McIntosh MC275 versions and differences

Discussion in 'McIntosh Audio' started by VintageMac, Feb 1, 2017.

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  1. VintageMac

    VintageMac McIntosh Junkie

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    Location:
    Portland, Oregon
    To date (February, 2017) McIntosh has produced 6 different versions of the MC275 amplifier based on electrical design, layout of the front panel and electrical specifications. Within some of those versions there are also variations - cosmetic differences.

    With only a couple of exceptions, each of these versions have been known as MC275. McIntosh had a different stock number for each version and variation, but from a branded aspect, all are known as MC275.

    Along the way there became a need to differentiate the various iterations of the amplifier. One way or another, these were given the unofficial “Mark” (MK) designation. However, the early use of this system was different than what has been settled on later. So some of the older information about a particular “MK” unit may no longer be valid.


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    [​IMG] [​IMG]
    MC275:..(1961~1970) Chrome chassis. Point-to-point wiring.

    (450 v power supply). Tubes: 4-KT88/6550 output, 12AX7, 2-12AU7, 2-12AZ7, 2-12BH7. S/N: 10,001~10,147 & 100E1~572E9

    Specifications: 16-40kHz (+0,-0.1dB). Distortion: 0.5%. Noise & Hum: -90 dB. Output impedance: 4, 8, 16 67 and 600 ohms.


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    [​IMG] [​IMG]
    MC275 CE (Gordon Gow Commemorative Edition):..(1993~1998) Chrome chassis. Gordon Gow Badge. Hybrid point-to-point and PCB wiring. Balanced inputs in addition to unbalanced inputs.

    (450 v power supply). Tubes: 4-KT88/6550 output, 3-12AX7A, 4-12AZ7. S/N: E1001~E????

    Specifications: 20-20kHz (+0,-0.2dB). Distortion: 0.5%. Noise & Hum: -100 dB. Output impedance: 4, 8, 16 ohms. Damping factor greater than 10.


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    [​IMG] [​IMG]
    MC275 SS [MK III]:..(1997~1998) Stainless steel chassis. Same design as MK II.

    (450 v power supply). Tubes: 4-KT88/6550 output, 3-12AX7A, 4-12AZ7. S/N: ??1001~?????

    Specifications: 20-20kHz (+0,-0.2dB). Distortion: 0.5%. Noise & Hum: -100 dB. Output impedance: 4, 8, 16 ohms. Damping factor greater than 10.


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    [​IMG] [​IMG]
    MC275G:..(1998~1999) Titanium gold chassis. Same design as MK II.

    (450 v power supply). Tubes: 4-KT88/6550 output, 3-12AX7A, 4-12AZ7. S/N: MC275G-01~MC275G-71

    Specifications: 20-20kHz (+0,-0.2dB). Distortion: 0.5%. Noise & Hum: -100 dB. Output impedance: 4, 8, 16 ohms. Damping factor greater than 10.


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    [​IMG] [​IMG]
    MC275 [MK IV]:..(2004~2006) Stainless steel chassis. Changes: Power on/off switch added. Power cord moved to a socket in the rear. Changes to the vertical and angled front panels. Printed Circuit Board wiring.

    (450 v power supply). Tubes: 4-KT88/6550 output, 3-12AX7A, 4-12AT7. S/N: VN1001~VN????

    Specifications: 20-20kHz (+0,-0.2dB). Distortion: 0.5%. Noise & Hum: -100 dB. Output impedance: 4, 8, 16 ohms. Damping factor greater than 14.


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    [​IMG] [​IMG]
    MC275 GOLD [MK IV]:..(200?~200?) Stainless steel chassis with gold finish. Same design as MC 275 [MK IV].

    (450 v power supply). Tubes: 4-KT88/6550 output, 3-12AX7A, 4-12AT7. S/N: VR1001~VR????

    Specifications: 20-20kHz (+0,-0.2dB). Distortion: 0.5%. Noise & Hum: -100 dB. Output impedance: 4, 8, 16 ohms. Damping factor greater than 14.


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    [​IMG] [​IMG]
    MC275 [MK V]:..(2009~2012) Stainless steel chassis. Changes: RoHS. Gain controls eliminated. Early small 5-way plastic binding posts changed to gold metal in later production. Changes to the vertical and angled front panels.

    (450 v power supply). Tubes: 4-KT88/6550 output, 3-12AX7A, 4-12AT7. S/N: WM1001~WM????

    Specifications: 20-20kHz (+0,-0.5dB). Distortion: 0.5%. Noise & Hum: -100 dB. Output impedance: 4, 8, 16 ohms. Damping factor greater than 14.


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    [​IMG] [​IMG]
    MC275 50th Anniversary:..(2012~2016) Stainless steel chassis with gold finish. Changes: Large WBT gold metal speaker binding posts. New design – new output transformers. Small tube light-up feature added. Feedback taken from the speaker side of the output autoformer (all previous versions the feedback is from the amp side of the output transformer). Changes to the vertical and angled front panels.

    (490 v power supply). Tubes: 4-KT88/6550 output, 3-12AX7A, 4-12AT7. S/N: ABH1001~ABH????

    Specifications: 20-20kHz (+0,-0.5dB). Distortion: 0.5%. Noise & Hum: -105 dB. Output impedance: 4, 8, 16 ohms. Damping factor greater than 22.


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    [​IMG] [​IMG]
    MC275[MK VI]:..(2012 ~ Current) Stainless steel chassis. Same design as the MC275 50th Anniversary unit.

    (490 v power supply). Tubes: 4-KT88/6550 output, 3-12AX7A, 4-12AT7. S/N: ABP1001~ABP????

    Specifications: 20-20kHz (+0,-0.5dB). Distortion: 0.5%. Noise & Hum: -105 dB. Output impedance: 4, 8, 16 ohms. Damping factor greater than 22.

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    If you have additions or corrections, please send them to: VintageMacPDX@gmail.com

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