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    Standby switch for ST-120

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    THOR-IUM

    Posts : 1
    Join date : 2009-10-10

    Standby switch for ST-120

    Post by THOR-IUM on Sat Oct 10, 2009 10:45 pm

    I've seen on different tube amps, along with my guitar amp, a Standby switch. Is there any benefit to installing one on a ST-120? What would it involve to install one?

    Bob Latino
    Admin

    Posts : 2413
    Join date : 2008-11-26
    Location : Massachusetts

    Re: Standby switch for ST-120

    Post by Bob Latino on Sun Oct 11, 2009 8:25 am

    THOR-IUM wrote:I've seen on different tube amps, along with my guitar amp, a Standby switch. Is there any benefit to installing one on a ST-120? What would it involve to install one?

    Hi,

    If you use a GZ34 rectifier or a Weber Copper cap solid state rectifier on the ST-120 or any tube amplifier then a standby switch is not really needed. A GZ34 has an indirectly heated filament which gives a 15 second or so "warm-up standby" built into the tube before high voltage is applied. The Weber Copper Cap has a shorter 3 or 4 second built in warm-up before high voltage is applied. I have used a Weber Copper cap (model WZ68) in my own ST-120 for almost 2 years and it has held up fine and gives a higher B+ DC high voltage than any tube rectifier AND doesn't "sag" the high voltage as much as a tube rectifier at higher volume levels.

    Where a standby switch may be useful is in a tube amp with a solid state rectifier "hard wired" into the amp. The Dynaco ST-35 and Dynaco SCA-35 are two such amps. The fact that many of these amps are still around and working fine after 40 + years WITHOUT any standby switch shows that the "need" for a standby switch on amps like these may be somewhat overstated.

    Bob

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