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Asher Guitars WD Music Products Amplified Parts Mod Kits DIY Nordstarnd Pickups Warmoth.com

Filament buss question

Discussion in 'Shock Brother's DIY Amps' started by moosie, Nov 23, 2017.

  1. moosie

    moosie Doctor of Teleocity Silver Supporter

    Age:
    60
    Jul 18, 2010
    Western Connecticut
    I'm wiring a Weber ReVibe kit, which is a mashup of a 6G15 and the harmonic trem/vibe from a brown Concert. Should sound glorious, if I can get it all tucked in such a small chassis.

    There are five tubes, hanging down from a tweed-style chassis. The thing I'm not used to (I maintain my SF amps) is the 6K6 octal is in the center (V3), and there are preamp tubes on either side.

    Does it matter how I wire the filaments? Should I start at V5, and go down to V1, which follows the logical path? Or should I start with the power tube, then branch in both directions from there, to the two preamps to the right, and the two to the left?

    If there's a difference, why? Noise?

    Thanks!
     

  2. clintj

    clintj Friend of Leo's

    Apr 4, 2015
    Idaho
    That's an excellent question. Generally whatever tube the signal sees first in a circuit should be at the farthest end of a filament string. Radiated hum and noise are a function of current carried, so putting that stage last minimizes that. My first reaction is the 6K6 first, then branch off to each set of tubes. I'll study the layout/schematic on the bus ride to work and see if that lights up the proverbial light bulb.
     
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  3. moosie

    moosie Doctor of Teleocity Silver Supporter

    Age:
    60
    Jul 18, 2010
    Western Connecticut
    Blencowe advises power tubes first, because of the higher current draw. That's all he says, but I presume it's because higher current means more potential noise, and the shorter the run, the better.

    I've also heard the other perspective, what you're saying, keep the hum far from unamplified input. But it wouldn't seem to make ANY sense to go V3, 4, 5, then 2 and 1.... would it? HUMMMMM... :lol:


    Weber Layout.jpg
    5h15_schem Weber ReVibe.jpg
     

  4. clintj

    clintj Friend of Leo's

    Apr 4, 2015
    Idaho
    I think I would start by running straight across from the pilot light past the filter caps, then in order L to R, rather than trying to cut diagonally across the chassis. My thought is tightly twisted, properly placed, balanced heaters will minimize any potential hum issues going "out of order" might bring.
     
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  5. moosie

    moosie Doctor of Teleocity Silver Supporter

    Age:
    60
    Jul 18, 2010
    Western Connecticut
    Yeah, that's what I did, thanks.

    Here's a pic. First time doing a 50s style chassis. Jeez. The backs of my hands are getting a bit chewed up.

    There's no tube socket in V1. Darn ceramic must have had a hairline crack, and broke as I was working on it. Much better to know now!

    20171124_191317.jpg 20171124_191349.jpg
     

  6. King Fan

    King Fan Friend of Leo's Ad Free Member

    Jan 1, 2013
    Salt Lake City
    Wow, a ReVibe -- so cool. I hadn't ever looked at the sockets or wiring -- for me just looking at the board is like seeing Mt. Everest from the plains of India. Inspiring, scary, and very distant. I have my huge telescope mounted on a giant tripod and will be watching your ascent. :)

    Edit: I recall Doug Hoffman built a rack-mount version. You've probably seen it, and it may not relate directly to yours, but just in case it could help:

    http://el34world.com/Forum/index.php?topic=13098.0
     
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  7. moosie

    moosie Doctor of Teleocity Silver Supporter

    Age:
    60
    Jul 18, 2010
    Western Connecticut
    http://web.archive.org/web/20140410144814/http://home.everestkc.net/jgehring/revibe1-4.html

    Jeff Gehring's was the initial build, I believe, and it seems his parts list was more or less made into the Weber kit. But he added the signal common elevation (above ground) later, so the kit needs some retrofitting to accommodate.

