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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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    ST 35 Options

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    TN Allen


    Posts : 159
    Join date : 2013-01-01

    ST 35 Options Empty ST 35 Options

    Post by TN Allen Wed Nov 16, 2022 10:16 am

    I recently reconnected an ST35 I assembled a few years ago starting with old output transformers, a new power transformer and the Triode PCB. I am impressed with how good it sounds, and started thinking about assembling another using newer components. I don't really need another amplifier, but do enjoy putting planning and making a chassis and putting the amplifiers together.

    If anyone has experience and or opinions regarding one or more of the various options for a new ST35, I'd appreciate hearing about that experience and opinions, suggestions as well. So far I've looked at:

    tubes4hifi version, I like the single board and toroid transformers.
    dynakitparts, I've used their transformers for a Mark lll and see some interesting layout possibilities with the separate PCBs.
    Ebay offers a single board option that is based upon the older single board version, I assume that may be the PCB I bought from Triode.

    Edcor offers power and output transfromers. I've used their transfromers in other projects, they seem like a good option using the dynakit parts PCBs or possibly the Ebay PCB.

    Perhaps there are other options I've missed, if so, I'd appreciate knowing about them.

    Thank you.
    peterh
    peterh


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

    ST 35 Options Empty Re: ST 35 Options

    Post by peterh Wed Nov 16, 2022 10:29 am

    TN Allen wrote:I recently reconnected an ST35 I assembled a few years ago starting with old output transformers, a new power transformer and the Triode PCB. I am impressed with how good it sounds, and started thinking about assembling another using newer components. I don't really need another amplifier, but do enjoy putting planning and making a chassis and putting the amplifiers together.

    If anyone has experience and or opinions regarding one or more of the various options for a new ST35, I'd appreciate hearing about that experience and opinions, suggestions as well. So far I've looked at:

    tubes4hifi version, I like the single board and toroid transformers.
    dynakitparts, I've used their transformers for a Mark lll and see some interesting layout possibilities with the separate PCBs.
    Ebay offers a single board option that is based upon the older single board version, I assume that may be the PCB I bought from Triode.

    Edcor offers power and output transfromers. I've used their transfromers in other projects, they seem like a good option using the dynakit parts PCBs  or possibly the Ebay PCB.

    Perhaps there are other options I've missed, if so, I'd appreciate knowing about them.

    Thank you.    

    A clone of Dynaco ST35 is available from dynakitparts.com and this is the only available that
    could be expected to have the same performance as a Dynaco ST35.

    The unit from tubes4hifi differs, it is best describes as an EL84 stereo amp. It does not use
    Dynaco st35 circuit, nor does not use Dynaco Z-565 transformers.

    Edcor does not have ( to my knowledge) clone of the Z-565 transformer, thus some adjustment of
    the NFB might be needed.

    But if one needs a "generic" EL84 amp, all the above will fit the bill.
    avatar
    TN Allen


    Posts : 159
    Join date : 2013-01-01

    ST 35 Options Empty Re: ST 35 Options

    Post by TN Allen Thu Nov 17, 2022 6:32 pm

    Thank you for the insightful response. I realize I should have been more critical of the association made by marketers between the ST35 designation and their products, which as you point out are not really Dynaco ST35 amplifiers, but EL84 amplifiers. If I assemble another amplifier, it probably will be using dynakit components.

    How critical do you think the Z-565 transformers are to the particular sound of the ST35? Perhaps they are the reason I find the amplifier I assembled using original Z-565 transformers so pleasing.
    Blitzen
    Blitzen


    Posts : 58
    Join date : 2009-07-10

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    Post by Blitzen Thu Nov 17, 2022 8:02 pm

    It's my opinion, and that of many others, that the Z-565 transformers or exact clones are essential to the sound of the ST-35.
    The same transformers were also used in the SCA-35.
    Here's another option for boards:
    http://tronola.com/html/daves_store.html
    I rebuilt an ST-35 using these boards and the Enhanced Fixed Bias (EFB) system board add-on. That amp compares well to any I've heard, at least until it runs out of power!

    corndog71 likes this post

    corndog71
    corndog71


    Posts : 839
    Join date : 2013-03-19
    Location : It can get windy here

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    Post by corndog71 Thu Nov 17, 2022 11:48 pm

    I second Dave Gillespie’s work.  I’ve built a few versions.  The EFB circuit is a real measurable improvement over the stock circuit.  I also incorporated an adjustable feedback circuit.

    Here’s my latest version.

    ST 35 Options 50160337361_3f938ecb49_w
    peterh
    peterh


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

    ST 35 Options Empty Re: ST 35 Options

    Post by peterh Fri Nov 18, 2022 3:01 am

    TN Allen wrote:Thank you for the insightful response. I realize I should have been more critical of the association made by marketers between the ST35 designation and their products, which as you point out are not really Dynaco ST35 amplifiers, but EL84 amplifiers. If I assemble another amplifier, it probably will be using dynakit components.

    How critical do you think the Z-565 transformers are to the particular sound of the ST35? Perhaps they are the reason I find the amplifier I assembled using original Z-565 transformers so pleasing.
    The transformers and Dynaco designs are intertwined. Thus using original design AND
    dynaco transformers will get a good result. Change either and you might have to
    resort to instrumented tuning to get the NFB and stability correct. Not impossible but it
    takes time and efforts to do, also needs some instruments and possibly an assortment
    of tubes with parameters spread and some different speakers to verify stability.

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