Build thread - Robrob Deluxe Micro and 5F2A

Discussion in 'Shock Brother's DIY Amps' started by Drew617, Jul 26, 2021.

  1. Drew617

    Drew617 Tele-Holic Silver Supporter

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    Why not start another one.

    I'm going to build two little amps in 6x4x2" Hammond chassis, a 12AU7 Deluxe Micro and a 5F2A clone. Both diode rectified, and both using WRVBPT power. That transformer is too awesome at $25 not to use frivolously. I'll resuse Hammond iron as OTs: a 1760C and their Fender reverb transformer.

    I'm going to do these point-to-point, which I haven't attempted before, although I'm still going to build power supplies on a little board since I at least have to mount a rectifier somewhere.

    I suppose these are inspired a bit by the little Milkman 5F2A clones that came out a few years back. As in, "I bet I could do that for $100." I would've liked a square chassis - might have been able to stuff everything into 4x4", but I've used a number of these Hammond 1441s now and know how to work with them, so used what sizes they offered.

    Cut a few up the other night with my Ryobi hand drill and christmas tree bit:

    upload_2021-7-26_14-2-34.png

    Punched, deburred, and painted. I scuffed the power coat on both of these pretty badly, so decided to paint these. Have thought about doing that with others but declined so far, assuming adhesion will be an issue.

    The green is satin Rustoleum, which sticks to the powder coat much better, but is harder to spray well. My paint looks amateurish but will do fine here. The tan is Krylon which applies beautifully, but doesn't stick too well. I've already knocked some off and will have to touch it up.

    My iPhone has hyped these colors up. They're a lot closer to OD and desert tan in real light.

    upload_2021-7-26_14-5-43.png

    Assembling and populating the chassis. The handles are $1.50 cabinet pulls.

    upload_2021-7-26_14-9-26.png

    upload_2021-7-26_14-10-1.png

    Insides:

    upload_2021-7-26_14-23-17.png
     
  2. James Knox

    James Knox Tele-Afflicted Silver Supporter

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    Nice!

    I wanna build a 5C1 SJ7 Champ in one of those box’s. I’ll be following your build and learning....
     
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  3. wallybob

    wallybob TDPRI Member

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    Good luck - that will be10 lbs of stuff in 5 lb boxes!
     
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  4. Drew617

    Drew617 Tele-Holic Silver Supporter

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    Thanks! Shouldn't be too bad - these boxes aren't that much smaller than a real 5F1 chassis. Don't think I'd want to lay the whole circuit out on a board and try to fit that, however.

    Transformers fitted to chassis:

    upload_2021-7-26_19-24-9.png
     
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  5. maccullt

    maccullt TDPRI Member

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    They look awesome. I was thinking of using circular led power switches. Are yours illuminated? Do you have the part number?
     
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  6. Drew617

    Drew617 Tele-Holic Silver Supporter

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    Yes! I’ve been using integrated IEC-fuse-rocker switch assemblies in bigger amps, plus a big LED up front that gives the impression of a jewel lamp. Still saves a ton of space and messy wire routing.

    These are more compact still. Feel a little cheesy versus a Carling toggle but they’re rated 10A and haven’t melted on me yet:

    Red Light SPST 3-Pin ON/Off Round Boat Rocker Switch AC 6A 250V 10A 125V 5 Pcs https://www.amazon.com/dp/B07CCJF2YR/?tag=tdpri-20

    The front mounting flange isn’t very wide so you have to be real careful cutting holes for these (see the bit of epoxy covering a goof on my green chassis.) Regardless what the spec says, a 3/4” knockout punch is perfect. Nibble a little notch at 270 degrees to accommodate the channel that keeps the switch from rotating.

    After building a large handful of amps for myself, starting with some faithful Fender clones, I’m happy to cast away some anachronistic nonsense normally associated with those. 6.3V pilot lamps especially included.
     
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  7. Drew617

    Drew617 Tele-Holic Silver Supporter

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    Wired a couple little power supplies:

    upload_2021-7-28_18-51-34.png

    upload_2021-7-28_18-52-7.png
     
  8. James Knox

    James Knox Tele-Afflicted Silver Supporter

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    Cool! The “little black box” is a Diode Rectifier?

