Audio research SP-10 pre amplifier, SP-10S pre amplifier Power supply

Description

The Audio Research SP-10 is a legendary two-chassis, all-tube stereo preamplifier widely regarded as a pinnacle of high-end audio design from the early to mid-1980s. It consists of two separate units: the main preamplifier control unit and a dedicated, massive power supply (SP-10PS). This dual-chassis design was implemented to isolate the sensitive audio circuitry from the noise and electromagnetic interference generated by the power supply, contributing to its exceptional sonic purity. The SP-10 is a full-featured preamplifier, offering comprehensive control and connectivity for serious audiophiles. It boasts a sophisticated phono stage with two independent phono inputs, each with selectable impedance settings to optimize performance with a wide range of moving coil and moving magnet cartridges. The line stage provides multiple high-level inputs for sources like tuners, CD players, and tape decks, along with two tape monitor loops.  

Operationally, the SP-10 offers flexible control, including a stepped gain control for precise volume adjustments, a balance control, a mute switch, and a unique "Direct" switch that bypasses much of the switching and circuitry for the purest possible signal path from the selected phono input directly to the volume control. The front panel typically features a clean and functional layout with clearly labeled controls.  

Sonically, the SP-10 is renowned for its exceptional transparency, dynamic contrasts, and a musically natural presentation. It delivers a wide and deep soundstage with precise imaging. While being a tube design, it is often praised for its extended and detailed high frequencies, rivaling some of the best solid-state preamplifiers of its time. Its phono stage is particularly lauded for its ability to extract nuanced detail and deliver a rich and engaging vinyl playback experience. The separate SP-10PS power supply is a substantial unit housing multiple transformers and a sophisticated regulation system to provide clean and stable power to the preamplifier section. This robust power supply is crucial to the SP-10's sonic performance, ensuring ample headroom and contributing to its dynamic capabilities. The two units are connected via a dedicated umbilical cord.  

Key Features (SP-10):

• Two-Chassis Design: Separate preamplifier and power supply for optimal isolation.  
• All-Tube Circuitry: Utilizes multiple vacuum tubes for a rich and detailed sound.  
• Dual Phono Inputs: Accommodates two turntables with selectable impedance.
• Multiple Line-Level Inputs: Provides connectivity for various audio sources.
• Two Tape Monitor Loops: For tape recording and playback flexibility.  
• Stepped Gain Control: Offers precise volume adjustments.  
• Balance Control: Allows for fine-tuning of the stereo image.
• Mute Switch: For silent source switching or pausing.  
• Direct Switch: Bypasses unnecessary circuitry for the purest phono signal.  
• Robust SP-10PS Power Supply: Ensures clean and stable power delivery.

Specifications (SP-10 - Based on available information):

• Type: Full-function stereo tube preamplifier with separate power supply.
• Tube Complement (Preamplifier): Typically includes multiple 6DJ8/ECC88 and possibly other small signal tubes (refer to specific model documentation).  
• Tube Complement (Power Supply): Typically includes rectifier and regulator tubes (e.g., 5881, 12AT7 - refer to specific model documentation).
• Gain: Selectable; High Gain (typically around 72dB for phono), Low Gain (12dB less).
• Input Impedance (Phono): Selectable (e.g., 47k Ohms, 100 Ohms, other options).
• Output Impedance: Typically around 500 Ohms.
• Frequency Response: Typically 5Hz to 50kHz (-3dB).
• Total Harmonic Distortion (THD): Typically less than 0.05%.
• Signal-to-Noise Ratio: Typically 72dB (phono, low output MC), 80dB (line).
• Dimensions (Preamplifier): Approximately 19" (W) x 5.25" (H) x 10.5" (D).
• Dimensions (Power Supply): Approximately 19" (W) x 5.25" (H) x 10.5" (D).
• Weight: Substantial due to the dual-chassis and large transformers.