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    ST-120 Review

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    audiobill

    Posts : 275
    Join date : 2014-03-13
    Location : Philadelphia

    ST-120 Review

    Post by audiobill on Thu Jan 05, 2017 12:26 pm

    By our own Boomzilla!!

    http://hometheaterhifi.com/reviews/amplifier/power-amplifier/vacuum-tube-audio-st-120-tube-power-amplifier-review/
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    Kentley

    Posts : 394
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    Age : 64
    Location : Worcester, MA

    Re: ST-120 Review

    Post by Kentley on Thu Jan 05, 2017 1:23 pm

    Now THAT'S a review. Not only is it well-written and accurate, it is detailed beyond any other I've read (or written myself, for that matter). And it is balanced by a few criticisms, which are justifiable. Bravo, Boomzilla!
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    arledgsc

    Posts : 374
    Join date : 2012-11-30
    Location : SF Bay CA

    Re: ST-120 Review

    Post by arledgsc on Thu Jan 05, 2017 2:26 pm

    Nice review Boom.  I agree with conclusions.  The positives far outweigh the few negatives and I feel the same way.
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    Rabindu

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    Age : 62
    Location : Mississauga, Ontario, Canada

    Re: ST-120 Review

    Post by Rabindu on Fri Jan 06, 2017 3:27 am

    As an owner of this amp and having built it myself, reading this review gave me that warm and fuzzy feeling all over. I can only say that it always gives me great listening pleasure driving my JBL L36's along with a Velodyne sub. The SP-14 pre and PH-16 phono stage are the icing on the cake. In the future I would love to build a pair of M125's just because building gives me great satisfaction. As for the article, well done!

    Mike Kampman
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    deepee99

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    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: ST-120 Review

    Post by deepee99 on Fri Jan 06, 2017 2:08 pm

    Getting a nice bit of chatter on Bob's Facebook page.
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    corndog71

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    Location : It can get windy here

    Re: ST-120 Review

    Post by corndog71 on Fri Jan 06, 2017 2:43 pm

    The best part is that for the creatively inclined one can fashion an amp to suit their needs. I too find the old dynaco chassis limiting, crowded, and ultimately unattractive.

    I made mine the way I wanted with the parts I wanted and it's been a real champ of an amp! I still want to build a custom ST70 but right now I'm building custom EL84 monoblocks.
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    sKiZo

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    Join date : 2013-04-01
    Location : Michigan USA

    Re: ST-120 Review

    Post by sKiZo on Fri Jan 06, 2017 2:49 pm

    Can't imagine why anyone would want to change anything ... leave well enough alone! ;-}
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    peterh

    Posts : 776
    Join date : 2012-12-25
    Location : gothenburg, sweden

    Re: ST-120 Review

    Post by peterh on Fri Jan 06, 2017 2:55 pm

    audiobill wrote:By our own Boomzilla!!

    http://hometheaterhifi.com/reviews/amplifier/power-amplifier/vacuum-tube-audio-st-120-tube-power-amplifier-review/

    Two of the negative issues is easily fixed, like i have done.
    -An IEC well can be positioned at the back, a shop with a mill can do that as
    a temporary solution. Suitable IEC intakes ( with built-in fuse) will be part of
    the kit.
    - A SSR ( Solid-state relay) and a power-control connector can be included,
    AT worst it need one or two screwmounts. The signal connector can use
    the unused fuse ( that is replaced by the IEC ). This will augument the
    powerswitch at the back with a remote control possibility.
    In the future this could be combined with the delay-board and some extra
    functionality ( such as a turn on delay that protects from power glitches)

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    deepee99

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    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: ST-120 Review

    Post by deepee99 on Fri Jan 06, 2017 2:56 pm

    sKiZo wrote:Can't imagine why anyone would want to change anything ... leave well enough alone!  ;-}
    Yeah, right, Dr. Monarch!
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    Maintarget

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    Join date : 2013-02-10

    Re: ST-120 Review

    Post by Maintarget on Fri Jan 06, 2017 7:06 pm

    deepee99 wrote:
    sKiZo wrote:Can't imagine why anyone would want to change anything ... leave well enough alone!  ;-}
    Yeah, right, Dr. Monarch!

    I was thinking the same thing deepee99
    I'm surprised the post didn't include a photo of the famous "Monarch Amp" of course I'm just jealous lol!

    Dogstar

    Posts : 166
    Join date : 2014-06-23

    Re: ST-120 Review

    Post by Dogstar on Fri Jan 06, 2017 10:06 pm

    Nothing much to this – plug in the tubes (they’re keyed only go in one way, so you can’t mess it up), set the output tube bias (a multimeter & small screwdriver will be required), hook up the speakers & inputs, turn it on – and instant music!

    We know this paragraph is not instructions for setup but just to be sure speakers need to be hooked up before the amp is powered up to set the bias.
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    Rabindu

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    Age : 62
    Location : Mississauga, Ontario, Canada

    Re: ST-120 Review

    Post by Rabindu on Sat Jan 07, 2017 3:27 am

    The only thing I found to be a nuisance is the power switch being on the back. I originally ordered my kit with the attenuator that's mounted in place of the stereo/mono switch which as time went by found that I could do without since building an SP-14. Therefore I removed it and moved the power switch in its place, no more reaching over hot tubes to turn the amp off. The only other thing that I can think of that would be an improvement is to have the RCA input jacks on the rear panel, otherwise the layout is just fine as is.