    Where does one find those?
     
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  9. Drew617

    Drew617 Tele-Holic Silver Supporter

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    Wiring the IEC inlets, fuse holders, and illuminated power switches.

    upload_2021-7-28_20-21-46.png

    upload_2021-7-28_20-22-30.png
     
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  10. Drew617

    Drew617 Tele-Holic Silver Supporter

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    Yes sir! Tubedepot and Mouser have them, at least. As far as I know it's just four diodes in epoxy inside a little plastic box. Could just as easily do the same thing with four diodes, and I've preferred to do that where there is space and just looks/feels better to me. Here though, there's a little bit less exposed lead, risk of shorting something, etc.
     
  11. James Knox

    James Knox Tele-Afflicted Silver Supporter

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    Hey @Drew617 are those Hammond box’s the 4X6X2 or the 5X7X2?
     
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  12. Drew617

    Drew617 Tele-Holic Silver Supporter

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    Hey James, these are 6-4-2. Was hoping to get these wired up today, now more likely over the weekend.
     
  13. Drew617

    Drew617 Tele-Holic Silver Supporter

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    Wiring pots and sockets on the 5F2A:

    upload_2021-8-1_15-38-11.png

    upload_2021-8-1_15-39-3.png

    upload_2021-8-1_15-39-27.png

    Power supply board installed:

    upload_2021-8-1_15-40-25.png

    upload_2021-8-1_15-41-24.png

    upload_2021-8-1_15-41-38.png

    upload_2021-8-1_15-41-58.png
     
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  14. James Knox

    James Knox Tele-Afflicted Silver Supporter

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    Nice job!

    I like the Patina look of the Trannies.

    Rattle can?
     
    Last edited: Aug 1, 2021
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  15. Drew617

    Drew617 Tele-Holic Silver Supporter

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    Woohoo... 5F2A is healthy right out of the gate. 379 B+ and dissipating about 15-16W. Successful first PTP build, or I suppose kind of a hybrid.

    upload_2021-8-1_17-40-46.png
     
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  16. Drew617

    Drew617 Tele-Holic Silver Supporter

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    Rust-oleum "hammered" black, although it's definitely a little silvery. Adhesion isn't great and it never feels like it's absolutely cured like real enamel does, but it's good stuff, hides all manner of sin. These Weber WRVBPT transformers are cheap as chips and super useful, but they're ugly.
     
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  17. James Knox

    James Knox Tele-Afflicted Silver Supporter

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    Can’t wait to see the next one!

    Did you raise the value on the first Filter Cap with the Diode Rectifier since you didn’t need to worry about the 5Y3? How high did you filter on the Power Rail?
     
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  18. Drew617

    Drew617 Tele-Holic Silver Supporter

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    Thanks - hoping to get the Deluxe Micro wired up within a few days, then finish my Nighthawk clone.

    Cap values are fairly stock, 22-10-10 here. My preferred compromise for an honest 5F1/2 combo is 33-22-10 but I have a Maggie build that’s essentially a huge 5F2 already, and am planning a Champ-ish KT66 somethingorother. Wanted to leave this one fairly true to the real thing.

    Later VCs used 40uf at the first node, so you don’t have to be guided strictly by the GE 5Y3 chart here.
     
  19. Drew617

    Drew617 Tele-Holic Silver Supporter

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    Here we go, a completed PTP (ish) @robrob Deluxe Micro. Didn't have opportunity to give this a shakedown tonight, but unless I've miswired something, we know how it will perform (stupid fun!) Time to dust off my Cortez the Killer.

    Wiring the tube sockets:

    upload_2021-8-5_0-7-55.png

    Power supply board installed:

    upload_2021-8-5_0-9-4.png

    Feets and bottom panel:

    upload_2021-8-5_0-9-39.png

    All done:

    upload_2021-8-5_0-10-4.png

    upload_2021-8-5_0-10-33.png
     
    Last edited: Aug 5, 2021
  20. James Knox

    James Knox Tele-Afflicted Silver Supporter

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    Beautiful Job!

    (I’m following in your footsteps...)
     
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