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WoodenSporkAudio t1_ixzlv43 wrote

Well, plenty are much lower levels than 10 μW… for example, campfire andromeda 2020, 7.01millivolts or 3.84 μW (these are 12.8 ohms) is good for 94dB at 1kHz. So the distortion numbers go up even more for lower impedance usually and lesser voltage/power.

Then you get into the impedance curve of a headphone or iem with dips below nominal impedance which have even more distortion levels still.

A little distortion isn’t the end of things and can actually soften the sound sometimes. People often don’t even really understand what a harmonic spike even is for a 1kHz tone. Distortion bad! But why do certain tube amps sound so rich and natural and alive?

For andromeda 2020 if my quick calculations are on track, 88dB is just below one μW

78dB is ~ 1/10 of one μW

All rough math since rounding tiny numbers compounds.

The Apple dongle being what it is, is not the point. It is good, but you can do better for many loads. Many amps that have been deemed “transparent” at 2 volts are simply not when it comes to actual power levels. And that isn’t a bad thing, but it does allow for the possibility of amps to impact performance within the threshold of audibility.

But then people come along and say none of that matters anyway. Can’t have it both ways; but the subreddit does, somehow.

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marvinNoMerge t1_ixzmkcq wrote

And in those edge cases where you can audibly hear the distortion and noise, it would be worth getting a lower noise source. For all other cases it doesn’t matter

The effects of the device are measurable, and it is calculable if the device will provide a sufficiently low distortion signal. Nobody is listening to music on a hd600 at 10µW, yet there’s endless, baseless discussion in this thread of how much (immeasurably) better their not-ultra-high-sensitive headphones are sounding from whatever amp.

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WoodenSporkAudio t1_iy1jydy wrote

If you actually check, tons of people listen at 68dB-73dB on peak, not average… the lower range there is pretty much close to 10 microwatts.

HD650 is close to HD600. 650 is ~98dB/mW, so -30dB is 1 microwatt. (68dB SPL)

I listen at this level often. I listen to speakers at 1mW often too. People over estimate power SPL factors into many loads.

89dB/1000mW speakers French Be tweeters, ~flat, 10mW is 69dB is on the loud end. 1mW listening is common. This has a ton of sound power. Headphones are often 10000x more efficient or more.

So no, people do often describe listening at 1/100 of 1 mW. Or 10microwatts on HD600 on forums. 70dB is commonly reported. Cranking it is 76dB or 80dB. For many listeners.

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marvinNoMerge t1_iy1oeso wrote

Hearing is significantly less discerning at low SPL. If you’re listening at 30db on open back headphones, I promise you will not notice 0.05% THD+N. In fact, I’d imagine it’s starting to get hard to hear the signal at 30db over the environmental noise. The room I’m in currently is 45db of background sound.

If 1microwatt is 30db, 16microwatts would be 42db, and still below the audibility threshold of THD+N, and your signal is still likely lower than environmental sounds so THD+N is likely not top of mind.

Lastly, your baseless condescension isn’t appreciated

Edit: typo, thanks for pointing it out in a non condescending way /s

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WoodenSporkAudio t1_iy1vzv1 wrote

Listening at 30dB huh? Ok. Well, have a good one then. Your math is way way way off.

Didn’t condescend to you, nor did I give any “condensation.”

Take it easy man.

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marvinNoMerge t1_iy1w616 wrote

Correct it please. I got the 30db from your post, you said you often listen at those levels. If you listen higher, it uses much more power and we’re back to being far away from audibility of THD+N.

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WoodenSporkAudio t1_iy29ujs wrote

-30dB meaning minus 30dB, not 30dB.

I just edited in the SPL marker when I realized you misread the factors and thought I meant listening at 1uW is 30dB- it’s ~68dB fwiw. 98dB/mW minus 30dB (a power factor of -1000x = 1uW)

With a stepped attenuator and signal meters on a pro unit, it’s easy to figure out with math that I am listening at the range I described, around 1-16uW and it is totally clear with HD650. Not everyone listens this low, but many do. When it’s even later I listen even lower. Again, Tons of people report topping out at around 70dB on many a listening session.

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marvinNoMerge t1_iy2bwvg wrote

Aha I did misunderstand. Going from the spec of 100db at 1mW, it would be 52db at 15microwatts. I still think that’s acceptable, maybe you don’t. Certainly on the threshold of audibility and at low spl.