    I've looked at Hoffman's too (thanks for the link, tho :)), but he's not handling the noise issue like Gehring. It's my understanding that these units (and 6G15s) are particularly noise-prone because of (real) ground loops. Not the ones everybody is paranoid of in their guitar circuit. Plug two high-volt devices into the wall, plug one into the other, and connect each unit's signal common directly to chassis ground. So now there's electrons trying to make it to ground every which way.

    One option, which I think Hoffman suggests somewhere, is to simply lift the ground on the ReVibe. But (again my understanding) that's dangerous. That means the ReVibe would be ungrounded, except as through the instrument cable. Or something like that.

    Gehring claims his build is dead silent, which I like. He runs all signal commons to that big-ass brass ground buss (say that three times quickly :lol:) and then that grounds to the chassis, but through a small resistor / diode / capacitor network. Again, my (limited) understanding is that this elevates the signal reference point to something greater than chassis ground (zero volts). There are no more multiple paths to ground, and hopefully, no noise.

    EDIT: this requires insulating the signal jacks from the chassis with fiber shoulder washers, and using long-bushing jacks.

    That's my goal. I haven't decided how I'm going to do the board yet. His method is fiber board, but looks turret board, if that makes sense. I'm used to my SFs. Not the mess so much as the tendency to route above board where problems can be addressed, and not having everything quite so square-looking.

    I'm not in love with all those individual grounds running back to the buss - all under the board. As he says, treat the underside as if it's headed to Jupiter - because you NEVER want to see it again. This thing is going to be hard enough to fit. Taking it out to fix a bad connection is not an option.

    Question for the experts: Do I really need such a large ground buss? Or can I just bring a few grounds together at various points, and then bring those few all the way down, and have that buss be a simple solid 12 AWG wire? One thing I don't care for is it seems like it might be difficult to desolder just one of those grounds from the buss.


    This is from Gehring's site. I took his 6 separate photos, and stitched them together, and oriented them more usefully (to me). But as I said, I'm considering routing much more over, rather than under.


    Screen Shot 2017-11-24 at 10.43.36 PM.png
     
    Last edited: Nov 25, 2017
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  8. keithb7

    keithb7 Friend of Leo's

    Age:
    46
    Jan 9, 2010
    Western Canada
    Nice work @moosie . I had not heard of this unit before. Harmonic trem and reverb! Wow. I look forward to hearing and seeing this when it's done.
     
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  9. moosie

    moosie Doctor of Teleocity Silver Supporter

    Age:
    60
    Jul 18, 2010
    Western Connecticut
    I feel like I'm going on a unicorn hunt. Not too many of these (in this form) out there, it seems.

    Victoria's Reverberato is probably the same circuit, or very close, and they get $1800 for one. He claims it's the most difficult build they do. I wish I hadn't read that. :)
     

  10. keithb7

    keithb7 Friend of Leo's

    Age:
    46
    Jan 9, 2010
    Western Canada
    It does look somewhat complicated.... I'll guess you've seen this? A quick YT search netted it. It does sound great. Certainly not unlike my 6G8-A harmonic trem.

     
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  11. moosie

    moosie Doctor of Teleocity Silver Supporter

    Age:
    60
    Jul 18, 2010
    Western Connecticut
    Not so fast, I've hardly done any work, yet. That's not my board... Mine has three resistors on it so far :lol:

    Some time ago, I assembled all the hardware, but then I had to remove it all when I realized more chassis drilling was called for. Then I put it back together. Then I took it apart again, because on a dry fit test, I couldn't get the board in with the pots in the way. So, the transformers and the rear face are assembled, now I'm populating the board, then I'll (try to) install it, then mount the pots, finish hooking up the AC, etc etc. Ship in a bottle. Plus, I've had to redrill the PT mounts, to angle it so it doesn't smush the tank.


    That's a great demo vid. I forgot about that. I did a fair amount of research three years ago, when I bought the kit. At the time, I thought it'd be a nice, easy first build. It's been sitting in the corner laughing at me ever since. Brave or stupid, I'm finally ready to try it.
     

