Electro Harmonix 5U4GBEH Vakuumrør

What a rectifier does

A rectifier valve is not in the signal path — it converts the amplifier's AC supply into the DC the other tubes run on. Its behaviour still shapes what you hear, because the way it delivers current under load determines how firmly or how softly the amplifier responds when you push it hard.

A straight bottle that fits where others do not

The Electro-Harmonix 5U4GB is a directly heated rectifier diode that stands in for all 5U4 types, including the NOS-style big-bottle valves. The straight-bottle construction is the practical advantage: it clears chassis and cages where a large-shouldered bottle is a tight fit, so it goes into more amplifiers without modification. It is also a sound choice for dual-rectifier designs that run two valves side by side.

Hi-fi and instrument amps alike

Electro-Harmonix builds this valve as a current-production design in Russia and recommends it for both hi-fi and instrument amplification. It uses an octal base. This item is a single valve.