Blackvibe 6v6 (First Build)

Discussion in 'Shock Brother's DIY Amps' started by Tele-Pastor, Jan 29, 2020.

  1. Tele-Pastor

    Tele-Pastor TDPRI Member

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    Hi all,

    I'm beginning my journey into amp building by starting with Rob Robinette's Blackvibe 6v6 head with an added Trainwreck-style PPIMV. I am currently putting together my own BoM, as being in the UK means there's a little narrower choice for some components and I just wanted everything to be in a neat spreadsheet with links to websites :). If there's anyone else in the UK trying to do a similar thing in the future, I can upload my spreadsheet when it's completed.

    This is to go with the guitar I just finished (photos attached if you're interested) and the pedalboard with mostly my own pedals hehe - I'm trying to have an entire rig of self-built gear!

    I have a few questions about components and about the BoM on RR's site (which by the way is incredible, massive thank you to Rob).

    1) It shows something called ELL2 of which there are 2 - what is that lol?
    2) It shows a 470Ω metal film resistor with no power rating (I can't find it on the layout either)
    3) I'm not sure what voltage rating of resistors to get - I'd imagine in some parts of the amp this is vital?

    Also a more general question about the build: will a PR chassis fit with the transformers for this build? I will use Hammond 1750H, 290BEX & 194A


    Thanks so much in advance!
    Felix Guitar 1.jpeg Guitar 2.jpeg Guitar 3.jpeg
     
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  2. sds1

    sds1 Tele-Afflicted

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    Possibly the board and transformer rectangles? Everything in that software (DIYLC) that you draw, it goes on the BOM. Even the stuff you don't need to buy. You can safely ignore.

    It's in that legend at the bottom of the layout. Again, everything in the drawing goes into the BOM.

    Anything touching DC should be rated 500V+. It matters less in the signal chain. My personal choice are the Xicon 294 series 1W/500V carbon film resistors. Then everything is 1W minimum, and you can pick up 2W (or 3W) metal film as indicated. If you select 1/2W resistors as your baseline, you will still need to select some 1W resistors as indicated. Simpler (and more robust) just to go all 1W... my 2 cents.
     
  3. John E

    John E Tele-Afflicted

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    I can't answer your questions but I love that guitar... love the SD mini-hums and I am thinking that guit is badazz!
     
  4. King Fan

    King Fan Friend of Leo's

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    Heh, @sds1 nailed it on the BOM -- I forgot that DIYLC wizards like Rob can have it build a BOM from a diagram. I always treat a BOM, human or computer-generated, as nominal and *minimal.* It's easy for humans to leave something out, and I'm not sure the DIYLC tool is as good as a human yet.

    Sounds like you're checking against the diagram, which is perfect, but don't get OCD on removing items; get OCD about adding 'em. For one thing these custom amps often have options or upgrades or mods that will add to the basic BOM. For another, better you should end up with extra bits than too few. Hmmm. Are Rob's 1.5K grid stoppers on the BOM?

    It may help others here to show Rob's layout (below).

    I don't usually think of resistors in terms of voltage ratings, though no doubt that's a thing. (Capacitors have voltage ratings, but Rob's diagram and note tell you what you need to know.) Rob essentially shows you on the layout the *wattage* rating of resistors where it matters, and tells you the rest should be 1/2W minimum (upsized 1W as sds1 uses are even quieter). Rob's gray resistors are likely metal oxide (flameproof, in the power amp -- you could use 3W if you can't easily find 2W) and his blue resistors are probably metal films -- for example, on the input chain, where their quiet nature is extra helpful.

    The 470R resistor on the PI cathode should be 1/2W or larger -- 1W is fine. The 470R grid stoppers should be 3w metal oxide (or other heatproof type). As a detail, I make the 1.5K grid stoppers on the power tubes at least 2-3W and heatproof (metal oxide etc.) as they sit over the hot tube sockets.

    Re transformers, you can always drill a single new hole to make the OT and reverb fit. For PT, taking the Mojotone chassis as the most common currently available (often copied by various small chassis shops) they note theirs fits a standard Champ/Princeton PT, which they say mounts 'on 2'' x 2-1/2'' centers.' If your PT does too, you should have a fit.

    EDITED to show 6V6 version...

    RR763_BLACKVIBE_6V6_Layout.png
     
    Last edited: Jan 29, 2020
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  5. sds1

    sds1 Tele-Afflicted

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    I don't either, but they do have voltage ratings ...

    Also I think I misspoke on the matter, I am now remembering the rating is with respect to the voltage drop across the resistor only. So what's the most we ever drop in a tube amp, somewhere around 200VDC?

    Anyhow, not much of a consideration.
     
  6. Uncle Daddy

    Uncle Daddy Tele-Afflicted

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    The Hammond website has all the dimensions for their transformers. The OT is probably less important as it's only a couple of holes, so one of them is bound to be right, and it's easy to drill another.

    The PT is different, and worth comparing with the dimensions for the Hammond version of the PR transformer. Also check against the chassis suppliers specs, as not all of them use the same size.
     
  7. backporchmusic

    backporchmusic Friend of Leo's

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    Cool guitar!
     
  8. Junior Little

    Junior Little Tele-Meister

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    Not to be too big of a stickler for details, but isn't the OP building a 6V6 version of this amp? The layout provided by @King Fan is the 6L6 version. Pretty sure the power tranny is smaller for the 6V6 version.
    Otherwise, carry on!!
     
