Determining Headphone Driver Amp Requirements via Scientific Calculations

Discussion in 'Sound Science' started by WoodyLuvr, Jun 14, 2017.
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  1. WoodyLuvr
    Last edited: Jul 7, 2017
  2. pinnahertz
    Perception is one thing, reality is another.
    If your amp can deliver enough power to hit 110dB SPL, Peak, do that without distorting, and have enough gain to do that with every source you use, and have an output Z about 1/8 to 1/10 of the load, you can draw that line right there.
    WoodyLuvr likes this.
  3. WoodyLuvr
    So there is no supporting science that would show that more power than what is required (reasonably beyond a point of distortion or clipping) = improved sound?
    Last edited: Jul 7, 2017
  4. pinnahertz
    "More power" sometimes comes with other properties, which is why I mentioned them. Power alone won't change the sound, as you apply power as desired for volume, varying it with the volume control (of course the music varies power too). But often higher power amps have lower output impedance, and that could improve things. Mostly it's the perception that because something is supposed to sound better, and more was paid for it, then it does.
    DavidA and WoodyLuvr like this.
  5. WoodyLuvr
    Gotcha :wink:
    Regarding the three amps I mentioned above they are all well under 1 ohm in output impedance so in this case that shouldn't be a factor but I definitely do get your point on this and it makes perfect sense.
    I really appreciate the thoughtful feedback. Exactly where I was coming to in my own conclusions from researching it. I am not finding nor seeing real solid audio science behind what many are saying/recommending in regards to headphone amps and it is a real shame as many people are probably spending way too much of their hard earned money for very little gain and/or improvement if any at all!
    Last edited: Jul 7, 2017
  6. pinnahertz
    After almost 5 decades in audio I find there is more mythology in the field than almost any other hobby or industry. Opinions come from fully biased auditioning, and listening to others opinions. Manufacturers know this, sales people know this, and pseudo-science (or non-science) litters promo literature and the interwebs.

    Welcome to the goofy world of audio. Proceed with caution, and don't pick up any green Sharpies. (Google that last one if you don't know)
    WoodyLuvr likes this.
  7. castleofargh Contributor
    people go for the "more power is better", like they do with more expensive is better, rare is better... there really is no need to give in to those social preconceptions.
    just think of the volume knob as a power knob. the knob changes voltage(=loudness) into a fixed load(the headphone), meaning it also directly changes the amount of power used. beyond getting enough power, which can be estimated within reason for a given load and a given loudness, to get more power into the headphone you need to listen louder. and that's about it. there is no other 7th dimension of energy making the headphone use more power at the same loudness.

    so as long as distortion levels are low and we still have to reduce the power to get our preferred listening level, it would be silly to argue that more power is needed(or used). I know many members do just that on the forum, it just shows how little they understand about electricity.
    I mention distortion levels because often you might get a max power spec, or a max power spec at 1%THD, and those aren't always the same. as an example, for Shiit the power specs aren't clearly specified at 1%THD, so are they? IDK. for the Chord mojo, you start getting mad distortions before reaching the maximum volume level into 300ohm. you will hit 1% somewhere around 5V into 300ohm I think, but then you can still push the Mojo up to about 7V(values from memory, might not be exactly right).
    so once again, knowing for sure what specs we're getting is an important factor before starting to draw BS anecdotal conclusions about how a device must lack power because I didn't like the sound. :wink:
    in the end different amps use different designs and some will do better with some loads at some loudness. generalizations are just that and too much power can sometimes be almost as much trouble as too little. trouble with the volume level setting, maybe channel imbalance depending on the kind of volume setting. sometimes a good deal more noise because of excessive gain. it's not like unlimited power always comes free of consequences.
    WoodyLuvr likes this.
  8. WoodyLuvr
    @castleofargh @pinnahertz @bigshot @DavidA @Archimago

    Apologies gentlemen for beating a dead horse here... :deadhorse: please set me straight; the harsher, the better!

