Balanced headphones w/ an unbalanced amp

Discussion in 'Headphone Amps (full-size)' started by phishneslo, Oct 30, 2012.
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  1. raybies
    I was hoping to get 100% more power; instead of 200mW balanced, 100mW SE.
    I fully understand balanced out, but I also assumed that they require balanced headphones with the correct circuit to merge + & -, while discarding the noise.
    I have no idea about the adaptor layout, but I assumed they would discard one of each sides extra pin.

    I read about all these people changing their SE cables to Balanced on their IEMs/Cans and getting amazing sound difference, which again makes no sense to me since "I thought" they need the circuit to merge and discard noise... I have no idea about balanced DAPs, because I always thought balancing was for cars, and AC power interference (my sub needs balancing) but since DAPs are portable the noise would be minimal.

    So I'm here asking questions.
     
  2. Redcarmoose
    Not mentioned here is the fact that his 4.4mm balanced out uses a completely separate amplifier section of the device. Balanced one amp, single ended, a different amplifier.
     
  3. Themordent
    Power varies with the square of the voltage. If voltage is halved (i.e. you discard half the differential signal), the power is quartered (i.e. 200mW becomes 50mW). You'll notice this number matches the SE spec you provided; I think you can guess why.

    Maybe your assumption about the adapter is correct. However, it is still of no benefit because at best you're wasting half of your hardware for no reason, and at worst the adapter perhaps does something different which could cause problems when you try to use it.

    Headphones are innately "balanced" by design. Whether you're running them in a balanced or single-ended manner depends on the wiring of the cable, that is all. There is nothing else, no extra "circuit" that performs any function or whatever you're saying.
     
  4. Redcarmoose
    06FEB76B-399E-4C88-97D2-B2025F1BA4C8.jpeg 4C980EFF-3BE5-48B5-A7C6-620BED493BCC.jpeg


    One device, two separate amps.
     
  5. Themordent
    Yes, balanced audio typically requires two amplifiers. However, I find it more likely that the SE uses half the balanced hardware (e.g. one of the two amps) like most balanced units rather than there being separate hardware for the two outputs which seems like a colossal waste.

    The pictures don't show much. If you have any other evidence for this claim, I'd love to see it (because that's really weird).
     
  6. castleofargh Contributor
    plugging a single ended cable into a balanced amp is a very serious risk for the amp as you end up joining 2 wires that really shouldn't meet. as explained here:
     
  7. raybies
    Thanks, now I'm a little lost.

    5 wires from source (R+R-/L+L-/Gnd).
    Speakers (transducers) just require a circuit, so +/-.
    Balanced amp has 1 amp for each channel, why does it need +/-/Gnd?

    If using an adaptor:
    Amp 1: L + Gnd
    Amp 2: R + Gnd (Gnd is going to be common on the PCB).

    What's the problem ^^?

    =======================

    My original understanding of balanced leads was:
    1.- To eliminate noise from 50/60Hz AC, or other induced noise on cables.
    2.- Send two mirrored phase signals + gnd.
    3.- On the other end by subtracting the signals you can eliminate the noise signature.

    Without performing this operation balanced headphones don't present any benefit.... or am I missing something?
     
  8. Redcarmoose
    DSC_0096.JPG





    Actually I meant to say there are three amps. One single ended on one side and one balanced amp on the other side using two separate channels. He is interested in hearing the balanced amp single ended as it’s the only amp section that includeds direct DSD. He also wants to know if the power will drive his single ended headphones better. Obviously getting a balanced cord is truly the right way to go for him, as we all know. I actually have all the adapters to listen to both outputs, both balanced and single ended safely. I will do it and report back,

    I use an adapter system to remove the choice of reconnecting and disconnecting the IEM MMCX connectors which can wear out. Thus my MMCX connectors are only connected up twice. Once by Sony and once by me to the adapter system. It should sound way louder in balanced mode.

    Edit:

    I just realized my test does not prove a thing as I have no way to listen to the balanced in single ended mode. I have no 4.4mm to 3.5mm single ended. Sorry. I can say balanced 4.4mm is way louder than the same song with single ended 3.5mm.


    The 2.5mm balanced cable termination is being able to go single ended when connected to the 3.5mm single ended by bypassing connectors I guess. So ending......at least this shows there is an adapter which takes 2.5mm balanced and adapts it to 3.5mm single ended.
     
