Nagra HD Phono

The HD Phono is the all-tube reference phono stage Nagra builds for the HD-line system — the analog inheritor of the legendary Nagra PL-P heritage, refined through three years of R&D and a fourth-generation custom transformer.

Phono reproduction sits at the heart of Nagra's hi-fi heritage. The first Nagra hi-fi product — the legendary PL-P preamplifier — drew its phono section directly from the microphone preamplifier of the Nagra IV-S reel-to-reel, the broadcast tape recorder that defined location recording for half a century. The HD Phono is the latest expression of that lineage, designed in parallel with the Nagra Reference Turntable and Reference MC Cartridge, refined over years of listening, and built for the customer who wants the analog source to match the rest of the HD-line system.

The HD Phono is uncompromising at every level. The signal path is 100% tube, pure Class A, dual-mono — four EF806S-Gold tubes and two E88CC/6922 tubes, each measured and selected by Nagra Lab before installation. The input transformers are a fourth-generation Nagra design with 26 dB of gain, hand-wound in a process the company describes as requiring watchmakers' type of skills. The cores are cobalt, cryogenically treated over the course of several weeks before assembly. Three tube-stage gain options — 30.5 dB, 36.5 dB, 42.5 dB — combine with the transformer's 26 dB and a ±6 dB fine adjustment to deliver up to 68.5 dB of overall gain, making the HD Phono comfortable with the lowest-output moving-coil cartridges in production. MC loading runs from 10 to 390 ohms in 5-ohm increments, remote-controlled, so the customer can dial in the cartridge match from the listening seat by ear rather than by spec sheet.

The power supply is a separate chassis built around a massive supercapacitor bank. The architecture provides all of the advantages of battery-based power supplies with the added advantage of accepting and delivering charges much faster and with higher current load — Nagra's words. Mechanical isolation comes from a damped, constrained-layer platform coupled to four isolator damped towers providing superior vibration resistance. Five EQ curves are selectable from the remote — RIAA, TELDEC, NAB 100 µS, VICTOR EUR, VICTOR USA — for the listener with a serious archival vinyl collection.

Connectivity is what the HD-line customer expects. Two MC inputs and one MM input on RCA, an option input for future custom transformers, MM capacitive loading at 0 / 47 / 100 / 150 / 220 pF, stereo/mono switching by remote, RS232 home automation. Frequency response runs 10 Hz to 100 kHz; signal-to-noise ratio sits at 80 dB ASA-A; dynamic range exceeds 150 dB; THD+N falls below 0.1 % at 1 kHz, 1 V output. The HD Phono is the analog front-end designed to partner the HD DAC X, the HD Preamplifier, and the HD Amp — the four-component HD-line statement Alma already carries in its complete form.

"This is the quietest phonostage I have ever used."
— Ken Kessler, Hi-Fi News, June 2025

Main Features

• 100% tube signal path, pure Class A, dual-mono
• 4× EF806S-Gold and 2× E88CC/6922 tubes, measured and selected by Nagra Lab
• Fourth-generation custom Nagra input transformers, 26 dB gain, cobalt cores, cryogenically treated, hand-wound
• Three tube-stage gain options (30.5 / 36.5 / 42.5 dB) plus ±6 dB fine adjustment — up to 68.5 dB overall
• MC loading 10–390 Ω in 5-Ω increments, remote-controlled
• MM capacitive loading 0 / 47 / 100 / 150 / 220 pF
• Five remote-selectable EQ curves: RIAA, TELDEC, NAB 100 µS, VICTOR EUR, VICTOR USA
• Separate chassis with massive supercapacitor power supply
• Damped constrained-layer platform with four isolator damped towers
• RS232 home automation
• Designed and manufactured by Audio Technology Switzerland

Specifications

Inputs: 2× MC on RCA (stereo/mono selectable by remote); 1× MM on RCA; 1× option input for future custom transformers

MC loading: 10–390 Ω in 5-Ω increments, remote-controlled

MM capacitive loading: 0 / 47 / 100 / 150 / 220 pF

EQ curves: RIAA, TELDEC, NAB 100 µS, VICTOR EUR, VICTOR USA (remote selectable)

Tubes: 4× EF806S-Gold, 2× E88CC/6922 (measured and selected by Nagra Lab)

Topology: 100% tube stages, pure Class A, dual-mono

Input transformers: fourth-generation custom Nagra design, 26 dB gain, cobalt cores, cryogenically treated, hand-wound

Tube-stage gain options: 30.5 dB / 36.5 dB / 42.5 dB

Maximum overall gain: 68.5 dB (with gain switch at +6 dB; ±6 dB fine adjustment)

Output level: 1 V RMS for 0 dB

Output impedance: < 500 Ω

Frequency response: 10 Hz – 100 kHz (+1.5 / –2 dB)

Signal-to-noise ratio: 80 dB ASA-A

Dynamic range: > 150 dB

THD+N: < 0.1 % @ 1 kHz, 1 V out, no load

Crosstalk: > 80 dB @ 1 kHz, 1 V RMS

Power supply: Separate two-chassis design with massive supercapacitor power supply

Power consumption: 170 W max

Mains options: 100 V / 115 V / 120 V / 127 V / 230 V / 240 V (±10 %, 50–60 Hz; not user-adjustable)

Mechanical: Damped, constrained-layer platform with four isolator damped towers

Audio chassis dimensions: 439 × 438 × 121–130 mm (495 × 438 mm with option modules)

Power supply chassis dimensions: 439 × 438 × 121–130 mm

Weight: 14.5 kg (32 lb) audio chassis; 16.5 kg (36.4 lb) power supply

Remote automation: 1× 3.5 mm input + 4× 3.5 mm relay outputs

Home automation: SUB-D9 RS232 (115200 baud)

Operating temperature: +15 °C to +35 °C

Operating environment: indoor only, IP30

Designed and manufactured by: Audio Technology Switzerland

Manufacturer page