Preamplifiers

conrad-johnson Classic Vacuum Tube Preamplifier with Phono Stage

ARTICLE INDEX


Introduction

conrad-johnson (lower case c and j) was formed in the mid-seventies, shortly after I became seriously interested in audio gear. I'm sure the two events were entirely unrelated. Their first product, a preamplifier, was immediately recognized as "state of the art," and so their storied history began. I encourage you to visit their website for more details. There, they provide a long list of products that have been reviewed as "Best of Class", and even "Best in the World." The Classic Preamplifier is the least expensive line-stage (the phono stage is optional) in their formidable product line. Both stages are zero-feedback circuits. The phono section uses two triode amplifiers separated by a passive RIAA equalization network. The second triode amplifier is direct coupled to a high-current output stage. The line-level section has a single triode amplifier also direct coupled to a high-current output stage. I considered using the descriptor 'entry-level,' but that would hardly do the Classic justice. As I immediately discovered, there is nothing entry-level about the Classic, except for the incredible price-to-performance ratio.

Specifications

  • Classic Line Stage:
  • Design: Stereo Vacuum Tube
  • Gain: 22 dB
  • Maximum Output: 9.5 VRMS
  • THD: less than 0.15%
  • MFR: 2 Hz to more than 100 kHz
  • S/N: -98 dB relative to 2.5 V output
  • Tube Complement: 2 x M8080
  • Optional Phono Stage:
  • Design: Vacuum Tube
  • Gain: 54 dB
  • Phono Equalization: within ± 0.25 dB of RIAA standard
  • S/N: Phono Stage 80 dB relative to 10 mV input
  • Tube Complement: 3 x 12AX7
  • Dimensions: 3.6" H x 19" W x 13.6" D
  • Weight: 14 Pounds
  • MSRP: $1,750 ($2,500 with Phono Stage)
  • conradjohnson Designs