Fender Super Tweed Build

Discussion in 'The Squawk Box' started by Cjsinla, Sep 23, 2017.

  1. Cjsinla

    Cjsinla Premium Member

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    Everything arrived from Weber today.
    IMG_1438.JPG IMG_1436.JPG IMG_1435.JPG

    I'm already lost. Should I mount the choke in the middle or on the end?

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  2. eslover

    eslover Senior Member

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    I'm paying attention to this, I want to build a tweed super but saving up the money is slow-going. I'm no expert on tweed era stuff, but I can see that's the "big" choke, filters entire power supply, and I've seen original tweed supers with them mounted on the end (with OT in the middle) and with it mounted in the middle.
    I think from a topology point of view, mounting it in the middle to me makes more sense keeps it close to filter caps. Just my opinion. Nice kit! Good luck, please keep us posted on developments....very exciting!!

    Fred
     
  3. Leña_Costoso

    Leña_Costoso Senior Member

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    nice..... now go get some Zinnser amber shellac, and two rattle cans of lacquer at Home Depot and get the cabinet finished before you get it all grimy from assembly.

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    I did this one sort of lightly.

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    This one got a more pronounced finish.

    BTW.... the Bassman is a 5F4, modified, using essentially the same transformers you have. It measures about 9.25v when I put 1k signal into it with perhaps... 2%-5% distortion (flat top wave). Do the math, and that is just short of 45 watts. The transformers, rectifier, and tubes will give you that (and a little more if you really push it). If you drive the split load phase inverter a little harder than stock, you'll get the wattage. Watch the bias over the "stock" 5F4 too. Only saying this because the Super is called a "20-30" watt amp, and... the measurements and math say way more.
     
  4. Splattle101

    Splattle101 V.I.P. Member

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    Nice Mercury OT. Is the power transformer Mercury too, or is it a Weber?

    Fender seem to have put the OT next to the PT on the vintage amps. That seems wrong to me and I didn't do it that way on mine. Cool amp. :thumb:
     
  5. Cjsinla

    Cjsinla Premium Member

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    Weber PT and choke. Having another problem. There is supposed to be 3 450v 16uf caps but they sent me 5 of these:

    image.jpg

    Can I use these in place of the others? If so, what difference can I expect in performance. I may have to go to my local electronics parts place to get the right ones.

    Coming along nicely otherwise. I just have to sort out the resistors as they all came loose in a bag.

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  6. Leña_Costoso

    Leña_Costoso Senior Member

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    The traditional capacitor is the Vishay/Sprague ATOM series, and you can get those in 16mfd @500v, or if you want a little less sag and more oomph, 20mfd @ 500v (which will fit the space, just). Folks aren't supplying ATOM capacitors since they took a ginormous price hike, but in my little world of tinkering with electronics over the last 50 years, I can say that a larger capacitor generally will take heat better, and therefore last longer and stay on spec better when its used in a high heat application - like a guitar amplifier. That's just me, though.... maybe. I can remember changing filter caps on ASUS motherboards, from whatever the heck they were to Panasonic ones, which were bigger by far, and took the heat. The stock ones ended up lookin like jiffy-pop popcorn on top.

    FWIW, Mojo supplies pretty much the same caps, but with 475v rating. I prefer the 500v personally....
     
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  7. Splattle101

    Splattle101 V.I.P. Member

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    The 20 uF capacitors will be fine. You probably won't notice any appreciable difference in sound. The impact of bigger filter caps is less hum (smaller ripple voltage), and better bass handling. Too big and the bass will flub out, even bigger and they'll kill your rectifier on startup.

    But 20 uF will be fine. A lot of people think Leo Fender skimped on his filtering anyway.
     
  8. Leña_Costoso

    Leña_Costoso Senior Member

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    And also, FWIW, I try to get the underboard wiring done first, then the components. If you're good, you can use the leads from the caps as the underboard ground buss. Make sure you have an air gap between the cathode resistors and the cathode bypass caps. No sense cooking those caps on purpose.
     
