Monoblock CMA15 Kitset

Radford Electronics Ltd.; Bristol

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  • Year
  • 1962 ?
  • Category
  • Audio Amplifier or -mixer
  • Radiomuseum.org ID
  • 360485

 Technical Specifications

  • Number of Tubes
  • 5
  • Main principle
  • Audio-Amplification
  • Wave bands
  • - without
  • Power type and voltage
  • Alternating Current supply (AC) / 50 Hz, 200/240 Volt
  • Loudspeaker
  • - This model requires external speaker(s).
  • Power out
  • 15 W (undistorted)
  • Material
  • Metal case, TUBES VISIBLE
  • from Radiomuseum.org
  • Model: Monoblock CMA15 [Kitset] - Radford Electronics Ltd.;
  • Shape
  • Tablemodel, Box - most often with Lid (NOT slant panel).
  • Notes

  • The Radford MA15 series of amplifiers was a well-regarded line of vacuum tube audio amplifiers produced in the 1960s.

    There were four versions:

    1. MA15 Mk1: This was the original version of the amplifier.
    2. MA15 Mk2 Early: An updated version of the original design.
    3. MA15 Mk2 Late: A further refinement of the Mk2 design.
    4. CMA15: This was a kit version of the MA15 amplifier.

    CMA15 (Kit Version)

    • Kit version of the MA15 likely based on the Mk2 Late design
    • Available for DIY enthusiasts to build themselves
    • Priced at approximately 60% of the fully assembled versions
    • Included detailed construction articles in Hi-Fi News (June to September 1962)

    Radford CMA15  Output Transformer (T2063G)

    • Resonance Frequency: The CMA15, the same as the Mk2 late output transformer was significantly improved, pushing its first resonance to approximately 150kHz.
    • Performance: This allowed for reduced phase shifts, better high-frequency stability, and lower distortion across the frequency range. It also enabled the amplifier to deliver its rated power up to 20kHz.
    • Design Complexity: The improved design contributed to a more refined sound and greater technical performance, addressing the limitations of the Mk1.

    These enhancements in the Mk2's & CMA15 output transformer were a critical factor in its superior performance compared to the Mk1.

    The kitset was priced at £17/15/- in August 1963.

  • Price in first year of sale
  • 17.75 GB £
  • Mentioned in
  • -- Original prospect or advert (HiFi News (UK) Sep 1962)
  • Author
  • Model page created by Gary Cowans. See "Data change" for further contributors.

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