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    Virgin Voyage - VTA ST-120 kit build

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    dalemurray

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    Join date : 2018-09-25
    Location : Wheaton Illinois

    Virgin Voyage - VTA ST-120 kit build

    Post by dalemurray on Mon Oct 01, 2018 1:05 pm

    My ST120 kit with upgrades should be delivered today.

    This will be my first ever tube amp experience, let alone building one.

    So, before I embark on this voyage, does anybody have any helpful hints, tips, or undocumented upgrades/updates (caps, etc)?

    My thoughts so far:
    - I initially thought about moving the input jacks to the rear but those will remain in front.
    - I do intend, unless I discover it will be horrible, to swap the mono and power switch locations. I am most concerned about my wife possibly getting burned turning it off.

    In the future I will likely rebuild in custom case. I'm a woodworker so it would be nice to make something pretty.
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    Peter W.

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    Location : Melrose Park, PA

    Re: Virgin Voyage - VTA ST-120 kit build

    Post by Peter W. on Mon Oct 01, 2018 2:35 pm

    dalemurray wrote:My ST120 kit with upgrades should be delivered today.

    This will be my first ever tube amp experience, let alone building one.

    So, before I embark on this voyage, does anybody have any helpful hints, tips, or undocumented upgrades/updates (caps, etc)?

    My thoughts so far:
    - I initially thought about moving the input jacks to the rear but those will remain in front.
    - I do intend, unless I discover it will be horrible, to swap the mono and power switch locations. I am most concerned about my wife possibly getting burned turning it off.

    In the future I will likely rebuild in custom case. I'm a woodworker so it would be nice to make something pretty.

    The best advice I can give in your circumstances:

    a) Enough room to work! Make sure you have enough room to work, to lay out parts and to not have clutter.
    b) Ventilation: Make sure you have _REALLY_ good ventilation. Solder flux is not good for you.
    c) Excellent light: Generally, when I do fine work, I have three articulated lamps working so as to eliminate any shadows, give me good color rendering, and did I mention, good light!

    Then:

    Work over a monochromatic, light colored (expendable) towel. Dropped things do not bounce, and tend to be caught in the fluff for easy recovery.
    Use good, fresh eutectic solder - 37/73 is the best if you are not fussy about lead-Free RHOs and such.
    Understand that a faster, hotter soldering iron will be easier to use than a cooler, slower one.
    Manage your soldering iron properly. I use either a 38-watt pencil-iron with a narrow (3/16") flat iron tip, or a soldering station where I can set the tip to 390F, about 30 degrees over the melting point, but not so hot as to damage components during the heating process.
    Melt the solder onto the heated part, do not melt the solder first onto the cold part.
    Keep the tip clean. A wet cellulose sponge (not plastic) is your best friend.

    Read the directions twice. Before you start. Ask questions if necessary, knowing that there is no such thing as a stupid question. Many dubious answers, but no bad questions.

    And, congratulations and good luck!
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    dalemurray

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    Re: Virgin Voyage - VTA ST-120 kit build

    Post by dalemurray on Mon Oct 01, 2018 2:54 pm

    Very sage advice.

    Though I already have some of these I bought:
    - a new one with temperature control.
    - new solder. I cannot claim anything special about it other than 60/40 and .031 and .06 diameters.

    As a woodworker I have very good lighting over my work spaces.
    As a professional photographer I can take REALLY GOOD photos of my mistakes so they can be corrected in forums or by Bob.

    As much as I want to immediately jump in, I will likely wait until Wednesday to start. I may attach various components but no wiring until later this week.
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    sKiZo

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    Re: Virgin Voyage - VTA ST-120 kit build

    Post by sKiZo on Mon Oct 01, 2018 3:01 pm

    Yellow sheet mod is always a good start when it comes to customizing the kit.

    http://dynacotubeaudio.forumotion.com/t1006-tube-rectifier-diode-mod

    As far as a custom case goes, I'd do that right from the start unless all you plan to do is wrap the stock chassis in wood. That's easy enough after the fact, but kind of a pita to disassemble and start over after the initial build is done. I will say that a full custom case can give you a lot more room to work with and open up a lot more options.

    DO follow the step by step instructions provided carefully. I highlighted all the "solder later" connections prior to starting, then checked off each step along the way. After I was "done", I went back through them again, and carefully reviewed each step and checked them off one more time, paying special attention to those "solder later" steps to make sure I didn't miss anything.

