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Asher Guitars WD Music Products Amplified Parts Mod Kits DIY Nordstarnd Pickups Warmoth.com
Asher Guitars WD Music Products Amplified Parts Mod Kits DIY Nordstarnd Pickups Warmoth.com

5F1 Champ build

Discussion in 'Shock Brother's DIY Amps' started by clintj, Apr 25, 2016.

  1. clintj

    clintj Friend of Leo's

    Apr 4, 2015
    Idaho
    Got asked to build a 5F1 for a friend, so thought I'd share a few pics along the way. Got the hardware mounted in the chassis - yes, it's a pain due to tight quarters in there.No surprises there, really. Left most of it finger tight so I can adjust placement and help cheat some extra room for easing the board later.

    Got the board built today as well. 3/4 turn wrapped all resistor leads around the turrets for a good mechanical bond before soldering. Top loaded all capacitors for ease of later replacement during servicing when it comes due. Bottom loaded all the flying leads after measuring for length and adding 3/4" for lead dress adjustments. Inspected the solder joints with a magnifying glass, and tug tested them all. I ended up touching up some of the filter cap leads after the pic was taken. They had a good bond, but I wanted a bit more coverage in the turret holes.

    [​IMG]

    Tomorrow, I'll go back and re-verify the board against the layout and schematic. A fresh look usually reveals problems.
     
    danlad and King Fan like this.

  2. King Fan

    King Fan Friend of Leo's Ad Free Member

    Jan 1, 2013
    Salt Lake City
    Nice -- I like the little details in the telling -- and in the building!
     

  3. clintj

    clintj Friend of Leo's

    Apr 4, 2015
    Idaho
    Sure enough, I did miss something. The 220K that serves as the V1b grid leak. Soldered that in, re-verified the board, and set it aside. Working on heater and PT wiring now.
     

  4. clintj

    clintj Friend of Leo's

    Apr 4, 2015
    Idaho
    Chassis is ready to drop in the board. It's easier to route wiring for the heaters, rectifier, switch, etc with the board out of the way (at least in this amp, anyway.)

    Twisting the heater wiring up to the socket is a huge PITA, but those last little runs are closest to the socket wiring and most prone to causing hum. The preamp wiring is run directly across the socket per Merlin's advice. That puts the AC heater wire at 90 degrees to the plate elements and socket wiring, and should also help minimize heater hum.

    The two PT center taps are soldered into a ring terminal, as is the mains ground. The mains ground must have a dedicated attachment point for safety with nothing else sharing that point. The CT nut is just sitting finger tight so I don't lose it. The board power grounds need to attach there, too.

    [​IMG]

    [​IMG]

    [​IMG]
     

  5. clintj

    clintj Friend of Leo's

    Apr 4, 2015
    Idaho
    Board is in. That's a tight fit to say the least. I loosened the fuse holder and light to cheat a little extra room to slide it in, then tightened them back down. The Fender eyelet boards are a little easier because you don't have to line them up with the standoffs.

    I'll let it sit overnight again, then go over the circuit and verify everything visually, then run through with a multimeter looking for opens, shorts, inadvertent grounds and so on. Then it's off to the light bulb limiter for startup testing. A couple of spots could probably use a touch more lead adjustment, too. We'll see what I think when I pick it back up.

    [​IMG]

    [​IMG]
     

  6. mungus

    mungus Tele-Meister

    149
    Dec 17, 2014
    York
    Nice build.

    This thread needs some background music while we wait. Some good demo vids here which show off the sounds you can get with a variety of Fender Tweed circuits.
     

  7. King Fan

    King Fan Friend of Leo's Ad Free Member

    Jan 1, 2013
    Salt Lake City
    Wow, Clint,. I admire your work inside that sardine tin. Nice!!!
    Someone made/makes a Champ chassis with fold-down side walls. Me, I'm just so relieved I built a 5f2a..
    Looking forward to the rest!
     

  8. clintj

    clintj Friend of Leo's

    Apr 4, 2015
    Idaho
    Thanks. This is by far the tightest chassis to date. The tweed Deluxe, blackface Fenders, etc are so much roomier to work in.

    Minor delay. I have to go find a new bulb for my limiter as the old one must have gotten bumped by something. Dead as a door nail.
     

  9. clintj

    clintj Friend of Leo's

    Apr 4, 2015
    Idaho
    Stinkin' incandescent bulbs are becoming as rare as hen's teeth. Had to buy a 3-way bulb at a significant upcharge. :(

    Ran through startup testing like, well, a Champ. PT worked, B+ rail charged up nicely, tubes lit up, and glorious sound came forth when asked. Even got the OT polarity right the first time. :D

    Tried the Les Paul and got a great rock tone, kind of an AC/DC type crunch. The Tele quickly found the Joe Walsh Funk 49 vibe.

    There's a couple of special order parts in here. One was an 8ohm Weber Signature Alnico in 8 ohm, the other is a set of old stock Tube sockets, including a Sylvania 9 pin. They fit super tight around the tubes - no wobbles or weirdness. The speaker needs a few months of break in to open up, but it's a nice pairing already. I wired the OT for it instead of the normal 5 ohm tap, the thinking being that the client can use an 8 ohm external cab easily that way.
     

  10. robrob

    robrob Poster Extraordinaire Ad Free Member

    Dec 29, 2012
    United States
    Clint, did you adjust the value of the 22k negative feedback resistor for the 8 ohm tap? If not you're going to get 41% more feedback. A 33k would get you close to stock level NFB.
     

  11. clintj

    clintj Friend of Leo's

    Apr 4, 2015
    Idaho
    I didn't, but I do have a 33k in spares if needed. I was planning on taking my toolbox out with me when I deliver the amp so we can make final tweaks to taste. He wanted this mostly for quieter playing (his main amp is a JTM45) and recording, so he may well prefer the higher feedback level for the lower noise floor and lessened output.
     

  12. andyfromdenver

    andyfromdenver Friend of Leo's

    Dec 21, 2011
    grandpa's

  13. clintj

    clintj Friend of Leo's

    Apr 4, 2015
    Idaho
    Thank you!

    We're leaving the feedback as it is now. I explained all the pros and cons of the higher feedback level, and he elected to stay with how it is now. I'll bag a 33k with the documentation and spare fuses, and leave him with the option. He knows his way around inside an amp (long time ham radio operator with a couple of tube amp builds under his belt), but prefers to have me build for him. Delivery date is set for the 11th.
     
    andyfromdenver likes this.

  14. boredguy6060

    boredguy6060 Friend of Leo's

    Mar 28, 2012
    Sou Cal
    Very thoughtful indeed, just last nite I decided to get an ext cab for a 5F1 I have.
    There is no such thing as a 4 ohm ext cab, if so I couldn't find it. 8 ohm is by far the more common.
    So I figured to just open it up and connect the 8 ohm tap instead of trying to find a 4 ohm cab.
    I should put it on a switch.
     

  15. clintj

    clintj Friend of Leo's

    Apr 4, 2015
    Idaho
    Had my week get rearranged suddenly, so I delivered the amp on Wednesday. The new owner is thrilled, to say the least. He's never owned any of the true tweed circuits - closest was a BYOC Tweed Royale. He played his Strat into it for a couple of hours and was surprised at the 3D quality of the sound, almost like there was a chorus pedal or some reverb built into that tiny amp. I've noticed the same shimmery quality in my 5E3 when playing, especially clean with a Tele.

    I was planning on a Bassman being next on the build list, but the little Champ is very tempting to add to my collection now.
     

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