  12. keithb7

    keithb7 Friend of Leo's

    Age:
    46
    Jan 9, 2010
    Western Canada
    Literally laughing out loud over here. "A nice easy first build". One of the easiest builds ever took about 4 plus hours of my time to troubleshoot over the past 24 hours. The 5F2A. It only has about 1/10th of the components as this ReVibe. Our prayers and thoughts are with you during this difficult time.
     
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  13. moosie

    moosie Doctor of Teleocity Silver Supporter

    Age:
    60
    Jul 18, 2010
    Western Connecticut
    Well, I did build an Allen Encore (and a Heathkit ham radio a very very long time ago). The Encore kit is so good, though, it's not really a build. It's paint by numbers. Amp works great, though.

    Right as I decided that I finally had to do this stupid build, I noticed a fairly rare Vicky Reverberato for sale on the Gear Page for $1100. I was really tempted for a moment. Just have it. Done. Yeah, yeah, the build's most of the fun. Dang it.
     
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  14. milocj

    milocj Friend of Leo's Ad Free Member

    Aug 21, 2005
    Michigan
    I built one a long time ago, before there was actually a kit, so I had to work my way through it slowly. The board that Weber supplied at that time was basically a reverb and the vibrato circuit from the two amps (brown Concert and the 6G15 if I recall) along with Geoff's mixing circuit on it.

    I started out by making my own set of "doghouse" boards for the PS filter and the SS rectifier to fit on the side of the chassis. I had that and the tube sockets wired and then shelved it for awhile. At that point I heard from Geoff that Weber had put their "kit" out prematurely and that their board would have been very noisy so I called Ted and he sent me a new board for free.

    I ended up cutting the power supply section off of it and kept only the Revibe circuit portion. It was an extremely tough fit to get everything into the chassis and soldered up, but it worked first try and always has. No noise that I can tell and no ground loop when used in the same wall circuit.

    I also decided to only use the "normal" style of grounding that you see most folks using during an amp build these days, with the power section grounding to one point and all of the "preamp" grounds to another point along a single buss wire that ends at the input jack. That turned out to work fine in my build.

    I have to retrieve the build pics from photobucket and then I'll post them.
     
    Last edited: Nov 26, 2017
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  15. milocj

    milocj Friend of Leo's Ad Free Member

    Aug 21, 2005
    Michigan
    Below are some pics. I had the cabinet made for me by JD Newell to match both my brown Deluxe and a blond Bassman that I had at the time.

    Revibe pics 010.jpg Revibe pics 012.jpg Revibe pics 025.jpg DSC01900.JPG DSC01913.JPG DSC01915.JPG
     

  16. milocj

    milocj Friend of Leo's Ad Free Member

    Aug 21, 2005
    Michigan
    Last edited: Nov 26, 2017
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  17. King Fan

    King Fan Friend of Leo's Ad Free Member

    Jan 1, 2013
    Salt Lake City
    Milocj, thanks for rescuing and sharing those pics. A detailed solution set to a complex problem.

    Moosie, I'm not sure you intended to start a build thread here, :) but I hope you'll keep us posted. Your funny, helpful notes about the circuit's history and issues got me hooked.

    Obviously, you don't need more ReVibe info -- sounds like you researched the heck out of this. Just for my own purposes (I considered one of these once, and if I get really bored and need a massive challenge someday I may revisit it) I'll remind myself here that Doug Hoffman also had a standard chassis version (although I think he thoroughly Hoffman-ized it with internal filter caps and a Doug-sano board). On that page he has a few notes and updates about the 'big ground loop' problem you point out. Later, also, he apparently used the Tore T. mod (which is what I was trying to recall when I went to EL34World) to eliminate hum, and if I understand what he says, he put *that* on his page about how the vibrato and reverb circuits got combined.

