Monoblock MA15 Mk 2 Late

Radford Electronics Ltd.; Bristol

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  • Année
  • 1962 ?
  • Catégorie
  • Amplificateur BF ou mélangeur BF
  • Radiomuseum.org ID
  • 360484

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 Spécifications techniques

  • No. de tubes
  • 5
  • Principe général
  • Amplification audio
  • Gammes d'ondes
  • - sans
  • Tension / type courant
  • Alimentation Courant Alternatif (CA) / 50 Hz, 200/240 Volt
  • Haut-parleur
  • - Ce modèle nécessite des HP externes
  • Puissance de sortie
  • 15 W (sans distorsion)
  • Matière
  • Boitier métallique, lampes visibles
  • De Radiomuseum.org
  • Modèle: Monoblock MA15 Mk 2 [Late] - Radford Electronics Ltd.;
  • Forme
  • Modèle de table boitier avec vouvercle
  • Remarques

  • 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.

    The Radford MA15 Mk2 Late Monoblock

    • Further refinement of the Mk2 design
    • Similar specifications to the Mk2 Early version
    • Possibly included minor component value changes or circuit tweaks

    Maintained the improved high-frequency performance and stability of the Mk2 design

    • Output power: 15 watts (maintained)
    • Circuit design: Revised for better performance
    • Phase inverter: Changed to pentode-triode configuration
    • Feedback: Increased to 27dB of negative feedback
    • Output transformer: Improved design with first resonance at 150kHz
    • Input stage: Added step network for high-frequency stability
    • Feedback network: More complex R/C step network across the feedback resistor
    • Performance: Significantly lower distortion, especially at high frequencies
    • Power delivery: Able to deliver rated power up to 20kHz
    • Phase shifts: Reduced at high frequencies
    • Stability: Carefully tuned for stability with higher feedback

    The Mk2 version demonstrated substantial performance improvements, particularly in distortion reduction and power delivery across a wider frequency range.

    Output Transformers
    The key difference between the output transformers of the Radford MA15 Mk1 and Mk2 models lies in their design and performance characteristics:

    Radford MA15 Mk2 Late Output Transformer (T2063G)

    • Resonance Frequency: The Mk2 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 output transformer were a critical factor in its superior performance compared to the Mk1

  • Littérature
  • -- Original prospect or advert (HiFi News (UK) Sep 1962)
  • Auteur
  • Modèle crée par Gary Cowans. Voir les propositions de modification pour les contributeurs supplémentaires.

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