Red Rose Music Model 5
The Red Rose Music Model 5 Stereo Integrated Amplifier was designed by Victor Tiscareno and Brian Hawkins. It was produced by Red Rose Music in Redmond. Manufacturing, Sales and Service continued in Redmond until the location was closed and tube electronics discontinued.
The Red Rose Model 5 was a tube dual mono stereo integrated amplifier incorporating four each 12AT7 and EL34 tubes, two each per channel. The chassis is aluminum with dampened skin and front and rear panel attached. A detachable IEC power cord was provided. with the line fuse contained in a pull-out drawer within the receptacle. An open output tube cathode fuse LED indicator for each output tube illuminates the tube socket if a cathode fuse opens. The cathode micro fuses are top mounted for easy access. A bias meter is provided to allow easy setting for each output tube. Nominal bias setting is 45mA.
The amp has five line input per channel and tape out. A 23 position stepped attenuator with discreet resistors provides up to 66dB of attenuation. Operating modes are Off, StBY and On. It had a turn on delay going between OFF and STBY (Standby) or ON for 30 second prior to switching to On to allow the tubes to warm up and reduce turn-on surge due to the large capacitors. A front panel bi-color LED indicates red for Standby, yellow during warm-up with the switch is ON and green when ready while On. Each channel had a rear panel switch that allowed floating the channel signal ground, connecting it to chassis ground or the other channel signal ground to obtain the lowest signal hum. Output binding posts for 4,6 and 8 ohms are provided along with a impedance switch to maintain feedback at 7.5dB. A switch to put both channel in Triode or Ultra-Linear is also provided.
The power transformer provided independent winding for left and right channel power supplies, a dual mono configuration. The high voltage windings generated a rectified 500VDC that was regulated to 450VDC for the output tubes and the regulated 300VDC supply of the gain and driver tubes. Additional windings were 12.6VAC for the output tube filaments in series, 14VDC for filament regulators and relays along with 50VDC for the output tube regulated bias. The transformer required replacement to change from 100-120VAC to 220-240VAC. An additional board provided power and relays for turn on delay and switching between Off, Stby and On. .
The 12AT dual section triode is operated with one section providing gain as a grounded cathode amp feeding the other section as the phase splitter. The driver tube used each section as a grounded cathode amp with an AC balance control capacitor coupled to the output tubes. The output tubes are operated with fixed, individually regulated bias in Ultra Linear mode. The Debut II and Model 2 had switches actuating relays to also operate in Triode mode and individual fuses for each of he cathodes of the output tubes..
The 12AT7 tubes used were selected Chinese. Tubes were selected for low microphonics, noise, distortion and 0.25dB balance between channels. The EL34 were and Electro- Harmonix EL34EH and installed as a quad matched sets..