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  9. Leña_Costoso

    Leña_Costoso Senior Member

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    Leo DID skimp and he was the A+#1 cheap bastid of a gent (aka NoCaster, hmmm?). Sometimes a happy mistake, the 16uf at 25 percent less filtration does contribute to the sag and softness of attack. I've played with that a whole bunch, and for me, my taste... the 20's are better. Folks talk about hum, but again, just me, I didn't notice any difference at all.
     
  10. Cjsinla

    Cjsinla Premium Member

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    20uf it is, then. These are a little on the small side. Is that an issue? And what's the deal with those yellow capacitors? Would I be better off buying some orange drops to put in there? By the way, you guys were right about the cost of those Sprague Atom capacitors. It they look to be about $12 apiece

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    IMG_0581.PNG
     
  11. Cjsinla

    Cjsinla Premium Member

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    You are right about the topology on real Fenders. The Weber chassis seems to be set up to put the choke in the middle. There probably needs to be another hole to route the wires from the OT closer to the power tubes to put the OT in the middle.
     
  12. Leña_Costoso

    Leña_Costoso Senior Member

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    The yellow capacitors are "Weber" brand, modeled after the Mallory 150

    Mallory 150's, real ones, are not bad caps. Who know what Weber is actually selling, but its the same color.

    I know, and spoke to, the Mallory folks years ago, and they were the makers of the repro ASTRON capacitors, and in fact, if you took the time to peel the ASTRON, you saw Mallory's name under it.

    Cannot say if those are Chinese, Korean, NewJoiseyean, whatever.

    My own take on things: If I'm spending my money to build an amp, I try to not cut corners to terribly badly. I don't have to have the very most expensive output transformer, I can't hear to difference in 'em and the middle of the road ones. I like good tubes but don't go gaga over vintage shmintage ones. If I can get good capacitors for a few bucks more, I do. I want my amps to be decent, if not great sounding, and they gotta be reliable as the ones that Leo made.
     
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  13. Splattle101

    Splattle101 V.I.P. Member

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    The yellow caps are just polypropylene film caps. They're the right kind, so they're fine. Orange drops are no better, & some would say inappropriate for a Fender.

    If you want to upgrade them, Dijons from Mojo or Mallory would be a better bet than ODs. If you want to go really top flight, you could try Zoso or Jupiter.
     
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  14. Cjsinla

    Cjsinla Premium Member

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    I like to get all the components in place before running the underboard wiring. That way I can check to make sure that everything is in the right place before anything is soldered.
     
  15. Splattle101

    Splattle101 V.I.P. Member

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    Agree.

    I figure that a few extra bucks for decent caps (as opposed to 'boutique' caps) is not just money well spent, it's also a relatively piddling amount of money I'll forget spending long before I finish my first gig with my awesome new amp.
     
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  16. Leña_Costoso

    Leña_Costoso Senior Member

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    Vanilla vs chocolate. I always seem to forget something underboard as things can get busy with the pass thru wiring. But I spent years doing component level diagnostic and repairs on thru hole boards with full size components, so components are still fairly second nature to me (haven't fixed boards in a decade or so).
     
  17. Cjsinla

    Cjsinla Premium Member

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    I just ordered some of the Mojo Dijons for the hell of it. I was ordering a tube rectifier anyway and had them throw the caps in. I also emailed Weber about them sending me the wrong filter caps. I actually like the sag so I'm thinking I might want the 16uf caps instead of the 20uf. I'll just wait to see what Weber does. Also, I got your message about twisting the wires for the secondary and the heaters.
     
  18. guidothepimmp

    guidothepimmp Senior Member

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    excellent, congrats and enjoy the build
     
  19. Cjsinla

    Cjsinla Premium Member

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    Thanks, this is my third build so far and I'm finding these projects to be very rewarding.
     
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  20. Cjsinla

    Cjsinla Premium Member

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    Coming along nicely. Had to use my multimeter and magnifying glass to sort out all the resistors and some of the ones paired with caps are too short. But, I'll make them work. I dropped one on the floor and could not find it. However, by coincidence, it does seem to be one that I don't need for some reason. I will continue to look for it just in case. Almost ready to start soldering the board.

    IMG_0583.JPG
     
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