4 tube Pe-Amp Phono Preamplifier attachment being sold separately. DC power supply sold separately. Red Rose was a creation by famed designer Mark Levinson. This model is the Reference Line Level Preamp, utilizing four tubes and a separate power supply to minimize interference. Featuring all Phillips NOS (New Old Stock) tubes, no phono stage, dual volume controls, and completely and thoroughly inspected and tested by our tube technician where it passed with flying colors. Original MSRP was $10,000. The below information is copied from Raptor Electronics site owned by Brian Hawkins who was an integral part of the AudioPrism - Red Rose engineering team. General Description All configurations were a tube line stage unit incorporating two each 6DJ8/6922 and 12AU7/5814 tubes, one each per channel, supplied by an external power supply The preamp board is isolation mounted to the black anodized aluminum chassis with the cover dampened. The external power supply has connectors for the preamp and AC power. It provides rectified and filtered DC voltage for both high voltage and low voltages. The external supply provides 500VDC for high voltage regulators, 11VDC for filament regulators and 11VDC for aux power. The preamp takes the 500VDC and regulates it to 450VDC for the two 295VDC 12AU7 and two 145VDC 6DJ8 regulators. Additionally the 450VDC regulator utilizes the 11VDC for a low voltage reference regulator. Each tube has an independent filament regulator that provides 6.15VDC in operate and 3.5VDC in Standby from the 11VDC. The preamp has five line inputs and a switched non-buffered Tape Out. Operating modes are Standby, Mute, On and -1.5dB. The last will reduce both channels volume by 1.5dB to provide finer steps in control. Two independent 23 position stepped ladder volume controls with discreet resistors provide attenuation with 3dB steps per position. The preamp is muted for 30 seconds after power is applied or when switched out of Standby position to either the On or -1.5dB position. Mute will defeat the output or restore immediately if the 30 second power on or Standby delay has occurred. A front panel bi-color LED indicates red for Mute, green un-Muted. A rear panel switch allowed floating the chassis or connecting it to circuit/signal ground to obtain the lowest signal hum. The 6DJ8 dual section triode is operated in parallel in grounded cathode mode and provides 20dB of gain. The 12AU7 White follower buffers the output without gain but provides a low impedance drive. No global feedback is utilized and the 6DJ8 is direct coupled to the 12AU7. Later Mantissa and all Red Rose Model 3 tubes were JAN/Philips 6DJ8 and 5814. These tubes were treated with a proprietary method. Tubes were selected for low microphonics, noise, distortion and 0.1dB balance between channels. The rejection rate from the selection process for the 6DJ8 was very high while the 5814 was much better. The 6DJ8 higher fallout rate was due to the stringent requirements imposed on the gain tubes for greater then 90dB Signal to Noise un-weighted and very low microphonics. The external power supply was painted black (not included even originally) and configurable for 100, 120 and 230 volts with transformer wiring changes. A detachable IEC power cord is utilized with the AC inlet providing a fuse within a pull-out drawer. The supply used a 9 pin connector for the umbilical cord for the preamp to connect to power or the amplifier (sold separately) Which is necessary for the power. The Mantissa Silver Signature Reference and the Red Rose Model 3 Silver Signature used a larger inductive capacitive supply with a 19 pin connector and larger umbilical cord from the preamp. The Silver Signature units had upgraded Kimber RCA connectors and KCAG silver signal wiring, silver contact volume attenuators with HALCO resistors, Multicap PPFX-S capacitors and Caddock resistors. Additional dampening was added to the chassis and the front panel thickness was increased. The Reference provided more independent supplies for the high and low voltage reference supplies and thicker umbilical cord for additional connections.