Build a fully balanced tube amplifier from ground up
There is nothing like Phantom from design concept to practical implementation. Apart from our portable products, Phantom gains the benefit of unlimited power supply and spacious enclosure to include whatever ideally suited audio performance. The first idea came to our mind is a full-balanced topology. Not catering to market hype for balanced amplifier, but to leverage the advantage of balanced topology leading to ultimate sound quality. Instead of a balanced to single-ended conversion at input and a single-ended to balanced conversion at output, we apply a much tedious and costly four-amplifier scheme for a true balanced stereo amplifiers. The decision follows by many design challenges when we determined to make it as ideally as we planned.
A high precision 4-channel volume control
The first challenge is how to make a 4-channel volume control with minimum tolerance. In a single-ended counterpart, a two-channel volume potentiometer with 10% tolerance is widely accepted, even though we usually found imbalance at low volume level between channels. However, using a 4-gang potentiometer in a balanced design, the huge tolerance may easily deteriorate the advantage we gain from balanced topology. One simple fact is the common mode rejection is seriously degraded by as much as the tolerance between gangs.
We use R-2R resistor ladders as volume control unit for zero tolerance between channels. The signal path is true analog with digital interface, so there is no signal imbalance among them. And the user interface is thoughtfully maintained the analog touch. The volume control is almost zero tolerance, high resolution even at lowest volume level and intuitive as traditional potentiometer.
Solid Chassis and Suspended Tubes Module
We have gained many experiences from portable amplifiers and well aware of the vulnerability of directly-heated tube (DHT) to vibration. By leveraging the luxury of enclosure space. There are several directions to stabilize the chassis and isolate vibration from tubes. One is an extremely solid and heft enclosure, though an 10kg+ chassis may beyond anyone’s expectation for a headphone amp. And second is independently suspended tube module. Through delicate mechanical design, the chassis is not just heavy but also as solid as machined from a single metallic brick. Every plate is machined from 10mm solid aluminum and faceplate is over 20mm. Four especially design pillars are used to support tube sub-assembly and dedicated springs are inserted to further dampen the minimal vibration. The chassis of Phantom is solid as a tank and gentle as a cradle.
The Heart of Phantom, 3Q4 (DL95) Directly Heated Tube
With all the dramatic progress, there is one thing we did not change. We adopted a directly heated tube – 3Q4 in Phantom. We are true believer in directly heated tube for their sensational audio performance of intimacy and lifelike sound stage more than none-filament type valves. Phantom with triode-connected 3Q4 immediately warms up into working condition, though it takes tens of minutes for optimum sound quality.
High Fidelity Output Transformers
We are proud to say the single-ended output has equivalent performance as balanced output by leveraging output transformers in Phantom. There are many praises about Phantasy’s audio quality and most are originated from its premium output transformers. Without exception, Phantom is integrated with high quality output transformers. Thanks to the roomy enclosure, we have plenty space to house high power iron cores without compromise. The model used in Phantom is newly developed especially for its output stages and driven by two amplifiers in a push-pull style to minimize distortion and noise.
The output transformer is the last mile in delivering music energy to headphone. The bandwidth, dynamics, distortion, and maximum output power are limited by this iron core. No matter how well active circuitry performs, an inferior transformer will choke them all. A dual secondary coils are wisdom borrowed from PHAntasy to adapt to wide variation of headphone impedance.
Simple and Elegant
Phantom has followed Phatlab’s highly regarded tradition – Simplicity. No matter how sophisticated internal architecture is, it is presented to user with a simple and intuitive interface through elegant and professional industrial design. Though the construction and component counts are many times of its portable predecessors. Phantom is strictly binding to principle of shortest signal path. From input buffer, volume control, up to power amplifiers, there is only one voltage gain stage. This is the only way to minimize internal generated noise. There is hardly a trace of hiss even paired with most sensitive headphones.
Critical music signals and outputs are routed through mechanical relays for highest purity. The relays used in Phantom is especially selected latch-type that means relay’s coil does not consume current after switching. Without the coil current, we avoid the electrical field next to signal path. Though a latch-type relay needs much more complex control circuits, it is our exhausted efforts to minimize interference.
Luxury Power Supply
Starting from portable devices, power supply is always a high priority on our design approach. Thanks to the desktop setting, we have plenty of luxury on power block. The power transformer is rated over 80VA and built with top-rated iron core. Running at pure class-A, Phantom is consuming most power after power on. The quality is assured by its slightly warm even after days of operation.
There are 6 regulated power rails specific for each function block ranging from input buffer, volume control, digital control, filament supply, and B+ high voltage.
Awesome ID and Mechanism
Phantom is another masterpiece designed by highly regarded ID and mechanical professionals. The enclosure ingeniously interlock through invisible tenons and notches is as solid as machined from a single brick to ensure best rigidity and precision. The marking is laser trimmed on. There is nothing shaky or loose. It is designed to last from ground up.
Overwhelming and Immersive
The listening experience is overwhelming and immersive. It is ultimately transparent with a warm touch. It drives headphone effortlessly and extends bandwidth well down to lowest octave and up to highest harmonics. The beloved music is presented with a familiar yet whole new face, they’ve rarely heard as natural or life-like as with Phantom.
5 Hz – 50 kHz (-3dB)
2000 mW + 2000 mW (30 ohm)
16 ohm – 600 ohm
Max. Input Voltage
1 x RCA; 1 x XLR
1 x 1/4″ TRS; 1 x 4-PIN XLR
275 mm x 405 mm x 170 mm