A harmonious blend of heritage and innovation, delivering 10 watts of exquisite sound through legendary British PX4 valves.
Inspired by our revered designs from the 1940s and 1950s, this amplifier pays homage to the legendary British PX4 valve – a beacon of acoustic excellence that prioritises revelation over raw power.
At its heart are two pairs of Direct Heated Triode PX4 valves - chosen not for their power output, but for their unrivalled ability to reveal musical truth. Delivering 10 watts per channel of exquisite sound, this amplifier embodies our philosophy that true fidelity comes not from brute force, but from purity of signal reproduction.
Every element has been meticulously considered, from the custom-wound transformers crafted in Dorset to the point-to-point wiring that eschews printed circuits in favour of a construction method that enhances both reliability and sonic qualities. The chassis, precision-machined from aluminium and finished with a bespoke powder coating, completes an instrument that is as beautiful to behold as it is to experience.
When paired with Lowther's full-range drivers, the PX4 amplifier creates a synergy that must be experienced to be fully appreciated.
Available in British Green or Black finish, with Push-Pull or Single-Ended topology
From £12,000*
* Prices may vary based on selected options. Contact us for a detailed quote.
Frequently asked
The Lowther PX4 is a handcrafted British Class-A valve (tube) amplifier built around the classic PX4 output triode. It delivers 10 W + 10 W into 6 Ω, uses automatic cathode bias, and can be run as either push-pull or single-ended. It is designed as a high-end partner for Lowther full-range and horn-loaded loudspeakers.
The Lowther PX4 can operate in both modes. Single-ended (SET) operation is prized for its purity and the directness of a single amplifying device, and it pairs naturally with high-efficiency Lowther drivers. Push-pull operation cancels even-order distortion and delivers more usable power and tighter bass control. By offering both, the PX4 lets the listener choose between the intimate directness of single-ended and the greater grip and headroom of push-pull, rather than being locked into one topology.
The PX4 produces 10 W + 10 W into 6 Ω. Because Lowther loudspeakers are high-efficiency (typically around 96–99 dB), this modest but pure valve output is more than enough to drive them to realistic levels. Its frequency response is 10 Hz – 45 kHz (-3 dB) with a 93 dB signal-to-noise ratio.
The PX4 is designed and handcrafted by Lowther, a British manufacturer with over 90 years of audio heritage. It is a high-end, made-to-order valve amplifier, using four PX4 output valves with 6SN7, 6J5 and 5U4G/5AR4 support valves, automatic cathode bias, and user-adjustable feedback from 0 dB to 10 dB.
Discover the stories, craftsmanship, and passion behind Lowther through our video series.
Episode 1
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Episode 3
