The Dynaco Tube Audio Forum

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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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peterh
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    tubes4hifi
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    Post by tubes4hifi Wed Sep 01, 2021 6:35 pm

    I've been making these custom amps for a few years now, but I'd like to standardize on the design.
    These layouts are shown using standard Dynaco/VTA transformers, rather than the round toroids.
    (the amps can be built either way, same price, same quality).
    The photo below makes the layout of the upper design with the output tubes staggered
    The 2nd layout at the bottom puts the tubes across in a straight line.
    Let me know your preference.
    BTW, with a steel chassis for the base, this only raises the price of an ST70 or ST120 amp by $50.
    With the wood chassis for the base, the price is $150 above the usual price.
    The photo at the very bottom was a custom ST120 I did about ten years ago.


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    Blitzen
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    Post by Blitzen Wed Sep 01, 2021 8:13 pm

    I much prefer the "staggered tube" config. Tubes better spaced, so cooler design. Also a cooler design Smile

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    New2Tubez

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    Post by New2Tubez Wed Sep 01, 2021 9:22 pm

    Blitzen wrote:I much prefer the "staggered tube" config. Tubes better spaced, so cooler design. Also a cooler design :)

    I agree. I also like not seeing the caps if it doesn't create a rat's nest under the hood.

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    knotscott
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    Post by knotscott Thu Sep 02, 2021 11:58 am

    Staggered, no caps = cleaner look
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    Post by corndog71 Thu Sep 02, 2021 3:20 pm

    I like them both. I prefer the 2nd pic but would not want the caps sticking up through the plate.
    Earl
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    Post by Earl Thu Sep 02, 2021 6:12 pm

    The partially hidden, or exposed - glass half empty or half full? - caps look(s) really silly. Mount them on top.
    wgallupe
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    Post by wgallupe Fri Sep 03, 2021 8:11 am

    I like the first pic. Staggered tubes, no caps showing, wood base. Very clean and classy looking.

    Never understood why Dynaco amps had/have exposed driver boards. What's the appeal in seeing exposed caps, resistors, transistors, tube sockets, etc.? I wonder why David Hafler did it to begin with?
    peterh
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    Post by peterh Fri Sep 03, 2021 9:08 am

    wgallupe wrote:I like the first pic. Staggered tubes, no caps showing, wood base. Very clean and classy looking.

    Never understood why Dynaco amps had/have exposed driver boards. What's the appeal in seeing exposed caps, resistors, transistors, tube sockets, etc.? I wonder why David Hafler did it to begin with?

    Dynaco never exposed driver boards, they had a cover over the amp.
    WLT
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    Post by WLT Fri Sep 03, 2021 7:31 pm

    And to add to PeterH comment. Use the covers. Once you need to work on them the board mounted on the chassis top makes these amps the easiest, most accessible of all the vintage gear. Work on the other vintage top manufactures products for a while and it is a pleasure to come back to a Dynaco. Simple and straightforward.

    They were not intended to be used without the cover and some of those exposed voltages make it a risk to do so. I suggest you buy those new chassis if you want good looks with minimal risk.
    jimmeq
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    Post by jimmeq Mon Sep 06, 2021 7:01 pm

    I like the first picture with the tubes staggered.
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    Wharfcreek

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    Post by Wharfcreek Sun Sep 12, 2021 11:32 am

    I like the first pic, but I don't care for the driver tube sockets sticking as they do when the output tube sockets are 'flush' with the deck. Not a 'deal-breaker'.....and I understand that you probably have them PC mounted unter the deck. BUT..... I just don't like the inconsistancy! I believe there are not people who are PC mounting output tube sockets on a board that screws to the bottom just like the driver board. So, if you were to adopt this technique as part of your design, 'yes!', you'd have two more PC boards to have to supply (one for each side). BUT..... with the quality of of today's boards, you'd make the kits themselves somewhat easier to construct, probably more reiiably built too since the wiring aspect of the output tube area would be controlled by the PC board..... AND, the tube sockets could all be equally protruding above the chassis deck. I know it's a petty comment, but seems like going through all the trouble to 'sub' mount the driver board (as opposed to 'open' mount it like in the OE Dynaco design), cut holes for tubes and sockets to make it all look 'neet', then to do the output sockets 'the old fashioned' way.....that just seems self-contradictory. Anyway, I much prefer the staggard look of the #1 pic!!

    So, while I'm at it, I have to ask: Are there standard type OTs under the round covers that are just mounted below the deck and then also protruding up through and just finished off with that round cover? And finally, is the PT a torroid also mounted under the deck?

    Thanks! Tom
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    Post by tubes4hifi Sun Sep 12, 2021 4:16 pm

    Tom,
    the first top photo uses all toroids, both outputs and power.
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    Post by tubesman7 Mon Sep 13, 2021 12:26 am

    Either style is OK with me, BUT move the input jacks AWAY from the output transformer and power transformer. Can you give details on the toroids used in the output?
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    Post by Wharfcreek Mon Sep 13, 2021 6:20 pm

    Yea, I'd like some detail on the torroid OTs as well. I wasn't aware there was such a thing.......

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