x 145 mm
  • Weight: 14 kg
  • Tubes: 5Z3P (x1), KT88 (x2), 12AX7 (x2)

GemTune GS-02 User's ManualUser's Manual

Note: I was originally going to feature the GemTune X-1 tube amplifier, but in researching it I discovered that the 5Z4P rectifier tube is no longer available directly from them. Therefore, I do not recommend buying the X-1 until a ready source can be found. The X-1 is an older design.

GemTune GS-02 Vacuum Tubes - RF Cafe

GemTune GS-02 Vacuum Tubes



Posted June 4, 2014

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