Gold Note PA-1175 MKII silver

Twenty years after its last power amps, Gold Note introduced the PA-1175 MKII, a stereo power amplifier designed to drive different types of speakers thanks to its adjustable damping factor. It delivers 200 watts per channel into 8 ohms in stereo mode and 520 watts in bridged mono. This class A/B amplifier in dual-mono configuration incorporates optical devices to regulate bias and protect the speakers. It is also inspired by the architecture of the older single-ended Demidoff amplifiers developed by Gold Note.

Dual-mono design and Demidoff heritage

The PA-1175 MKII marks Gold Note’s return to stereo power amplification, the brand’s first stereo amplifier created after more than 20 years of electronic design. It merges the know-how acquired with the famous single-ended Demidoff amplifiers and a level of power never before reached. The Demidoff, transistor integrated amplifiers operating in single-ended stage like triodes, are renowned for their fluid, natural musicality. The PA-1175 MKII follows this philosophy while adopting a balanced push-pull class A/B topology, better suited to power requirements.

The amplifier uses a dual-mono configuration with 4 pairs of matched transistors per channel, for a total of eight transistors per side. Each channel operates in fully balanced class A/B push-pull, delivering 200 watts per channel into 8 ohms in stereo mode. This complete separation of left and right channels limits interference and improves stereo separation. The chassis, consisting of a solid steel frame covered with thick aluminum panels, helps contain electromagnetic interference (RFI and EMI).

Optical BIAS: regulation by light

The optical BIAS regulation controls the reference voltage with much greater precision and stability compared to traditional systems. Instead of using conventional electronic components to adjust the bias of the output transistors, Gold Note employs optoelectronic devices. Being much more stable than traditional electronic devices, optical devices ensure outstanding audio performance.

Two circuits use this optical design: the first regulates the bias of the bipolar output transistors, the second monitors the maximum output power to engage protection if the current exceeds a predefined safe value. The optical analysis of the signal takes place separately from the audio path, ensuring speaker protection and unbeatable performance. This separation guarantees that the protection circuits introduce no degradation in the musical signal.

An adjustable damping factor for all speakers

The PA-1175 MKII features technology that enables you to select the damping factor directly from the front panel. A button labeled “DF” lets you choose between two values: 250 or 25. This changes the output impedance from 0.03 to 0.3 ohm. A blue LED indicates the high-impedance mode (250), a green LED the low (25).

Setting the damping factor to 250DF allows you to exploit the full potential of large, low-sensitivity speakers. With this high value, the amplifier exerts tight control over the cone’s movement, particularly in the bass region. The low frequencies are tight, articulated, with a fast transient response.

The 25DF value is perfectly suited to high-efficiency speakers or small monitors that do not like the high output current of large amplifiers. By reducing the damping factor, the amplifier behaves like a low-power tube amp, leaving more freedom to the driver. This approach can bring a certain roundness and depth to the bass, with speakers that prefer less strict control.

This duality is unique on the solid-state amplifier market. It makes it possible to use the PA-1175 MKII with speakers of very different character without compromising sound quality.

BTL mode: doubling the power in mono

BTL (Bridge-Tied-Load) technology allows you to bridge the stereo amplifier to turn it into a mono amplifier, increasing its output power from 200W@8Ω per channel to 520W@8Ω. Into 4 ohms, power reaches 300 watts per channel in stereo and 600 watts in BTL mono mode.

To activate this mode, a small switch located on the back panel, labeled BTL Mode, converts the amplifier into a bridged mono block delivering 520 watts. In mono mode, you must connect the minus plug (usually black) to the red terminal on the left side of the rear panel (marked “-” in the white square) and use the red terminals of both channels for the mono output. The amplifier must be connected correctly for the output to be in phase.

This power doubling is particularly relevant for current-hungry speakers or vertical bi-amping configurations. Mono mode also improves the solidity of the bass range, bringing the perceived strength of mids and lows closer together.

A spiral-core toroidal power supply

The amplifier benefits from a very high-quality power supply featuring a 640 VA toroidal transformer equipped with a spiral core machined from a single piece. The refined mechanical process makes the core completely stable, eliminating any mechanical vibration to guarantee outstanding performance and perfect isolation.