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  9. King Fan

    King Fan Friend of Leo's

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    Nice catch. There's no such thing as too much of a stickler for details. :)

    I assume the OP has the right trannies for the 6V6 version, and my info about the 'standard' Mojo PT may still pertain, but I'm gonna go back and try to sub in the right diagram -- who knows what else changes.

    Thanks, @Junior Little !!!
     
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  10. Tele-Pastor

    Tele-Pastor TDPRI Member

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    Thanks for all your help everybody!

    I can confirm that the PR chassis I have my eye on ( https://modulusamplification.com/Blackface-princeton-reverb-chassis-P4314031.aspx ) will fit my PT ( https://www.don-audio.com/Hammond-325-0-3255V3A-63VCT3A-290BEX )

    Also thanks for making my component gathering that much easier - I've now swapped all 0.5W resistors for 1W. There is still a mix of carbon comp, carbon film, metal film and metal oxide resistors which I have studiously copied across from RR's layout - is that necessary?

    Also I have attached screenshots of my BoM as it stands now, could anyone possibly let me know if there are any glaring mistakes? I've cropped out the bottom (backup rectifier diodes and fuse). Screen Shot 2020-01-29 at 21.53.02.png Screen Shot 2020-01-29 at 21.53.19.png
     
  11. Tele-Pastor

    Tele-Pastor TDPRI Member

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    I also have a question regarding the bright cap and treble cap - these are given as 120pF 600null and 250pF 600null respectively. What does this 600null mean? What kind of caps can I spec for these parts?

    In fact, looking at this Hoffman list, I can see it can be 400-630V https://el34world.com/Hoffman/files/Hoffman_AB763_1_BOM.pdf

    I'm beginning to think I am taking RR's BoM too strictly? I guess that's a side-effect of my Idon'tknowwhatI'mdoing-itis.

    I am however adding hyperlinks to my spreadsheet for where I've found each component, which may be of some use to UK beginners out there. Once I've finalised it all (with help from you guys) I will post it somehow.
     
  12. sds1

    sds1 Tele-Afflicted

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    It's up to you, it's kind of a style thing. Part of Rob's style is he likes to use carbon comp resistors in select areas of the audio circuit, for maximum vintage sound. Not really sure why he used metal film on the input jack. You could condense all of that to carbon film if you wanted. The metal oxide resistors are what you want for the 2W/3W resistors in the power supply.

    It means Rob forgot to specify "volts" as the unit of measure. 600V

    Silver Mica caps are popular, the decent ones (Cornell Dubliner) are expensive though. Folks say the SM branded ones are unreliable. You can also use a film cap. You can avoid the ceramic discs, they are less ideal for audio circuits.
     
  13. Tele-Pastor

    Tele-Pastor TDPRI Member

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    Thank you sds1!
     
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  14. King Fan

    King Fan Friend of Leo's

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    I always like and trust what @sds1 says. But then I always agree with Rob, too. :)

    So here's my $.02 on the (non-critical) issue of resistor types. We had a big discussion of this recently, and there are thousands on amp forums. Carbon film is nice and quiet; carbon comp may have (evidence-based) attributes in certain places but they also have (well-known) noise and drift issues. Metal film can be even quieter (much quieter) than carbon film, and though CF is often considered 'quiet enough', I bet Rob (and many of us) like that extra quiet in the part of the amp that's gonna get amplified the most. BTW, your 1W resistors will hiss a good deal less (is it 3X? I forget) than 1/2W.

    For most resistors on the board, 1/2W or 1W CC, CF, or MF are all commonly used. So building to Rob's colors is great, but if it's simpler, or your style sense wants just CF and MF, or all MF, or all CF, you can do it. Are you a Wranglers guy or a Levi's guy? (I'm not sure that translates into British.)

    For the flameproof ones, metal oxide isn't just about quiet -- it's also about tough.
     
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  15. Tele-Pastor

    Tele-Pastor TDPRI Member

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    Thanks very much for this! Gonna place some orders and I'm sure I'll be back with more questions...

    And yes that does translate, it just translates to tights and ruffs rather than jeans :D
     
  16. robrob

    robrob Poster Extraordinaire Ad Free Member

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    It looks like the op's questions have been answered.

    As said above, resistor type isn't critical, I just show my preference.

    Everything you draw in DIYLC shows up on the BOM so you can ignore the "nonsense" parts.

    "null" means I didn't specify a value or type. I'll try to fix the layout and BOM.
     
  17. Tele-Pastor

    Tele-Pastor TDPRI Member

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    Hey Rob, thanks for the reply and above all thanks so much for your website! Been an odyssey working my way through it and you’ve really sparked my passion for this.

    I can’t seem to find carbon comp in anything above 1/2W - is that just their nature and hence why you speced them in your builds? They add a certain ‘vibe’ I assume?
     
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  18. jman72

    jman72 Tele-Afflicted

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    Definitely watching your progress- I've been meaning to build one of these for months, but haven't had the time. Good luck!
     
  19. robrob

    robrob Poster Extraordinaire Ad Free Member

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    You used to be able to find 1w carbon comps but I think the supply is drying up. I speced them because that's what the AB763 used but I'm not a stickler. On my "optimized" 5E3 layout I use CCs only for the phase inverter load and tail resistors for possible CC "mojo". I now like to use carbon film in place of them but like metal film for the input and V1 grid stopper resistors for minimal resistor hiss injection into the first gain stage.
     
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  20. Tele-Pastor

    Tele-Pastor TDPRI Member

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    Thanks Rob!

    Completed my first mouser order so ball is officially rolling

    I’m sure I’ll have some more questions soon but for the meantime thanks so much everyone!
     
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