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Testing audiophile claims and myths

Discussion in 'Sound Science' started by prog rock man, May 3, 2010.
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  1. bigshot
    Balanced connections are for pro installations with long cable runs. A home audio system that has been properly designed should do just as good with normal connections. I think putting balanced connections on consumer DACs is like putting mag wheels on a VW bug. It might look nice, but it isn't necessary.
     
    gopack87 and CactusPete23 like this.
  2. Slaphead
    It depends. If the the DAC is also intended to be a monitor controller then yes, I can fully understand balanced connections as XLR is the most common input for powered pro audio monitors. Admittedly most pro monitors do have the facility for RCA input, but if you're using RCA to the monitors then 3 metres is generally considered the maximum safe length. thereafter you may be prone to interference, but it's an environmental thing and therefore YMMV.

    From my point of view using the the equipment that I do then balanced is much preferred, if only for compatibility. If I was using a DAC to power amp/s and then to passive speakers then yes I completely agree with you that balanced is unnecessary.
     
    Last edited: Jan 5, 2019
    CactusPete23 likes this.
  3. castleofargh Contributor
    balanced output was initially brought up in the thread asking about DAPs not DACs. so IMO the situation is different from your example. practicality and compatibility are really the last reasons to go balanced on a DAP.
     
  4. CactusPete23
    I really do appreciate all of the responses to my Balanced DAP Question. Have learned a lot; and had a total misunderstanding of how it worked in cables vs devices.
    Thanks to everyone for taking the time both to answer, and to "dumb it down" so that I could understand !
     
  5. Glmoneydawg
    scientific evidence to the contrary....for the vw bug comment anyway:wink:
     
    Last edited: Jan 5, 2019
    GearMe likes this.
  6. old tech
    Just to be pedantic, while not necessary, putting mag wheels on the VW may actually improve the ride by reducing unsprung weight.
     
    Glmoneydawg, GearMe and Phronesis like this.
  7. Glmoneydawg
    Right!...having said that I've done the balanced cable thing. ...other than a slight adjustment on the volume knob it appears to have no advantages...to me anyway.Its fun to prod Bigshot though isn't it:)
     
    old tech likes this.
  8. Slaphead
    Ahh DAP - I missed that, my bad. In that case yes 100% agree with you - totally unneeded.
     
  9. KeithEmo
    There are several different contexts in which balanced might apply to a DAP.

    1) At the level of headphone compatibility - The drivers themselves used in headphones are basically balanced; it's just inherent in how they're designed. Obviously you can connect headphones wired as balanced to the output of a balanced amplifier with no problem, and you can connect unbalanced headphones to an unbalanced output. You can also connect a pair of "balanced" headphones to an unbalanced amplifier output with a simple adapter cable. You simply connect one wire on each of the drivers together and wire them as a common ground connection. However, if a pair of headphones are wired as unbalanced, then they have three wires, which includes a common ground for the two channels. You CANNOT connect this to a balanced amplifier output. All four output lines on a balanced output carry signal, and none are grounded; if you attach a balanced output to a common ground load you are shorting two of the amlifier outputs together.

    2) At the level of the amplifier - Assuming the amplifier is really balanced, your stereo amplifier actually is a fully differential amplifier, which means that each channel is really made up of two amplifiers cnnected in a bridge configuration. This gives you the benefits credited to any fully balanced amplifier - mainly cancellation of certain sorts of distortion. There are certain reasons why avoiding a common ground connection on the headphone cound conceivable have some really minor benefits, however the main reason most people get balanced headphones is so they can connect them to a balanced amplifier. Because the distortion on most reasonably well designed modern amplifiers is already extremely low, it's doubtful that the reduction in distortion would be significant.

