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    New upgrade boards for the PAS-2, PAS-3 from tubes4hifi ...

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    Bob Latino
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    Join date: 2008-11-26
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    New upgrade boards for the PAS-2, PAS-3 from tubes4hifi ...

    Post by Bob Latino on Sun Feb 28, 2010 3:38 pm

    Hi all,

    Roy Mottram who runs the tubes4hifi web site has informed me that he has just introduced a set of three new boards for the Dynaco PAS-2 or PAS-3 preamps. The use of the three boards will effectively make your PAS-2 or PAS-3 into one of his SP-6 preamps.

    Phono board - The circuit is a hi-gain phono preamp using a 12AX7 gain stage followed by a highly accurate passive EQ, followed by another 12AX7 gain stage, for a total gain of 45 db.

    Line board - This stage uses a 12AU7 in a cascode SRPP gain stage for high gain with excellent linearity and low output impedance, for a gain of 15 db.

    Power Supply board - This makes use of the original 12X4 tube rectifier for soft-start, with 500uF of B+ power supply capacitance (compared to the original 80uF).

    The original PAS tone controls are bypassed for lower distortion. All parts are high quality, Dale mil-spec precision resistors, WIMA polypropylene caps for phono equalization, and Solen polypropylene caps for output coupling and power supply bypass. Printed Circuit Boards are mil-spec FR4 double-sided with plated-thru holes.

    Check out the two links below for more information. Photos of the boards and installed boards below.

    Bob

    Tubes4hifi new PAS-2, PAS-3 upgrade boards

    PAS3-Z modification sample manual





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