Is there any objective way to determine whether the Apple dongle is capable of powering a headphone to 100% capability?

[danadam]

The DT770 specs say 105dB, but it doesn't give a power or voltage. I assume that's sensitivity at 1mW...

The spec for DT 770 PRO says nominal SPL 96 dB. From measurements of different DT 770 models on reference-audio-analyzer.pro, it seems to me they aim at 96 dB SPL/mW on all models and then by choosing models with different impedances (32, 80, 250) you get different dB SPL/Vrms.

Btw, this old converter (webarchive) calls dB SPL/mW efficiency and dB SPL/Vrms sensitivity. I don't know how common it is, but I like the distinction.

 

[Palladium]

I mean, it's only a *insert expletive* $10 USB dongle. At worst it doesn't get loud enough and you are out of a paltry $10 at the end so why even overthink this?

 

[tigerapostle]

It's not overthinking if there's an actual straightforward answer.

The main reason that I'm interested in the question is for the sake of being able to save people money when they're asking "which amp/dac to buy?". If there's an objective way to determine if the dongle is able to power the headphones to their full potential, it will extinguish the constant question of "surely there must be more, and I should buy a more expensive amp/dac".

I frequently encounter people who say things like "even if it can get loud enough in general, bass requires more power to amplify, and thus the headphones will be lacking in bass potential" or similar arguments.

 

[majingotan]

It's not overthinking if there's an actual straightforward answer.

The main reason that I'm interested in the question is for the sake of being able to save people money when they're asking "which amp/dac to buy?". If there's an objective way to determine if the dongle is able to power the headphones to their full potential, it will extinguish the constant question of "surely there must be more, and I should buy a more expensive amp/dac".

I frequently encounter people who say things like "even if it can get loud enough in general, bass requires more power to amplify, and thus the headphones will be lacking in bass potential" or similar arguments.

I tried running the Susvara off the Apple Dongle and it gets loud enough for a relaxed listening session but definitely clips when playing Pirates of Carribean OST. You can use an amp that can do 3 watts at 60 ohms to play loud enough at 100 dB SPL.

I use a single ended triode strapped KT88 tube amp since it's naturally able to deliver high voltages to power my Susvara to over 100+ dB SPLs without clipping . You can also use a speaker amp that can get 10 watts at 60 ohms and you should be able to run the Susvara comfortably with ample of headroom

 

[Anderlfs]

My Koss Portapro was very quiet with this apple dongle. I thought about getting a lightweight dongle amplifier to use with it, but I couldn't find one.

 

[staticV3]

My Koss Portapro was very quiet with this apple dongle. I thought about getting a lightweight dongle amplifier to use with it, but I couldn't find one.

The Apple dongle (US version) is capable of driving the Koss PP to about 115dB SPL Peak, which is very loud indeed:

I can think of a few reasons why you might still lack volume:

• You have the EU Apple dongle with 35% reduced volume compared to US.
• You're using the dongle on an Android device, which will apply a further 75% volume reduction by default.
  Here's how to disable this particular limit: Link
• You have an extra volume reduction via a slider somewhere, that you're not aware of.
• You music has very high crest factor and very low dBFS Peak levels, robbing you of headroom.

 

[Anderlfs]

I mean, it's certainly loud, but it lacks punch, the music is a bit anemic. Couldn't it be the low mW supplied? It's the USA model, used on an iphone, apple music, any music.

 

[staticV3]

I mean, it's certainly loud, but it lacks punch, the music is a bit anemic. Couldn't it be the low mW supplied? It's the USA model, used on an iphone, apple music, any music.

With a 60Ω load, the Apple dongle plays perfectly flat even when pushed to its limit (100% volume, 0dBFS input).

The Koss PP OTOH quickly breaks apart when played loud and deep, perhaps that's the issue?

 

[MbphotoX]

Chiming in here, because I'm curious about this subject.
All the theorycrafters tend to flat out recommend the Apple dongle for any application, simply based on the sensitvity rating of a headphone.

The users then sometimes report issues.
"Cannot get loud enough.."
This is the most likely explanation:
1. They use an EU dongle, an Android device, or both.. the dongle doesn't provide the full power it could

or: "The sound lacks punch.. there's no bass.."
this is not due to lack of volume but due to power.
And, this always gets overlooked, the sensitivity is a measurement taken at 1 kHz. Stuff like the Beyer DT990 (quoted in this thread) and probably also all other dynamic headphones have an impedance curve, much like speakers do, too.

the HD650, for instance, has a nominal impedance of 300 Ohms, but peaks at over 500 Ohms around 100 Hz

there's more:

with planars, this should not be an issue, because they are usually flat:

(if they have horrible sensitivity, that doesn't help.. but at least they are not picky about the output they are fed from..)




Doesn't this mean that these headphones will need twice as much power to produce the same SPL in the bass as they do for 1 kHz?!
Why does nobody talk about this?

 

[staticV3]

Doesn't this mean that these headphones will need twice as much power to produce the same SPL in the bass as they do for 1 kHz?!
Why does nobody talk about this?

Because that's not how it works.

The impedance peak significantly reduces the amount of power required at that frequency, not the other way around.

 

[MbphotoX]

Because that's not how it works.

The impedance peak significantly reduces the amount of power required at that frequency, not the other way around.

Okay, you're right.. that's how I remembered it from speakers, especially with impedance dependent amplifiers like my tube amp.

But how is it possible that so many people report issues with dynamic headphones not working properly with dongle DACs?
The Apple Dongle has incredibly low output impedance, so shouldn't have any issues, right?


Is there a measurement we are missing to be able to properly pair amps and headphones, or is this all down to expectation bias?
(I mean, the HD600 are absolutely crappy headphones when it comes to bass anyways.. maybe people just tell themselves that bass is suddenly there once they spent hundreds on an amp?)

 

[staticV3]

But how is it possible that so many people report issues with dynamic headphones not working properly with dongle DACs?

It's just Equal Loudness contours.

Is there a measurement we are missing to be able to properly pair amps and headphones

I don't think so.