    3) At the level of the DAC - Since any digital audio player with an analog output includes a DAC, considerations about DACs are automatically included in this discussion. Most modern DAC chips have a balanced stereo output. This means they have four outputs: L+, L-, R+, and R-, each of which is actually output by a separate DAC. As with a balanced amplifier, the two DAC outputs for each channel are out of phase, and contain certain distortions that cancel out between the outputs in each pair. if your device has a balanced output, you're going to use all four of those output signals. However, even if the output of your DAP is unbalanced, if you want the lowest distortion, you're going to use all of them. If you connect the R+ line to one input on your right channel amplifier you will get a certain amount fo distortion. However, if you connect both the R+ and R- signals to the two inputs on an amplifier with a differential input, some of the distortion will cancel, and the overall distortion will be lower. There are two things worth knowing here. First, the distortion numbers we're talking about are very low... Second, ALL op-amps, and almost all other modern amplifier designs, have differential inputs, so doing it this way does NOT make the design more expensive or more complicated. It is literally a matter of connecting a few more wires, rather than not connecting them, and about 20 cents worth of additional parts. Now, in addition to all this, most DAC chips allow you to connect each stereo DAC chip to provide a singel monaural output. By cross connecting the all four outputs to a single amplifier in the proper way, you get a slightly lower level of distortion, and typically a S/N that is between 3 dB and 6 dB better. Again note that we're talking about specifications that are very good to begin with. The drawback is that, since each DAC chip only serves one channel, you need to use two separate DAC chips for the two channels. Because the DAC chip is one of the more expensive parts in your DAP, and can cost as much as $10 each, using two rather than one tends to raise the price. (However, regardless of whether you expect it to be audible or not, the best performance specs with a given DAC chip will usually be had with "two separate DAC chips connected in fully differential mono mode". Also note that many DAC chips, designed for surround sound equipment, include eight channels rather than two. WIth these chips, you can have two complete sets of multiple DAC channels, each set connected in differential mono mode, or even cross connected in sets of four, and all on the same single DAC chip.)

    The real bottom line of all this is that the performance of any modern DAC chip is extremely good - so we're talking about really tiny differences here.
    Likewise, there will be a measurable difference between the distortion spectra of balanced and unbalanced amplifiers, but both are really low, so it's doubtful that those differences would be audible.
    (Odds are that, in most cases, other differences in the design of a DAP will make a much more significant difference in the sound than the DAC chip they use.)

    I personally don't bother with balanced headphones or headphone amps.

    HOWEVER, if you're purchasing headphones, and you have any intention of purchasing a balanced amplifier, then the compatibility issue is worth noting.
    If your headphones are wired as balanced, you will be able to connect them to both balanced and unbalanced amplifier outputs, with - at most - an adapter cable.
    But, if your headphones are wired as UNBALANCED, then you will NOT be able to connect them to the output of a balanced amplifier.
    (There are a few amplifiers that support both - but, when you connect unbalanced headphones to them, they are NOT functioning as a balanced amplifier.)

     
    Last edited: Jan 6, 2019
    CactusPete23 likes this.
  10. gregorio
    This highlights one of the issues in the audiophile world, an issue that's been going on for 3 decades or so but has evolved and got a lot worse during the last two decades and is responsible for a fair percentage of the audiophile myths. The issue originally was along the lines of: "If studios do it, then audiophiles/audiophile equipment should too." - As a principle it's false, because what studios are dealing with is quite different from what consumers are dealing with. Not to mention that it's only applied when it suits a particular audiophile marketing narrative but the exact opposite can be applied with a different marketing narrative. For example expensive audiophile cables, which are never purchased for use in commercial studios. In fact, expensive balanced audiophile cables are doubly ridiculous because the basic reason for using a balanced architecture for signal transmission over long cable runs in the first place, is to eliminate any need for expensive cables!

    The second part of the equation is the blurring of the line (for marketing purposes) between "consumer" and "pro" equipment. As the pro audio industry became more reliant on computer chips and as the power of those chips increased, while their cost tumbled, it became practical for consumers to create "home studios", initially it was just serious enthusiasts (or musicians) but a whole category of equipment sprang up around 20 years ago to cater to this market, later dubbed "Pro-sumer" equipment. However, "pro-sumer" equipment isn't just pro audio equipment that's cheaper, it's typically designed for a different purpose/usage, a different environment and with different functionality, and it's therefore effectively completely different equipment! Of course though, this fact is routinely abused by marketers, who fallaciously apply terms like "professional", "pro audio", "studio" and "reference" to their products. Getting back to the quote, there really are no studio DACs "also intended to be a monitor controller", such a DAC (typically an ADC/DAC with a couple of channels of mic pre-amps) is really a consumer product rather than a commercial studio (pro audio) product. Likewise, I've never seen a "pro" monitor with unbalanced RCA inputs, in fact an RCA input on a monitor would be an indicator of a consumer product being marketed as "pro audio"! This would seem to imply that a balanced monitor input is beneficial but we always need to come back to the basic question: What interference AND what signal level?

