What is balanced? What are balanced amps? Do they sound better? Discussion for noobs and boobs.

Discussion in 'Headphone Amplifiers and Combo (DAC/Amp) Units' started by Marvey, Dec 5, 2015.

  1. PoochZag

    PoochZag The Shadow knows - Friend

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    Just to clear this one part up, any headphone that it dual entry (wires to each cup) can be balanced because it already uses 4 wires, + and - for each driver. So in the case of a hardwired headphone, you can cut off the TRS, figure out which wire does which, and solder on a 4 pin XLR.

    The reason a TRS isn't balanced even though it has four wires is simply because both L- and R- share the single sleeve (ground) on the TRS connection.

    Then as already addressed, you can make a xlr to TRS adapter with your cut off TRS portion.
     
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  2. Mars

    Mars Rando

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    What about the 3.5mm TRRS balanced jacks that are used for example in the GOV2? Is it safe to plug them into a regular female 3.5mm output, to use the phones single endedly? It seems to me that the two ground pins will just be connected this way.
     
  3. Mshenay

    Mshenay Slightly aspie. Don't make fun of.

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    Really great points! I was the "BALANCED IS BETTER" Idiot for a while, I took some time to actually learn a little more about the design and reached the point that purring came, though in terms of "cost" to "performance" I still found that Audio GD's balanced Dac/Amp combo for around $600 was a hell of a deal! Additionally my iBasso PB1 and PB2 are excellent as well, the PB2 cost me around $300 with the LME 49990 OP amps and adapters, and it almost matches the NFB10ES2 in terms of output quality, the only think lacking on the PB2 is headroom

    Still though Purrins point is great, having a balanced headphone amp does not guarantee "better" sound, in fact after dropping like $12 on a tube, I found that my Project Starlight sounds damn good compared to the fully balanced out of the NFB10ES2. Though I'd like to see a balanced Hybrid by Garage 1217, and 9/10 I'd throw my money at that they second they launch one.

    Though correct me if I'm wrong but I thought that balanced amps also offered inherit noise resistance through phase cancellation?
     
  4. Airquotes

    Airquotes Rando

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    Just a thought: This is a very informative thread, but is still mostly full of subjective impressions. I've still never seen anyone actually measure a headphone level matched on the same amp in balanced and unbalanced mode. If there are really audible differences to had, shouldn't that show up somehow in measurements? Maybe not in frequency response but in impulse response or something else. If someone had the equipment and time to do some measurements I'd love to see them. I think it would be really informative for a lot of people.
     
  5. johnjen

    johnjen Friend

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    It would be like comparing apples to oranges.
    Yes they are both fruits, and round and sweet, but not the same…

    My point being the circuit topologies are very different between them, so having both a balanced and an 'equal' unbalanced amp in the same chassis is unlikely.
    And unbalancing a balanced amp is unfair to the balanced amp and conversely an unbalanced amp isn't nor can it become a balanced amp.

    IOW as has been stated previously pick the amp that works best for you, and for most whether its balanced or unbalanced is a secondary (or tertiary) consideration.

    And lastly subjective impressions IS what this is all about.
    Numbers don't tell you HOW it sounds, when playing music, which is their intended purpose in the first place.

    JJ
     
  6. dubiousmike

    dubiousmike Friend

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    @Airquotes if you take a differential/push pull amp where the se out is simply two channels driven and the bal out is 4 in a differential toplogy, there will definitely be measurable differences. For starters, the output impedance of the latter is double that of the former which does change FR with any phones that don't have a ruler flat impedance curve. (I.e. all dynamics). Generally speaking, even order distortions will cancel out in the push pull while odd will not. This is also measurable. Which one actually sounds better to a given set of ears is purely subjective though. Nelson Pass and others have written about how different ears have different preferences and sensitivities to different sorts of distortions - so there is plenty of room in the industry for good designs of different sorts.
     
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  7. TwoEars

    TwoEars Friend

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    In regard to tube amps and fully balanced drive:

    I've been fortunate enough to have some long winded discussions with some of the big names in the tube amp business, and also a friend of mine who's an EE. The general consensus has been that when it comes to tube amps a fully balanced design (from input to output) is neither desirable nor cost effective. Rather all it would do is increase cost and complexity for very questionable gains, potentially there would even be degradation in sound quality compared to SE.

