Leopard - 12AX7 - 6CK4 3W Single‑Ended Triode Power Amplifier

Step into the music.

Leopard is a single‑ended Class A triode amplifier built around a completely original circuit that reimagines what a single-ended triode amplification design can be. Delivering 3 watts RMS into 8 Ω, it offers a level of bandwidth, linearity, and quietness that challenges the expectations of traditional single‑ended amplifiers. At 1 watt, the frequency response is –3 dB at 10 Hz and 40 kHz, providing a very wide bandwidth. Channel balance is held to an exceptional 0.2 dB for a stereo image that is wide and deep. 

Input sensitivity is 970 mV RMS for full output, making Leopard easy to pair with modern sources and speakers with 90dB sensitivity and above (1W @ 1 meter).

The signal path is elegantly simple:

2x 12AX7 input stage for voltage gain and drive

2x 6CK4 power triodes, each biased for maximum linearity

5Y3 (S or GT) rectifier feeding a dual‑mono power supply

The power supply is one of Leopard’s defining features. The 5Y3 feeds two fully independent high‑voltage rails, one for each channel, giving the amplifier outstanding separation and stability. The result is a noise floor so low that even with your ear pressed against the tweeter or woofer in a silent room, there is no audible noise.

Leopard’s aesthetic reflects its purpose: performance. The powder coated steel chassis is framed by hand‑sanded, oil‑finished solid leopardwood panels with a natural patterning that gives the amplifier its name. A toroidal power transformer and USA‑made Edcor EI output transformers anchor the design with robust magnetic performance and wide bandwidth.

The amplifier’s voice is shaped by the 6CK4, a triode rarely used in audio, yet capable of remarkable linearity when optimized. In Leopard, it becomes the heart of a presentation that feels open, dimensional, and immersive. This is an amplifier that doesn’t just reproduce music, it lets you step into it. Instruments float in real space and the performance venue becomes a place you can sit and listen.

Leopard is a ground‑up, original design built to show what a modern SET can be when distortion is low, bandwidth is wide, and noise is essentially nonexistent.

Leopard: The single‑ended triode amplifier, redefined.

Specifications

Output Power:  

3W RMS per channel into 8 Ω (sine‑wave tested)

Frequency Response (1 W):  

–3 dB at 10 Hz

–3 dB at 40 kHz

Tube Complement:  

5Y3 rectifier

2x 12AX7 input stage

2 ×6CK4 single‑ended output stage

Transformers:  

Edcor Output transformers (USA)

Hand‑selected power transformer

Topology:  

Single‑ended Class A

All‑tube signal path and power supply

Construction:

100% point‑to‑point wired

Hand‑built and voiced

Weight: 13lbs

Dimensions: 12" W x 8" D x 3" H