LUXMAN C-7f

Commentary

Control amplifier developed as a successor to C-7 and C-7i.

The C-7f is designed as a power amplifier driver with an emphasis on this point. It not only controls the audio signal, but also emphasizes the form of the sound, adds thickness to the harmony, and clarifies the character of each sound.

ODNF circuit is mounted on the flat amplifier section.
In this circuit method, we developed an ultra-wide band, high-slew rate, low-distortion circuit that does not require phase correction for the amplification circuit part of the music signal, thereby eliminating the complementation that cannot be avoided with conventional NFB. In addition, we focused on the part where distortion was suppressed for each music signal in conventional NFB, and by changing the method to feed back only the distortion component from the output to the final stage of the amplification circuit, only the distortion component is removed from the output waveform. This realizes a high initial slew rate that rises instantaneously and an ultra-wide band.
In addition, by eliminating the DC servo amplifier for ultra-low frequency control, which has been the cause of unnatural coloring in the low frequency range in the NFB circuit, we are attempting to unify the timbre of all bands.

High-inertia power supply is used for the power supply section.
In the conventional method of controlling power supply according to music signals, the power supply is always delayed from the real time of music, which is a factor inhibiting the sense of dynamism. Therefore, a special electrolytic capacitor with excellent instantaneous discharge characteristics is installed in the high-inertia power supply to minimize the delay control by creating an environment in which a comfortable power supply can always be pooled.

Noise isolation structure and independent power supply are adopted for the internal construction, and unnecessary vibration and noise are completely suppressed.
The C-7f is based on an FRP chassis base with excellent vibration absorption mode. Vibration noise is eliminated by firmly fixing parts in a thick chassis. The layout is designed so that the power transformer, electrolytic capacitor, and amplifier board do not directly interfere with each other. In addition, each block is shielded by a shield plate, and the internal filter is strengthened to eliminate flux and noise interference.
In addition, the power supply section is separated by a partition structure, and is connected to the main body chassis by semi-floating processing in an independent power supply room system. By isolating both electromagnetically and mechanically, leakage flux is strictly shut off within the same housing.

It uses custom-made parts exclusively for Luxman.
Based on an acoustically excellent carbon film resistor, we have studied a wide range of materials, including selection of alumina, etching, carbonization, terminal material, terminal shape, and press-fitting method, to improve the information transmission cost.
In addition to large power transformers and large-capacity block capacitors, we use electrolytic capacitors, copper-styrene capacitors, copper bus bars, and high-purity cables to improve sound quality.

High-quality 4-series volume is used for the balance circuit.
The C-7f has a new gain-1 position for this volume so that you can take advantage of the C-7f without losing the balance of the audio levels of each channel set by a home theater multi-channel audio processor, etc.

It has a coaxial Line 5 and two balanced inputs, two coaxial and two balanced outputs, and bi-amplier balanced / unbalanced operation.
There are two input / output terminals for the sound recorder.

The front panel is treated with hairline processing.

There was a glossy wooden cabinet as an option sold separately.

Model Rating

Type	Control amplifier
Input Sensitivity / Impedance	CD : 250mV/50k Ω Tuner : 250mV/50k Ω Line1/2/3 : 250mV/50k Ω Bal. Line1/2 : 250mV/100k Ω
Output Level / Impedance	Coaxial : 1V/300 Ω, Maximum 7.5 V (Rating) Balanced : 1V/600 Ohm, up to 7.5 V nominal
Total harmonic distortion factor	0.005% or less (rated)
Frequency characteristic	20 Hz ~ 20 kHz + 0 -0.1 dB 10 Hz ~ 100 kHz + 0 -2.2 dB
Signal-to-noise ratio	119 dB or More (1 kHz, IFF-A)
Tone control	Treble: Bass: Turnover 3 kHz ± 8 dB max 10 kHz ± 6 dB Turnover 300 Hz ± 8 dB max. 100 kHz ± 6 dB
Attachment	Tape dubbing : 2 systems (1 → 2, 2 → 1) Rec off Straight-through switch Output Selector Output phase selector switch Stereo / mono selector switch Remote terminal Line phase sensor
Power supply voltage	100 VAC, 50Hz/60Hz
Power consumption	23W (Electrical Appliance and Material Control Law)
Maximum external dimensions	Width 467x Height 187x Depth 435 mm
Weight	21.0kg
Sold Separately	Wood Cabinet OP-C7W (¥ 34,000)