    Last edited: Dec 28, 2017
  9. Redcarmoose
    Search Results
    Single Ended vs. Balanced Connection - Moon Audio
    https://www.moon-audio.com/single-ended-versus-balanced-connection
    You can convert a balanced connection back to single ended. This is not a problem at all as long as your main headphone cable is balanced, then you can add an adapter cable. For example, we make adapters that convert the Astell & Kern balanced 2.5mm plug to a 3.5mm plug for use with your phone or another device ...





    He could get an adapter from Moon Audio, but he should be sending his headphones there.:)
     
  10. Themordent
    I feel like you're asking the same question over and over. Again, there is no "thing" that does the "balancing" (unless you count the transducer itself). Thinking of balanced audio as coming out of a black box that "performs the operation" is conceptual, to help people grasp the nature of the phenomenon.
    Balanced architecture is typically two stereo amps (producing two pairs of signals, normal and inverted). Each ear of the headphone has two leads: Balanced scheme gives it signal+ and signal-, SE feeds it one signal and GND.

    All this makes me wonder why you don't just grab a cheap balanced cable from somewhere and move on with life. This direction you're investigating does not lead anywhere beneficial.
     
  11. raybies
    I'm focusing on balanced headphones, and I don't quite understand how they can be balanced in the classical sense when there is no differential circuit between the amp outs and the transducers, and a transducer accepts an IN and an OUT, whether you want to call it +/- +/gnd or i/o; you can't feed a transducer two mirrored phases (signals), there's only in and out.

    So if you could explain how 5 goes in to 3 I wouldn't have to ask the same question :)
    At most 4 lines can be employed with the 5th just functioning as some pseudo em shield, and not part of a circuit.

    Amp1 > R+ > transducer1+
    Amp1 > R- > transducer1-
    Ground > No where to go
    Amp2 > L+ > transducer2+
    Amp2 > L- > transducer2-

    An answer could be: some people think sharing ground to the headphones on the return path is bad, even though the amps are sharing ground.
     
    Last edited: Dec 29, 2017
  12. Themordent
    Your "IN" and "OUT" characterization moves me to suggest that you read about what audio signals look like electronically, how they interact with transducers, as well as some circuit theory (V = IR and the like), then think about why connecting V+ and V- to a transducer works just as V and GND do (examine the direction of current flow on either side of the load and see if it is consistent with your IN/OUT notion in either case).

    Yes, what you've written with the arrows is correct. Yes, in balanced scheme GND is typically connected to the shield of the wire. Incidentally, take note of the difference between "balanced" and "differential," though in this sphere the two terms tend to bleed together and create confusion (like how I used it above).
     
  13. abm0
    Anything more serious though? Why should the R- and L- outputs of a balanced amplifier never be shorted together? What's the worst that could happen if you try to power SE headphones from a balanced TRRS-out, and their TRS plug causes the aforementioned short with its larger S section?
     
    Last edited: Jan 9, 2018
  14. castleofargh Contributor
    well I can't say it's something I have experimented with. I'm curious but only to a point ^_^. I repeat what I've read from various sources over the years as it's something people have been curious to try pretty much since balanced amps exist.but I admit I don't understand all designs well enough to predict what would exactly happen. it's even harder given all the mess that fall under the balanced denomination on consumer gears.

    the very first time I got warned not to do it was from Ray Samuel (RSA) when I had a portable amp with the RSA/kobicon plug and I wasn't willing to have a special cable for all my IEMs. so I asked what matters of adapters I could get as any other guy who hoped he could outsmart electricity to save money.
    there was the same story with the Pono DAP and some A&K DAP, I guess it has become a trend now to make DAPs with balanced outputs(I find that so stupid on DAPs, we pay more to get small portable stuff, and then we ask to double the components because some guys got the wrong idea about what it was doing...). anyway I couldn't find the relevant pages with my weak google-fu, sorry about that, but they do or did exist somewhere. but I still landed there https://www.moon-audio.com/single-ended-versus-balanced-connection where they mention that possibility around the second big red quote.

    personally I'd always ask the manufacturer of my amp if it's ok before trying to turn the balanced output into SE with an adapter. also they might know better what's exactly going to happen on their design.
     
    abm0 likes this.
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