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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. Phronesis
    Regarding 'balanced' cables, beyond the exotic bling aspect, the word 'balanced' itself will surely send a message to the subconscious mind of the audiophile that the sound will be more balanced in some positive sense (e.g., sonic up and down flaws removed). Words can be powerful.
     
    Steve999 and CactusPete23 like this.
  2. gregorio
    It's myth!

    In the pro audio (recording studio) world, the equipment is always balanced but that's for three reasons: Firstly, we have all sorts of different level signals to deal with. The output level of a microphone for example, is typically around 100-1000 times lower than the output level going to speakers or headphones, so it needs to be massively amplified and any noise/interference picked-up along the way is also going to be massively amplified. This isn't the case for consumers though, who effectively only have two levels to worry about, line level (the output from the source) and speaker/HP level (the output from the amp), both of which are far higher in level than many/most of the signal levels we have to deal with in the studio. Secondly, the term "recording studio" is a bit of a misnomer, commercial recording studios are not just one room: We typically have the musicians in one room (the live room), the engineer/producer working in another room (the control room) and some/most of the audio equipment in another room (the machine room). Typically therefore, the signal has to travel through two or three different rooms, along several cables, the total length of which is almost certain to be at least 100ft and might be double that (depending on the size and layout of the studio complex). And thirdly, a commercial studio will typically have dozens of pieces of equipment, producing a far greater amount of noise/interference than anything a consumer is ever likely to encounter. Add all this up; higher amounts of interference, far longer cable runs (to pick-up that interference) and far lower level signals to start with (which will require massively amplifying that interference), and using a balanced architecture is entirely justified.

    But for a consumer DAP, it makes no difference at all, unless maybe you've got a 100ft long HP cable and live next door to a magnet factory! Actually, that's not entirely true, as a fully balanced architecture would result in roughly 6dB more amplification and this, I suspect, is what audiophiles are hearing and thinking is "better", but of course they could get exactly the same audible result with a single ended architecture and just turning their amp up a bit. From a marketing point of view though, the term "balanced" sounds impressive and they can charge a much higher price than the few extra bucks the balanced architecture components actually cost, a win - win scenario for them!!

    G
     
    Last edited: Jan 4, 2019
  3. iridium7777
    thank you for the above explanation, it was very interesting to read.

    i have perhaps a stupid question, let's say you're at 99% setting for amplification, right before you start hearing discernible distortion and you're with a non-balanced output. if you went ahead and switched over to balanced and got the +6dB, would it cross you into the distortion area or would there actually be a "clean" 6dB gain?

    i'm not sure if i'm asking my question in the right way so please let me know if you understand what i'm asking?


    [QUOTE="gregorio, post: 14696946, member: 69811... as a fully balanced architecture would result in roughly 6dB more amplification and this, I suspect, is what audiophiles are hearing and thinking is "better", but of course they could get exactly the same audible result with a single ended architecture and just turning their amp up a bit. From a marketing point of view though, the term "balanced" sounds impressive and they can charge a much higher price than the few extra bucks the balanced architecture components actually cost, a win - win scenario for them!!

    G[/QUOTE]
     
  4. bigshot
    I was evaluating the PM-1s for Oppo prior to them being released. They sent me several pairs when I was doing that and I tested them all side by side. There was no audible difference between them either before or after being used a while. But that isn't surprising because the designer of the cans told me that the manufacturing tolerance on them was +/-1dB. That's tight enough to eliminate sample differences from copy to copy.
     
    iridium7777 likes this.
  5. iridium7777
    burn-in is real, it's an effect. all electronic components will have some burn in and will continue to drift over the life of the component and eventually will degrade to out of spec or will fail completely.

    the above may not happen in your lifetime, but given a definite/indefinite timeline of any individual component the effect is real.

    what you guys are arguing about is the affect. and yes, there will be an affect. is it discernible in music? can you hear a difference between 0.005% THD and 0.002% THD? how about 0.005 and 0.05? if you can then the affect of the burn-in is real to you.

    in my opinion, if you can hear a discernible affect of the burn-in then the manufacturer is garbage. if their sensors drift that much that my ears can actually pick that up then they don't know what the hell they're doing. the only time i want to hear an affect of a burn-in is when something breaks and i've blown my speakers or the amp blew up (well, i don't really want to hear that, but i hope you get my point).