    Mike Kampman

    monkuboy

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    Join date : 2016-03-23

    Re: ST-120 Review

    Post by monkuboy on Sat Jan 07, 2017 12:51 pm

    Rabindu wrote:The only thing I found to be a nuisance is the power switch being on the back. I originally ordered my kit with the attenuator that's mounted in place of the stereo/mono switch which as time went by found that I could do without since building an SP-14. Therefore I removed it and moved the power switch in its place, no more reaching over hot tubes to turn the amp off. The only other thing that I can think of that would be an improvement is to have the RCA input jacks on the rear panel, otherwise the layout is just fine as is.

    Mike Kampman

    When I reach over to turn off the amp after using it a while, if I'm wearing short sleeves I always think about making sure they don't catch on fire. Very Happy
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    pichacker

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    Join date : 2016-08-01
    Age : 52
    Location : Near to London - UK

    Re: ST-120 Review

    Post by pichacker on Mon Jan 09, 2017 9:17 am

    I moved my RCA's to the rear (see my posts) and the only observation I can make having fitted mine centre rear is that the mains transformer has a large magnetic field and this can easily induce hum onto the input leads.

    In hindsight best for it to be to one side and move the speaker terminal? Not going to do it as cutting the stainless was a real chore!

    http://dynacotubeaudio.forumotion.com/t3126-vta-st-120-born-in-the-uk
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    peterh

    Posts : 776
    Join date : 2012-12-25
    Location : gothenburg, sweden

    Re: ST-120 Review

    Post by peterh on Mon Jan 09, 2017 11:13 am

    pichacker wrote:I moved my RCA's to the rear (see my posts) and the only observation I can make having fitted mine centre rear is that the mains transformer has a large magnetic field and this can easily induce hum onto the input leads.

    In hindsight best for it to be to one side and move the speaker terminal? Not going to do it as cutting the stainless was a real chore!

    http://dynacotubeaudio.forumotion.com/t3126-vta-st-120-born-in-the-uk
    Keeping the input jacks on the front will keep the leads as short as possible
    inside the amp, and give the maximum distance from the power transformer.

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    sKiZo

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    Join date : 2013-04-01
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    Re: ST-120 Review

    Post by sKiZo on Mon Jan 09, 2017 8:10 pm

    If you do decide to move the jacks, you can minimize any chances of interference by twisting the wires. Solid core works well for that, as it keeps it's shape. Just chuck one end in a vise, and the other end in a drill and give it a spin.

    Also not a bad idea to try and route the wire as far away from the iron and such as you can. The extra length shouldn't hertz.



    I'm told it helps to also include a third "drain wire" with each channel pair. Let one end float, and attach the other end to common ground. Theory is, this wire should collect any stray nastiness that could impact sonic purity.

    PS ... I knew I could fit a pic of the Monarch in this thread! geek


    Last edited by sKiZo on Tue Jan 10, 2017 12:53 am; edited 1 time in total
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    j beede

    Posts : 375
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    Location : California

    Re: ST-120 Review

    Post by j beede on Mon Jan 09, 2017 11:52 pm

    sKiZo wrote:

    [cut]

    I'm told it helps to also include a third "drain wire" with each channel pair. Let one end float, and attach the other end to common ground. Theory is, this wire should collect any stray nastiness that could impact sonic purity.

    I always add a fourth "drain the swamp" wire. This is similar to the "drain" wire referenced above (near end grounded, far end floating). The terminations of the fourth wire are opposite--near end floating and far end grounded. This gives purer purity.
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    pichacker

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    Age : 52
    Location : Near to London - UK

    Re: ST-120 Review

    Post by pichacker on Tue Jan 10, 2017 4:22 am

    Although the electronic engineer in me says that the twisted pairs above should not be used for interconnects in this situation as they are not connected in a balanced configuration.

    But that's another topic for discussion elsewhere.
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    sKiZo

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    Join date : 2013-04-01
    Location : Michigan USA

    Re: ST-120 Review

    Post by sKiZo on Tue Jan 10, 2017 5:54 pm

    ?

    They're connected in exactly the same way as the stock connections to the board.

    By balanced, do you mean one running down each side of the chassis? That would have put one channel right on top of the PT. That said, any design will include some compromises - best I can say is it turned out dead quiet, so hey, I'm good wit it ...

    PS ... can't say as I was all that concerned with maintaining the "correct" 8 turns per inch recommended (somewhere or other) for best results in the target frequency range either. ;-}
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    corndog71

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    Re: ST-120 Review

    Post by corndog71 on Tue Jan 10, 2017 6:19 pm

    pichacker wrote:Although the electronic engineer in me says that the twisted pairs above should not be used for interconnects in this situation as they are not connected in a balanced configuration.

    But that's another topic for discussion elsewhere.

    That's weird. I've seen twisted pairs for unbalanced interconnects as well as internal wire in probably hundreds of various types of audio gear. I thought it was fairly standard practice.

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