first build 5e3 - question on tubes and parts

Discussion in 'Shock Brother's DIY Amps' started by agent_zed, Aug 22, 2019.

  1. Wyatt

    Wyatt Tele-Afflicted

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    The pink wire is from a different supplier. Valvestorm offers it as a period-correct cosmetic option because late '60s Marshalls used pink wire to the pots.

    [​IMG]
     
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  2. Diverted

    Diverted Tele-Meister

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    Doug Hoffman's cloth solid core pushback wire is THE BEST. Easiest and most attractive wire to work with by far.I love it and don't use anything else.
     
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  3. King Fan

    King Fan Friend of Leo's Ad Free Member

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    That Marshall is sick and wrong, and not in a good way.

    I may have said so, but for Fender style builds Doug's wire is superb.

    Thanks, Paul, for the TT link. Here's their vintage wire...

    [​IMG]


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  4. King Fan

    King Fan Friend of Leo's Ad Free Member

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    And as suspected, Doug's wire almost certainly is Mojo's; they’re NC neighbors, after all.

    I wonder what the solid core is here. Tinned copper? I've had solid core utility wire in the past that broke after minimal shaping, but this stuff is extremely robust.

    [​IMG]


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  5. Paul-T

    Paul-T Tele-Meister

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  6. King Fan

    King Fan Friend of Leo's Ad Free Member

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    I hadn't seen that -- good eye. It sure looks a lot the same, and I know TT does bring over a good bit of Mojotone.

    Now we need someone to buy a foot of each type discussed here and see how they bend, hold shape, and stand up to reshaping.

    But (chuckle) did you ever notice how useful research and comparison discussions like this get stuck at the end of unrelated threads where the info isn't likely to get many eyeballs? By contrast, you find lots of top-level threads where people ask "What's best?" and almost all respondents just say "I do it this way" or "that way is best" without evidence, research, or comparison... well, it is only the internet after all. :)
     
    Last edited: Aug 28, 2019
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  7. Paul-T

    Paul-T Tele-Meister

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    It is indeed super-hard to find and then catalogue all these disparate bits of info. Would perhaps be easier if one could re-name threads but unfortunately that doesn't seem possible.

    I always think of the terrific re-vibe build thread that has the weirdest name. Still, at least the "chassis" thread does what it says on the title!
     
  8. D'tar

    D'tar Friend of Leo's

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    I have a feeling @King Fan may have a few TB's worth of files saved on a hard drive somewhere!
     
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  9. Wyatt

    Wyatt Tele-Afflicted

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    Just avoid the "cloth" wire with the PVC wire inner insulation, it's crap. the cotton is not coated and will continue to fray and unwind after cut.

    I don't think it's been mentioned, so I say it for the anyone who hasn't worked with it. It's called pushback wire because you DO NOT strip it...instead you cut it and push the insulation back to reveal the wire.
     
    Last edited: Aug 28, 2019
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  10. King Fan

    King Fan Friend of Leo's Ad Free Member

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    Heck no, that would require organization and effort.

    Seriously, I’m just lazy—and know only a very few resources: Google “valve wizard” or “geofex” plus some search word. Go to Rob's site. Go to el34world. Search TDPRI (the computer version) for “Princeton” posts by Muchxs, or “1028” posts by Wally... or “5e3” threads by @D'tar.

    That, and “image” searches and screen capture take just a few seconds...


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  11. agent_zed

    agent_zed TDPRI Member

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    Thanks all, still reading through all the above and taking it in so apologies if i haven't addressed something mentioned above. I was planning on using the cpc wire https://cpc.farnell.com/concordia-t...-10m/equipment-wire-16-0-20mm-blue/dp/CB19941 which is tinned copper so hopefully that will be ok.

    I've seen some lovely looking builds on google images so i planned to try and get as neat as they have with twisted wires etc nicely shaped and the correct length. I'm not sure how to hold the wires in place though so wondered if a dob or 2 of hot glue would be ok, just enough to hold it down.

    Sadly not near Lincoln, I'm down Bristol way, but thanks for the tip.

    Ah yes oh course power transformers for 240v is rather important or it isn't going to work. I'm not 100% sure what i need as the list only says 1 power transformer and 1 output transformer (probably to stop people using their list of parts for their own build ;) ). From my reading so far it a 330-0-330v (the originals seem to be higher voltages but it seems to suggest this is more suited) push pull transformer is what i need along with an 8ohm 20w output transformer. Is this correct? Is there anything else i need to look out for?

    thanks for all your responses, it's much appreciated.
     
  12. agent_zed

    agent_zed TDPRI Member

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    So i found a IEC socket with a built in fuse holder (https://cpc.farnell.com/multicomp/jr-101-1f/conn-inlet-iec-fused-6-3a-panel/dp/CN18631) which seems like a good idea to me as less wires in the chassis, less soldering, less chance of being able to accidentally bypass the fuse etc.

    So i then looked at the stewmac plans (https://www.stewmac.com/freeinfo/i-10730/10731.doc.0718.pdf on page 10) and i am a bit confused. They have a black and white wire. I am assuming white is live (or hot i think in the US) and black is neutral. In the picture this would mean that live is going through the switch then through the transformer and then the fuse.