     
  6. CactusPete23
    [/QUOTE]
    No Question in Headfi is a dumb question. It's all about learning more about audio and music.
    When you go to the balanced output (and different jack), you start using a second Parallel Amp in addition to the Primary amp that is used for Single Ended 3.5mm jack. So you will be able to turn down the volume setting a bit, and eliminate that "max power distortion" (IF your amp has that to begin with).

    I believe that 2 identical amps will allow double the mw output; And that should be an extra 3db by my memory. Every ~3db = double the power: Every ~10db = double the perceived volume. Though I will yield to @gregorio who has much more knowledge and experience !
     
    Last edited: Jan 4, 2019
  7. KeithEmo
    I would agree with you.... MOST electronic components don't drift much over their service life.
    I would not expect any noticeably audible effects with modern electronic components.
    However, there are many notable exceptions, for example the short-arc bulbs used in many projectors actually age relatively rapidly.
    (The electrical performance of vacuum tubes changes significantly over the first few hundred hours of use.)

    However, such effects are far more common among mechanical components and devices.
    Many engine parts, like pistons and valves, actually aren't a perfect fit until run for some time, and most car manufacturers recommend some sort of break-in period.
    Car manufacturers used to suggest that an automobile would probably deliver poorer fuel mileage and not meet emission ratings for the first few hundred miles.
    It was also widely recommended to make the first oil change relatively soon - because a disproportionate amount of wear occurs during break-in period.
    (I'm told that this is less true today than it was ten or twenty years ago.)

    And we all know how shoes and gloves, both leather and synthetic, get softer and more pliable after being worn for several hours.
    (The surround on a typical loud speaker is made of a similarly flexible material.)

     
  8. castleofargh Contributor
    warning /!\ I suck at this so I'm really trying to stick to general concepts that I think I understand. I hope I'm not mistaken, but I very much could^_^.
    it depends on what's causing the distortion. even without looking into more complicated stuff, your amplifier could first reach either a voltage or a current limit. the amp will of course play a role in that, but so does the load(IEM/headphone), as it's the load that will determine how much current can flow through it and the sensitivity will decide the actual output setting.

    then the typical doubling of the impedance for the amp's output will impact certain(rare) situations with incredibly low impedance loads.how, will be a case by case problem.
    in practice you will still listen to music at your preferred level, so going balanced will just increase the gain so you will lower the volume setting to get the same preferred level. you may encounter that rare moment where the difference between usable and unusable was 6dB, but I certainly wouldn't make that my reason to go balanced. instead I would simply pay more attention to make sure the device has enough output for my for my headphone.


    the result of going balanced (all else being equal) is double the amplitude of the voltage(+6dB).
    it doesn't mean all "balanced" devices will have +6dB over the SE output, people design their stuff however they want and you can have less or maybe the guy will apply a different gain on that output for the lolz. just like we usually expect double the impedance on a balanced output, but it's not always the case. still a good rule of thumb to expect an increase when balanced though.
     
  9. KeithEmo
    The justification for using a balanced output in a piece of portable equipment has changed over time.
    A lot of portable equipment has a relatively simple power supply - where power is provided by one or two batteries.
    In that sort of equipment, the maximum output power is often limited by the available voltage swing, which is limited by the power supply voltage, which is limited by the batteries.
    In that sort of equipment, a balanced output, which is also known as a bridged output, offers you double the available voltage swing.
    Since power is a function of the square of the voltage this would raise the maximum available power to quadruple the previous limit.
    This would apply, for example, to a simple portable headphone amplifier powered by alkaline batteries.
    However, virtually all modern portable equipment includes some sort of switching regulator, which can be designed to boost the voltage from the batteries to whatever is desired.
    Therefore, this is no longer really an issue.
    (It was never an issue with AC-powered equipment which can be designed to use whatever supply voltage is desired.)

    Another historical benefit of balanced amplifiers is that certain types of distortion may be lowered because they cancel out between the two amplifier sections.
    However, because the distortion is so low on most modern equipment to begin with, this is rarely relevent these days either.

    And, finally, a balanced connection between two components yields much greater immunity from outside noise pickup.
    However, this is mostly an issue when you have low signal levels and/or long cables (which is why it is still favored by studios).
    It is really unlikely to make a significant difference in a headphone amplifier.

