IGS Audio PHOM – Tube Phono Stage with the Passive RIAA Filter

OVERVIEW

The IGS Audio PHOM is a high-end phono preamplifier created for the modern revival of vinyl, where more listeners than ever are rediscovering the emotional depth of analog playback. As turntables return to living rooms, the need for a truly refined phono stage becomes essential; sometimes it’s just you, the record, and a moment that speaks for itself. PHOM is designed for demanding audiophiles who want to extract the full potential from their records, offering full support for both MM and MC cartridges. The MC input is transformer-coupled, ensuring extremely low noise while boosting the delicate signal at the very first stage. In addition, PHOM allows precise system matching through selectable resistor and capacitor ladders, enabling perfect tuning to any cartridge. Every nuance, every subtle groove detail is preserved; nothing lost, nothing forced, just pure analog truth.

Precision Circuits, Pure Analog Truth.

PHOM is built as a two-stage tube amplifier using carefully selected NOS military-grade tubes. Each stage operates in a cascode configuration, providing high gain with excellent linearity and low noise. Between the stages, a fully passive RIAA equalisation network is implemented, offering superior accuracy and transparency compared to feedback-based designs. This approach preserves signal integrity and avoids the artifacts often associated with active equalisation. The RIAA network itself utilises premium Paper in Oil capacitors, contributing to a natural and fluid sonic character. The power supply section features a tube rectifier GZ34 along with a large choke for effective voltage smoothing. The use of a tube rectifier not only enhances musicality but also provides a soft-start behaviour, extending tube life and ensuring stable operation.

Minimal Form, Maximum Presence.

PHOM is housed in an elegant enclosure made from 3 mm CNC-machined aluminum, with dimensions of 380 × 290 mm. The front panel follows a minimalist philosophy, featuring subtle, finely printed labelling and a single small LED indicator placed at the centre, signalling the presence of power. The rear panel provides RCA connectors for both turntable and amplifier connections, along with an MM/MC switch, grounding terminal, and power inlet. The top panel incorporates ventilation openings to ensure proper heat dissipation, as well as a CNC-cut PHOM logo that emphasises the product’s refined and purposeful design. Every detail reflects careful consideration and a commitment to both aesthetics and functionality.

Engineered for Absolute Analog Fidelity.

PHOM delivers a gain exceeding 60 dB, making it fully suitable for any MM cartridge, and up to 80 dB for MC cartridges, placing it among the most capable phono stages in its class. The unit offers adjustable resistive loading for MC cartridges ranging from 56 Ω to 1000 Ω, as well as capacitive loading for MM cartridges from 22 pF to 290 pF. The amplification stage is based on a hand-selected quartet of 6N1P-EV tubes, ensuring consistency and low noise. The passive RIAA network incorporates NOS Paper in Oil capacitors, Silver Mica, and Mundorf EVO components for optimal sonic performance. The unit is powered by a heavily oversized transformer supplied by UTM Industry, while the GZ34 tube rectifier and choke-filtered power supply ensure stability and musicality. The entire design results in a robust device weighing 9 kg.

KEY HIGHLIGHTS

Fully Tube, All-Analog Signal Path

PHOM uses a completely tube-based analogue architecture designed to preserve the natural character, dynamics and emotional depth of vinyl playback.

Support for MM & MC Cartridges

Flexible MM and MC compatibility makes PHOM suitable for a wide range of cartridges, with dedicated circuitry for each cartridge type.

Transformer-Coupled MC Input

The MC input uses transformer coupling to provide extremely low-noise amplification of delicate moving-coil cartridge signals right at the first stage.

Precision Passive RIAA Equalisation

A fully passive RIAA network sits between the two tube amplification stages, providing accurate and transparent equalisation without relying on feedback-based circuitry.

Selectable Cartridge Loading

Adjustable resistive loading for MC cartridges and capacitive loading for MM cartridges allow the phono stage to be precisely matched to your cartridge and system.

Premium Audio-Grade Components

The RIAA network combines NOS Paper in Oil capacitors, Silver Mica and Mundorf EVO components to support a natural, detailed and fluid sonic presentation.

Hand-Selected NOS Tubes

A matched quartet of military-grade NOS 6N1P-EV tubes provides consistent, low-noise performance across the two-stage amplification circuit.

GZ34 Tube Rectification

The linear power supply uses a GZ34 tube rectifier and large choke for effective voltage smoothing, soft-start operation and stable performance.

Oversized UTM Industry Transformer

A heavily oversized, hand-wound power transformer supplied by UTM Industry provides a robust foundation for the analogue circuitry.

Precision CNC-Machined Aluminium Chassis

The 3 mm CNC-machined aluminium enclosure combines structural rigidity with a minimalist, refined aesthetic designed for premium listening environments.

FEATURES

• Fully tube, all-analog signal path
• Two-stage cascode tube amplifier design
• Passive RIAA equalisation between amplification stages
• Designed without global negative feedback
• Transformer-coupled MC input
• MM/MC cartridge selection
• Selectable cartridge loading for precise system matching
• Premium NOS Paper in Oil, Silver Mica and Mundorf EVO components
• Hand-selected, matched NOS military-grade tubes
• GZ34 tube-rectified linear power supply
• Large choke-filtered power supply
• Hand-wound audio transformers and power supply choke
• Oversized UTM Industry power transformer
• Minimalist 3 mm CNC-machined aluminium enclosure
• Dedicated turntable grounding connection
• Designed and manufactured in Poland

TECHNICAL SPECS

Fully Tube, All-Analog Signal Path

Passive RIAA Equalisation

Designed Without Global Negative Feedback

Output Level: 0.775 V RMS (2Vpp)

Maximum Gain: 62 dB

MM / MC Cartridge Selection Switch

Transformer-Coupled Input for MC Cartridges

Selectable Resistive Loading for MC Cartridges

16-Step MC Resistive Loading: 56 Ω – 1000 kΩ

Selectable Input Capacitance for MM Cartridges

16-Step MM Capacitive Loading: 22 pF – 390 pF

Hand-Selected Matched Quartet of NOS 6N1P-EV Tubes (Military-Grade Stock)

Audio-Grade Capacitors: NOS Paper-in-Oil, Silver Mica, Mundorf EVO

GZ34 Tube Dual-Diode Rectified Linear Power Supply

Hand-Wound Audio Transformers and Power Supply Choke

Turntable Ground Connection

Power Consumption: 55 W

Package Dimensions: 55 cm × 45 cm × 20 cm

Shipping Weight: 11 kg

Country of Origin: Designed and Manufactured in Poland