    As I say, this won't be news to you, and you obviously have all sorts of info I don't -- but if other folks get interested, I thought the 'Doug stuff' I was *actually* looking for might be more use than the rack version I linked first. :D
     

  18. moosie

    moosie Doctor of Teleocity Silver Supporter

    Age:
    60
    Jul 18, 2010
    Western Connecticut
    I thought I might start a build thread when I got further along, having taken a few earlier photos. In case I crashed and burned, I'd just not start a thread :rolleyes: What ReVibe? That's a Tolex footstool...

    But yeah, it appears this is the build thread. Confusing and discombobulated, just like me. I emailed the mods to see if they wanted to change the subject line for me, to "ReVibe Build - Filament Buss Question", thereby keeping the original for context, but making more sense overall. Not sure if that'll happen, or even if it's a good idea.

    @milocj, thanks for all those great photos. This is a very nice resource. I'm always happy to see that someone has actually built one of these. I was interested to see your choice of separate filter cap board. I'm planning to stuff it all inside, following Gehring's lead; because it seems like less work and less custom fitting (doghouse cover?); and because it seems pretty tight back there, with little clearance between tank and chassis. But boy, I could sure use that clear space around the PT hookups.

    Speaking of that, how did you mount your tank? Vertical, like the 6G15? Weber sent me a Belton 3-spring, horizontal mount tank, which doesn't seem right. So I've ordered my favorite modern tank that I use in combos, but for a vertical mount. MOD 4AB3C1C. Two spring, long decay. I think the three spring is smoother sounding, and I'm not sure that's what's called for here. But, I can always swap it out.

    The kit came with a bunch of apparently useless T-nuts and springs. Springs are shown in the pic below, along with how I'm mounting the tank. That's the wrong tank, but same idea. The tank is mounted with nuts, to bolts that were already mounted to the front panel when the kit arrived. I have a feeling the springs are to shock-mount the tank somehow, but I'm not seeing how, and there's no room anyway. Even with the PT repositioned on the chassis, there's still only about 1/8" depth clearance between top of tank as mounted, and top corner of the PT.

    I figure I won't be moving the unit much, or placing it on a bouncy stage, so it should work with a hard mount, just like a combo tank does. Right?

    20171127_234018.jpg 20171127_232927.jpg



    @King Fan, you can never have too much data, so any pointers and links are helpful. Aside from Gehring, it's Hoffman's chassis version that I've been looking at over the years.

    I've had some confusion over the Tore T aspect of this. There's a ToreVibe, which Weber sells as kit 5H15T. Same 6G15 as the 5H15 ReVibe, but with the much simpler bias-mod tremolo. Then there's different versions of the ReVibe, and different variants (Gehring's original, and Hoffman). Seems like the Tore T mod has nothing to do with the ToreVibe (except same author?), and it started with Hoffman's variant, and then Gehring picked it up, too. And incorporated it (I think) into the v1.4 that I'm building from. I still need to trace those bits down, and make sure I'm building the Tore T modded unit.

    It's daunting to note that Weber rates the ToreVibe as complexity level 1 (a monkey could do it?), and the ReVibe is level 4 (out of 5?).

    This particular Hoffman layout shows the Tore T mod differences. It's not very clear at this resolution, but it appears to be just 6 components around V1 and V4.

    RevibeOld - Hoffman showing Tore-T mod.jpg


    I'm currently attempting to rework the Weber layout, so I don't have such a mess underneath with all the signal returns now running down to the buss on the far side of the chassis. If I just make a mess on paper, then I'll meekly follow Gehring's lead.
     
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  19. moosie

    moosie Doctor of Teleocity Silver Supporter

    Age:
    60
    Jul 18, 2010
    Western Connecticut
    This Gehring-built ReVibe sold on Reverb a couple years ago.

    I found this gut shot interesting. (I clipped it, to get higher resolution. The one on the Reverb listing shows the tubes).

    Just me? I've never seen a board like this, with those big ground pads.


    Completed chassis - Gehring [ CLIP ].jpg
     

  20. King Fan

    King Fan Friend of Leo's Ad Free Member

    Jan 1, 2013
    Salt Lake City
    “Ooh, shiny!” as Homer Simpson would say. Maybe it’s supposed to double as shielding?
     

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