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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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crkohut
Kramer
6 posters

    Completed VTA ST120 2018

    Kramer
    Kramer


    Posts : 50
    Join date : 2018-02-11
    Age : 36
    Location : Chicago

    Completed VTA ST120 2018 Empty Completed VTA ST120 2018

    Post by Kramer Mon May 14, 2018 12:27 pm

    Ordered the st120 Kit earlier in the year, has been completed for a few months now and I find myself listening more and more. I got the auto bias board installed recently, highly reccomended to everyone. Figured I would share some photos of the completed, for now, amp.

    It is powering a pair of 1982 Klipschorn loud speakers I was lucky to find a good deal on. I took some time rewiring the drivers and had some new crossovers built.

    Here is the amp with flat black transformers, I used some 3m thermal tape and heatsinks I had around on the back of the power transformer to keep it cooler in the summer.

    Completed VTA ST120 2018 Image13
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    Completed VTA ST120 2018 Image17
    Completed VTA ST120 2018 Image15
    Completed VTA ST120 2018 Image14
    Completed VTA ST120 2018 Image22


    The new crossovers that I had built. Deans superX
    Completed VTA ST120 2018 Image18

    Klipschorns with original Crossovers
    Completed VTA ST120 2018 Image19
    Completed VTA ST120 2018 Image20

    Let me know what you guys think, still want to build some larger wood horns to replace the k-400's.
    crkohut
    crkohut


    Posts : 24
    Join date : 2016-11-02
    Age : 62
    Location : Sudbury, Ontario, Canada

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    Post by crkohut Thu May 17, 2018 3:51 pm

    Nice!! Both the amp and crossovers!
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    Surfing1


    Posts : 3
    Join date : 2018-05-25

    Completed VTA ST120 2018 Empty Re: Completed VTA ST120 2018

    Post by Surfing1 Fri May 25, 2018 2:37 am

    Well done, I’m getting ready to build up a 120 myself to drive some BW DM-603’s........should be fun
    Kramer
    Kramer


    Posts : 50
    Join date : 2018-02-11
    Age : 36
    Location : Chicago

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    Post by Kramer Sun Aug 05, 2018 12:02 pm

    Completed VTA ST120 2018 Image12

    Adding the bias-board with fuses and solid state rectifier really cleaned up a bunch of distortion. Made a new set of interconnects using Neotech LEST as signal wire, KLEI absolute harmony plugs, and silver plated copper neutral. They sound very nice.

    Completed VTA ST120 2018 Image13

    http://www.image99.net/blog/files/category-002ahelix-speaker-cable.html
    These cables are all very nice and cheap to build. Greatly improved my listening experience. If your going DIY I highly suggest giving them a shot.
    avatar
    Ed Chambers


    Posts : 9
    Join date : 2017-06-20

    Completed VTA ST120 2018 Empty Maintenance?

    Post by Ed Chambers Mon Jan 14, 2019 7:12 pm

    About 18 months ago I built one of Bob Latino’s VTA 120 amps. I’ve been totally pleased; it has performed flawlessly. I have heard and read recently that tube amps should be taken to an expert every few years or so for maintenance or adjustments. Allegedly, (unlike solid state) their performance degrades as they age. I have checked the bias of the output tubes every six months with minimal adjustment needed. Should I worry that my amp will need maintenance as the hours accumulate? Ed.
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    Dale Stevens


    Posts : 201
    Join date : 2014-07-06
    Age : 74
    Location : Loris, SC

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    Post by Dale Stevens Mon Jan 14, 2019 9:22 pm

    Kramer, what are the two jacks in the middle beside the power cord in the rear? Dale
    bbqjoe
    bbqjoe


    Posts : 98
    Join date : 2018-12-03

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    Post by bbqjoe Tue Jan 15, 2019 1:18 am

    Dale Stevens wrote:Kramer, what are the two jacks in the middle beside the power cord in the rear? Dale

    I'm betting a dollar they're additional outputs, maybe for subwoofers?

    I also affixed some heat sink action.
    I only did it on the power transformer though, as I find the other two don't get nearly as warm.
    Kramer
    Kramer


    Posts : 50
    Join date : 2018-02-11
    Age : 36
    Location : Chicago

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    Post by Kramer Tue Jan 15, 2019 12:32 pm

    Dale Stevens wrote:Kramer, what are the two jacks in the middle beside the power cord in the rear? Dale

    They're connections for subwoofers, inside the amp the wires are tightly twisted and go around the bottom of the chassis to the front where they connect to the signal after the attenuator before the CCS board. Wired that way I can adjust the volume of my entire system using the one knob. I don't get any hum from the wire or location of the jacks.
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    Ed Chambers


    Posts : 9
    Join date : 2017-06-20

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    Post by Ed Chambers Tue Jan 15, 2019 2:23 pm

    I apologize for inserting my message above about maintenance. I meant to start a new topic. Ed Chambers
    Kramer
    Kramer


    Posts : 50
    Join date : 2018-02-11
    Age : 36
    Location : Chicago

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    Post by Kramer Tue Jan 15, 2019 2:46 pm

    Ed Chambers wrote:I apologize for inserting my message above about maintenance.   I meant to start a new topic.    Ed Chambers

    Not a problem, the amp shouldn't really need maintenance outside of wiping it down of dust and keeping the bias in check. If you recently built the amp you may want to check over the solder joints after a year just to make sure they all still look solid. Electrolytic capacitors drift out of factory spec over the course of 20 years and should be replaced eventually.
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    Ed Chambers


    Posts : 9
    Join date : 2017-06-20

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    Post by Ed Chambers Tue Jan 15, 2019 6:57 pm

    Thanks Kramer. I suppose modern capacitors are much better than those of the 60s, but don’t last forever. Ed
    Kramer
    Kramer


    Posts : 50
    Join date : 2018-02-11
    Age : 36
    Location : Chicago

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    Post by Kramer Thu Mar 14, 2019 12:02 pm

    After some issues everything is back up and running perfectly. Some more pictures of the new drivers, horns, and interior wiring of the amp and speakers. Should have taken more time wiring the amp but it turned out ok for my first kit.

    Eventually going to refinish the exterior of the speakers with new veneer and fix some chips since the previous owner seemed to beat them up a little bit. I will likely rebuild the bass bins with a solid back so I can pull them away from the wall without losing some of the low end. Very relaxed but detailed sound, very happy with my entire system.



    Completed VTA ST120 2018 Image210
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