Cayin - Soul 170P - Power Amplifier

The Soul 170P is our latest power amplifier built upon over 32 years of Cayin’s expertise in vacuum tube amplification. Designed to deliver exceptional musicality and power, it adopts a Class A architecture with powerful TUNG-SOL KT170 tubes. This is also the very first time we’ve implemented Class A amplification in our Soul series amplifier, aiming to present a fresh and emotional take on the KT170 sound.

The Soul 170P offers both Stereo and Mono operating modes to accommodate speakers with higher power demands.

Tubes & Topology

At the heart of the Soul 170P are four TUNG-SOL KT170 beam tetrodes, operating in a Class A push-pull configuration. The amplifier also features:

• Voltage Amplification Tubes: 2 × 12AU7. In the voltage amplification stage, two JJ 12AU7 tubes are responsible for initial signal gain, providing the necessary voltage amplification before driving the output stage. Their low distortion and noise characteristics contribute to stable signal handling.
• Driver Tubes: 2 × 6SN7. Employed in the driver stage, the JJ 6SN7, known for its musicality and powerful drive, contributes to a sound that’s both emotionally engaging and analytically revealing.
• Rectifier Tube: 1 × 17AX4GT. This classic rectifier tube supplies a stable DC voltage to the driver stage, ensuring reliable performance and a refined sound with beloved tube body musical expression.

Flexible Operating Modes

• Stereo Mode: 60W (Ultralinear, per channel)
• Mono Mode: 120W (Ultralinear, per channel)

Users can easily switch between Stereo and Mono operation using a secure rear-panel switch, allowing the Soul 170P to be used in both two-channel and high-power mono configurations.

Negative Feedback Circuitry

To achieve a more refined and natural sound presentation, the Soul 170P employs a carefully tuned Negative Feedback (NFB) circuit. Cayin engineers applied a moderate global feedback loop, striking a balance between control and musical expression.

In addition, the Soul 170P features two selectable NFB levels—High and Low—allowing users to fine-tune the amplifier’s sound signature.

Choose Low for a more open, expressive, and emotionally engaging sound, or High for tighter control, improved precision, and a more analytical presentation. This flexibility allows the Soul 170P to fully showcase their character across a wide range of speakers and musical genres.

Dynamic Auto Bias

• Silver-plated internal wiring
• Aluminium alloy anti-resonance feet
• Customised hand-wounded Toroidal power transformer and EI wide-band output transformer

Protective Features

• Tube soft-start circuit (60-second delay)
• MCU-controlled protection logic
• BMI indicators (to detect power tube faults and automatically engage safety mode)

Connectivity

• Inputs: 1 × XLR, 1 × RCA
• Speaker Terminals: 4Ω and 8Ω outputs

The Soul 170P features a fully integrated Dynamic Auto Bias servo circuit, allowing seamless power tube replacement without manual adjustment. This system precisely regulates the operating status of each KT170 tube, ensuring optimal matching and extending tube lifespan—all while maintaining operational safety and tube longevity.

Component Selection & Internal Build

The amplifier is hand-assembled with point-to-point wiring, ensuring low signal loss, minimum crosstalk and interference.

Specifications

• Rated Output Power: Stereo Mode: 32W + 32W (RMS, Triode mode) 60W + 60W (RMS, Ultralinear mode); Mono Mode: 64W (RMS, Triode mode) 120W (RMS, Ultralinear mode)
• Frequency Response: 8Hz – 70kHz (–3dB, RCA/XLR)
• Total Harmonic Distortion: less than 2% at rated output power 105dB (RCA, A-weighted)
• Signal-to-Noise Ratio: 102dB (XLR, A-weighted)
• Input Sensitivity: 820mV (NFB: LOW) 960mV (NFB: HIGH)
• Input Impedance Output: 18kΩ
• Output Input: 4Ω, 8Ω
• Terminals: 1 × RCA (pair), 1 × XLR (pair)
• Tubes Used: KT170 × 4 12AU7 / ECC82 × 2 6SN7 × 2 17AX4GT × 1
• Dimensions: 430mm × 420mm × 238mm
• Net Weight: 37.5kg
• Maximum Power Consumption: 420W (Maximum)