• Melpomene VAT913-18 2-channel Vacuum Tube Power Amplifier by GRA & AFCH
• It is a stereo Amplifier designed for home audio and home music systems that produces 5 Watts per channel
• Designed to work with any home audio source: CD player, laptop, smartphone, PC/Mac, etc
• Inputs: RCA, Bluetooth (aptX HD), USB (DAC)

Professional Stereo Tube Amplifier

The VAT913-18 is a fully assembled High-End stereo vacuum tube power amplifier developed and manufactured by GRA & AFCH for audiophiles seeking the musical character of vacuum tubes combined with carefully engineered circuit design and proven long-term reliability.

The VAT913-18 is a mature design that has undergone extensive testing and refinement to ensure consistent performance, excellent sound quality and dependable operation.

Every aspect of the amplifier has been developed with a clear engineering objective: to preserve the natural character of vacuum tube amplification while maintaining excellent technical performance and wide frequency bandwidth.

Proven SRPP Output Stage

At the heart of the VAT913-18 lies a carefully optimized SRPP (Series Regulated Push-Pull) output stage.

Unlike conventional single-ended tube amplifiers, the SRPP topology operates as a push-pull circuit while eliminating direct current through the output transformer. Since no DC component magnetizes the transformer core, the amplifier can fully benefit from the unique advantages of high-quality toroidal output transformers.

This design approach provides several important benefits:

* Extended low-frequency response due to higher primary inductance.
* Excellent magnetic coupling between primary and secondary windings.
* Wide high-frequency bandwidth with low phase shift.
* Lower output impedance resulting from reduced primary winding turns.
* Improved damping factor for better loudspeaker control.
* Higher power-to-weight ratio compared to conventional EI-core transformers.

Optimized Toroidal Output Transformers

The amplifier was specifically developed for use with toroidal output transformers employing sectioned layer-by-layer winding.

This transformer construction combines two characteristics that are often difficult to achieve simultaneously:

• High magnetic coupling.
• Low parasitic capacitance between primary and secondary windings.

The result is excellent bandwidth, accurate transient reproduction and a highly linear frequency response across the audible spectrum and beyond.

With the GV-50 output transformer, the amplifier achieves a measured frequency response of 6 Hz to 28 kHz (-3 dB).

Engineered for Musical Transparency

Rather than relying on unnecessarily complex circuitry, the VAT913-18 follows a carefully optimized signal path that preserves the natural harmonic structure of vacuum tube amplification.

The design philosophy focuses on maintaining excellent measured performance while delivering the openness, clarity and tonal richness that vacuum tube enthusiasts appreciate.

Its combination of wide bandwidth, low distortion and carefully optimized operating conditions makes the VAT913-18 suitable for demanding high-fidelity audio systems.

Fully Assembled and Ready to Use

The VAT913-18 is supplied as a complete, professionally assembled stereo power amplifier.

Each unit is manufactured using high-quality printed circuit boards, carefully selected electronic components and undergoes functional testing before shipment to ensure reliable operation and consistent performance.

Vacuum Tubes

Input Stage

• 6H9C (6N9S)
• 6H8C (6N8S)*

* The optional 6H8C input tube can provide lower harmonic distortion but requires an input signal level of approximately 6 Vrms.

Output Stage

• 6H5C (6N5S)
• 6H13C (6N13S)

Listing includes:

• Stereo Vacuum Tube Power Audio Amplifier Melpomene [VAT913-18]
• Vacuum Tubes: [2 x 6N5S output vacuum Tubes] and [2 x 6N9S small signal Tubes]
• Nixie Tubes: [2 x IN-18]
• Power Cord

Features:

The Melpomene VAT913-18 Amplifier built on SRPP scheme and in fact is a push-pull power amplifier, not a single-ended gain stage.
The peculiarity of the SRPP circuit is that there is no direct current flown through the audio output transformer
and therefore it does not magnetize its core, this design allows the use of toroidal audio output transformers.

The use of toroidal audio output transformers results in a number of advantages:

• lower output frequency – up to 10 Hz (due to higher inductance);
• better flux linkage between the primary and secondary windings,
  this allows to obtain a higher frequency at the output, right up to 40 kHz;
• lower output impedance (due to fewer turns), resulting in increased damping factor
• higher power-to-weight ratio

Our output transformers use layer-by-layer sectioned winding,
which makes it possible to simultaneously achieve two seemingly opposite characteristics:
high inductive coupling and low capacitive coupling between the primary and secondary windings.
This allows for an absolutely linear frequency response from 10 Hz to 40 kHz
(see below in the description of the measurement graphs).