    Fairly common to get some hum if you don't get clean grounds along the way. Get the multi-cap tight to the chassis, and not a bad idea to rough up the metal some when attaching the ground lugs and jacks. DO twist any long signal leads to minimize any interference.

    Follow the start up instructions to the letter.

    I'd also add getting a Copper Cap solid state rectifier, at least as a backup. Darn shame to lose a bottle and not have a good spare on hand.

    Mostly, take your time, and have fun with it.
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    Peter W.

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    Re: Virgin Voyage - VTA ST-120 kit build

    Post by Peter W. on Mon Oct 01, 2018 3:06 pm

    dalemurray wrote:Very sage advice.

    Though I already have some of these I bought:

    - new solder. I cannot claim anything special about it other than 60/40 and .031 and .06 diameters.


    Really, and emphatically:

    PLEASE DO NOT use 60/40 solder.

    a) It has (for electronic solder) a wide plastic range, meaning that the chances of poor and cold joints is increased exponentially.
    b) It has a higher melting point (370F vs. 361F) - meaning you will be putting a LOT more heat onto the connection. 7 degrees (F) may not seem like much, but it is quite significant, especially as it applies to circuit boards.

    I am OK with 60/40 solder when I am restoring vintage radios, or making repairs to leaded glass window - the former is a common practice, the latter on rare occasion. But for anything with a circuit board or post 1960-or-so, I use 37/73 exclusively. I keep eutectic silver-solder (lead-free) for repairing jewelry and/or anything to do with food or drink.
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    dalemurray

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    Re: Virgin Voyage - VTA ST-120 kit build

    Post by dalemurray on Mon Oct 01, 2018 3:20 pm

    Peter W. wrote:
    Really, and emphatically:

    PLEASE DO NOT use 60/40 solder.  

    a) It has (for electronic solder) a wide plastic range, meaning that the chances of poor and cold joints is increased exponentially.
    b) It has a higher melting point (370F vs. 361F) - meaning you will be putting a LOT more heat onto the connection. 7 degrees (F) may not seem like much, but it is quite significant, especially as it applies to circuit boards.

    I am OK with 60/40 solder when I am restoring vintage radios, or making repairs to leaded glass window - the former is a common practice, the latter on rare occasion. But for anything with a circuit board or post 1960-or-so, I use 37/73 exclusively.  I keep eutectic silver-solder (lead-free) for repairing jewelry and/or anything to do with food or drink.

    I specifically ordered this solder based on what I read here:
    tubes 4 hifi . com /sp14-B . htm      <-- I had to space these out because I am a new user and cannot post outside links.

    do yourself a favor, use small .031 guage 60-40 solder for 90% of the work,
    use large .062 guage 60-40 for the large diodes and tube sockets only.
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    dalemurray

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    Re: Virgin Voyage - VTA ST-120 kit build

    Post by dalemurray on Mon Oct 01, 2018 3:24 pm

    sKiZo wrote:Yellow sheet mod is always a good start when it comes to customizing the kit.

    http://dynacotubeaudio.forumotion.com/t1006-tube-rectifier-diode-mod

    As far as a custom case goes, I'd do that right from the start unless all you plan to do is wrap the stock chassis in wood.

    I tried sending you a message to learn more about your mods.

    A couple items I want to add:
    - meter for bias
    - output meters pr channel because dancing needles make music sound better.

    I will review the link in a few.
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    peterh

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    Re: Virgin Voyage - VTA ST-120 kit build

    Post by peterh on Mon Oct 01, 2018 3:30 pm

    dalemurray wrote:My ST120 kit with upgrades should be delivered today.

    This will be my first ever tube amp experience, let alone building one.

    So, before I embark on this voyage, does anybody have any helpful hints, tips, or undocumented upgrades/updates (caps, etc)?

    My thoughts so far:
    - I initially thought about moving the input jacks to the rear but those will remain in front.
    - I do intend, unless I discover it will be horrible, to swap the mono and power switch locations. I am most concerned about my wife possibly getting burned turning it off.

    In the future I will likely rebuild in custom case. I'm a woodworker so it would be nice to make something pretty.