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WoodenSporkAudio t1_iy2cuam wrote

1 microwatt is 1/1000 of a milliwatt. So spec of 100dB/mW divided by a power factor of -30dB or minus 10^3 is 70dB/uW not 52dB at 15 microwatts, which would be around 82dB SPL for that load.. give or take.

Can I help you with the fundamentals of the decibel (in relation to power output) which is a logarithmic scale? -3dB is half power, -6dB is 1/4 power, -10dB is 1/10 power. And vice versa for positive factors. 2x, 4x and 10x.

-6dB is a halving of voltage

-12dB is quartering voltage

So you can take any efficiency at dB/mW and figure out the equivalent at a microwatt by subtracting 30 decibels. 10 microwatts is subtracting 20dB from the dB/mW rating, etc.

Be mindful of dB/Volt ratings

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marvinNoMerge t1_iy2ghgd wrote

https://physics.stackexchange.com/questions/366774/twice-the-audio-source-3-6-or-10-db-spl

Not once did I mention mV. I haven’t confused them. Double the spl is 6db additional. You might be confused about perceived volume vs power.

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WoodenSporkAudio t1_iy2hbht wrote

I didn’t say you did. I said be mindful of headphones rated in dB/V since it is different than dB/mW - IE - HD650 ~98dB/mW or 103dB/V

You might be confused about the output power levels we are discussing (in relation to the amp’s distortion and noise at these levels) and how the decibel scale reflects power output factors of amps and therefore SPL… factoring for certain efficiencies at certain nominal impedances and the associated decibel levels they produce.

You’re tripping over your shoelaces correcting me, when my math is spot on.

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marvinNoMerge t1_iy2lklo wrote

Edit: I am wrong! See below

here’s a calculator, let’s try. https://reference-audio-analyzer.pro/en/splfull.php#gsc.tab=0

Enter 100db/mW sensitivity, 300ohm, and 0.0001 mW load on amp gives 60db. 66db at 4microwatt, 72db at 16microwatt. By 70db, the THD+N of the apple dongle is audible transparent. If you’re listening less than that and can pick up noise over background sounds on your open back hd650s, then you can surely justify spending more than $9 on an amp.

Remember we’re talking about THD+N of 0.05% which is 66db below the fundamental measured. You’re not gonna hear that at 70db signal with open back headphones.

It’s a ~6db change for double output power (as I hope you found by using the calculator!) 10db is a doubling of perceived volume. Please read the link, I think it would bridge this gap. Instead, you assumed that I don’t understand logs lol. This won’t go much further, but I do encourage you to at least read it. Fun talking with you.

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WoodenSporkAudio t1_iy2p4gz wrote

I’m done arguing with you. You are either trolling or stubbornly confused.

+6dB when referring to amps and power/voltage as we are here and have been, is a voltage factor of 2x, which is a power factor of 4x. Hard fact. Period. Written in stone. +10dB (when talking about power factors of amps) is a factor of 10x power. Again, hard fact. Period.

Arguing points on something we aren’t taking about which is SPL in the air you are bringing up, aside from what the peak output level will be from a given power level serves nothing except to prop up your broken talking points and bad math.

You typed in 0.0001 mW rather than 0.001 mW

0.0001mW or 0.1 uW is at a power factor of ten less than a microwatt, again, a microwatt of power into this load makes for 70dB SPL output in this example. 100nanowatts is 60dB.

So, if people want to believe you, they are free to. But you are mistaken about we have been discussing, well, trying to. While I’m sitting here listening to a mastering converter with amp at no more than 4 uW and down to about 0.25uW or 250 nanowatts on this song that is averaging about -12dBFS with HD650. All known variables.

You know how I know this? A Stepped attenuator with 1dB steps, a known power output and also professional dBFS meters with peak values and average values. Along with the actual math needed to figure all this out. Even ~approx calculation is possible for a one dB step with an easy to remember power factor.

So, when I say to people, yes, an Apple dongle can drive most headphones pretty well… I mean it. I use one too. With many headphones. But it doesn’t mean it sounds exactly the same as a mastering oriented pro voltage level DAC/amp, especially when listening rather low.

4uW for 74dB peaks isn’t that outlandish is it? It’s like 33dB ambient right now.

Have a good one man.

