• Welcome to IRebuildMarantz.com

    Welcome to IRebuildMarantz.com

  • IRM World HQ

    IRM World HQ

  • Vinyl Played Here

    Vinyl Played Here

    LPs get played every day at IRM. Testing rebuilt phono amps is one of the perks of the job. I like to use certain vintage components as my baseline for comparative listening. The test system in the workshop uses a Dual 740 turntable with a Shure M15III cartridge, with JBL 4312Cs for speakers.

    Final critical listening takes place in the big room playing LPs on a Dual 510 with another Shure M15III cartridge. Larger Klipsch KG 4.2 speakers let the amps really open up before going getting boxed to ship back home.

  • Dual-Sweep FM Signal

    Dual-Sweep FM Signal

    The vintage FM signal generator I use has a "dual sweep" signal feature, and the output is shown in this picture of the oscilloscope screen. This provides a visual way to aglign the FM tuner section. The Sound Technologies 1000A FM Signal Generator was used in the Marantz factory and by Marantz dealers in the nineteen seventies. It and the HP3044A Distortion Analyzer are recommended in the service manuals of later models, and are featured in a Marantz/Superscope guide. Given the many different tools and procedures for doing FM alignment, I like to follow a modified combination of the specific service manual procedures for each model and add fine tuning with the dual-sweep procedures, using equipment from the period.