Phonostages — Treehaus Audiolab LCR Phono

The LCR Phono is a vacuum-tube phono preamplifier from Treehaus Audiolab, a Connecticut maker founded in 2017 that also builds field coil loudspeakers, 300B single-ended amplifiers, a TVC line preamplifier and a moving coil step-up transformer. It was introduced at AXPONA 2025 at USD 24,000 including tubes, and its name refers to the inductor, capacitor and resistor network that performs the RIAA equalisation.

Key specs that matter

Gain is 46 dB, enough for moving magnet cartridges directly and for moving coil types through a step-up transformer. The unit has three inputs. Input 1 offers loading at 620 ohm, 15k, 30k, 47k, 68k and 100k ohm, input 2 offers 620 ohm, 2k, 3.5k, 6.8k, 10k and 47k ohm, and input capacitance is 120 pF. There is one line output with an output impedance of 3 kohm. Frequency response is 20 Hz to 20 kHz within 1 dB, THD is 0.09% at 0.55 V RMS output from a 2.5 mV input, and signal-to-noise ratio is 90 dB or better. The tube line-up is a 7308 twin triode in the first stage, a 12AT7 in the second stage and a 6CL3 for rectification.

Engineering and use context

In the equalisation network only the inductors sit in series with the signal, while the capacitors and resistors are connected in parallel. The inductors are wound on Finemet cores and hand-coated with Urushi lacquer. The 7308 was chosen for the input position because of its low noise and resistance to microphonics. Power comes from a separate enclosure, so this is a two-chassis design. The supply uses a toroidal transformer in a CLCLC filter with a Finemet choke in the last stage, tube rectification, DC heated filaments and a high voltage shunt regulator for each channel. A front-panel switch selects mute, stereo or mono. Buyers choose between two industrial designs - Kinsuido, drawn from 1970s Japanese hi-fi and mid-century modern style, and A/Machines, which references early Western Electric and Klangfilm equipment - and custom finishes are offered on request.

Pairing

The 3 kohm output impedance suits a preamplifier or integrated amp whose input impedance is reasonably high, and short interconnects. Low-output moving coil pickups need a transformer ahead of the inputs, and Treehaus offers its own Finemet-core MC SUT for that role. The company's TVC preamplifier, built around the 4P1L tube with Finemet line-out transformers, is the in-house partner, and its 300B single-ended amplifiers complete the chain for high-efficiency loudspeakers. Two loadable inputs let two tonearms or cartridges stay connected at once.

Alternatives

Treehaus Audiolab makes no other phono stage, leaving the LCR Phono as the sole RIAA preamplifier in its catalogue.