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    Adding A choke To My ST-35 Kit Amp

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    JimOfOakCreek

    Posts : 13
    Join date : 2011-06-25
    Location : Oak Creek, WI

    Adding A choke To My ST-35 Kit Amp

    Post by JimOfOakCreek on Mon Aug 01, 2011 6:41 pm

    I am really enjoying my Dynakit Parts ST-35 Amp. I noticed that there is a choke available for it as a mod. What does the choke do to improve performance?

    Bob Latino
    Admin

    Posts : 2377
    Join date : 2008-11-26
    Location : Massachusetts

    Re: Adding A choke To My ST-35 Kit Amp

    Post by Bob Latino on Mon Aug 01, 2011 7:57 pm

    Hi,

    The choke won't really make the amp sound any "better" but it should remove the last vestiges of AC ripple that may be riding on the DC. You may notice the residual noise level of the amp drop a little. The nice thing is that there is a place for the choke on the top front of the amp. Just drill two 9/32" holes 2 3/8 inches apart and make another small hole behind the choke for the wires to enter the chassis. The choke replaces the 50 ohm resistor on the quad cap. See photo below.

    Bob



    JimOfOakCreek

    Posts : 13
    Join date : 2011-06-25
    Location : Oak Creek, WI

    Re: Adding A choke To My ST-35 Kit Amp

    Post by JimOfOakCreek on Wed Aug 03, 2011 12:16 pm

    Bob, thanks for your expert evaluation. I think I'm going to leave my ST-35 completly stock. It already sounds great and is very very quiet. I can barely hear an extremely faint hum with my ear 1/4" away from the speaker cone. My speakers are rated at 95db/watt@1meter.

    Placement of the interconnects are critical since they will pick up EMF hum. I found that keeping the interconnects underneath, down the middle and tight to the chassis results in near zero hum.

    I also made some standoffs for the tube cage. The cage tends to resonate slightly unless damped.

    Thanks again....jim

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