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Ampeg PF-20T to (power) amp

Discussion in 'Amps and Cabs [BG]' started by Zbysek, Nov 21, 2018.


  1. Wasnex

    Wasnex

    Dec 25, 2011

    Sometimes just using a hardwired XLR to 1/4" adapter cable works. Cables are not always wired properly, but may work depending on the topology of the balance output circuit.

    Better to use a device with an isolation transformer. An Ebtech Hum Elimator XLR is a fairly low cost option.

    Here's a page that explains Sound System Interconnection
    Here a link to the Ebtech Ebtech - Audio Solutions
     
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  2. Zbysek

    Zbysek

    Mar 23, 2017
    Czech Republic
    I, too, always pay very close attention to what agedhorse has to say...as he is the star for me being Genz Benz fan!
     
    Last edited: Nov 23, 2018
  3. Zbysek

    Zbysek

    Mar 23, 2017
    Czech Republic
    Wisebass likes this.
  4. ficelles

    ficelles

    Feb 28, 2010
    Devon, England
    Ideally yes, but a balanced signal is just a divided unbalanced signal with one side inverted to take advantage of common mode rejection, so in theory you can just use one side i.e. the tip of a TSR or XLR pin 2 (I think) as an unbalanced signal. I have a neutrik converter that does just that, from XLR to mono jack. You get a slightly weaker signal of course.
     
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  5. Wasnex

    Wasnex

    Dec 25, 2011
    I believe the inference is you need to know/understand the topology of the balanced circuit and configure the adapter appropriately. In some rare instances the sending equipment may be damaged if the adapter is configured improperly. Basically you need to be an engineer :(.

    Pretty sure it's always safe to use an isolation transformer to make the conversion.
     
  6. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    This has been a go-to reference for many years: Sound System Interconnection
     
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  7. Wisebass

    Wisebass

    Jan 12, 2017
    Lost in Space
    Hi Charlie :)

    Great information! :thumbsup:

    (There is even a direct link to Mr. Ohm) :D


    greetings

    Wise
     
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  8. Transformer balanced out to Markbass. Post EQ DI out of the Markbass to FOH ftw?
     
    Wasnex likes this.
  9. Thanks! That Rane page is great. I've referred to it before for AV applications at work and will save it it my tech info folder.
     
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  10. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    I remember when those Tech Notes were in paper hard copy. Yel_wink.
     
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  11. Wasnex

    Wasnex

    Dec 25, 2011
    1. I believe if the output is transformer or impedance balanced you connect pin 3 to Ring (ground) and pin 2 to Tip (hot). Connect the shield on the output connector only. If the output is transformer balanced, letting pin 3 float will not work because there is no path for the electrons to return to the transformer winding.

    2. If the output uses a differential amp you may need to let pin 3 float to avoid shorting one side of the amp to ground and releasing the magic smoke. Connect the shield on both the output and input connectors. I think it's rare to find equipment that would be damaged by this. Some would work fine with the adapter in 1. above, but half the signal would be shunted to ground.

    3. You also need to be aware that some older equipment had pin 3 hot instead of pin 2. For this equipment reverse the connections of pin 2 and pin 3.

    I am not an engineer....please offer corrections if I have stated something inaccurately.
     
    Last edited: Nov 23, 2018
  12. Graeme2

    Graeme2

    Jan 24, 2017
    Micro VR fx loop send to PF20T instrument input.
    PF20T XLR to return to Micro VR.
    If the set up this correct?
    Which XLR it’s more appropriate to use?
    The one on the right or the one on the left?
    The PDF is a bit ambiguous .
     
  13. Wasnex

    Wasnex

    Dec 25, 2011
    Do you mean, "How do you chose between Preamp Out, and Transformer Bal Line Out on the PF20T?"

    It's really a matter of the sound you want. If you want to capture just the PF20Ts preamp sound, use Preamp Out. If you want power tube drive use Transformer Bal Line Out.

    Take a look at the simplified schematic on page 13 of the manual (attached):
     

    Attached Files:

  14. Graeme2

    Graeme2

    Jan 24, 2017
    That makes a lot of sense.
    Going to order one tomorrow.
    That’s my Christmas present sorted.
    Thanks
     
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  15. ficelles

    ficelles

    Feb 28, 2010
    Devon, England
    Preamp out is a lot hotter than balanced line out, in case that’s important.
     
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  16. Graeme2

    Graeme2

    Jan 24, 2017
    Page 13’ wiring diagram
    D’ho
     
  17. daveman50

    daveman50 Supporting Member

    Feb 24, 2007
    Westchester County NY
    Whoever writes the Rane manuals deserves a medal. I have a Rane PE17 parametric EQ and the manual is crystal clear, concise, and quite funny.
     
    Passinwind likes this.
  18. Zbysek

    Zbysek

    Mar 23, 2017
    Czech Republic
    So I did it! I pulled the trigger yesterday. I can't wait for the amp to be delivered...
     
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  19. Zbysek

    Zbysek

    Mar 23, 2017
    Czech Republic
    IMG_1958[1].JPG She's here!
     
    High Camp, ficelles, Wasnex and 3 others like this.
  20. Wisebass

    Wisebass

    Jan 12, 2017
    Lost in Space
    Hi Zbysek :)

    Let' s look what' s inside the box! :D

    maru-cat-box-o.

    Happy NAD! :hyper::hyper::hyper:


    greetings

    Wise(b)ass
     
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