Electro-Harmonix 300B Gold: the best-value premium 300B

The 300B is the classic directly heated triode behind the single-ended amplifiers audiophiles love for their rich, lifelike voices and acoustic instruments. The Electro-Harmonix 300B Gold is EH's premium version of its standard 300B, with gold-plated grid wire for greater bias stability, more consistent performance and long service life.

How does the EH 300B Gold sound?

Reviewers describe the 300B Gold as smooth, clean, balanced and sweet, with deep, solid bass and no harsh or aggressive edges. Compared with EH's standard 300B, it adds more treble extension, air and detail, and vocals sound noticeably more refined and natural.

It is widely regarded as the value pick among current 300Bs. In Wall of Sound's comparison of seven popular 300Bs, the reviewer named the EH Gold Grid the best choice for getting maximum performance on a tight budget, with no weaknesses that stood out. Its slightly relaxed character also suits systems that lean bright or forward.

Who should choose the EH 300B Gold?

• Upgrading stock tubes: many 300B amps ship with basic tubes, and the 300B Gold is an affordable step up.
• Building or rebuilding a SET amp: a reliable, well-balanced reference tube at a sensible price.
• Bright or detailed systems: its smooth top end helps tame forward-sounding speakers and sources.

Want the ultimate in scale and detail? See the Genalex Gold Lion PX300B. For the most affordable option, see the standard Electro-Harmonix 300B.

Matched pairs and quads, fully tested.

Every 300B we sell is tested on our own equipment before it ships. Pairs and quads are matched on plate current (Ip) and transconductance (Gm), so both channels sound and behave the same.

• Matched pair: for stereo single-ended (SET) amps with one 300B per channel
• Matched quad: for push-pull 300B amps, parallel single-ended designs or a pair of monoblocks with two tubes each

Compatible amplifiers

The EH 300B Gold suits any amplifier designed for the 300B, including the Willsenton R300, Cayin A-300B and CS-300A, Line Magnetic LM-210IA and LM-300IA, YaQin MS-300B, Fezz Audio Mira Ceti, Allnic 300B models, Elekit TU-8300 and Australian-made Weston Acoustics Time Machine amplifiers.

Note: the 300B uses a 4-pin (UX4) base and a 5 V filament. It is not interchangeable with octal power tubes such as the KT88, EL34 or 6550.

Fitting, bias and care

• Fixed-bias amps (often with a bias meter or adjustment on top) must be re-biased after fitting new 300Bs. Self-biasing (cathode-bias) amps need no adjustment. Always follow your amplifier's manual.
• Give new tubes time to settle. Many listeners hear them open up over the first few dozen hours.
• Let the amp warm up before playing loudly. A slow-start rectifier tube such as a 5U4G is kind to 300B filaments.
• A single-ended 300B amp makes around 8 watts per channel, so pair it with efficient speakers (ideally around 90 dB/W or more).

Electro-Harmonix 300B Gold specifications

Download the Electro-Harmonix 300B Gold datasheet (PDF)