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Bent Audio Slagleformers: my passive preamp endgame

Discussion in 'The Cutting Edge' started by Redboy, Jul 10, 2014.

  1. Redboy

    Redboy a few good watts Subscriber

    Messages:
    11,091
    Location:
    Twin Cities, MN
    For a couple of years, I have been using a passive preamplifier built with "Slagleformer" modules, which are Dave Slagle's excellent autoformers packaged in a remote-control friendly circuitboard by John Chapman of Bent Audio. They are absolutely wonderful modules, allowing volume and balance control in 1dB steps, mute and optional source selection from the comfort of your favorite audio chair.

    I am an admitted passive preamplifier junkie, having experimented with nearly everything: cheap potentiometers with plastic conductive elements, stepped attenuators built with discrete resistors, high-end switches with SMD resistors, and several other brands of transformer volume controls. I’ve learned firsthand that here are many good solutions out there, some of which I could live with quite happily, but to these ears the Slagle iron is the best. Also, it doesn’t hurt that the Slagleformer package adds a remote control to the mix - a luxury, yes, but a luxury that I would now be loath to live without!

    That Slagleformer preamp was the pinnacle of preamplifiers for me.

    Was

    A couple months ago I sent another email to John Chapman, asking him if there were any truth to the rumor that these magical modules could be wound with silver wire. Oh, and dare I ask how much they might cost? He replied quickly (as John always does) that yes, they could be wound with silver. Yes, they are expensive and if it were him he would rather try to ignore their existence and spend the cash on a pile of records, instead. A very sensible thing to do, I thought, as I considered the option...


    But I am not a sensible audiophile.


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    Last edited: Nov 20, 2017

     

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  2. Redboy

    Redboy a few good watts Subscriber

    Messages:
    11,091
    Location:
    Twin Cities, MN
    Eventually, I intend to put this in an enclosure like the one I used before, but for now I've just been listening.

    They sound... sublime. If the copper version was a game changer for me, the silver just ends it: I know it's dangerous to say something like this in our hobby, but I think I'm done for now... I've reached preamplifier Nirvana! :)

    [​IMG]
     
    Last edited: Nov 20, 2017
  3. Billfort

    Billfort Addicted Member

    Messages:
    8,486
    Location:
    Newmarket, ON, Canada
    What a beautiful build Nate.

    I'm an active tube pre guy - in my experience, the good ones just have a kind of drive and dynamic 'hit' that I just haven't heard in passives - but then I haven't listened to something like this!

    It sure does go to my less-is-more paradigm though...so if I could hear it somehow...
     
  4. marantzfan

    marantzfan ... Subscriber

    Messages:
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    Location:
    Peoria, Arizona
    Why do you post stuff like this Nate? Ten minutes ago the thought of a new preamp project wasn't anywhere in my mind...
     
  5. Redboy

    Redboy a few good watts Subscriber

    Messages:
    11,091
    Location:
    Twin Cities, MN

    Thanks, Bill. The sweet deal with this one is that if it didn't hit all the right notes for you as a standalone passive, it could be incorporated into your favorite active tube pre as a major upgrade to whatever volume control you're currently using.

    Oh, and stop over anytime for a listen. :)
     
  6. Redboy

    Redboy a few good watts Subscriber

    Messages:
    11,091
    Location:
    Twin Cities, MN

    So sorry. :)
     

     

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  7. WhiteSE

    WhiteSE Is Lute Gluten Free?? Subscriber

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    nate, do you know what your doing??
     
  8. Billfort

    Billfort Addicted Member

    Messages:
    8,486
    Location:
    Newmarket, ON, Canada
    If his builds are the result, I really hope he doesn't.

    Keep floundering Nate! :)
     
  9. fredgarvin

    fredgarvin AK Subscriber Subscriber

    Messages:
    1,159
    Boy, that makes me want want one too. I remember how good the old Bent NOH sounded. This looks like something Jules Verne would use.
     
  10. Redboy

    Redboy a few good watts Subscriber

    Messages:
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    Location:
    Twin Cities, MN

    Fred (I assume your name is Fred), I would encourage you to send an email to John Chapman to get the ball rolling. He's the nicest guy in the biz!
     
  11. 240sx4u

    240sx4u Lunatic Member

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    Location:
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    Nice job Nate, that's a real work of art there.
     

     

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  12. Redboy

    Redboy a few good watts Subscriber

    Messages:
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    Thanks Evan. FPE has really helped me explore some new territory.
     
  13. kfringe

    kfringe New Member

    Messages:
    46
    I'll vouch for the silver slagleformers as being qualitatively different from any other passive I've heard. Dynamic "hit" isn't something they lack.

    The copper models aren't exactly deficient, mind. The silvers sound just a little more natural to me, but the copper is no slouch. Similarly, I find that John Chapman's remote boards are a big part of the total sound, but the cheapie autoformers ($350) direct from Dave Slagle are a pretty good taste of what you can get with the full boat.

    They're worth trying.
     
  14. cubdog

    cubdog banging through drywall Subscriber

    Messages:
    21,337
    Location:
    Oregon IL.
    Your work never ceases to amaze me.

    cubdog
     
  15. OldSch00l

    OldSch00l Seeking a Happy Medium

    Messages:
    879
    Holy hell that is quite a beautiful and clean design, very nice work! :thmbsp:

    I've been curious about passive pres for some time, never had the chance to hear one...
     
  16. marantzfan

    marantzfan ... Subscriber

    Messages:
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    Out of curiosity, what does a pair of those slagleformers run nowadays? Either silver or just the copper ones....:scratch2:
     

     

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  17. kfringe

    kfringe New Member

    Messages:
    46
    The manual, barebones, supply-your-own-everything-else is $350 from Intact Audio. The full boat, single ended, copper version is about $1600 from Bent Audio.

    The silver ones are godawful pricey depending on the market that day. Redboy's build quality is priceless.
     
  18. tomlinmgt

    tomlinmgt Addicted Member

    Messages:
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    Location:
    Arlington, TX
    There's not a single damn good reason for someone as early in the game as I am to be seeing something like this. :no:

    Thanks for sharing, and that really is some outstanding craftsmanship...but I'll be moving along now.
     
  19. cubby01

    cubby01 aka Buck

    Messages:
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    Location:
    Kansas City area
    Nice Nate. So what are you doing with the lowly, unlistenable, copper wound on? :scratch2:


    I assumed his name was Dan. :D

    https://screen.yahoo.com/fred-garvin-male-prostitute-000000541.html

    [​IMG]
     
  20. Redboy

    Redboy a few good watts Subscriber

    Messages:
    11,091
    Location:
    Twin Cities, MN

    That one appears to have found a nice home. :)
     

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