    I believe I am experiencing some wimpy bass performance (minor bass roll off) when using my Nhoords with my DragonFly Black but I don't know if it is just in my mind... based on the below specs and calculations (as well as previous posts in this thread) my DragonFly should have more than enough power to handle extremely dynamic bass peaks. When I directly plug my Nhoords into a Benchmark DAC3 or MHA-100 or into a MC2105 or Woo WA5 (using either the DAC3 or the line-out feature of my DragonFly) I seem to hear a similar and noticeable change in bass... is this really possible and happening? If so, would the culprit be the combination of the DragonFly's usage of USB power supply and being a single integrated op-amp + DAC chip? As I can’t seem to find a voltage value for my DragonFly Black at a 32 ohm load (so I might be grossly assuming this) could it be that the power output may not be consistent at all loads? DAC wise I have carefully and repeatedly compared my DragonFly with the DACs on the DAC3, MHA-100, and Deckard and neither I (nor my friend) can discern any difference between them using my Nhoords and only a very, very minor difference when with his HD-800s so I don't believe this is a DAC or source issue but an amping issue or am I out of my mind? What say you?

    AudioQuest DragonFly Black 1.5
    32-bit ESS Sabre 9010 Integrated Op-Amp DAC
    Power Output & Impedance: 1.3 Vrms (1.85 Vmax; 3.68 Vp-p) @ 0.61 ohms (1kHz 0dBFS 16/44 square wave)

    Nhoord Audio Red v2
    32Ω; 95dB/1mW; 18hz -20,000hz
  9. castleofargh Contributor
    you still want it to be about power ^_^.
    install RMAA and test your own rig with loads(I can't understand measuring something with an amp section unloaded, what's the point?). or get a microphone and start recording the output of your headphone fed by different sources to measure changes. but all it will tell you is that different gears have some differences, and if you're dreaming or if the differences are very real. the actual cause of those changes probably won't pop right out as a conclusive evidence. different devices just have too many variations and going with the good old "the bass was meh, it must be the lack of power", that so many audiophiles love for it's convenient simplicity, is still just random correlation assumed to be the direct cause. and it stays that way until a great deal of objective testing is done that nobody will do. so basically a guess.
    WoodyLuvr likes this.
  10. WoodyLuvr
    Really appreciate the response.

    Not trying to sound like a complete lunatic or troll: why/how does bass come across so differently between amps that I am testing or is it again something just in the head and not sound science based?
  11. bigshot
    It's probably small differences in volume level. The sound is probably the same. The volume isn't. You have to calibrate that to get a true comparison. Bass and dynamics are most affected by volume differences.
    WoodyLuvr likes this.
  12. DavidA
    @WoodyLuvr, while I'm not smart enough to give you a scientific reason for the differences what @bigshot and @castleofargh noted are great points. I think this is one reason I have and keep the 4 amps on my main listening setup, its because they all react differently to various headphones due to the different designs of the individual amps.
    I'm one that doesn't like USB for audio due to the use of drivers in Windows based systems and like the simplicity of either coax or optical. I also don't like the use of the USB cable/port being used to also provide power to a device since the power and signal wires are in so close proximity to each other.
    WoodyLuvr likes this.
  13. WoodyLuvr
    Thank you all for the feedback... desperately trying to avoid drinking the "kool-aid" and falling into the rabbit hole. Respects
    Last edited: Nov 5, 2017
  14. WoodyLuvr

    So after having my Foobar2000 and music files "un-FUBAR'd" (corrected by an audio professional) I am finally rocking from my DragonFly Black hearing plenty of low bass now with no noticeable roll off or distortion as heard before. So as many of you correctly suggested it was only a guess before and my DragonFly was wrongly accused as it appears it is indeed outputting more than 1V across all loads and thus providing my Nhoords with more than the required 30 mW to reach 110 dB SPL.

    Regarding Foobar2K... music tracks were corrected with replay gain * (some music files were replaced with better quality ones); Meier Audio Crossfeed DSP plugin was loaded and set at 15; the Graphic Equalizer properly set (ever so slightly) for my Nhoords weaknesses and my listening preference; Tal TUBE VST plugin installed and set on "Gentle Tube" (I know it is distortion but I like the effect and it is easy to turn on/off).

    * Really surprised when I was shown that some of my quieter ambient electronic/classical tracks were up to 23 dB in dynamic range and that between my music genres there was over 36 dB difference in range!
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