By avoiding feedback and minimizing dynamic distortion,
the amplifier achieves ultimate High-End sound while maintaining the genuine warmth of tube audio.

Unique Features:

• The world’s first Vacuum Tube Amplifier featuring IN-18 Nixie Tube indication
• Nixie Tube meters elegantly display the current volume level
  as well as a countdown timer during Amplifier power-on and power-off.
  Since Amplifier Tubes require cathode heating to initiate electron emission,
  there is a short delay before the Amplifier reaches its optimal operating state
• The countdown clearly indicates this delay showing the time before high voltage is applied to
  or removed from the Tubes. It is an essential feature that helps maximize Tube lifespan
• Automatically restores the previously set volume for a smooth and uninterrupted experience
• Supports IR remote control for convenient power switching and smooth volume control

Additional Features and Technologies

Multiple Audio Inputs

The VAT913-18 combines classic vacuum tube amplification with modern connectivity options, allowing seamless integration into both traditional and contemporary audio systems.

Supported audio inputs include:

• Stereo RCA line input (Left / Right channels)
• Bluetooth wireless audio input
• USB audio input

When connected via USB, the VAT913-18 operates as an external DAC (Digital-to-Analog Converter), allowing direct high-quality audio playback from a computer without requiring a separate external converter.

High-Resolution Bluetooth Audio

The integrated Bluetooth receiver supports the following audio codecs:

• aptX HD
• AAC
• SBC

Support for aptX HD allows significantly higher wireless audio quality than standard SBC transmission, while AAC ensures excellent compatibility with Apple devices. Similar high-end audio products use aptX HD, AAC and SBC as their primary Bluetooth codecs.

Illuminated Input Selection

The currently selected audio source is indicated through the illumination of the vacuum tubes themselves, creating a unique visual effect while providing immediate status feedback.

Input indication colors:

• Red – RCA input
• Blue – Bluetooth input
• Green – USB input

This approach combines functionality with the distinctive visual aesthetics expected from premium vacuum tube equipment.

Nixie Tube Volume Display

One of the most unusual features of the VAT913-18 is its volume indication system.

Instead of using conventional LEDs, LCD displays or digital readouts, the amplifier displays the current volume level using a pair of legendary IN-18 Nixie tubes. The IN-18 is one of the largest and most sought-after Nixie tubes ever produced. Due to their size, rarity and visual appeal, they are highly valued by collectors and enthusiasts. The use of large IN-18 Nixie tubes for volume indication is an exceptionally uncommon solution, especially in vacuum tube audio equipment and virtually unheard of in conventional audio amplifiers. This combination of classic vacuum tube amplification and vintage gas-discharge display technology creates a distinctive visual centerpiece that sets the VAT913-18 apart from ordinary audio equipment.

Intelligent Tube Life Extension System

The VAT913-18 incorporates a unique tube protection and life-extension technology designed to reduce cathode stress during startup.

In many vacuum tube amplifiers, high voltage is applied immediately after power-up. In the VAT913, the startup sequence is carefully controlled: heater power is first applied to the vacuum tubes. The tubes are allowed to warm up and reach proper operating temperature. High-voltage power is applied only after a controlled delay.

This soft-start process helps reduce stress on the tubes during power-up and contributes to extended tube life. During the warm-up period, the IN-18 Nixie display does not remain idle. Instead, it presents a countdown timer showing the remaining time before the amplifier becomes fully operational.

This creates a visually engaging startup sequence while informing the user exactly when the amplifier is ready for listening.

Specifications:

• Output Power: 2 × 5 Watts per channel
• Output Impedance: 8 Ohm
• Frequency Range (-3 dB): 6 Hz – 28.000 Hz
• Distortion (THD): 0.5% at 1 Watt output
• Supply Voltage: 100 – 240 V, 50/60 Hz
• Amplifier Dimensions: L: 33,5 cm x W: 24 cm x H: 13 cm (without Tubes)

Measurement Graphs:

Materials:

The Amplifier is made of noble materials:

• The case is made of 100% natural solid ash made on a CNC machine
  nd finished to perfection by hand by a high-class craftsman with over 40 years of experience
• The wooden surfaces of the case are covered with 7 layers of piano lacquer
• The top cover is made of stainless steel
• the volume knob is lathe-made from a solid brass billet and anodized to prevent oxidation

Melpomene VAT913-18 Vacuum Tube Audio Power Amplifier with Nixie Indication by GRA & AFCH