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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


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Dale Stevens
Peter W.
mijohn
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    PH16X Hum/Buzz

    Peter W.
    Peter W.


    Posts : 1351
    Join date : 2016-08-07
    Location : Melrose Park, PA

    PH16X Hum/Buzz - Page 3 Empty Re: PH16X Hum/Buzz

    Post by Peter W. Thu Jun 20, 2019 3:34 pm



    It sounds the same as it does when connected to the ground lug of the phono preamp.

    There should be NOTHING connected to phono pre-amp ground lug. It should not even be there.

    Please describe exactly what you have done.
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    rjpjnk


    Posts : 262
    Join date : 2018-07-18

    PH16X Hum/Buzz - Page 3 Empty Re: PH16X Hum/Buzz

    Post by rjpjnk Thu Jun 20, 2019 4:28 pm

    thermionicvinyl wrote:

    I used "Adobe audition" to record and analyze the noise. It's an Asus Xonar sound card connected to a laptop, with which I then record the output via an RCA to 3.5mm jack cable. The recording is then analyzed after the fact. I'm pretty sure if you want RTA you'd have to use REW.

    Thanks. I'm going to add an analog mic input on my macbook pro so I can do the same. Apparently the headphone jack on these is actually a mic jack as well I just found out. Just need a special 4 conductor 3.5mm jack to access the mic. Isn't Apple clever Wink

    If I can't get this option to work I will look into a mic adapter for the USB port (a.k.a. external sound card).
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    thermionicvinyl


    Posts : 32
    Join date : 2018-06-10

    PH16X Hum/Buzz - Page 3 Empty Re: PH16X Hum/Buzz

    Post by thermionicvinyl Mon Jun 24, 2019 4:54 pm

    Tried something unusual today. I got my hands on a variable auto transformer to see if the high line voltage in my could be causing any kind of issue. (126-128VAC at times.) So I stepped it down first to 120, and then to 115. I honestly cannot notice a difference but it was worth a short and at least I can say that it gave it a shot.
    Roy Mottram
    Roy Mottram
    Admin


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    Join date : 2008-11-30

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    Post by Roy Mottram Mon Jan 06, 2020 5:05 pm

    I got an email from a customer the other day who had some hum with his phono preamp, finally solved the problem by moving his AC power cord away from the turntable cables.
    Makes perfect sense!! If they must be anywhere near each other, make sure they cross at right angles. Most power cords are NOT shielded !! (the expensive ones are!)

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