A Wondrous Adventure: SLO Clone Build (Now with Clips)

Discussion in 'Amps and Cabs' started by FourT6and2, Jun 5, 2014.

  1. FourT6and2

    FourT6and2 Supporting Member

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    Made some progress today. Preamp board is mostly finished. I just have a few small bugs to work out like the wrong wattage on two resistors in the power section and still need to install some jumpers. Also missing a ceramic disk cap.

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    Test fitting the boards in the chassis:

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  2. FourT6and2

    FourT6and2 Supporting Member

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    Installed most of the rest of the chassis stuff (except for the pots, still have to cut the shafts to length):

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    One issue I've run into is this corner of the PCB board. The stand-off mounting hole in the corner of the board is too close to one of the F&T caps. So I can't get the nut on. I'm trying to figure out a way around this. There is another hole in the PCB to mount the cap a little farther away from the stand-off mount. But that would require me unsoldering the cap, cleaning up the solder/flux, rebending the cap leads and re-soldering.

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  3. Mattbedrock

    Mattbedrock Silver Supporting Member

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    That's really great looking work. I've never built a amp with PCB's, but this has got me thinking.

    Maybe a spring circlip for that tight fit mounting bolt?
     
  4. bbaug14

    bbaug14 Supporting Member

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    How did you source all the parts/materials and documentation to do this project? I assume it's not all just a kit and you pieced it together with help from the SLO CLONE guys. Anyway, very curious. I've wanted to do one of these, but I'm not at a point yet where I have the time (too many projects, too many kids). When I am ready, I'd love to pick your brain for some help! You're doing a fantastic job!
     
  5. FourT6and2

    FourT6and2 Supporting Member

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    A spring c-clip? That could work. You have a photo or something so I can see what you're talking about?

    Some of the parts I sourced. Most of them I just got at C3 since he stocks pretty much everything. Just gotta tell him what you want. In retrospect I wish I had gone with better caps like the Vishay MKT, which are rebranded versions of the ones used in the original SLOs. Hopefully the Sprague 716s sound good enough though.

    Only documents available are schematics, which can be found on the SLO Clone Forum.
     
  6. FourT6and2

    FourT6and2 Supporting Member

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    Removed the powder coat around the switches and pots for chassis-ground. Was a lot harder than I thought. Wound up using a Dremel. White powder EVERYWHERE. Should have worn a mask :)

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  7. FourT6and2

    FourT6and2 Supporting Member

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    Ok, on to the preamp heaters. Usually wiring up heaters is my least favorite part of building an amp. It's a pain in the ass. The normal way, I'll just throw some wire into the chuck of a drill and twist away. Then cut lengths as needed and bend and wire and weave it all together. Easier than doing it by hand, but still torture.

    I was actually looking forward to doing the heaters on this build, though. Just some straight wire and you're done! Love it :)

    If you've ever wondered how to get straight bus wire, this is how I decided to do it. I used an armorer's block that I use to strip down my 1911 and drilled an 18-20 AWG hole thru it. Then I put one end of the wire in a drill and "extrude" it through the block while the drill rotates. I move the block back and forth slowly and carefully until the wire is as straight as I can get it and/or until I get super bored. Then I'll roll the wire under a wine bottle on a flat counter a bit for good measure. Seems to do the trick. Just takes a while.

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  8. FourT6and2

    FourT6and2 Supporting Member

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    Ugh! Broke a pin on a power tube socket. They aren't as flexible as the ones on the preamp sockets. The metal is much more brittle. I am going to get some different sockets that use similar solder lugs as the ones on the preamp. Probably these: http://angela.com/8pinceramicbottommounttubesockets.aspx Hopefully they stand up to bending better.
     
  9. Jason_77

    Jason_77 Member

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    Woah! I've never seen heaters done like that before (I've also never seen the inside of a SLO before either). That's wild! There's no issue with noise like that?
     
  10. zzmoore

    zzmoore Member

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    I am more naive than you.
    With a "Thru-Hole" PCB is there a metallic sleeve that connects top and bottom...or are there traces on both sides of the PCB...solder pads on both sides and traces on just one side...what exactly is implied by Thru-Hole construction.?
    Thank You
     
  11. grizdeluxe

    grizdeluxe Member

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    Your solder skillz are amazing. Very nice work. Looking forward to seeing/hearing the finished product.
     
  12. FourT6and2

    FourT6and2 Supporting Member

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    Shouldn't be any more or less noise than twisted-pair wiring. The whole point is to keep the conductors in perfect parallel either way. Twisting does this and so does running the heaters in parallel like in the SLO. It's sure as hell a lot easier!

    All of the above. Depends on the design. A thru-hole is just a hole. A "plated" thru-hole is a hole that is plated all the way thru it. If the PCB is double-sided (has traces on both sides), then it is a "double-sided, plated thru-hole." Usually plated thru-holes have solder pads on top and bottom. This is my understanding of the matter. Maybe there are exceptions here or there.

    Thanks! Soldering isn't that hard. Just gotta practice a bit.
     
  13. Jason_77

    Jason_77 Member

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    With through-hole, there is a solder pad on both sides of the hole and the inside of the hole is also plated, essentially making it one piece. This is great if you have to de-solder because it decreases the chance of the solder pad lifting off.
     
  14. zzmoore

    zzmoore Member

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    FourT6.....Jason -
    Thank You Both.
    I guess I DID know what it is.....:)
    Thanks Again
     
  15. FourT6and2

    FourT6and2 Supporting Member

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    Sort of at an impasse for the time being. Can't do much else until I cut the pot shafts and replace the power tube sockets. But I got most of the switch stack done (at least all I can for the moment).

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  16. eddy999

    eddy999 Member

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    I love the SLO style heater bus, works really well, I've never had an issue with it. A badly routed twisted pair can be worse, especially when looped around the socket.

    I just stretch the wire between two sets of pliars - I find that straightens them really well, and very quick too.

    In addition to my SLO clone also used this type of heater wiring on these builds (both very quiet)

    Mini SLO style preamp
    3w EF86 amp
     
  17. eddy999

    eddy999 Member

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    Switch wiring looking good. The SLO tone comes from those 90 angles didn't you know? :)
     
  18. FourT6and2

    FourT6and2 Supporting Member

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    Been busy with work and life and such lately. But managed to make a little more progress: Pot shafts are cut to correct size now, started on wiring 'em up. And got new power tube sockets.

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  19. Mattbedrock

    Mattbedrock Silver Supporting Member

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    Nice work. Keep it coming!
     
  20. FourT6and2

    FourT6and2 Supporting Member

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    More progress today. Just the two shielded coax cables going from the gain pots to V1 and V2. They took a while to do because of how perfect you have to strip them, get the lengths correct, and splice in a resistor on V2. But having the coax stripper really helps. I had to adjust the blade depth a few times to get it right. Out of the box it was cutting through the shield. Here's what it looks like all stripped and tinned. Nice and perfect! :D You know it's tinned well when you can still see the braid. Too much solder and each wire in the braid would be covered.

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    I had a heart attack when I went to check continuity on the coax. I was getting a short between the shield and the conductor. And I was like ****! I'm gonna have to redo this all again! But then I realized the gain pots were on zero, thus shunting to ground. I was super relieved. :)

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