Ray Tubes Launches Select 5U4 Rectifier Tubes

Ray Tubes added another tube model to its Ray Tubes Select Collection. The Oakland-based vacuum tube company expanded its line-up with new-production 5U4 rectifier tubes in its Select Collection Rectifiers. Although the 5U4 aren't always top-of-mind, they’re a crucial component of tube amps for high-end audio, besides being an essential component in guitar amplifiers, prized for its ability to handle high peak currents. Select 5U4 vacuum tubes are now available from Ray Tubes' global network of retail partners.

The driver we tested is from Airborne, produced in China by long-time OEM manufacturer and high-end audio catalog retailer, Solen Electronique, Canada. The HR124B8-10L 4.5" midrange is intended for home hi-fi applications. This driver is built on a 6-spoke cast frame and the cone assembly consists of a curvilinear wood grain fiber cone and dust cap, suspended by an NBR rubber surround and a 2.75" diameter flat cloth spider. This article was originally published in Voice Coil, August 2010.

Published in two separate parts in audioXpress October and November 2007, this hybrid amp design is a detailed and interesting project, frequently referenced by other DIY audio enthusiasts. We thought it was time to make it available online in its entirety, in the best possible quality. The article discusses the unity-gain, single-ended MOSFET output stage, the valve voltage amplification stage and wraps up with the power supplies, printed circuit boards, and construction.