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marvinNoMerge t1_iy2pqst wrote

Oh my goodness it’s true! I mistyped it! It is 70db and you were right my bad. Yeah I could imagine at low levels THD+N could be high then. I am sorry, I was thrown off by the tone rather than content

Legitimately, thank you for helping me better understand real world listening level distortion.

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WoodenSporkAudio t1_iy024ek wrote

> And in those edge cases where you can audibly hear the distortion and noise, it would be worth getting a lower noise source. —-> For all other cases it doesn’t matter <—-

Dissent in the interest of knowledge and in common hobby with all of you:

Purportedly. Or if it sounds good, you can embrace it. Whoa, what is this sourcery? (Sorcery) “Get you a topping DAC amp and it’s the best it will ever sound.” Maybe. It depends?

Just as the prevailing notion for years and often still is that lossy 320 kbps doesn’t matter vs FLAC for most listeners is purported… since, usually drawing false conclusions from fact based datasets provides the easy false consensus to win arguments with zero honest discussion en masse and sustained in a tick tock manner of forum discourse over time.

Very similar and same are not synonymous. With the tendency to exclude all cases that buck the tailored talking point that “none of this matters… “audibly” and for anything within the constraints to make it easy to defend, at that - is a convenient way to dominate the conversations on the internet at large. Forever. Perceptually is a better term here, and all listeners are not the same. Perception is not consistent, changing the parameters of the listening changes the outcomes.

plain and simply, though close in sound quality, the atom amp is not identical to an O2. For me and my hardware. Not for all potential listeners that don’t demonstrate ability to discern fine differences between mostly alike signals on blind tests with statistics will notice anything at all.

Considering this to be based only in placebo or bias is the easy and quick surefire way to discount and nullify any anecdotes that are, for an individual, assessments that are actually based in reality. “Prove it!” Is the cry. Since the social psychology of forums has perpetuated this type of discourse and made it worse with downvote and upvote buttons.

There is no IRL universal comparator hardware rig like with for music files at ABX.digitalfeed.net to allow swaths of hobbbyists to “test” in a consistent and rigorous manner to even find out.

It is the MO of this subreddit to approve and support tests of something like a D10 and a Modi DAC that do not find any difference. Despite that the methodology is so poor, why bother. Even the best posters’ methodology that mention they did notice something almost always gets dinged for their levels matching or whatever can be used to discount the test, no matter how well people try.

So unless we can have everyone that tries to look into have not only a perfect method with blind or double blind testing proctor, along with a dummy load and a high precision multimeter or an analyzer with an o-scope and levels displays to whatever factor is needed to match the voltages/power levels precisely, then also have seamless and silent instantaneously but blindly controlled switching, that has to be totally non destructive to the signal to try this out at a large enough scale to even matter statistically and remain consistently rigorous; what are we even doing? One or five songs on one day is not a meaningful test. People that pass lossy vs FLAC tests can fail with a couple mistakes despite accurately reporting what they heard.

People that are of the mind that none of it matters need not even actually try to pass the test. Click no difference. Click. While people that do notice fine differences in other tests would have to listen and pick carefully. Why bother to try to prove to people that won’t believe you anyway and will bury even the best and most rigorous testing with the tides of text in a matter of three days. Fail and they mock you. Pass, for real, they mock you. It couldn’t be so, I don’t notice anything type reasoning in what is on an individual listener/music/hardware basis a variable equation.

if this is the demand of the pro “mildly different sound profiles exist” camp but not of the “none of it matters” camp this isn’t good science. Especially if we restrict and exclude all these verifiably different scenarios in place of a mindset which is limiting the consideration to hardware that is supposed to be “transparent” and act on a “very similar is equivalent to same” assumption with the demand of proof on the opposite side, it creates a lazy and uninformed majority to defend all this. One that also demonizes anyone who demonstrates why it matters, even with amps that if you look at the SINAD, most would say it’s all transparent and same = same. It depends on a lot of factors.

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SpecialistCourt3634 t1_iy0dzsr wrote

This can be a science if you want it to be. Has a double blind abx test ever shown a difference for solid state headphone amplifiers? What difference do you perceive? Is there a way you could imagine measuring such a difference?

I’d love for there to be some way to compare amps together if there is such “unmeasurable” differences. Imagine abx testing an amp against known ranked amps to decide the rank of the new one. An amp hierarchy could be made!

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