    One advice : keep the power switch at the back, with short wires it hums the least. But
    to avoid burns or dangerous movements : power the vta from a switched power strip,
    one with a current sensing relay would be perfect, that way when the preamp ( connected
    to the controlling outlet) is turned on the VTA is also turned on.

    To be sure of success; do it exactly as per the instructions. When more experienced
    you could rebuild the amp later. And stay clear of leadfree solder !

    ( myself uses SSR aka solid state relays mounted inside the poweramp and
    controlled via a 12V line with the 12V taken from the preamp. It's even better then
    the power strip as all turning on or off is done at zero crossing)

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    corndog71

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    Re: Virgin Voyage - VTA ST-120 kit build

    Post by corndog71 on Mon Oct 01, 2018 3:37 pm

    I strongly recommend building the amplifier stock first. Live with it for a month or two. And then consider upgrade / rebuild options. The yellow sheet mod is a good one.
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    Peter W.

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    Re: Virgin Voyage - VTA ST-120 kit build

    Post by Peter W. on Mon Oct 01, 2018 4:02 pm

    do yourself a favor, use small .031 guage 60-40 solder for 90% of the work,
    use large .062 guage 60-40 for the large diodes and tube sockets only.


    60-40 solder, similar to slow-blow (spiral wire) fuses, is an invention from the nether regions. Something that Wormwood would come up with, whereas Screwtape figured out the fuses.

    It is horrible stuff, it multiplies bad joints, it has a l-o-o-o-o-o-o-o-n-g plastic stage, and you will curse the day you start using it for fine electronics. I keep it in the same kit I keep my 100/200-watt soldering gun. It has its purposes, but not anywhere near fine electronics. Really. If you have never used eutectic solder, you will not understand entirely until you do.

    One last thing - the stuff is more brittle than good eutectic solder, and will harden with use. Useful when working with vintage radios and direct-to-chassis solder joints (hence the 100/200 watt gun). Not otherwise.

    https://www.amazon.com/Kester-24-6337-8800-Activated-Solder-No-Clean/dp/B00068IJOU/ref=sr_1_11?s=automotive&ie=UTF8&qid=1538423486&sr=1-11&keywords=electronic+solder  

    I would tell you what I really think, but that would require both a snark and a rant warning.
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    ggnarley

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    Re: Virgin Voyage - VTA ST-120 kit build

    Post by ggnarley on Mon Oct 01, 2018 4:47 pm

    Just finished my build about a month ago and was my first go also.  The two things that helped me the most were.

    1) Get a hold of Bob if there is even a small doubt on something.  He saved my bacon a couple times.

    2)  I tried to do a 4 way match on all wiring.  Before any soldering, I tried to match

    1) Instructions
    2) colored hand drawn wiring diagram
    3) photo of wiring
    4) my build.  

    If there were any discrepancies then I backed off, retraced my steps, and asked Bob for clarification.  

    Good Luck.
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    dalemurray

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    Re: Virgin Voyage - VTA ST-120 kit build

    Post by dalemurray on Mon Oct 01, 2018 8:09 pm

    I checked with Bob, 60/40 is just fine.

    I really want to add some of sKIZo's mods to this.

    What I am likely to do is build as is; figure out all the changes and rebuild some time down the road.
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    sKiZo

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    Re: Virgin Voyage - VTA ST-120 kit build

    Post by sKiZo on Mon Oct 01, 2018 10:05 pm

    You'll never guess what solder I recommend ... clown

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    ArlanB

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    Re: Virgin Voyage - VTA ST-120 kit build

    Post by ArlanB on Mon Oct 01, 2018 10:42 pm

    Just to let you know that 60/40 solder does work.  I purchased my VTA ST-120 over 10 years ago and at that time 60/40 was recommended.   I built my kit before the forum had been instituted.  Bob was the only go to guy at that time.  Help was outstanding.  The amp worked on the first smoke test and has not had any malfunctions other than power tubes.  So have at it.  The cardinal rule is "Take Your Time".  You will be greatly rewarded.  Just a little note, my kit is as original as you can get, I ordered it with no upgrades, and I would not change a thing.  It sounds wonderful  in original configuration.
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    dalemurray

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    Re: Virgin Voyage - VTA ST-120 kit build

    Post by dalemurray on Tue Oct 02, 2018 12:45 am

    I think I'll stick to the peasant soldier I've already purchased.
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    Peter W.