    So when it comes to tube amps there are very good reasons why 99% of them, including the best ones are with SE inputs. There are however quite a few on the market which are "faux balanced". That is to say they have balanced inputs but the internal wiring is single ended. One way to do this is to simply connect 2 of the signal pins rather than all 4 and then connect ground to shield. Another way to do it is to use a transformer circuit which converts the signal from balanced to single ended just as it enters the amp. Neither of this is really desirable but is done for marketing reasons because some consumers have gotten it into their head that "balanced is better". So when they have a balanced DAC they want a "balanced" tube amp to go with it "just because".

    There are a few truly balanced tube amps on the market but they are few and far between, the Little Dot MK 6 is fully balanced from input to output as far as I know. From what I've heard it's a great sounding amp with the right tubes, but it does use a lot of tubes and is it really better sounding than a SE design? Hard to say. It's an intriguing exercise in tube amp design nonetheless.

    Balanced outputs for headphone drive is another matter, due to the way the tube design functions it's actually quite easy to get a balanced output. It doesn't really change the internal tube circuit design, rather it's just a matter of final wiring and how to connect the headphone output to the right internal points. There might be some factors you have to consider d/t changing of the load characteristics. But in general it's not that complicated to equip an SE tube amp with balanced outputs, the internal circuit design is in essence already prepared for balanced outputs.

    These were things which confused me quite a bit a couple of years ago when I started learning about tube amps, but hopefully it can help someone out.
     
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  8. OJneg

    OJneg The Most Insufferable

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    Tubes and balanced/differential doesn't need to be particularly complicated really.

    Balanced input can be done relatively easily and offers serious benefits (both measurable and sonic). Long-tailed pair differential input, or just an input transformer. LTP gets you gain and very high Zin. Input transformer gets you near-ideal isolation, and can also give you a bit of gain if you use a step-up. Both are valid way of a "true" balanced input and only the input transformer can be considered adding an extra "stage" to degrade the signal.

    Balanced output can be done with a push-pull tube pair, which obviously requires 2 devices for each channel that need to be reasonably well matched. Push-pull output transformer offers serious benefits over a single-ended direct-feed transformer which needs to carry an unbalanced bias current and will saturate accordingly. Push-pull output stage also gives you twice the swing of course. You'll see push-pull output more in the big speaker tube gear for that reason.
     
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  9. mtoc

    mtoc SBAF's Resident Shit-Stirrer

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    Little fact: the amp HEV90, yes, is a SE amp. No balanced input ≠ BS.
     
  10. OJneg

    OJneg The Most Insufferable

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    Probably uses a balanced, differential-drive topology inside. SE input for convenience as people will want to plug in their CD players. Doesn't speak at all to the merits of a true balanced amplifier, so don't read too much into these stupid things.
     
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  11. Rex Aeterna

    Rex Aeterna Friend

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    I use balanced from source to preamp. Thought once balanced was bs till I went the route. It does in my situation help. Signal is so much more dead silent with zero electrical noise compared to se connections. Even using decent xlr jacks shut more noise out than 75ohm quad shielded coaxial/bnc connectors. I use just plain 24awg cloth shielded lynx xlr jacks that was like around 15 bucks for 3ft length.
     
  12. spwath

    spwath Friend

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    Im not sure if I missed anything, but why are RCA connections unbalanced?
    It seems like they would be balanced, as there are 2 grounds.
    What am I missing?
     
  13. OJneg

    OJneg The Most Insufferable

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    What second ground?
     
  14. spwath

    spwath Friend

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    Well for a stereo pair, each one has its own ground
     
  15. PoochZag

    PoochZag The Shadow knows - Friend

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    The two RCA grounds are connected together internally in the amp (or whatever), so its r+ l+ and common ground, just like a SE headphone cable would be
     
  16. spwath

    spwath Friend

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    Ah, OK. But in theory, the connectors could be used for a balanced connection?
     
  17. Armaegis

    Armaegis Friend

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    This here is a fundamental misunderstanding of what "balanced" is...

    But yes, in theory there is nothing inherently preventing RCA plugs from being used in a sort of "balanced" fashion.
     
  18. spwath

    spwath Friend

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    So is balanced not basically one dedicated ground per channel?
     
  19. OJneg

    OJneg The Most Insufferable

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    The amount of channels does not make the transmission line balanced.

    Go back and do a bit more reading, I'm not sure how you inferred this. You can expect the chassis ground (Pin 1 on XLR) to be a shared shield/chassis ground for a balanced connection.

    You might be confusing with the term "dual-mono". You can have a SE dual-mono so long as the ground connections between channels aren't shared. But that's nothing to do with balanced.
     
  20. spwath

    spwath Friend

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    OK, ill read it more carefully and try to get the right info out of it.
     

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