    If i use the fused IEC socket then it would be fuse -> switch -> transformer. Is there any reason not to do this. To me this seems better as everything is behind the fuse and no part of the circuit is unprotected.

    It almost seems to me that they are doing it the way they are as the fuse holder is being used to join the transformer wire back to the neutral wire.

    any thoughts?
     
  13. Paul-T

    Paul-T Tele-Meister

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    I would suggest the Modulus layout for mains switching and fuse, it uses a DPDT and switches both live and neutral, with fuse and switch acting on the power as it comes in. Which I think is current Euro spec, and significantly safer.

    I think it's been commented here before that Stewmac configurations use older, less safe practices for mains switching etc. (edit - after a quick look, I see hot goes via fuse to transformer, neutral goes via switch to transformer, it's confusing because the transformer pictured has two black cables for mains in... so would work fine but not as safe as Euro spec, and I feel it's better to switch the hot than the neutral wire). I'm certain the Modulus method is better.
     

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    Last edited: Aug 30, 2019
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  14. Bill Moore

    Bill Moore Tele-Afflicted Silver Supporter

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    In the US, white is neutral, black is the hot/live wire.
     
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  15. King Fan

    King Fan Friend of Leo's Ad Free Member

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    ^^^ what he said. The problem with 'complete instructions' is that even one little ambiguity, much less any out-of-date drawings or practices, can lead you astray. The other approach, figuring out each detail as you go, is also prone to error, but at least teaches you principles and reasons.

    If you look through recent build threads here you'll find several where a) your EU / UK brothers worked out the power wiring and PT issues b) the Modulus plans and Rob's plans were hybridized to produce optimal modern builds c) some issues with the StewMac plans were discussed.

    You're doing a good job planning. Keep asking questions, compare Modulus, StewMac, and Rob, and where you see any uncertainty, ask. Tons of little things can alter any single plan. For just one example, some PTs don't have a 6.3V center tap, and will benefit by 100R artificial CT resistors, which can be added to the heater wiring in a few different ways.

    At the risk of adding too many trees to your forest, I've been meaning to draw EU switching onto Rob's superb DIYLC 5E3; while I was at it I deleted standby (see Valve Wizard on the topic). Just if it would help:

    Rob 5e3 EU trial.png
     
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  16. Paul-T

    Paul-T Tele-Meister

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    thanks for the update King Fan.

    From what I know, and I knew about electronics at one time, switching neutral is extremely bad practice - the neutral line is essentially earthed back at the local step-down transformer, so if you're only switching that off, you still have 240V potential in a metal chassis. Weird...
     
  17. King Fan

    King Fan Friend of Leo's Ad Free Member

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    I agree, switching the neutral is not good practice, though not having an EE background I didn't understand exactly why for a long time -- I got some help in this thread. The safety differences, as the pros note there, aren't massive, but it's still not a good idea. In any case switching both limbs avoids all the likely and unlikely risks -- even if you switch the hot only, some unlikely rat-chewed, dropped-amp, broken-fuse scenarios, or a wrongly-wired socket (all too common here) can get you hurt.

    Speaking of US problems, switching the neutral with a separate safety ground is still better than leaving an old 2-prong US plug, something I've seen more than a few folks advocate over the years. Of course having 240v, and those massive 3-prong plugs, and IEC, makes all that moot in the UK. Wrongness comes in all degrees.

    I do know various small-shop small-amp (eg, 5e3) layouts have been ambiguous or just plain wrong about this. Luckily, you in the UK/EU only have to do it the 'right' way to be doing it the best way. We Yanks are catching up, though. I've noted more experts here starting to switch both hot and neutral.
     
  18. agent_zed

    agent_zed TDPRI Member

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    cool thanks all. Seems like my thinking was correct then. I don't want to deviate too far from the plans but something like this just seemed wrong when i looked at it. I really do wonder if they just did it as the fuse holder was a convenient way to join the neutral back in to the flex!

    The attached pics look a lot better way of doing it so i'll be doing it that way. Although should be even simpler with the IEC socket with built in fuse.

    I like to follow the ancient chinese saying 'to ask is a moments shame, not to ask and remain ignorant is a life of shame!' ... 'and might get you electrocuted' (I don't think the end bit is normally on there :) )

    I'm waiting on parts now so it'll be a while before they arrive so i will have a look through more threads etc and try and improve my understandin of what is doing what and why. Also got to finish spraying the guitar neck i've made so i can finally put the guitar i'm building together :)

    I've still got to buy transformers so that could be a bit of a challenge to make sure i get 240v ones and if they are wired in differently etc. I've seen a few so far that use different wires for 110v and 240v etc.

    thanks all
     
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  19. Paul-T

    Paul-T Tele-Meister

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    Good luck with transformers. I'll be keeping an eye on what you source. I used Mouser for my 5F3a transformer, a 290CAX, but they advertise without VAT then add it once everything's in the basket. Tube-town would have been cheaper. I don't know if Digikey do the same as Mouser.
     
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