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    Re: Virgin Voyage - VTA ST-120 kit build

    Post by Peter W. on Tue Oct 02, 2018 7:12 am

    Alrighty, then!

    Just understand that one cannot go back. Once the equipment is polluted with 60/40 solder, (which will "work" of course), it remains so-polluted forever. Meaning that servicing it in the future will be more difficult, the chance for errors is multiplied and so on and so forth.

    Now, ask yourself - is it really worth it?
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    dalemurray

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    Re: Virgin Voyage - VTA ST-120 kit build

    Post by dalemurray on Tue Oct 02, 2018 8:47 am

    One persons cut corner is another persons absurd excess.

    This is my work bench (prior to applying finish).
    The top is 8'x32" of hard maple with hand cut black walnut dovetailed ends; the walnut was in my grandfathers basement for 40+ years.
    The base is all maple, and uses draw bore mortise and tenon construction with maple panels.
    The leg vise is 12/4 maple with book matched curly maple face. (Hardware from BenchCrafted)
    The chain drive twin screw end vise is walnut; I used snake wood under the bench as screw guides to minimize sag when the vise is opened several inches. (Hardware from Veritas)
    All 22 bench dogs are individually fitted black walnut and use quarter saw white oak as spring retainers.
    It took more than 6 months of evenings to build.
    Weighs over 800lbs.
    It will eventually have a dozen drawers with curly maple faces and a curly maple raised panel door.

    Some people might think it is excessive; I cannot imagine using anything less.
    Some have said it is to nice to use; I use it all the time and it does have, gasp, some tool marks on it!

    If you do not have a bench like this I wonder, is it even worth having?



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    Peter W.

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    Re: Virgin Voyage - VTA ST-120 kit build

    Post by Peter W. on Tue Oct 02, 2018 8:58 am

    That is gorgeous - and a credit to your talents!

    Snark Warning!

    Compare your curly maple (37/73) to red pine (60/40) and we are on the same page.
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    dalemurray

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    Re: Virgin Voyage - VTA ST-120 kit build

    Post by dalemurray on Tue Oct 02, 2018 9:14 am

    I was making a point but also pointing a finger back at myself - we all have TOTALLY REASONABLE excesses.

    I would consider 60/40 as red oak, that stuff is EVERYWHERE, relatively cheap, and most people are just fine with it.

    I am sure there are qualities benefits with the solder you suggest, I just don't know if those are ones I would actually notice. Like most would never understand the benefits of a massive woodworking bench - once you start using hand tools you do.

    I could see disassembling the ST120 once, only if I decide to make a custom cabinet and mounting plate for it. Since this is likely a temporary build, I may use crimp terminals in some locations to ease disassembly. Once reassembled in final home I would solder all connections. <-- maybe a REALLY bad idea, I am sure.

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    Peter W.

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    Re: Virgin Voyage - VTA ST-120 kit build

    Post by Peter W. on Tue Oct 02, 2018 9:30 am

    Last points on this subject:

    a) Eutectic solder has multiple virtues that are difficult to explain to those who have never used it.
    b) That something is cheap, common, and easily available makes it cheap, common, and easily available. So is a McDonald's hamburger, and many are just fine with that.
    c) What you will notice (and come to appreciate after a few hundred - or thousand connections) is the lack of a 'plastic' stage.
    d) There are lethal !!DC!! voltages inside that amp. DC will arc. A crimp connection will potentially support arcing, which is no fun at all. Nor is it very good for tubes, transformers and, possibly, real-estate.

    Promise!
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    dalemurray

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    Re: Virgin Voyage - VTA ST-120 kit build

    Post by dalemurray on Tue Oct 02, 2018 9:41 am

    I do not disagree with any of your points above.

