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6V6 2204...

Discussion in 'Shock Brother's DIY Amps' started by Che_Guitarra, Dec 5, 2017.

  1. FenderLover

    FenderLover Poster Extraordinaire

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    Cool project. But in practice, you have created several ground loops. It is similar to the old school method where the chassis is used as the ground conduit. If the design is not a high gainer, it'll probably still work fine.

    I've milled several hundred boards using a specialty machine designed for the purpose. You have overcome the cutting depth problems nicely with your equipment.

    There really is no added ground plane capacitance. There would need to be a second plane, not ground, that is a few mils away from the ground plane in order to have significant board capacitance. That means a multi-layer fabrication. That's a high frequency decoupling technique, and doesn't really apply to audio.

    Anything that makes a design clean and still work is game to me. Looking forward to the rest of your project.
     
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  2. Che_Guitarra

    Che_Guitarra Tele-Holic

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    Holes drilled, turrets in, board loaded... apart from a couple of components that are TBC.

    Was going for a Marshall Astoria vibe to the PCB... didn't quite nail that brief but still very pretty, neat, organised, and solid. And best of all, mostly DIY.

    [​IMG]
     
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  3. Tom Kamphuys

    Tom Kamphuys Tele-Holic

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    Very neat!

    I think I see some very good solder joints. I've had trouble with the wetting, especially on top of the turret. What the trick?
     
  4. Che_Guitarra

    Che_Guitarra Tele-Holic

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    This idea has bugged me today. I've not paid a single dot of attention to the ground loops. Tried to do as much reading on the matter as I could, but slim pickings of information at circuit stage. It's not a high gain amp by modern standards, but definitely by 1970s standards.

    I wonder if I could work around this by using composite standoffs on all but one of the legs?
     
    Last edited: Jul 8, 2020
  5. Che_Guitarra

    Che_Guitarra Tele-Holic

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    Haha thanks :) I'm not sure. I'm no expert, but I guess I have made quite a bit of stuff over the years, so maybe that experience is finally working in my favour.
     
    Last edited: Jul 8, 2020
  6. Tom Kamphuys

    Tom Kamphuys Tele-Holic

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    So your telling me to practice...
    Yeah right, as if my next expensive guitar isn't gonna make me a guitar god!
     
  7. egotrip

    egotrip TDPRI Member

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    solid state rectification gives less sag and is supposedly more reliable . i've had my home made amp rebiased a few times . i'd like a Vox 4 watt point to point amp next . amp pictured is very clean and Dirty when cranked . 22 watt Deluxe reverb design point to point without Reverb channel . chromed copper chassis . in Ash cabinet DSC01950.JPG
     
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  8. elpico

    elpico Tele-Afflicted

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    The "tricks" are basically:

    1. getting both sides of the joint heated evenly, in a short time, on the first attempt.
    2. owning flux

    To pull off trick #1 you need to always be thinking about the mass and heat sinking ability of both sides of the joint. A little component lead is going to heat up way more easily than a big chunky turret. To raise the temperature of such different things evenly you need to bias your heating heavily to the turret. A chisel bit with the flat on the turret and the thin edge a hair away from touching the component lead is a good starting position. With your other hand hold the solder on the turret to watch it's temperature. When the turret begins to melt the solder nudge your bit over so you have good contact with both the turret and lead as you quickly fill the hole and complete the joint. Don't linger longer than needed, remove and reapply heat, or try to touch it up. It should be done in one smooth flow.

    And when that doesn't work... let the joint cool then apply flux to the joint and simply try again to raise the temp of both parts evenly, flow the solder in one go, then get the heat off. If you find the turrets you're working with resist wetting every time then you may want to apply flux before the first attempt even.
     
    Last edited: Jul 8, 2020
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  9. Che_Guitarra

    Che_Guitarra Tele-Holic

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    And now for the chassis build. 500mm x 500mm x 1.8mm steel plate. Trafo on top for an idea of the size.

    Never made an amp chassis before, although I have a pretty solid workshop and fabrication background.

    That said, I think i'll be looking at this plate for the next week, wondering "what the F have I got myself into", and "how on earth am I going to tackle this" :)o_O:lol:


    [​IMG]
     
    Last edited: Jul 9, 2020
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  10. awasson

    awasson Poster Extraordinaire Silver Supporter

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    I’m following along with interest. I wish I had a sheet metal brake. I switched from electronics and fabrication to programming and software development 20 years ago and I really miss having a shop at my disposal.
     
  11. Che_Guitarra

    Che_Guitarra Tele-Holic

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    Slow progress. But progress nonetheless.

    The pile of parts is now turning into... a thing.


    [​IMG]

    [​IMG]
     
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  12. Che_Guitarra

    Che_Guitarra Tele-Holic

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    I'm beginning to think this build might be cursed.

    After six weeks, I got my chassis back on Friday! I couldn't work out how to fold the chassis with my own set of tools so I called a former colleague who has his own sheet metal brake. Unfortunately he got stuck interstate due to covid travel restrictions, so hurry up and wait has been my motto.

    But he did a top job. No complaints with the results:
    (sorry about the crappy camera work - photography is not my strong suit!)

    [​IMG]



    And with one (ONE!!!) hole to go, my beloved step drill bit tip broke off!

    [​IMG]



    So here's the final hole being drilled out:

    [​IMG]
     
  13. Che_Guitarra

    Che_Guitarra Tele-Holic

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    And after an evening of loading the chassis up, this is the current state of affairs:

    [​IMG]

    [​IMG]


    So much space! In the past i've always tried modding and stuffing as much as possible into wee little tweed chassis - this feels like a city block in comparison.

    Now stuck waiting again... the power trafo needs 5/8 UNC nuts to fix to the chassis... i'm pretty sure there's more Polar Bears in Australia than there are 5/8 UNC nuts. Ebay to the rescue.
     
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  14. Che_Guitarra

    Che_Guitarra Tele-Holic

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    My gosh... building an amp in Australia during covid is proving painfully slow.

    After almost a month of waiting, my power trafo nuts arrived. Can start to make progress again.

    Slowly chipping away. Power section almost done. Hitting the pause button for a while and do some research - my power trafo (Classictone 40-18017) has two centre taps, need to research wire orientation, if it matters at all.


    [​IMG]
     
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  15. elpico

    elpico Tele-Afflicted

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    red with yellow stripe is the center tap. That goes to the negative end of the first filter cap. (ideally it's dressed with the reds)

    red with blue stripe is a bias supply. If you're doing a fixed bias output stage you'll use this, if cathode biased you can heat shrink it off and bundle it away.

    edit: oops not a champ thread. originally added some irrelevant champ info
     
    Last edited: Oct 18, 2020
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  16. Che_Guitarra

    Che_Guitarra Tele-Holic

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    Thanks Elpico.

    Now my next query. Input jacks. I've never used Marshall style input jacks before, and i'm a little tired/fried from overanalysing my circuit, so I have a question to confirm.

    Can I translate this input section to use Fender/Switchcraft style switching jacks (to maintain an all-metal front panel asthetic).

    [​IMG]

    Or will I be required to use the Marshall style plastic switching jacks?
     
  17. Tom Kamphuys

    Tom Kamphuys Tele-Holic

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    It's hard to get a good image, but here is mine:

    IMG_20201020_160151940.jpg
     
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