The Red Rose Music Model 5 is a dual monaural integrated amplifier, designed to deliver high-quality audio performance through a combination of vacuum tube technology and meticulously engineered power supplies. The amplifier's design philosophy centers on achieving a natural and human sound, emphasizing quality and simplicity over complexity.
Function Description:
The Model 5 serves as the central hub for an audio system, integrating both pre-amplifier and power amplifier functions. It takes low-level audio signals from various sources, boosts them to useful levels, and drives speakers. The amplifier features five line-stage stereo inputs, allowing connection to multiple external program sources such as CD players and tuners. It also provides unbuffered line-level Tape outputs for recording. A key feature is the switch selection between Triode and Ultralinear modes, offering different sonic characteristics to suit listener preferences and speaker types. The Triode mode prioritizes improved audio quality with lower noise and less distortion, while the Ultralinear mode provides maximum power output and dynamic impact. The amplifier incorporates a standby mode to reduce power consumption and extend tube life.
Important Technical Specifications:
- Tubes Compliment: 2 each 12AT7 per channel, 2 each EL34/6CA7 per channel.
- Power Output: 45 watts / 1 kHz / 1% THD.
- Frequency Response: 5 Hz to 50 kHz, -3 dB @ 1 watt.
- Power Bandwidth: 16 Hz to 30 kHz, -3 dB @ 35 watts.
- Input Sensitivity: .125V for full output, attenuator set at maximum.
- Input Attenuator: 23 positions, 66 dB of attenuation.
- Input Impedance: 75k ohms.
- Output Taps: 4, 6 and 8 ohms for optimal speaker impedance matching.
- Overall Negative Feedback: 7.5 dB.
- Hum and Noise: >85 dB SN Ref 1 W, no weighting.
- Power Requirements: 350 watts maximum.
- AC Requirements: 100v/120v/220~240V (CE countries set to 230V).
- Dimensions: 12.5 d x 17.0 w x 7.5 h (31.75cm x 43.18cm x 19.05 cm).
- Weight: 54 lb (25 kg).
- Shipping Weight: 64 lb (29 kg).
The amplifier's internal design emphasizes high-performance power supplies. It features regulated power supplies for output tubes, separate reference supplies for high voltages, heavy-duty power transformers with separate windings for each channel, and separate bridge rectifiers and regulators for each channel. All transformers are electrically isolated and mechanically shock-mounted. The chassis is an all-aluminum laminated two-layer design for resonance damping, with additional internal damping material. The printed circuit board is .093-inch (2.3 mm) FR-4 mil-spec with heavy plating, wide traces, solder mask over bare copper, and double-sided plate-through holes. High-quality components are used throughout, including computer-grade capacitors, MIT® tin-foil polypropylene capacitors, Holco® and Roederstein® resistors, Rel-Cap® polystyrene, Cardas® binding posts, Neutrik® XLR Connectors, and Hubbell® IEC 320 power connectors.
Usage Features:
- Front Panel Controls:
- Program Selector: A rotary switch to select one of the five input sources (CD, Tuner, Phono, Tape, Video/Aux). Users are advised to turn the Volume Control down before changing programs to prevent speaker damage.
- Volume Control: A precision step attenuator switch that adjusts output volume in 3 dB increments.
- Mode Indicator: A multi-color LED (green for ON, red for Standby, orange for warmup, dark for OFF) indicating the amplifier's operational status.
- Power Switch: Three positions: OFF, STBY (Standby), and ON. Standby mode keeps tube filaments warm and capacitors charged without passing a signal, useful for quick restarts or switching between Triode/Ultralinear modes.
- Rear Panel Controls:
- Input Connectors: Five pairs of RCA inputs for line-level audio sources. Note that the amplifier does not include a phono preamp stage, requiring an external unit for turntables.
- Tape Out Connectors: Unbuffered RCA outputs carrying the selected program source at a constant level, unaffected by the Volume Control. Users are warned against creating feedback loops by monitoring a recorder's input while simultaneously playing back from it.
- Feedback Control (Right/Left): Rotary switches to set optimal feedback levels based on speaker impedance. A small screwdriver or alignment tool is used to adjust the red mark to match the speaker's impedance. Adjustment should be done with the amplifier off.
- Speaker Connectors (Right/Left): Five-way binding posts for connecting speakers. Positive (+) terminals should connect to the amplifier terminal closest to the speaker's impedance, and negative (-) terminals to the 0Ω (Common) connector.
- Ground Switch (Right/Left): Three settings (COMMON, FLOAT, GROUND) to eliminate hum caused by ground loops. COMMON ties signal grounds together, FLOAT isolates the channel's signal ground, and GROUND shorts it to chassis ground.
- Output Tube Operation Switch: Two settings: ULTRALINEAR for maximum power output (pentode operation) and TRIODE for improved audio quality with lower noise and distortion (triode operation), albeit with approximately 50% less output power. The amplifier should be turned off before changing this setting.
- AC Power Connector: Standard IEC three-wire AC socket.
- Fuse Holder: Contains two fuses: one active and one spare, protecting against AC power surges.
- Top Panel Controls (under cover):
- Line Stage Tube Sockets: For the four 12AT7 vacuum tubes.
- BIAS MONITOR Switch: Selects which output tube's plate current (V1, V2, V3, or V4) is displayed on the Bias Meter. An OPERATE position is for normal amplifier operation.
- Bias Adjust Controls (V1, V2, V3, V4): Trim pots for setting the plate current of each EL-34/6CA7 output tube.
- Fuses for Output Tubes (V1, V2, V3, V4): 250 mA Micro fuses protect individual output tubes from overcurrent. A red LED indicates a blown fuse or missing fuse.
- Bias Meter: Displays the plate current of the selected output tube.
Maintenance Features:
- Tube Replacement: The manual provides detailed steps for replacing output tubes (EL-34/6CA7) and input tubes (12AT7). It recommends replacing all four output tubes with the same brand and notes that the on-board bias adjustment allows matching any set of four tubes. Tubes are expected to operate for at least 10,000 hours, but plate current should be monitored as they age.
- Bias Adjustment: Users can adjust the plate current of each output tube using the Bias Adjust controls and the Bias Meter. The recommended plate current is 45 mA ±4mA in Ultralinear mode. This adjustment is crucial for optimal performance and tube longevity.
- Fuse Replacement: Instructions are provided for replacing the main AC power fuse and individual output tube fuses. Users are explicitly warned against using fuses with higher ratings.
- Troubleshooting Guide: The manual includes a section to diagnose common issues such as no audio/lights, no audio with lights, and distorted audio, offering solutions like checking cable connections, power sources, fuse status, and tube bias.
- Cleaning: Users are advised to wipe the glass parts of tubes with a clean, soft cotton cloth to remove fingerprints and oils, which can reduce tube life.
- Safety Instructions: Emphasizes keeping the amplifier out of reach of children and pets, avoiding exposure to water, moisture, and excessive heat, ensuring proper voltage connection, and never defeating the safety ground. It also states that there are no user-serviceable parts inside and warns against operating the unit if visibly damaged or with covers removed.
- Warranty: A five-year limited warranty covers manufacturing defects for the amplifier, with vacuum tubes separately warranted for one year. The warranty is void if the unit is altered or modified by unauthorized personnel and does not cover normal maintenance, transit damage, or damage from misuse.
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