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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


4 posters

    Starting the st120 up without speakers

    jsl1234
    jsl1234


    Posts : 79
    Join date : 2017-08-28

    Starting the st120 up without speakers Empty Starting the st120 up without speakers

    Post by jsl1234 Sun Jul 24, 2022 2:03 pm

    Hi,

    I want to start my amp up to make sure all the tubes are in good order but I no longer have speakers. Is there a safe way to fire up the amp without speakers (like terminating the speaker terminals with resistors).

    Thanks in advance.
    peterh
    peterh


    Posts : 1689
    Join date : 2012-12-25
    Location : gothenburg, sweden

    Starting the st120 up without speakers Empty Re: Starting the st120 up without speakers

    Post by peterh Sun Jul 24, 2022 3:54 pm

    jsl1234 wrote:Hi,

    I want to start my amp up to make sure all the tubes are in good order but I no longer have speakers. Is there a safe way to fire up the amp without speakers (like terminating the speaker terminals with resistors).

    Thanks in advance.

    Don't power on without load !!!


    Or connect 8 ohm resistors of enough power on the output terminals before
    powerin on. ( 10w should do if you are observant on their temp)

    jsl1234 likes this post

    Bob Latino
    Bob Latino
    Admin


    Posts : 3172
    Join date : 2008-11-26
    Location : Massachusetts

    Starting the st120 up without speakers Empty Re: Starting the st120 up without speakers

    Post by Bob Latino Sun Jul 24, 2022 3:57 pm

    jsl1234 wrote:Hi,

    I want to start my amp up to make sure all the tubes are in good order but I no longer have speakers. Is there a safe way to fire up the amp without speakers (like terminating the speaker terminals with resistors).

    Thanks in advance.

    Yes - you need some type of "dummy load" on both output transformers. Check out the link below for a relatively inexpensive solution. You will need two of these > one for each channel. These are from China. If you look on Parts Express in the USA, they also have them but they are more expensive.

    Dummy load 8 ohm 100 watt resistors

    Bob

    jsl1234 likes this post

    jsl1234
    jsl1234


    Posts : 79
    Join date : 2017-08-28

    Starting the st120 up without speakers Empty Re: Starting the st120 up without speakers

    Post by jsl1234 Sun Jul 24, 2022 4:02 pm

    Thanks all.
    jsl1234
    jsl1234


    Posts : 79
    Join date : 2017-08-28

    Starting the st120 up without speakers Empty Re: Starting the st120 up without speakers

    Post by jsl1234 Sun Jul 24, 2022 4:04 pm

    Thanks all. Should I also null the input?
    Bob Latino
    Bob Latino
    Admin


    Posts : 3172
    Join date : 2008-11-26
    Location : Massachusetts

    Starting the st120 up without speakers Empty Re: Starting the st120 up without speakers

    Post by Bob Latino Sun Jul 24, 2022 4:26 pm

    jsl1234 wrote:Thanks all. Should I also null the input?

    Yes - Just keep your interconnects plugged in to the amp and your preamp and you will be OK.

    Bob
    cci1492
    cci1492


    Posts : 334
    Join date : 2016-05-09
    Age : 62
    Location : NJ

    Starting the st120 up without speakers Empty Re: Starting the st120 up without speakers

    Post by cci1492 Tue Jul 26, 2022 8:14 am

    If you need to have amp powered on without load, shorting the output will protect the amp.

    Tubes4ever likes this post


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    Starting the st120 up without speakers Empty Re: Starting the st120 up without speakers

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