This 630-volt transformer with special core is said to be mechanically rock silent, yet it is still decoupled via viscoelastic isolators that also appear as Vibrastop engine mounts on Ducati racing motorcycles. These high-quality silicone dampers, originally used to isolate engines from vibrations on racing bikes, limit the transmission of vibrations from the transformer to the chassis.

This power supply is coupled to numerous capacitors to maximize current capacity and respond instantly to musical demands. The power supply contains 80,000 µF of substantial capacitance, a reserve that allows the amplifier to handle power peaks without weakening. A second transformer powers the auxiliary functions with dedicated circuits separate from the audio path; this 6 VA transformer handles management tasks without polluting the musical signal.

Connectivity and ergonomics

On the back of the robust aluminum chassis, the PA-1175 MKII offers an unbalanced RCA input and a balanced XLR input. It can therefore be easily paired with any hi-fi preamplifier or home cinema preamp. Input sensitivity is 1 volt on RCA and 4 volts on XLR, with an input impedance of 47 kilohms.

The proprietary GN Link connectors allow you to set the amplifier to master or slave mode with other compatible equipment. This lets you turn all the equipment in the hi-fi system on and off simultaneously. Trigger sockets located just below the BTL Mode switch allow you to power up the amplifier when you turn on your preamplifier.

The rear panel features heavy-duty binding posts as well as balanced XLR and unbalanced RCA input sockets. The speaker terminals are gold-plated, ensuring a stable connection resistant to oxidation. The minimalist front panel sports only two small buttons on the right-hand side: one labeled “DF” for damping factor, the other serving as the power on/off switch. On the left side, two channels recessed into the front face reduce visual fatigue from the large metal surface, and house the Gold Note emblem inlaid like a coin, as well as a blue/green LED indicating the selected damping factor.

Evolution from the MKI

The PA-1175 MKI, the first version of the amplifier, delivered 175 watts per channel into 8 ohms and 350 watts into 8 ohms in BTL mono mode. The MKI also used a 630 VA toroidal transformer and already featured the adjustable damping factor and optical BIAS regulation.

The transition to the MKII brought several improvements. Power per channel increased from 175 to 200 watts into 8 ohms in stereo, and from 350 to 520 watts in mono. The internal design evolved significantly between the two versions, with the transformer going from 630 to 640 VA and changes in component layout. When 75 days had passed without delivery, Gold Note confirmed that they were updating the design to improve it inside and out, which was taking longer than expected.

Technical specifications

Power and audio performance

• Output power
  • Stereo mode: 200 W per channel into 8 Ω
  • Mono BTL mode: 520 W into 8 Ω
• Frequency response: 1 Hz – 100 kHz, ± 1 dB
• Total harmonic distortion: less than 0.01% between 20 Hz and 20 kHz
• Signal-to-noise ratio: 110 dB
• Slew rate: 20 V / µs
• Damping factor: selectable between 25 (low) and 250 (high)

Connectivity

• Audio inputs
  • Unbalanced RCA input: sensitivity 1 V, impedance 47 kΩ
  • Balanced XLR input: sensitivity 4 V, impedance 47 kΩ
• Audio outputs
  • Gold-plated speaker binding posts

Power supply

• Power consumption
  • Maximum: 1200 W
  • Standby: 1.2 W
• Mains voltage: 100 – 120 V or 220 – 240 V, 50 / 60 Hz
• Transformers
  • Main toroidal transformer: 640 VA
  • Secondary transformer for auxiliary functions
• Fuses
  • 6.3 A T for 220 / 240 V mains
  • 10 A T for 100 / 120 V mains

Dimensions and weight

• Dimensions (W x H x D): 430 × 135 × 370 mm
• Net weight: 20.5 kg
• Shipping weight: 27 kg

Advanced features

• BTL mode: converts stereo mode to mono mode to increase output power
• Damping factor selector: allows adjustment of the response according to speaker sensitivity
• Optical BIAS technology: ensures low distortion and precise control of the reference voltage
• Speaker protection: independent optical analysis of the audio path for optimal protection

Construction and protection

• Solid aluminum panels: robust construction minimizing radio frequency and electromagnetic interference
• Spiral toroidal power supply: ensures maximum mechanical stability and perfect isolation