NAGRA PL-P

Pre owned. In excellent condition. Free from any obvious signs of wear. Supplied without original packaging.

Battery-powered tube preamplifier with phono stage, designed for pure Class A operation and equipped with four independent inputs, one of which is dedicated to phono sources. The phono stage supports both Moving Magnet and Moving Coil cartridges and uses hand-wound Nagra transformers specifically developed for this circuit.

The power supply is one of the defining features of the PL-P. The preamplifier uses a set of rechargeable D-size batteries, powered via an external AC charger, thereby isolating the audio circuits from the mains supply and reducing the risk of interference and ground loops. The internal regulation also uses two proprietary DC-DC converters, designed to eliminate power supply ripple and provide stable voltage to the various electronic stages.

The phono stage is built around selected tubes and dedicated Nagra transformers, with particular attention to low noise and the handling of low-level signals. Cartridge loading can be adjusted through capacitive settings from 47 pF to 837 pF and resistive settings from 30 Ω to 330 Ω, allowing the phono stage to be matched to a wide range of cartridges. The load selectors are mounted directly on the circuit board, in an internal position designed to minimise interference with sensitive phono signals.

Each channel uses two triode sections biased for pure Class A operation. The circuit comprises two separate stages, the first dedicated to input signal level management and the second to output level management and the tape loop. The tube heater voltage is precisely regulated to minimise noise and ensure stable operating conditions for the tubes.

The output stage is also tube-based and operates in Class A. It is directly coupled to the output connectors and can drive loads down to 600 Ω. The PL-P also features a full tape loop, allowing recordings, tape transfers and connections to external signal-processing equipment.

Input selection is carried out via a precision rotary switch positioned on the left side of the front panel. In addition to the phono input, three line-level inputs are available. The levels of the different sources can be adjusted independently for the left and right channels using two front-panel potentiometers, or simultaneously thanks to a geared clutch mechanism that allows the two channels to remain independently adjustable when required.

The main circuit board is mounted on elastomer supports that help isolate the circuitry from external vibrations. To reduce battery consumption and extend tube life, only the tubes required for the selected input are switched on. The audio output is also automatically muted when switching between inputs.

The front panel features the Nagra modulometer, a precision measuring instrument developed by the company and derived from the one used in the professional Nagra IV-S recorder. Its two coaxial internal pointers separately represent the left and right channels and allow precise monitoring of various system parameters. The modulometer can be used to adjust volume and balance, compensate for level differences between recordings, monitor the DC input level of the power supply and check the amplifier output level when correctly set.

Technical specifications:

• MC phono stage: sensitivity 0.1 mV; loading 0.1–47 kΩ; signal-to-noise ratio 74 dB, 0.5 mV, A-weighted
• MM phono stage: sensitivity 0.5 mV; loading 47–837 pF; signal-to-noise ratio 80 dB, 5.0 mV, A-weighted
• Line stage: input impedance >100 kΩ; output impedance 60 Ω; signal-to-noise ratio >88 dB, A-weighted; bandwidth 22–60 kHz +0/-1 dB; distortion <0.02% at 1 V, no load, 1 kHz; <0.1% at 1 V into 600 Ω; <0.1% at 1 V into 3 kΩ
• Phono stage tubes: 1 × 12AT7 / ECC81; 1 × 12AX7 / ECC83; 5,000-hour usage timer
• Line stage tubes: 2 × 12AT7 / ECC81; 4 × 12AX7 / ECC83; 5,000-hour usage timer
• Power supply: 8 rechargeable nickel-cadmium D-size cells; 4 Ah capacity; recharged via Nagra PLP-CCC3 AC power supply
• Dimensions: 310 × 254 × 76 mm (W × D × H)
• Weight: 4.45 kg with 8 D-size cells