The P-750u is a meticulously refined evolution of LUXMAN's P-700u, itself an industry standard, high-end headphone amplifier. Central to the design is LECUA (LUXMAN Electronically Controlled Ultimate Attenuator), a high fidelity computer controlled attenuator as the ideal volume adjustment. The P-750u also features ODNF Version 4.0 (Only Distortion Negative Feedback), a proprietary feedback circuit integral to this perfectly balanced headphone amplifier. The addition of a 4-pin XLR balanced headphone output completes the evolution by extending the choice of compatible headphones.
LUXMAN’s ODNF (Only Distortion Negative Feedback) original amplification feedback circuit achieves a high-speed primary slew rate, ultra-wide bandwidth and low-level distortion by feeding back only the distorted elements of the audio signal from the output amplification circuit. The design resulted in even lower output impedance and a higher signal-to-noise ratio, due to a paralleled first stage and a Darlington-equipped second stage amplification circuit. It features the very latest version of ODNF, offering improved accuracy in detecting distortion by using a triple-paralleled input stage error detection circuit. The final stage of the P-750u's ODNF-equipped amplifier circuitry is a 4 channel, fully balanced output system. A Bridge Tied Load output configuration is used for balanced headphones while a dual-paralleled configuration is used for unbalanced headphones.
The design features a solid state (IC) circuit, achieving a significant reduction in size, together with the LECUA computerized attenuator, which we believe is the ideal level control system. This multifunctional amplifier suppresses the deterioration of quality by offering three selectable levels of sensitivity, depending on the impedance and efficiency of the headphones, and by integrating left/right balance adjustment with LECUA.
The P-750u is equipped with ODNF Version 4.0, LUXMAN’s original high sound quality amplification feedback circuit on each of the four identical output channels. Utilizing a BTL balanced output configuration enables a great improvement in left-right separation, sound localization and power supply regulation, while cross-modulation distortion is also significantly reduced. Then using unbalanced headphones, the four channel amplification circuitry is divided into 2 channels each for left and right, driving each in parallel, thereby doubling the output current supply capacity. This improves absolute driving force and intensifies sound reproduction with dynamic intonation. An enhanced sound stage can be enjoyed with a rich range and the superb detail that is characteristic of a balanced connection.
The P-750u features a choice of headphone outputs including a standard stereo jack output terminal, a stereo pair of balanced 3-pin XLR terminals with the addition of a 4-pin XLR balanced terminal for compatibility with high-end headphones.
The design of the P-750u is enhanced with the inclusion of a highly stable power supply circuit consisting of a highly regulated OI-core power transformer, two 10,000μF custom block capacitors in the power amplifier stage and two 3,300μF custom block capacitors in the pre-driver stage achieving immense power and stability.
To realize a smooth signal transmission, LUXMAN's Beeline construction is utilized. This allows the wiring and signal transmission to take the shortest optimal route. Our non-angled wiring pattern with straight and smoothly curved traces on the circuit board also contribute to the smooth passage of audio signals.
In addition to the 3-step sensitivity selection, allowing the output sensitivity to be chosen according to various headphones, the P-750u also features a left-right balance adjustment control. Both functions are controlled by LECUA, a high quality computerized attenuator, to minimize the deterioration of sound quality.
The dual design of the base chassis, constructed from 3mm steel, maximizes rigidity and makes the center of gravity lower. A mirrored, rhodium plated logo plate on the front panel combines beautifully with the blaster white metallic cabinet for a truly refined finish.
|Customized legs||Gradation cast iron legs are used for the LUXMAN 900 series separate amplifier have been customized for the P-750u, taking thorough countermeasures against vibration|
|Output||Unbalance: 4W + 4W (8Ω), 2W + 2W (16Ω) 1W + 1W (32Ω), 53mW + 53mW (600Ω)
Balance: 8W + 8W (16Ω), 4W + 4W (32Ω) 213mW + 213mW (600Ω)
|Input sensitivity/input impedance||Unbalance: 1.0V/15kΩ
|Frequency response||20Hz to 20kHz (+0, -0.1dB)
10Hz to 170kHz (+0, -3.0dB)
|Total harmonic distortion||Unbalance: 0.003% (1kHz)
Balance: 0.002% (1kHz)
|S/N ratio (IHF-A)||Unbalance: 113dB, Balance: 116dB|
|Power supply||230V~(50Hz) / 115V~(60Hz)|
|Dimensions||440(W) x 92(H) x 400(D) mm