Starting on the Stewmac '59 tweed 15w kit

Discussion in 'Shock Brother's DIY Amps' started by Boxla, Mar 25, 2020.

  1. Boxla

    Boxla Tele-Meister

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    My wife bought me the StewMac '59 Tweed 15 watt amp kit for my 45th birthday. It arrived yesterday.

    I'm a tad anxious to start it as all the electrical stuff and soldering is out of my element. But I'm also very excited to start it. I plan to read through the instructions a couple of times before I start.

    I'm sure I'll be back here for questions and reading other threads. Any helpful hints before I start would be welcomed.

    I'm starting to buy some of the extra things I need which I don't have. One item that Stewmac recommends is their snuffer stick. It's out of stock at the moment and I was curious if something like this from amazon is the same thing? Thanks all! https://www.amazon.com/dp/B082HR2WL3/?tag=tdpri-20
     
  2. D'tar

    D'tar Friend of Leo's

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    Just fyi... You can make probably 10 or more of those snuffers for the price of the components.

    https://www.ifixit.com/Guide/Constructing+a+Capacitor+Discharge+Tool/2177

    If you have a multimeter you can watch the voltage drop to a safe level before working. This of course is only needed after the amp is built and the caps are charged.

    For All things 5E3 and then some I recommend reading through as many builds here as well as Robs site

    https://robrobinette.com/Amp_Stuff.htm

    you can start practicing your soldering by making your own snuffer and a light bulb limiter which is highly recommended piece of safety equipment for new builds.

    https://robrobinette.com/5e3_Modifications.htm#Light_Bulb_Current_Limiter

    Best of luck

    Post lots of pictures and ask every question!
     
  3. OldPup

    OldPup Tele-Meister

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    I second making your own device to drain capacitors. You can use alligator clips and a resistor. Grab one leg of a resistor with a clip, then fasten the other end of the alligator clip to the amp chassis. Touch the unclipped resistor leg to the positive terminal leg of the capacitor to be drained for 10 seconds and that's it.

    However, the kit looks identical to the Mojotone 5E3 (awesome kit, btw!), whose filter caps are all wired to ground and discharge automatically. It is best to verify this with a multimeter after you fire it up for the first time, which you won't do until basically the end of the build.
     
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  4. Lowerleftcoast

    Lowerleftcoast Tele-Holic

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    If you are new to soldering, watch some tutorials on youtube. Practice.

    As mentioned above Rob Robinette has a site devoted to the 5E3. When in doubt use Rob's suggestions over info given with the kit. A good grounding scheme is important. Proper layout and use of shielded wire for the input helps to make a quiet amp. Rob mentions those and other recommendations. Follow his advice.

    Having good tools is very helpful - soldering iron, small wire cutters, wire strippers, small offset (bent) needle nose pliers, multi-meter.
    The shape of the soldering tip can help heat the joints better. (show some pictures of your soldering iron.)
    A heat sinc to keep the parts from overheating is important, especially for a soldering noob.

    The resistors and capacitors are delicate treat them as such. Use the needle nose pliers to support the lead at the body of the part when bending leads. It is easy to break resistors and damage capacitors which allows moisture to penetrate.

    If I was building the kit I would replace *some* of the carbon comp resistors. (Others here would replace them all.) Carbon comp is what was used back in the day. CC are known for hiss/noise. In the right places they may help with mojo so some of us use CC in those places. (Hence my suggestion to replace *some* of the resistors.)
    I would get 1 watt metal film resistors in the following values.
    3 - 1 meg
    4 - 68k
    4 - 1.5k
    1 - 820R
    2 - 200k
    You may want screen resistors for your 6v6 (probably not included with your kit.) These help the tubes and smooth harsh distortion a little. (There is a thread discussing this topic on TDPRI this week.) These should be 2 watt resistors. You would need 2 - 470R. (Metal oxide are ok here.)

    I applaud you for taking this challenge. The kind folks here will help. Have fun. (It will test your patience.):cool:
     
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  5. King Fan

    King Fan Friend of Leo's

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    Good for you. Don't be in a hurry to get going. Why? Planning, reading, research, review, and learning are all 100% safe, free, fun, and lifelong. The actual build will in fact go by very fast, and once it's done it's done. Phase 3, troubleshooting if it doesn't work, can be a huge giant pain.

