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The Dynaco Tube Audio Forum

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

    measurable resistor noise


    Posts : 269
    Join date : 2011-04-04

    measurable resistor noise Empty measurable resistor noise

    Post by sailor on Tue Jun 21, 2011 7:00 pm

    I know a lot of people talk about the amount of noise you get from different kinds of resistors. But I have never seen anyone measure the noise. Also the noise from a cheap pot. a better pot, resistors in series and ladder style pot. Is there really enough noise to measure or not.
    I would think you could hook up a signal generator to a string of resistors and measure the noise on an oscilloscope? I would try it but I don't own a scope.
    Anyone with comments? Or please send me to a site where this has been done.
    Bob Latino
    Bob Latino

    Posts : 2916
    Join date : 2008-11-26
    Location : Massachusetts

    measurable resistor noise Empty Re: measurable resistor noise

    Post by Bob Latino on Tue Jun 21, 2011 8:19 pm

    Usually resistor noise goes something like as the list below from lowest noise down to highest noise

    wire wound
    metal film
    metal oxide
    carbon film
    carbon composition

    Wire wounds are not usually found in larger resistance values but are found in larger wattage values.

    The resistors on the VTA driver board on the ST-70 and ST-120 amp kits are all 1% tolerance metal film. Metal film resistors are very quiet. They also hold their values well as the years roll by and the amp has many hours of play time. Carbon composition resistors are what you usually find on older vintage tube gear. As the years roll by many carbon comps do not hold their value well. Many carbon comps go high in value after years of use. Carbon comps can also be noisy. Is there a "hisssss" in your old vintage tube amp that you just can't get rid of? Change out all the carbon comps to metal film and that hissss may just go away ...


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