Slagle autoformers volume control

Discussion in 'All Things Analog' started by gable, Nov 27, 2018.

  1. My lovely wife bought me a pair of Dave Slagle autoformers for our anniversary last week. I've been wanting to try avc's for some time now, so I decided to build a box, add a selector switch and take a stab at soldering a bunch of tiny wires.

    These are clearly well made units, clearly designed and made by someone who loves what they do, thank you for that Mr. Slagle.

    The box face is a chunk of south Texas Mesquite, some off cuts from a few slabs that I scored last summer. The sides are ~12mm UHMW, in white. The rear is ~6mm black Delrin. The 'finish' for the sides and rear is accomplished by simply sanding the surfaces with a random orbital sander with 220, 320, and 400 grit sandpaper. I didn't want to try to polish those surfaces, as I think that would be a ton of work, and I tire of all shiny.

    I'll add some current progress pics after my first round of soldering.

    The wire is all Jupiter copper wire in cotton, 26g, and 23g for the wiring to the input/output rca connectors.

    The selector switch is a nice little Grayhill unit, the volume control switch is a NOS German RFT switch. It was a 4 deck switch, but I just yanked the two extra decks off. I have a handful of these RFT switches and they are awesome, very sturdy and easy to use.

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    I'll post more pics as I progress.

    Negatron, opa1, rogerfederer and 4 others like this.
  2. Redboy

    Redboy Knobophobe

    Ooh, that’s nice! You’re in for a treat, once it’s all wired up. :)
  3. TubeHiFiNut

    TubeHiFiNut Administrator Staff Member

    Very nice.

    I see great sound in your future. :)
  4. Thermionics

    Thermionics Post Whore In Training

  5. rogerfederer

    rogerfederer Junior Member

    love that wood
  6. Thanks everyone!

    I got a bit more wiring done before I had to wrap it up for the evening. Hopefully I can wrap it up in the next few days.

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  7. Redboy

    Redboy Knobophobe

    Neat! It's fun to see other people's approaches to these projects; I wouldn't have thought to use those materials in an enclosure, but they look really good!

    Those RCA jacks are familiar but I don't recall who makes them. I have a few pairs of them around here, somewhere...

    And that Jupiter wire... man, I hate "stripping" that stuff! :)
  8. Wntrmute2

    Wntrmute2 Junior Member

    Looks nice. Not that I really understand what is going on here.
  9. Thanks! I like the Delrin and uhmw and have used hdpe as well. They are all easy to machine with woodworking tools, which is very handy for me.

    I’m going to try to flatten the uhmw with my planner and flattening sled, as I don’t have a jointer...... yet.

    It is a bit fiddly to strip hah.

    Redboy likes this.
  10. inthewoods

    inthewoods AARP Member

  11. You will enjoy the fruits of your labor! I have been using a Slagle copper AVC for nearly a year, and I like it very much. When it’s up and running, you will need to run signal through it for a week or so to get everything settled in. People told me it would take hundreds of hours but I can’t honestly say I noticed any changes after a week of use.
    JohnVF likes this.
  12. Thank you, I will run some signal through it before I test it out in the main system.
  13. I had a few minutes last night to make a bit of progress, I got the input selector switch wired up. The switch I'm using is tiny, so it took me a bit longer than I had anticipated.

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    StevenZ, rogerfederer and MikeyFresh like this.
  14. Nice wiring job! You make me feel a little guilty because I bought the version that is already mounted to a circuit board and 47-position switch. I used a box from another project that already had holes for jacks, so all I had to do was connect wires to the circuit board for the inputs, outputs and ground. To make it even easier I use a single set of inputs so no selector switch. If the whole project took me 20 minutes, it's because I move so slow....
  15. Redboy

    Redboy Knobophobe

    What's bothering me is the guy's workbench. It's so damn tidy!
    Thermionics, OldNuke and JohnVF like this.
  16. Trust me, it's really not. Well, I'm picky about it so maybe my view is skewed, I'll snap a pic in a few for proof.

    Not that I'm going to clean it between now and then, hahaha.

    Thermionics and Redboy like this.
  17. Guilty? Baah, you made the smart choice, if.. *cough*, when I build another, I'm buying the pcb version.

  18. OK, so not super messy. The 'main' bench, and the 'assembly/whatever' bench. I'm about to re-arrange my office and build some better shelving for tools, scope, dmm's, etc.

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    opa1 and Redboy like this.
  19. JohnVF

    JohnVF Administrator Staff Member

    You are in for some happy listening. I'm a preamp snob of the snobbiest order, and I stopped right in my tracks with a slagleformer AVC, sat down and...what is this? Contentment? What?
  20. Now that is a glowing review! I'm very excited to get it in the system. It's replacing a First Watt B1 clone, so my system is adjusted to no gain from the 'pre'.


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