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Balanced system into single ended power amp...

Discussion in 'audio' started by JemHayward, Apr 16, 2018 at 10:48 PM.

  1. JemHayward

    JemHayward pfm Member

    My current system is all balanced - Audiolab MDAC, Putzeys balanced preamp, and my power amp is balanced too.

    I want to use a single ended power amp for a time, and when I was using the MDAC on its own, I would have just used the single ended outputs, but I have my balanced volume control in the way now, so that isn't an easy option.

    So, should I just make up and XLR to phono lead (and if so, could someone remind me of the right way to do that) or would I be better off using a transformer, which was how my old EAR890 did it? I may also need to attenuate as well, as my present power amp is low gain, and the temporary one will be high gain. What would be the best method of attenuation (I have some decent -10dB XLR in line attenuators, but may need more than that).
     
  2. Arkless Electronics

    Arkless Electronics Trade: Arkless

    Just take outputs from one polarity of the balanced outputs and take that to phono plugs. IE there is +, - and ground at each balanced output so use either + and ground of each output or, for phase reversal, - and ground of each output. You lose half the output signal anyway by using it single ended so may not need any attenuation, depending on just how sensitive the new power amp is.
     
  3. JemHayward

    JemHayward pfm Member

  4. JemHayward

    JemHayward pfm Member

    I think sensitivity is 500mV for full output, so I think things may be a bit loud... though halving the output by losing half the voltage would be a start...

    Pro/Con of using a transformer arrangement? Cost is one obvious con.
     
  5. Arkless Electronics

    Arkless Electronics Trade: Arkless

    I refer you to my first post.... It's both the best, the simplest and the cheapest.
    There are no advantages and lots of disadvantages to the transformer unless you are planning on using 100 yards of interconnect..
     
    linnfomaniac83 likes this.
  6. linnfomaniac83

    linnfomaniac83 I bet you can’t wheelie a unicycle!

    It just isn’t necessary, also transformers aren’t particularly linear devices and can cause more issues than they solve. Just do as Jez suggests and you’ll be fine. Add the attenuators if necessary.
     
  7. ChrisPa

    ChrisPa pfm Member

    If you're taking the output from the BPBP then you should connect pin 2 to the centre/live terminal of the RCA and pin 3 to sleeve/ground. It doesn't have 2 active "halves" at the output, rather it has a balanced impedance output, and the output signal only exists between pins 2 and 3. The is no signal between either of those pins and XLR "ground".

    Have a look at the circuit diagram. It's in "The G Word" document

    For other balanced output devices, then generally follow Jez's suggestion. For these devices if you follow my suggestion above you'll short out one half of the output circuit, but not in the case of the BPBP

    PS. For all the reasons given by the others, i agree: avoid transformers
     
  8. Arkless Electronics

    Arkless Electronics Trade: Arkless

    I hadn't looked at the specific balanced pre in use but a quick google of the schematic says you're quite correct:)
     

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