Classic M7 preamplifier was released in the late 1980s. It gained fame along with the legendary power amplifier ONGAKU.
While maintaining the emotional sound impression of this preamplifier, it was polished with updated crafts and technologies. Base on a well-thought-out circuit and high-quality parts that were inspected further by our eyes and hands, performance is improved and matching with modern systems is also improved.
On top of specification, wide and stable sound stage, lively emotions, and low noise level are realized.
Phono amplifier unit
The modularization of the phono amplifier realizes advantages of both handwiring and short signal paths comparable to PCB. The signal loop is minimized by placing a decoupling capacitor near the module independently.
The SRPP circuit of ECC803S (12AX7) are adopted for the first stage. 6072 (12AY7) are used for plate follower, cathode follower of the second and the third stage. It achieves a highly accurate equalization with both vivid and quietness.
Line amplifier unit
The line amplifiers are also modularized like a phono amplifier unit, and the decoupling capacitors are located near right and left independently.
Direct couple of plate follower and cathode follower using 6072 (12AY7) achieves the lower output impedance 500Ω and 18Hz cutoff frequency (at 20kΩ load). It has strong driving capabilities.
Power supply, the shunt heater circuit
Rectification tunes is 6CA4. The power transformer and chokes are arranged so that minimum vibration is obtained. 3 kinds of decoupling capacitors are selected for well balance of tonal characteristics. Power supply is strengthened by clearly separating the ripple filter capacitors and decoupling capacitors.
Combining capacitor groups and a newly developed shunt type DC heater power supply circuit, ripples at power line is highly eliminated and heater voltage is regulated within ±5%.
Audio Note original silver foil capacitors, original electrolytic capacitors, silver lead resistors, SSW wiring material, copper main chassis, interconnect KSL-VzII, original RCA Jacks, original power transformers, chokes and a lot. Other parts such as market capacitors and resistors are selected carefully for each specific positions.
Product Stereo preamplifier
Product M7 Heritage
Input / Impedance Phono RCA 2pairs, Unbalanced / 47kΩ
Line RCA 3pairs, XLR 1pair, Unbalanced / 50kΩ
Output RCA x2, XLR x1 (unbalanced, over 20 kΩ load)
RIAA Declination ±0.3dB (30Hz-20kHz, Excluding LCF)
Frequency Response 8Hz ～ 280kHz (+0dB, -3dB / with 100kΩ load, Unbalanced)
Distortion (THD) 0.07% (1kHz, 1V, Line part)
Noise less than 0.15mV(Line),
less than 5mV(Phono)
Gain 25dB (Line in → Line out),
63dB (Phono in → Line out)
Vacuum Tubes ECC803S x2, 6072 x2 (Phono)
6072 x4 (Line)
EZ81 x1 (Rectification)
Power consumption 38W
Dimensions 438mm(W) 160mm(H) 330mm(D)