Pragma Pre1 Specification

Part 1 – Overview

Chassis – outer chassis is 3mm aluminium finished with Nextel coating for a highly tactile and durable finish. Electronics are mounted within a separate internal chassis providing excellent protection from external sources of interference.

Power supply – separate toroidal transformers and circuits for audio and auxiliary components. Both transformers have electrostatic screens and EMI/RFI shields to maintain the integrity of the audio signal.

Attenuator – the heart of the Pre1 is the attenuator with 127 0.5dB steps, exceptional low noise and distortion and less than 0.05dB deviation between left and right channels at all settings.

PCB – The amplifier is built on a single four-layer PCB which provides exceptionally low power supply and ground impedance whilst maximising the separation between the signal path and the power and logic circuits.

Outputs - Two balanced outputs and two unbalanced outputs (one always on). All outputs can be operating simultaneously to allow a single volume control for mains and subwoofer or bi/tri/quad amplification.

Electronic Components – All signal routing is through very high-quality latching relays with gold contacts, all resistors in the signal path are metal thin film with 0.1% tolerance or better. AC coupling is achieved with Wima MKS capacitors whilst NP0/C0G 1% capacitors are used to set time constants. All of this means that the lowest levels of distortion are maintained along with excellent channel matching and the most accurate reproduction of the source material.

Connectors and Switch Gear – RCA inputs with RCA and XLR outputs, all gold plated and of the highest quality. Front panel rotary switches are from Blore Edwards and are of a type used in high end recording equipment with excellent ‘feel’ from two leaf springs.

Phono Stage – A matched pair of Lundahl transformers give an initial 28dB of gain to Moving Coil cartridges followed by a 34dB RIAA stage. Further gain of up to 16dB may be added via a selectable second stage. A high pass (rumble) filter can be applied to the phono input to cut bass below 15Hz. The capacitance and impedance of the phono inputs can be adjusted with dip switches on the rear panel.

 

Part 2 – The numbers

Please note the Pre1 is currently near the end of production prototyping, this page will be updated if there are any changes to specification for the final product.

Inputs: 4 Line, 1 Moving Magnet, 1 Moving Coil

Outputs: 2 XLR balanced, 1 RCA unbalanced, 1 RCA unbalanced (always on). All outputs can be used simultaneously.

THD+N:  < -120dB / 0.0001% (1kHz @ 6dBV)

IMD SMTPE < -100dB

IMD ITU < -115dB (18 & 10kHz -6dBV signals measured at 1, 17 & 18kHz)

Channel Matching Average < 0.01dB deviation

Max Deviation < 0.05dB

Channel Separation (crosstalk) > 115dB (1kHz @ -6dBV)

Input Impedance 68kΩ

Output Impedance 50Ω

Phono noise floor at 34dB Gain < 80µV RMS

MM Gain 34-54dB

MM Input Capacitance 15-300pF

MM Cartridge Loading 47kΩ

MC Gain 62 - 78dB

MC Cartridge Loading 39-298Ω

RIAA Tolerance < 0.15dB deviation

RIAA Channel Matching Average < 0.03dB deviation

RIAA Channel Separation > 85dB (1kHz @ -45dBV)