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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 Dynakitparts.com products


    Oh Henry!!!!

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    Oh Henry!!!! Empty Oh Henry!!!!

    Post by Guest Sat Jul 18, 2015 10:38 am

    It has been documented that it is advisable to change out the 50 ohm resistor after the first cap in the Dynamo ST-35 power supply with a choke. Most of the chokes I have seen are 200mA-250mA and 1.5H. This is supposed to aid in reducing ripple current. (Adding more capacitance in the power supply would help too.)

    How about adding a choke with 4H instead? If the other parameters are the same, will the increase in inductance help even more? Can you have too much inductance?
    Tubes4ever
    Tubes4ever


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    Location : Star, Idaho

    Oh Henry!!!! Empty Re: Oh Henry!!!!

    Post by Tubes4ever Sat Jul 18, 2015 11:37 am

    4H will work fine. Do you already have the choke?  Make sure it will handle the current.  Also replacing the 50 ohm resistor with the choke will change your B+ since the DC resistance of the choke will be different from the resistor.  You may need to add a resistor in series to keep the B+ from going above its current level.  Most old tube circuits recommended at least 4H, so you are safe.
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    Post by Guest Sat Jul 18, 2015 3:10 pm

    Thanks Tubes Smile

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