Posted by mqracing (M) on July 26, 2005 at 10:38:02

Hi Pistoljoe, Keto and others:

you guys were asking for an EXO-173 junior... a design that could be used at the input of your power amp and be good for say 4 to 6 vrms signal volts as opposed to an interstage sized (say 75 vrms) sized 173...

Brainiac (born as Paul Joppa) and I were brainstorming this morning and are kicking around some pretty neat ideas.... an input level sized critter that would have tons of flexibility...

we were discussing a unit that could potentially be employed as a two winding transformer or an autoformer. That could be used PP:PP, SE:PP, SE:SE and which could be used for unity gain (1:1 voltage ratio), step up (1:2 or 1:4), and step down (2:1 or 4:1)... and which could also be used as a high quality phase invertor...

so... just to let ya know... we are bustin' brains (and... geez... it gets smoky) on this and giving it a lot of thought and evaluation...

in the meantime... for a quicky experiment on the cheap... I just grabbed four 15335A's off the bay for like $95 delivered... this is a 15K to 15K critter (single ended both sides)....

but... for experimental purposes... hook this guy up with the primary and secondary windings in series (observing correct polarities) and give it a try as a small signal (input level) phase splitter and you MIGHT be surprised with the results...

check out the bay... there are several more on the bay as of yesterday....

if you cop a pair let me know and I will show you how to hook them up for the experiment.

cheers,

msl

• Can 15335A be used for pp:pp? - nc 18:25:22 07/27/05 (0)
  In Reply to: Huckleberry posted by mqracing on July 26, 2005 at 10:38:02:

  On the primary

  V+ to 1
  V- to 6
  resistor connects 1 to virtual ground 1
  resistor connects 6 to the sam virtual ground 1 as above

  On the secondary
  7 to grid of tube 1
  8 to grid of tube 2
  7.5K resistor connects 7 to virtual ground 2
  7.5K resistor connects 8 to virtual ground 2

  Is the above connection possible?
  where should GND (2) connects to?
  
  

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• Re: Huckleberry - Steve Eddy 13:09:26 07/27/05 (0)
  In Reply to: Huckleberry posted by mqracing on July 26, 2005 at 10:38:02:

  
  
  but... for experimental purposes... hook this guy up with the primary and secondary windings in series (observing correct polarities) and give it a try as a small signal (input level) phase splitter and you MIGHT be surprised with the results...
  

  Why not just wire a pair of 7.5k ohm resistors in series across the secondary and reference the node between them?

  se

  
  

  
  
  
  
  

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• Re: Huckleberry - pistoljoe 15:24:24 07/26/05 (0)
  In Reply to: Huckleberry posted by mqracing on July 26, 2005 at 10:38:02:

  Roger that, Mike.

  Actually my usage is 1:2 step up.

  I've been on the bay alot looking for another 4722 for myself. I'll pick up a pair of the 15335s and report back against the exo-173 I'm using now.

  Joe
  
  

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• You've got my attention--15335 input-phase splitter - mwiebe 15:03:55 07/26/05 (3)
  In Reply to: Huckleberry posted by mqracing on July 26, 2005 at 10:38:02:

  Mike,
  Here I was looking for a small phase splitter for a 6EM7 P-P amp and your email hits. I got a pair of 15335's but never considered them. Since I have two voltage amps with the 6EM7s I may use them as input phase splitters.

  I assume input goes to pin 6 as well as on to one grid, pin 1 and 8 grounded and pin 7 to other grid. Or what do you suggest? If I decide to use it as a phase splitter between the voltage triodes and power triodes I would need to parallel feed it. Just what I was looking for so thanks for the suggestion.
  Matt

  
  
  
  

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  • hooking up 15335 for phase splitting duty - mqracing 18:45:41 07/26/05 (2)
    In Reply to: You've got my attention--15335 input-phase splitter posted by mwiebe on July 26, 2005 at 15:03:55:

    first tie pins 6 and 7 together and this will become the grounded center tap.

    feed a signal from your voltage amp to pins 1 and 6. Pin six is grounded and pin 1 goes also to the grid of a tube.

    next is that pin 8 goes to the grid of the other tube....

    so pins six and seven are at ground and form the CT. And you feed pins one and six as your "primary"... and you derive an equal voltage output but of opposite phase btwn the CT and pin 8 (which feeds other grid)...

    is this clear?

    
    and remember that you can only put a max of 6.15 volts across pins 1 and 6. So the grids your driving must be say approx -8 volts or less.

    
    msl
    
    

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    • Re: hooking up 15335 for phase splitting duty - mwiebe 18:56:22 07/26/05 (1)
      In Reply to: hooking up 15335 for phase splitting duty posted by mqracing on July 26, 2005 at 18:45:41:

      Mike,
      Thanks, not what I was expecting but I understand. Hopefully I will get to try it this weekend or next. Nice to use those things other than as interstages.
      Matt
      
      

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      • keep us apprised... - mqracing 08:02:44 07/27/05 (0)
        In Reply to: Re: hooking up 15335 for phase splitting duty posted by mwiebe on July 26, 2005 at 18:56:22:

        Hi Matt:

        if you try out the 15335 as a phase splitter let us know your what you think.

        the 15335 was not designed as a phase splitter... but... it might work a whole lot better (though not to the ninth degree of purrfection) than anticipated...

        remember that the impedance is very high... nominally the primary and secondary have 15K impedances... for many tubes this may be much higher impedance than necessary.

        also... you can use this device (I saw a discussion on another board) as a 1:2 step up transformer... would be worth a try if you get a pair off the bay for pennies on the new retail dollar...

        
        cheers,

        msl
        
        

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