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Dedicated to the restoration and preservation of all original Dynaco tube audio equipment - Customer support for Tubes4hifi VTA tube amp and preamp kits and all products

    Impedance Curve vs Manufacturer Nominal


    Posts : 10
    Join date : 2020-12-03

    Impedance Curve vs Manufacturer Nominal Empty Impedance Curve vs Manufacturer Nominal

    Post by texbychoice Mon Sep 06, 2021 11:35 am

    I understand loudspeaker impedance varies over frequency and manufacturers provide a single nominal value. A reputable manufacturer says 8 ohms. Measured with a multimeter says 2.6 ohms. Impedance curve shows lowest under 3 ohm and under 5 ohm in the mid frequency range. 8 ohm nominal rating does not seem plausible?

    Explored the possibility of an internal/crossover problem, although both speaker measured the same. No problems found. All crossover components measure to spec, although pretty cheap stuff. Next, upgraded the quality of crossover parts (nothing crazy expensive). Same impedance as stock. Hmmmm?

    Running off the 4 ohm ST-70 tap before and after sounded fine and nothing ran too hot. Added series resistor to the crossover bringing up multimeter reading to 4.3 ohm and impedance curve lowest value just above 4 ohm. Can hear no difference in sound quality. However, preamp volume control 2-3 notches lower to match previous power meter reading and listening level. Seems like have achieved a better match between speaker and amp?

      Current date/time is Mon Dec 06, 2021 3:49 pm