Package Include
1. 12AU7 Balance Tube Preamplifier Kit ref AR (Stereo) - No Tube
2. Assembly Manual 

 

INTRODUCTION

The circuit design is referenced to Audio Research preamplifier. It supports both single-end and balance input and output (RCA and XLR). Basically, the circuit is differential amplifier with two cascade stages. The input stage uses 12AU7 with moderate voltage gain, whereas the output stage uses 6DJ8 (6N11).  The differential amplifier provides high PSRR and capability to noise rejection. The signal paths of this PCB layout are designed in symmetry for both channels. Dedicated power rails, ground, and signal paths, altogether are taken into design considerations so that all are to minimize the parasitic, cross interference, and influence of RFI.

FEATURES

·         Two 12AU7 and two 6N11 (6DJ8) vacuum tubes.

·         Voltage gain: 16dB (single-ended) and 22dB (balanced)

·         Bandwidth: 20-100KHz

·         Frequency Flatness: 40-20KHz (+/-0.1dB)

·         S/N Ratio: >94dB

·         THD: 0.147% @Vin = 0dBV and 1KHz

          0.243% @Vin=10dBV and 1KHz

·         Input impedance 500K Ω

·         Output impedance 400 Ω

·         Two single-ended and balanced inputs.

·         Two single-ended and balanced outputs.

·         Symmetric layout design and signal paths with minimum parasitic.

·         Dedicated ground and power rails layout design.

·         Two large reservoir decoupling capacitors for power rails.

·         Power requirements: one 260V (80mA) DC, one 12.6V (0.5A) DC and one 6.3V (0.8A) DC.

·         PCB dimension: 21.8mm (W) x 13.5mm (L)

·         PCB thickness: 2.4mm, double layer, 2oz copper.

 

Options

1. Toroidal Power Transformer T30
2. HV400D BJT Variable HV Regulator Kit