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    Tone Bypass on PAS-3 vs PAS-3

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    drewrf

    Posts : 1
    Join date : 2018-09-20

    Tone Bypass on PAS-3 vs PAS-3

    Post by drewrf on Thu Sep 20, 2018 1:03 pm

    I recently acquired a Dynaco PAS-3 and am going through the process of restoring it along with a few modifications to improve the sound while staying true to the intent of the design. I am trying to bypass the tone controls and found a great thread on this forum about how to do it on a PAS-3x. Is there any reason that the same modifications wouldn't work on the 3? I know the pots are different, I don't have a 3x to compare to see if the boards are.
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    peterh

    Posts : 1070
    Join date : 2012-12-25
    Location : gothenburg, sweden

    Re: Tone Bypass on PAS-3 vs PAS-3

    Post by peterh on Thu Sep 20, 2018 3:38 pm

    drewrf wrote:I recently acquired a Dynaco PAS-3 and am going through the process of restoring it along with a few modifications to improve the sound while staying true to the intent of the design. I am trying to bypass the tone controls and found a great thread on this forum about how to do it on a PAS-3x. Is there any reason that the same modifications wouldn't work on the 3? I know the pots are different, I don't have a 3x to compare to see if the boards are.
    The boards are identical.
    How about using it for a while before changing ? Then you could actually compare the
    results.
    And what are your goal with the proposed changes ? What do you need that a stock PAS
    cannot deliver ?

    rjpjnk

    Posts : 117
    Join date : 2018-07-18

    Re: Tone Bypass on PAS-3 vs PAS-3

    Post by rjpjnk on Thu Sep 20, 2018 3:42 pm

    Can you send a link to the article you found? I’d prefer to read it before commenting. The 3x is already bypassed when the controls are centered.

    Most of what you need to know can be found here:
    http://www.audioregenesis.com/documents/PAS%20Tone%20Control%20Bypass.pdf
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    PeterCapo

    Posts : 635
    Join date : 2008-12-05

    Re: Tone Bypass on PAS-3 vs PAS-3

    Post by PeterCapo on Thu Sep 20, 2018 6:35 pm

    The Audio Regenesis article for bypassing the tone controls is the reference standard for this procedure.

    PAS-2X/3X should not need the bypass procedure provided the pots are in good working order, though the original 1.0µF electrolytic DC blocking capacitors should probably be replaced.

    PAS-2/3 can have its tone controls bypassed if you wish, but I suggest doing it very carefully and non-destructively so that the procedure can be reversed and the tone controls reinstated if ever desired.  You should probably think about adding DC blocking capacitors even if you don't do the bypass.

    Agree with peterh that you might not want to rush to bypass the tone controls.  In fact, I'd suggest taking things in stages; don't do too much at once.  Here's a post I made a little while ago that describes what I think are good first steps to refreshing a PAS: http://audiokarma.org/forums/index.php?threads/original-dynakit-dynaco-pas-preamp-a-low-cost-refresh.755387/

    Also agree with rjpjnk about seeing the thread to which you refer.  Please post the link.

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