    For example, given a nominal amount of interference (say a typical consumer sitting room) and passive speakers, unbalanced is going to be absolutely fine, probably even for a cable run of 10 metres or more. That's because even with this relatively long cable length, the amount of interference should be below audibility and the signal level is as high as it's going to get (speaker level). However, if this were say a microphone level signal, then the interference would still be below audibility but as we need to amplify that signal to a usable level (line level), by say 100 times, the interference will also be amplified by 100 times and probably to audible levels, but a speaker level signal does not undergo any further amplification, so the interference is not amplified and remains inaudible. Powered monitors though are fed a line level signal, which IS amplified (inside the monitor, to speaker level) and therefore any interference picked-up along the cable run is also amplified (though not by anywhere near as much as a mic signal). However, in pretty much all consumer/prosumer applications a balanced connection would still provide no audible benefit because we're talking about nearfield powered monitors, with the "prosumer" DAC (with integrated monitor controller) along with the powered monitors all being within the 1.5 metre listening triangle. Even in the worst case scenario (for example without an integrated monitor controller) we're still probably only talking about 5m or so, which would be fine for an unbalanced line level signal in a consumer environment. In a commercial studio though, the DAC would likely be in the machine room, the analogue line level signal would be routed to a monitor controller and then out to the control room to either the nearfields or main monitors. So each line level analogue signal would go through 4 different connectors, at least 2 cables and would likely travel at least 20 metres (possibly 50 metres or so) plus, it would go through the machine room, which is packed full of noisy (interference inducing) equipment. That's why pro audio monitors (nearfields or mains) always only have balanced inputs, why consumer/prosumer monitors don't need them and why @bigshot's assertion that balanced is only necessary in pro installations, was correct.

    G
     
    Last edited: Jan 6, 2019
  11. bigshot
    I've done a simple experiment to determine that every time someone uses an analogy in this forum everyone ends up arguing the analogy, not the actual point. It's like the wise men describing the elepha... no. not going there again!
     
  12. Kammerat Rebekka
    I think most of these ‘problems’ stem from language and perhaps more importantly how we use the very same.
    Just the word balance gives off a wonderful connotation that most likely stays with the listener throughout the listening session ‘damn this is one balanced sound I’ve lured out of my set-up’.

    ...just like mp3s are called lossy..oh no I am losing information! There’s stuff that goes missing!

    Granted, invite many of these folks to do a proper blind test in order to find out what exactly they CAN hear and you get crickets or a good spin on the infamous whatabout-carousel.
     
    Last edited: Jan 7, 2019
    bigshot and CactusPete23 like this.
  13. KeithEmo
    I agree with your sentiment - but not with your example.

    I do agree that a lot of audiophiles have totally unreasonable expectations that balanced connections, or balanced circuitry, will improve the sound of their system.
    However, I'm not convinced that many of them really believe it will "make their system sound more balanced" specifically because the description includes the word "balanced".
    I suspect it has more to do with the idea that anything that improves the specs will produce an audible improvement.

    I do, however, disagree with your example - MP3.
    Yes, when you apply LOSSY MP3 compression to an audio file, you are losing information; there is no question about that; the purpose of MP3 encoding is to save space by discarding information.
    (In contrast to LOSSLESS compression, where all of the original information is retained.)
    Feel free to argue that you may not notice that information has been lost, and that you personally find that MP3 files sound just fine, but it would be inaccurate to neglect to describe MP3 as LOSSY compression.
    It seems quite reasonable to me to expect a copy of an audio file to be complete, and to expect someone to specifically notify me when parts have been discarded, whether I notice the omission or not.
    (Describing an MP3 file as having undergone LOSSY compression is not at all misleading - in fact it is rather the opposite - it is simply an accurate description of the process.)

     
    CactusPete23 likes this.
  14. Phronesis
    IMO, both of you have valid points on "lossy". The term is technically appropriate, but it will also likely influence many listeners to perceive the sound to be worse (relative to lossless) than it actually is.
     
  15. Kammerat Rebekka
    That is my point. I am not suggesting that we change the lingo in order to cuddle up the natives, no, I am suggesting that people try their best to leave their presumptions at the door. The easiest way for one to do this is doing a simple blindtest via Foobar. If you hear or can’t hear the difference, then you’re well on your way to better understanding the word lossy in context with your ears.
     
    Last edited: Jan 7, 2019
    CactusPete23 likes this.
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