    Considering I have done nothing more than install five tube sockets, speaker terminals, and the on/off switch thus far, I am only speculating this is a possibility.
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    solderblob

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    Re: Virgin Voyage - VTA ST-120 kit build

    Post by solderblob on Tue Oct 02, 2018 3:15 pm

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    dalemurray

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    Re: Virgin Voyage - VTA ST-120 kit build

    Post by dalemurray on Tue Oct 02, 2018 3:33 pm

    Now I feel like I am missing out on something.
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    sKiZo

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    Re: Virgin Voyage - VTA ST-120 kit build

    Post by sKiZo on Tue Oct 02, 2018 3:58 pm

    Trade offs in whatever your solder choice may be. 60/40 was the standard for decades - I have 50 year old radios that are still working fine. Modern solders with lower lead levels are more prone to forming whiskers - not so much a problem with the type of connections we're working with, but requiring a bit more skill and practice, as well as better irons, for good results. I'd say it's more practical for someone who makes a living at this sort of stuff, but the 60/40 is fine for what we do.

    PS - couple schools of thought on solder temps ... some prefer the "cold" iron for longer plasticity, some (me included) going nuclear to keep contact time to a minimum. For board work, I keep my iron at around 725F, then touch it to the component lead and slide it down to the pad while applying solder to the iron and letting it spread. Equal temps on both the lead and pad are critical - Works like a charm. Point to point like a tube socket or wire, just touch the iron to the connection and apply solder directly at the mating point. Also a good thing to allow recovery time on the gun tip between connections - touching it to cold metal cools it quickly.

    Oh - another trick - for socket connections, I tin both the tab and wire first, then insert the wire and crimp the tab fairly tight to get max surface area at the joint for solder. Kind of a PITA to break the connection later, but less chance of failure that way. I suppose the real trick is to be sure you do it right the first time ...

    New2Tubez

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    Re: Virgin Voyage - VTA ST-120 kit build

    Post by New2Tubez on Tue Oct 02, 2018 5:52 pm

    My experiences-

    I hadn't soldered in 20 years. No unhappy surprises and I didn't have to turn the power strip off! I was going to review my ST120 at some point but since you asked here goes...

    I spoke w/ Bob before buying in February 2018. I read the instructions over and over. Checked off completed steps. When I finished a page, I read the page again while going through my work. I got the Russian caps and attenuator (no preamp). I did the yellow sheet diode mod. I looked at lots of soldering on YouTube (didn't go full NASA/FAA). I read up everywhere I could.

    I've since gotten the auto bias board. I would've heat shrunk the caps had I known about the AB. I'll install this when it gets cooler.

    I cleaned the board and components before and after soldering w/ 99% isopropyl alcohol. As per Bob, I used 60/40. Mine was Kester #44 .031" I used a Hakko station at 650-700º. I got some more tools: a wire stripper,  round nose pliers (great for bending leads and not hurting insulation) and solder wick . I used soldering "tweezers" to take the heat off of components (diodes, transistors, etc). I measured each component against the specs (they were ALL with in spec). I had Joe Popp's ST120 build (FB) on my laptop screen, the included photo, and the drawing, for reference. I used heat shrink if I nicked insulation and it wasn't too bad. Also used it if I thought wires could be hurt by friction and also on the center fuse terminal. I spent 15-20 hours on it. I would check that the 12AU7's line up nicely after soldering the sockets to the board. I soldered over heavy cardboard over plywood with an air purifier behind the solder station. I had good light and a lighted magnifier visor.

    Bob and Roy answered questions along the way. Bob talked me off the ledge more than once- the most patient man I know! Also got advice from Kramer on this forum. Bob posted a pic of my build on his FB site (it's a comparison- mine's the one w/o the wine glass) I corrected the yellow wire path after this pic, btw. The instructions are very thorough. I ended up w/ 11" of left over hookup wire.

    When I do the AB board, I'll put in a Weber WS-1T. I'm using Tung Sol 6550's (@.50ma) and a TS 5AR4. Bob's mil-surplus (at that time) RCA 5963's sound great (I've tried clear top's and to me, the 5963's sound better). A Brimar CV4003 center tube tops them all. My 122vac is set to 117 on a variac.

    It sounds great- way better than the modern receivers I've used for years. I play CD's and vinyl (schiit mani pre), w/ bluejeans interconnects. No noise, no drama, no blown tubes. I bias every 1-2 months. Doing the auto bias so I can put the cage on (with screws and fan). Did I mention it sounds FANTASTIC!?

    I'll post photos soon.

    Have fun (no sarcasm),

    Ned

    PS, I cut my red oak with a sawzall on a cinderblock (definite sarcasm).


    Last edited by New2Tubez on Wed Oct 03, 2018 1:00 pm; edited 2 times in total

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