    There's one other thing worth noting.....

    If you have an amplifier with a balanced output - then that output must be used with headphones wired for balanced operation.
    (You cannot safely connect a balanced output to an unbalanced load it. It probably won't work and may cause serious damage.)

    However, even if you have headphones with a balanced cable, or which were modified for balanced wiring...
    You can still safely connect them to an amplifier with an UNBALANCED output using a simple adapter cable.
    (It is perfectly safe to connect a balanced load to an unbalanced amplifier output as long as you wire everything correctly.)

    No Question in Headfi is a dumb question. It's all about learning more about audio and music.
    When you go to the balanced output (and different jack), you start using a second Parallel Amp in addition to the Primary amp that is used for Single Ended 3.5mm jack. So you will be able to turn down the volume setting a bit, and eliminate that "max power distortion" (IF your amp has that to begin with).

    I believe that 2 identical amps will allow double the mw output; And that should be an extra 3db by my memory. Every ~3db = double the power: Every ~10db = double the perceived volume. Though I will yield to @gregorio who has much more knowledge and experience ![/QUOTE]
     
    Last edited: Jan 4, 2019
  10. CactusPete23
    Thanks for correcting me. I get easily confused by the terminology used with Audio Equipment. I mean I'm not sure if some "Balanced" DAC/AMPS are really "Dual Mono" Dac/Amps.... (Just a dac and amp combo for each channel)
    - And also find confusing... "balanced" 2.5mm (or 4.4mm) iem/headphone cables only have a ground and a signal wire for each channel (4 wires total)? Where true balanced should be 1 ground wire, and 1 positive signal wire, and 1 negative signal wire for each channel (6 wires total) ?
     
  11. Slaphead
    Just for completion

    "Every ~3db = double the power: Every ~6db double the amplitude: Every ~10db = double the perceived volume."
     
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  12. JRG1990
    XDUOO X20 , is cheap and has loads of features , measurements here: https://reference-audio-analyzer.pro/en/report/amp/xduoo-x20.php .
     
    CactusPete23 likes this.
  13. KeithEmo
    Actually you're confusing several different concepts.....

    "dual-mono" -
    Actually simply means that "you have a completely separate amplifier for each channel".
    This is actually used by many people to mean slightly different things in different contexts.
    If you're talking about a speaker amplifier, it generally means that each channel has a totally separate amplifier and power supply, including separate power transformers (literally like two monoblocks in a single box).
    When you're talking about things like headphone amps or DACs, it generally means that each channel has at least mostly separate parts... but the definition is a bit relaxed.
    So, for example, your DAC has a separate DAC chip for each channel, or a separate amplifier chip for each channel, rather than a stereo chip that serves both channels.
    (But, while you may see a dual-mono power amp with separate power transformers, I've never seen a dual-mono headphone amp that used separate sets of batteries for each channel.)
    It may also have a special meaning in some cases.
    For example, many stereo DAC chips have a special "mono mode"; you can cross connect both channels in the chip into a single channel, using each stereo chip as a mono chip, and get somewhat better performance.

    "balanced" -
    Balanced means different things depending on whether it is applied to a connection or to a device.

    In a balanced connection, you have two signal leads, both carrying out-of-phase versions of the same signal.
    At the receiving end, the two signals are subtracted from each other.
    Starting with the first wire, when you subtract the out of phase signal, you are subtracting a negative, and the result is twice as much signal.
    However, because both wires are run next to each other, any noise that is picked up from outside will probably be almost the same in both wires.
    Therefore, when you subtract the signal in the two wires, the noise is cancelled out.

    In a balanced device, like an amplifier, you have two entirely separate amplifier channels, one amplifying the original signal, and the other amplifying an inverted (out-of-phase) version of it.
    The speaker or load is connected across the outputs of the two amplifiers... which results in the speaker seeing the difference between the two - in effect subtracting them.
    Since one signal is inverted, the difference between them is simply twice the original amount of signal.
    However, assuming that both amplifier channels are identical, and so produce the same exact type and amount of distortion, the distortion cancels out, reducing the overall amount of distortion.
    (Ceratin types of noise, like power supply hum, which may occur equally in both channels, may also cancel out, although random noise like hiss won't.)

