Luxman C-900u Control Amp
Luxman C-900u control amplifier won Soundstage! Network Product of the Year 2014.
Using trickle down technology from the award-winning C-1000f control amplifier, the Luxman C-900u control amplifier is a fully balanced design. Three single-ended, plus one dedicated external processor {Home Theater Bypass} and three balanced inputs. Two single-ended and two balanced outputs. A fully balanced design with tone controls is extremely difficult to implement but the Luxman engineers have achieved this to allow music lovers to enjoy all of their music collection. The C-900u uses Luxman’s latest compact version of the LECUA 1000-WM volume control (Luxman Electric Controlled Ultimate Attenuator with Weighting Matrix Technology), as well as the electronic input selector. Luxman’s most advanced ODNF circuit is employed—release 4.0.—and delivers state-of-the-art musical performance.
Luxman C-900u control amplifier Features
Simple circuit configuration
LECUA 1000WM unifies the C-900u amplifier, volume control functions and power supply in a three-dimensional module, resulting in a circuit that is electrically very simple. Long-term reliability is excellent, with performance and sound quality that will remain unchanged also after prolonged use.
LECUA 1000WM uses analog processing
The LECUA 1000WM circuit converts the music signal from a voltage into a current, switches gain by switching on the attenuates, and then reconverts the current into a voltage. The entire process is carried out in the analog domain.
Same ergonomic feel as a conventional high-quality volume control
The counter balanced volume control knob position is detected by a dedicated CPU which in turn selects the current switches for LECUA 1000WM operation. Operating the knob therefore feels exactly the same as with a conventional control, and operation via the remote control is also possible.
Mute and Balance control are also implemented by LECUA 1000WM
The functions of the attenuator and the left/right balance control are covered by the LECUA 1000WM circuit as well, eliminating the need for additional circuit stages. Keeping the configuration simple helps to maintain high performance and sonic purity.
LECUA 1000WM is a radically different volume control principle that eliminates all variable resistors from the signal path and provides top-notch performance and sound quality. Because the music signal is not affected by changes in impedance, high signal-to-noise ratio and low distortion are maintained at any volume control setting.
LECUA 1000WM ensures high S/N ratio and uniform frequency response
Unlike conventional volume controls, LECUA 1000WM does not introduce a change in impedance at any volume setting. Consequently, there is no deterioration of S/N ratio and frequency response remains totally uniform. The benefits are especially apparent at settings that correspond to normal listening levels, because the sound remains perfectly transparent and the tonal quality is not altered in any way.
No more left/right tracking differences or crosstalk
Because LECUA 1000WM is an electronic circuit employing fixed-value resistors, there is virtually no left/right tracking error also at low volume levels. Since channels can be kept separate, crosstalk also does not present a problem.
Volume Control
The integrated amplifiers also benefit from the C-1000f in that they use a variation of the LECUA 1000 volume control. At any single volume setting only a few resistors are in circuit per channel. The less devices in the signal path, the purer the sound, the cleaner the music.
At low listening levels, potentiometers have trouble keeping both channels in balance, so one channel might easily be 3dB louder than the other. With the volume control made of discrete parts, this is no longer an issue.
ODNF
Luxman holds many patents for audio engineering, amongst them is the application of Global Negative Feedback to the output stage, which while widely used throughout the audio industry, they no longer use themselves.
Today, Luxman uses a distortion reduction circuit called Only Distortion Negative Feedback (ODNF). This system works by isolating noise & distortion at the output from the music signal and sparingly applying negative feedback to suppress them. Conventional negative feedback systems can have an adverse effect on the music, introducing phase distortion. “The circuit features such an ultra-wide range, ultra- high slew rate and ultra low distortion that it does not use phase compensation for the music signal amplifying circuits.” This new technology also ensures that need for a DC servo circuit is alleviated, again improving sound quality.
| Item | Value |
|---|---|
| Inputs | Unbalanced 3 system, balanced 3 system |
| Outputs | Unbalanced 2 system, balanced 2 system |
| Input Sensitivity/Impedance | unbalanced 255mV / 43kΩ, balanced 255mV / 86kΩ |
| Output Voltage / Impedance | unbalanced rated 1v/90Ω Maximum 11V balance rated 1V/180V Maximum 22.5v |
| Harmonic Distortion | 0.009% (20Hz – 20kHz), balanced 0.005% (20Hz-20kHz) |
| Frequency Response | 20Hz – 20kHz (+0, -0.1dB), 5Hz – 120kHz (+0, -3.0dB) |
| Signal-to-noise ratio | Unbalanced 123dB, balanced 126dB |
| Power Consumption | 42W, 2.2 (at standby) |
| Dimensions (W x H x D) | 440 x 130 x 430mm |
| Weight | 19.7kg |
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“The M-900u and C-900u provide wide and deep look into the soundstage of the London´s Barbican. The Luxmans excel in instrumental separation yet they manage to convey the wholeness of the symphonic orchestra. They can dissect if you want them to dissect – Allegretto begins with muted cellos and the Luxmans bring the smell of resin on strings to the listening room. You can feel how variable is the pressure of bows on strings, you see the incidental moves of the cellists, and if you wish you can just pick up one cello and follow it through the rest of the piece with its full front to back perspective.
“Imaging of the Luxmans is pinpoint sharp. Not only within the depth and width of the soundstage but also in vertical space – tympani, for example, sit recessed in the soundstage at a level slightly above the orchestra. One of the best tests for imaging can be found at Chesky´s Jazz sampler. Four musicians with percussive instruments (shaker, maraca, hand drum and wood blocks) are marching through a reverberant chapel, approaching a microphone, making three rounds around it and disappearing through the gate in the back of the chapel.
“The anniversary Luxman M-900u/C-900u combo is a fantastic piece of audio that signifies a new era for the company. I can say aloud that both amps are first affordable amps, however relative is this term, I can imagine to spend the rest of my life with. Actually, I am considering to replace my all Accuphase set up with them. Cannot be more enthusiastic.”
“The Luxman C-900u amazed me. It makes me wonder how different my audio journey might have been had I listened to that salesman 33 years ago and bought the used Luxman integrated he recommended. The C-900u’s build quality is outstanding, its styling is superb, and its unique feature set will be useful for those who need things such as tone controls and a Loudness contour.
“But even if such features don’t float your audiophile boat — and for many audiophiles, they won’t — the C-900u’s sound will. It’s beyond reproach, even when compared with a topflight preamplifier with minimal controls. Incredibly detailed, stupendously spacious, and essentially flawless throughout the audioband, the C-900u did no wrong in my system and in my room. While I doubt I’d ever use its tone controls or Loudness contour, I’d be happy to own the C-900u as a sonic reference, and consider everything else it offers icing on a world-class cake.
“I absolutely loved the Luxman C-900u. In my estimation, it’s a preamp for the ages — and perhaps in a decade or two, it will have proven to be another classic from Luxman that will still be outperforming whatever’s new in 2024 or 2034.”
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