    Do buy a small generic board (Doug Hoffman Amps has many) that's either eyelets or turrets, whatever yours is, and order up a few dollars worth of components (resistors) and practice soldering them.

    For sure you don't need most of the many spendy StewMac tools they suggest -- and the few specific tools you do need can be found either at a good hardware store or any decent amp shop online -- I like the tools like small pliers and wire cutters at TubeDepot, for example.

    Stewmac has pretty decent instructions but also a few ambiguities or non-standard steps. Here's a Google search you might try out: <<5e3 StewMac instructions site:TDPRI.com>>

    Rob's layout as noted above is more specific and modern than the StewMac version in a few important areas. But *don't* plan on doing any of his (varied and numerous) *circuit* mods until you've built the amp stock. His layout shows the modernization mods you want.
     
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  6. scooteraz

    scooteraz Friend of Leo's

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    One more thing. Don’t worry about your mistakes. You will make a few, and they will all be learning opportunities. Ask how I know....LOL
     
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  7. Lowerleftcoast

    Lowerleftcoast Tele-Holic

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    I don't think any amp kit or off the shelf chassis has a hole drilled for the ground wire of the power cable. It is easier to drill the hole when the chassis is bare.

    The power cord will probably be near the last piece you will install. The Stewmac kit instructions do not meet UL/IEE standards. Rely on the Rob Robinette 5e3 site for a safer way to install the power cord.

    KingFan just gave you great advice. Learn as much as you can. Ask questions.

    There are areas that are *understood* when working with the components. It is hard for a noob to glean information when it is just *understood* by people with more experience. It is important to know capacitors lifespan is shortened when they get hot. Several of the resistors in a circuit get hot. The layout may show a capacitor and a resistor touching each other (piggybacked). It is *understood* there is an airspace between these components so the caps do not get cooked.

    It is up to the builder to think about the heat created by the resistors (and other components). Heat rises. Is there a heat sensitive part above a hot resistor? Can the parts be adjusted so the heat sensitive part is not directly above the hot resistor? The 5e3 board is roomy enough to alleviate several potential heat related problems if the builder chooses.

    Likewise the hot resistors should not be touching the eyelet board they should have a little airspace between the resistor and the board. Cut the leads of the resistors long enough to create a little space.

    There is a thermal image of an amp at:
    https://robrobinette.com/5F6A_Modifications.htm
    The image helps to visualize where the hot components of an amp are located. This is very good information for a noob to understand.
     
    Last edited: Mar 26, 2020
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  8. aguynamedben

    aguynamedben TDPRI Member

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    Sweet, will be following along. I'm building Rob Robinette's Blackvibe into a 1x12 Princeton cabinet. Just ordered the transformers and choke. Doing a little extra work to get a custom chassis to fit it all.

    Rob Robinette's site recommends the guide for the exact kit you got, and I'm going to be following that guide for my build, just with a different schematic.

    Also go watch a bunch of Uncle Doug on YouTube! I collected some of the best videos at the top of this doc: http://bit.ly/blackvibe I'm a first-time builder too so if anybody has any feedback on my plan to build a 1x12 Princeton Blackvibe (tiny 40w amp!) happy to hear it via DMs or whatever!!!
     
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  9. Old Deaf Roadie

    Old Deaf Roadie Tele-Afflicted Silver Supporter

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    Don't be anxious about soldering. It is easy if you practice a bit. I would suggest learning to splice 1st, using pieces of wire. Then, maybe practice grounding on a pot using a piece of copper pipe to simulate a surface. You will eventually get to the point where it becomes 2nd nature to you.
     
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  10. Wally

    Wally Telefied Ad Free Member

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    Soldering to the chassis requires a heavier tipped iron with more power than one finds in the smaller iron we use for the circuit connections. The ‘net has many tutorials on soldering...I hear Uncle Doug’s tutorial is a good one.
     
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  11. King Fan

    King Fan Friend of Leo's

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    Wally's totally right about it being hard to solder to the chassis. Luckily, you should be OK without chassis soldering on the kit you got. As suggested by @Lowerleftcoast , I drill two holes in the empty chassis for #8 anchor bolts, one (power amp ground) in the empty stretch of floor between the lamp and the rectifier, the other (household safety ground) in the sidewall next to where the PT will sit.

    upload_2020-3-26_8-32-48.jpeg
     
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