    In fact, a true balanced connection only requires two wires, one for the positive signal and one for the inverted signal.
    The third wire is often connected to the shield... and many modern op amps and similar circuits require that both of the other signals be "referenced to a real ground".
    However, strictly speaking, neither a shield nor a ground connection is necessary (although both do offer benefits in certain situations) - the two signals are already referenced to each other.
    Many older transformer-based balanced inputs and outputs omitted the third wire... and some omitted the shield as well... using a simple unshielded twisted pair of wires.

    If you look at the wiring on a typical speaker or headphone driver, you will find that almost all of them use only two wires, and are in fact symmetrical and balanced.
    (Each ear of your headphones has its own driver - and each has two wires - neither of which is specifically required to be connected to ground.)
    The typical three wire common ground cable used by most headphones is simply an expedient to save using an extra wire.

     
    CactusPete23 likes this.
  14. CactusPete23
    @KeithEmo Thank you for taking the time to explain. Think I understand at a "10,000 foot level" now. I can better see the potential and real benefits of balanced devices and connections.
     
    Last edited: Jan 4, 2019
  15. gregorio
    That situation wouldn't really occur. In effect with a balanced architecture you've got the original input signal on the "hot" wire and an exact copy of the input signal (but 180deg out of phase) on the "cold" wire. If on the receiving end (the amp for example) you flip the phase of the cold wire and sum it with the hot wire, you would end up with the signal being +6dB, while any interference picked-up along the way would now be out of phase and would cancel out. In practice, the amp (or other device) itself, is internally almost always a single ended architecture, it's just the signal being transmitted between devices that is balanced. In other words, immediately behind the input connector (of the amp for example) is circuitry which converts the balanced input signal to a +6dB single ended signal, the amp then does it's amplification on this single ended signal and at it's output connector is more circuitry which converts it to a balanced signal again for transmission to the next bit of kit in the chain (speakers for example). Apart from the input and output connectors (and the balancing/unbalancing circuitry next to them) the amp is internally effectively the same in a balanced architecture as an in an unbalanced architecture, except it's obviously designed for a 6dB hotter single ended input signal.

    If you "switched over" to a balanced output, you'd effectively be adding another small (+6dB) amplifier to the output connector, which is a relatively inefficient (noisy) way of doing it. It's only with long cable runs and relatively high interference where a balanced architecture is actually beneficial, where the amount of "picked-up" noise/interference rejected by the balanced architecture is greater than the amount of noise added by balancing the signal in the first place. Therefore in theory at least, assuming relatively short cables and normal levels of interference (a typical consumer environment), a single ended architecture is actually slightly superior (less noisy) to a balanced architecture!

    One last point, it's generally a bad idea to run an amp at 99%. As a general rule of thumb, a setting of no more than about 70% is typically optimal. So, rather than thinking in terms of switching to a balanced architecture, buying a more appropriate (powerful) single ended amp would be the higher fidelity solution.

    Caveats: 1. Some of the above might only apply to pro audio kit. There's different ways of skinning this (balancing) cat and audiophile manufacturers are notorious for doing things differently, typically for marketing purposes only, with no benefit (and sometimes even detrimental) to the actual signal integrity. 2. There are some pro audio power (speaker) amps which operate internally with a fully balance architecture, though very few I'm aware of. However, all the other bits of analogue kit in a typical studio are always internally single ended, it's only the input and output connections that are balanced. 3. Although a balanced architecture is technically more noisy, it shouldn't be enough noise to be audible.

    You're not the only one! As is often the case in the audiophile world, definitions are not uncommonly "blurred", if not entirely changed, to suit some marketing narrative, so it's often very confusing. I'm not entirely sure what some audiophile equipment manufacturers are doing or if what they're marketing as "balanced" sometimes actually even qualifies as "balanced"!

    Yep, +3dB is double the power (watts) and +6dB is double the amplitude (volts). However, +10dB being double the perceived volume is more of a rough general guide than a precise fact. The perception of volume/loudness is dependent on variables other than just level, so +10dB = double the perceived volume is only roughly true and even then, only under certain circumstances.

    G
     
    Last edited: Jan 5, 2019
    Slaphead, bfreedma, Steve999 and 2 others like this.
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