Sylvania 7408 1960-70 - Clear - Red RCA Marking (6V6 GT)

For sale is a premium, beautifully matched pair of vintage RCA 7408, made by Sylvania, beam power tubes.

These are "Coin Base" versions, which were originally manufactured by Sylvania in the USA (OEM for RCA) during the late 1960s / 1970s. The 7408 is a heavy-duty, industrial/computer-grade version of the 6V6GT / 6V6GTA. It features tighter electrical tolerances, enhanced zero-bias characteristics, and a ruggedized mechanical structure designed to minimize distortion and withstand high plate dissipation.

It is considered one of the absolute best 6V6 family upgrades for high-end tube gear and premium headphone amplifiers like the Cayin HA-3A. 

[TONAL CHARACTERISTICS] Tonally, this Sylvania-made pair sits in the sweet spot of American vintage audio. It delivers a much tighter, more impactful low-end than standard 6V6s, alongside a clean, highly dynamic mid-range. The top-end is extended, extremely crisp, and resolving, offering a beautiful stereo imaging and an accurate soundstage. If your amplifier sounds a bit too dark or sluggish, these 7408 tubes will wake it up with spectacular transparency and bite.

Tubes are clean, flash getters are strong, and they come in vintage RCA boxes (as pictured).

Both tubes have been thoroughly tested on a calibrated tube tester and show an identical 100% matched output. They measure well into New Old Stock (NOS) territory: - Tube 1: 94 / 56 (Minimum required is 56) - Tube 2: 94 / 56 (Minimum required is 56) These numbers are written on the vintage box flaps as shown in the photos. Completely stable, quiet, and free of any microphonics.