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Specifications


  • Tubes: 1 X 6H30,   2 X 6922  4 X KT88
  • Power output:  2×75W (8Ω ULTRALINEAR); 2x 140W (4Ω ULTRALINEAR)
  • Input: 1 x RCA, 1 x XLR
  • Frequency response: 10Hz60kHz
  • THD: 1%(1kHz)
  • Input sensitivity: 2 V
  • Input impedance: 50 KΩ
  • Output impedance: 8Ω, 4Ω
  • S/N ratio: > 90 dB
  • Dimensions: 500×330×240mm
  • Net weight: 29Kg x 2
  • Power consumption: 550W maximum

Full balance designed M-75

The M-75 paired monoblock amplifier is designed for those who seek the performance based on high power and full balance design, while concern the reliability and easy maintenance for years to run. This M-75 mostly designed for full balance input scenario gaining the ultimate performance supported by transformer assembly including power, input, output and balance newly designed and manufactured by StereoKnight. Two 6922 tubes were used for amplification when simply XLR input selected; a 600 ohm input transformer were designed to split phase for balanced amplification when RCA input turned on.           

                     Click to S-40 high definition gallery

High power with excellent drive & control: transformer and KT88

Four matched pair of KT88 driven by 600W ultra wide bandwidth C-core type output transformer, just conservatively designed to output 75WPC at 8Ω or 140W at 4Ω for two considerations:

  • power is not single bench mattering the performance; capability of drive and control supported by qualified transformer are more critical;
  • at 75WPC output set, M-75 has provided excellent drive and control as well as plenty of power, which easily makes it a winner in most tough scenarios.
  • exceptional high power output by exhausting tube’s ultimate will easily damage the tube in short term, and further cause unstable and reliable troubles to the unit.  

With four KT88, we may set its output over 125WPC to gain applaud and more attention, but we do care the reliability of our product as well as customer’s long term benefit. Sacrificing some power does not mean we compromise the performance.       

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KT88 or 6550 are used for power amplifying, which maybe the just preferred power tubes by StereoKnight. We just value KT88 based on following considerations:

  • Designed and engineered properly and assisted with high quality transformers, KT88 can produce all typical ‘tube sound’ which maybe only marked to 300B, 2A3 or 845.
  • KT88 is stable, reliable and long life time tube
  • KT88 is typical power tubes that means it outputs more power
  • Plenty of stock, low cost

Two ZEROs

As for noise, which has annoyed tube gears for decades, it will never be a conern any more. ZERO noise concern will be the basic promsie which StereoKnight bring to your hifi enjoyment.  

Another ZERO is about negative feedback: ZERO-NEGATIVE-FEEDBACK concept and technology are fully applied in this M-75, which brings single ended class A only characteristic to M-75’s push-pull based nature. 

 

MOSFET technology is used to stabilize voltage most precisely, which offers faster rectification, and has the ability to address a much higher capacitance than the older tube rectifiers. Tube rectifiers are designed to handle only 50 microfarads (mf) at maximum, while MOSFET rectifiers can handle capacitances greater than 4000 mf. MOSFET also offer far better reliability and don't age as quickly as tube rectifiers. Tube rectifiers age and eventually short out the power supply cap, which is an expensive repair. It can also help to reduce electro-magnetic noise (dead silent background?) and operate unit more stably and reliably.

 

Parts and manufacturing

As always, all components and each measurement which may improve sound performance or enhance the reliability of the unit will be under careful consideration. StereoKnight do design and manufacturing all from picky and ambitious audiophiles’ view.  For example, most wires connecting parts inside chassis were insulated by TEFLON tube (Teflon insulated wire is more suited to the higher working voltages. High voltages run on separate wires avoids copper crystallization (whiskers, due to high voltage) between layers of fiberglass when high voltage is run on PC board traces. Teflon wire also has better thermic stability and can withstand higher current for a short time). 

 

Some wires were hand made by compositing several kinds of selected enameled wires in proportion.  We widely used Japan made POCC rectangular solid core copper wire as the wire inside the unit for passing the signal, which is usually used by big brand to make high cost interconnect cables. Another example about what grade parts selected is capacitor: Japan made Nichicon and USA Hovland (musicap) are used in M-75 all the way.

 

Sonic characteristics                                                              back to top

This M-75 immediately makes clear its wider power bandwidth with more speed, top-end air, improved details and impactful bass. Textures and timbres are finely rendered and silky-smooth, which makes M-75 sound like a single ended class A amplifier. The M-75 is highly engaging, musically rewarding and an unparalleled performer at its price. For the music lover who wants the best attributes of tubes in both style and performance, the M-75 is highly on top notch.

 

Featureahights:

  • Full balance design.
  • High grade 600W EI type power transformer, extra wide band C-core output transformer (StereoKnight signature).
  • High end components (Nichicon and Hovland capacitor), parts (StereoKnight designed heavy duty gold-plated binding post) and wire (TEFLON insulated wire and Japan made POCC rectangular solid core copper wire) all the way.
  • ZERO-NEGATIVE-FEEDBACK technology.
  • ZERO noise: dead silence background.
  • MOSFET voltage stabilization.
  • High control power (75WPC or 140W at 4Ω), capable of driving a wide range of loudspeakers.
  • Easily accessible individual output tube bias measurement and adjustment points on side chassis.
  • Detachable IEC power cord, high quality gold-plated StereoKnight custom binding posts and RCA jacks.
  • Full high quality aluminum alloy body construction, power meter in faceplate and acrylic enclosure cover design: sturdy built with art.

And do not forget modern style appearance designed by StereoKnight, full armed with high quality aluminum alloy faceplate, chassis and acrylic, the art of metal and crystal.

 

SIMPLE, BEAUTIFUL, RELIABLE is the compact oath StereoKnight born for. With 18-MONTH WARRANTY, the M-75 will give you lasting value and listening pleasure for years to come.

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Suggested preamp: StereoKnight signature passive preamplifier: use balance input; for ultimate performance, CD player with XLR output is recommended.

 

Retail Price : 3850 US$ pair

 

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Copy right® 2007 Stereoknight HiFi Technology LLC. All right reserved, the art of design & engineering / 7890 Grove Ct. E. / Germantown, TN, USA 38138 
Phone: 1-901-283-0073 / Fax: 1-901-248-6866 / email: info@stereoknight.com / sales@stereoknight.com