SOUL 170P

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Class A Push Pull 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 theoutput 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.

Cayin Soul 170C tube power amplifier
Tube assembly	4× TUNG-SOL KT170, 2× 12AU7, 2× 6SN7, 1x 17AX4GT
Rated output power stereo mode:	2 x 60W Pure Class A – 120W Bridged mode
Rated output power mono mode:	64W (RMS, triode mode)120W (RMS, ultralinear mode)
Frequency response	8Hz – 70kHz (-3dB, RCA/XLR)
Total distortion	0.2% (1W/1kHz); less than 2% at rated output power
Signal-to-noise ratio	105dB (RCA, A-weighted) 102dB (XLR, A-weighted)
Input sensitivity	820mV (NFB: LOW)
Input impedance	18kΩ
Output impedance	4Ω, 8Ω
Input connections	1 × RCA (pair), 1 × XLR (pair)
Dimensions	430mm × 420mm × 239mm
Net weight (W × D × H)	37.5kg
Power consumption	Max 420W

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 BiasThe 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. Key components include:

 Silver-plated internal wiring

 Aluminum alloy anti-resonance feet

 Customized 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

SOUL 170P

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SOUL 170P

Cayin Soul 170C tube power amplifier