PPIMV w/ 1959 Superlead

Discussion in 'The Tone Zone' started by matttornado, Jan 16, 2020.

  1. matttornado

    matttornado Well-Known Member

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    I have a 1974 100 watt Super Lead that I bought back around 93' or 94'. Over the years I tried every type of master volume and must have taken them out & re-installed them 10 times by now.

    Right now I have a Lar mar PPIMV installed & I'm using it along with an Attenuator.
    When comparing the sound at different master volume settings, the amp sounds no different with the master set at 4 and cranked (out of circuit, same as stock).

    As I turn the master from about 4 to all the way up, the sound is EXACTLY the same. The only thing I notice is the the Presence control starts to work at about half way maybe?

    So why use the attenuator? I don't hear any magical output tube distortion start to kick in as I turn the master all the way up.

    Just sharing some observations. IMG_2301.jpg
     
  2. ampmadscientist

    ampmadscientist Well-Known Member

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    There should be output tube distortion and it should sound better than just the preamp/PI alone.
    But it's not very practical to put a PPIMV on a super lead without changing the preamp to 2203 first.
    I kind of get the indication that the preamp isn't driving the output like it should...
     
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  3. matttornado

    matttornado Well-Known Member

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    How do I check if it is?
     
  4. ampmadscientist

    ampmadscientist Well-Known Member

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    What DC voltage is on CT of the OT?
    Do you have any test equipment he said hopefully?
     
  5. MickeyJ

    MickeyJ Well-Known Member

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    This is just poppycock.
    These sound great with a simple Lar mar master volume.
    I have firm evidence of this sitting about 10 feet away from me.
    Can the attenuator, and just play thing with the master volume at around 5-6 +.
    If that's too loud, then it may be time for a smaller amp, It is difficult going from one of those to any other amp, but the world unfortunately is an imperfect place.
    That is a clean amp btw, beautiful.
     
  6. matttornado

    matttornado Well-Known Member

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    Can you please explain exactly how to do that?
     
  7. pedecamp

    pedecamp Well-Known Member

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    I agree with you, Ive done extensive testing of my 2204 at volume 7 with an attenuator vs volume 1 with an OD pedal and it sounds pretty much the same. If you have a ppimv I dont think you need the attenuator, if you didnt have a ppimv then you would use the attenuator for volume control.
     
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  8. South Park

    South Park Well-Known Member

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    A lot of the tube distortion comes from the phase splitter being overdriven. When you cut the signal you can’t overdrive the tubes.
     
  9. junk notes

    junk notes Well-Known Member

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    yes, no need to prove. Application of attenuator (of choice) is a personal pref for others.
    OP Perhaps think about a variac in that equation, subtracting the attenuation.
     
  10. SkyMonkey

    SkyMonkey Well-Known Member

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    Sorry, but I've got to ask, what does PPIMV stand for and mean exactly.
    I am still learning about all this stuff.
     
  11. junk notes

    junk notes Well-Known Member

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    Everyday, so am I.
    post phase inverter master volume
    post meaning after the preamp section on the circuit board.
     
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  12. SkyMonkey

    SkyMonkey Well-Known Member

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    Cheers.
    I assume there is a type where the MV is elsewhere?
     
  13. jimmyjames

    jimmyjames Well-Known Member

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    Ah yeah, Pre Phase Inverter Master Volume (PPIMV) ;)
     
  14. mickeydg5

    mickeydg5 Well-Known Member

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    It would be most helpful if you gave all of the amplifier's conrol settings, any input jumpers, any front end pedals/effects used and their settings as well.

    All this talk is pretty much useless without this basic information.

    By the way, how are your power tubes set/biased and what cabinet/model speakers are you using?
     
  15. matttornado

    matttornado Well-Known Member

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    So i’m plugged straight in.
    channels jumpered with y cord both going into high inputs.
    settings: P=7, B=0, M=8 ,T=4,V1=7,V2=4
    new el34s 480B+ biased around 34mA
    plugged into a 4x12 with 25 watt greenbacks
     
  16. mickeydg5

    mickeydg5 Well-Known Member

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    I actually figured all of that.

    Bass should never be at zero, move to at least 3.
    Drop Midrange and boost Treble as necessary.

    A "Y" cord at the inputs is not smart as it kind of defeats some of the good stuff. A plain short patch cord is what is needed, from one channel to the high of the other. Do I need to explain?

    So main signal is through Volume 1 at a setting of 7. That is practically maxed and maximizing all other preamp tubes including the PI. Everything is already distorted so any PPIMV or outboard output attenuator will not make much difference in the sound as it will in the volume itself.
     
  17. matttornado

    matttornado Well-Known Member

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    Don't like those settings. I had this amp for over 20 years and tried every possible setting imaginable. Not a newby with this amp.
    My bass control is either on or off - no adjustibility that I can hear/ LOL
    I been gigging with this amp ever since I bought it.

    Been doing that too for as long as I had the amp. I switch back and forth between a Y and small patch cord.
    Y cord sounds just as good, maybe a tad better? Hard to tell most of these things are very subtle.

    Yes. That was the point I made in the OP.
    I am very familiar with these type amps....maintenance, bias, repairs.... it's all I ever used up till about a year ago when I bought a DSL 40CR.
     
    Last edited: Jan 20, 2020
  18. junk notes

    junk notes Well-Known Member

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    pay no attention to that.
     
  19. mAx___

    mAx___ Active Member

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    How are you comparing sounds? Did you record both setups?
     
  20. matttornado

    matttornado Well-Known Member

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    I just turned the master up while using an attenuator and listened. The sound didn't change into power amp distortion that I could hear.
     

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