Audio balanced output to unbalanced input - a brief visual guide

Discussion in 'General Audio Discussion' started by atomicbob, Oct 29, 2018.

  1. atomicbob

    atomicbob dScope Yoda

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  2. gixxerwimp

    gixxerwimp Professional tricycle rider

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  3. Azimuth

    Azimuth FKA rtaylor76, Friend

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    I know a lot has been covered on this topic and many have already accepted passive transformer based solutions. What about active solutions?

    I know in radio station broadcasting, they use more active solutions and if needing a balanced signal for long runs with only a unbalanced source, they would use something like an active converter, like the Henry Engineering Matchboxes. This box uses a linear power supply (not a switcher), and op-amps for the conversion. Looks like a pretty good and fairly inexpesive solution on the used market.

    I would be interested to hear what others had to say about it.

    [​IMG]
     
  4. fastfwd

    fastfwd Friend

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    That Henry Engineering box works great. So does the Rolls MB15b, which is less expensive and has a couple features that make it even more useful.
     
  5. monacelli

    monacelli Friend

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    This is one way to go about it. It's basically the same summing approach used by Yggdrasil and Gungnir for their single-ended outputs, except using opamps rather than discrete parts. Almost all pro amplifiers (e.g., Crown CDi1000) have a circuit very similar to this at their inputs. Even though most of them have XLR inputs, the amplification stages are generally single-ended. I personally would probably prefer to use a Freya S (rip, hopefully resurrected soon), which constructs the single-ended output by taking a single phase of the balanced signal (post Nexus). I'm pretty sure this is how Bifrost 2 works as well, only using the LME49724 rather than Nexus. Even though summers preserve the benefits of differential signaling on paper, a lot of folks seem to feel that they negatively impact sound quality. And I wouldn't expect this Henry Engineering box to perform meaningfully better than the summing stages that are already found in the high-end Schiit DACs, or the transformers used by Metrum.
     
  6. Koth Ganesh

    Koth Ganesh Friend

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    @fastfwd , the Rolls MB15b was a great recommendation. I currently use the Jensen Isomax PI 2XR and also have the PC 2 XR and the Radial J-Iso. The PI 2XR was the best of those three with the other 2 suffering from noticeable SQ due to the 4:1 transformers used (to my ears).

    I received the Rolls like 15 minutes ago and by using it in place of the PI 2XR, I definitely hear more extension at either ends (I use the Modius balanced into the Mogwai SE and Utopia is the HP). The funny thing is that I am hearing this extended FR with the level attenuator at 3/4 of the way to being "completely open". Turning it all the way just makes the sound louder. There is no hum or other issues.

    I now need to try it with the Convert 2 as a truer test of pro balanced to consumer SE conversion.

    Thanks
     
  7. fastfwd

    fastfwd Friend

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  8. Koth Ganesh

    Koth Ganesh Friend

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    Thanks. I did not even get the one pager. I googled the manual though to get the specs and the schematic.
     

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