Home Resources What is Sensitivity in Headphones? [Explained]

What is Sensitivity in Headphones? [Explained]

by Stuart Charles Black

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This is part 2 in a series on Headphones and Their Drivers. Don’t hesitate to share and comment if you found these helpful!

  1. What is Headphone Impedance?
  2. What is Sensitivity in Headphones? (You are here)
  3. What is Output Impedance?
  4. What is a Headphone Driver?
  5. What is a Planar Magnetic Driver?

Greetings friend and Welcome aboard!!

Before we get into the question of What is Sensitivity in Headphones, grab a snack, sit back, and relax because…

You’ve come to the right place!!

What I will bring you in this review

  1. Introduction
  2. What is Sensitivity in Headphones?
  3. SPL and Loudness
  4. Amps and Impedance
  5. Final Word

Now without further ado, let’s get rolling!!


Introduction


I previously never gave the word Sensitivity much attention.

For the longest time, it was just an obscure term that you could find in the Specifications area of most audiophile headphones.

It was just a number and didn’t mean a whole lot.

In reality, it’s pretty important!

What’s unfortunate is that a lot of companies don’t specify it very well, and it’s becoming harder and harder to pinpoint a number a lot of the time.

Many times in my research, I will sift through countless pages in Google before I find a number.

This should never be, as Sensitivity is crucial in determining if your headphones will need Amplification or not.

So…


What is Sensitivity in Headphones?


To start:

Sensitivity is simply a measure of how efficient a headphone driver is at using the power it receives.

This power is used to deliver to us the sound we hear (free of distortion).

Sensitivity also refers to the amount of current that a headphone requires.

Put another way, if there’s no current flowing through the voice coil of the driver, then there’s no magnetic field.

If there’s no magnetic field, there’s no interaction with the magnet.

If there’s no interaction with the magnet, there’s no movement of the diaphragm.

No movement of the diaphragm = No sound. You can see how important Sensitivity is becoming!

For instance:

  • If you have a headphone with a higher Sensitivity, it requires less power (from the amp) to reach optimal listening levels. Hence, it’s more efficient.
  • If you have a headphone with a lower Sensitivity, it requires more power (from the amp) to reach optimal listening levels. Hence, it’s less efficient.

This is why it’s essentially useless to buy a powerful headphone amp for a headphone that has high Sensitivity. It just doesn’t have any use for all that power.

So in a nutshell:

  • Low Sensitivity = Lots of power required.
  • High Sensitivity = Less power required.

SPL and Loudness


Focal Utopia ReviewGeneral standards for loudness are around 110 dB. If you prefer it louder than that, 115. If you prefer it quieter, 105.

Generally speaking, 97dB is about the middle ground, and is right on the cusp of what I would consider “low.”

A headphone like the HD600 has 97dB of Sensitivity and a 300 Ohm Impedance.

This basically means that it requires around 20mW of power to reach this ceiling of 110dB that we talked about.

A great example of this is the relationship between the Audeze LCD-4 and the Focal Utopia.

On October 10th, 2018 I got a chance to attend the Music Matters Convention at Audio Advice here in Raleigh, NC.

There was a plethora of companies and reps present, including guys from both Audeze and Focal.

I have already demoed the Utopia’s on many occasions and to this day they are still the best headphones I’ve ever heard.

I wanted to do an A/B comparison with the LCD-4 to see if I liked those better.

I was using the fantastic NAIM DAC-V1 and first started with the LCD-4.

It took quite a bit of knob-turning to get the music to an optimal listening level. Why? Because it’s not very efficient. Its Sensitivity is 97dB.

Once I finally got it high enough (around 100+ on the NAIM) I really liked the sound but thought it lacked a certain energy.

It’s a very dark headphone in general, keeping in line with the theme of most Audeze headphones.

The Utopia’s Sensitivity is 104dB/mW, so it needs less juice to reach optimal levels.

You can easily tell since the volume must be turned back down before listening to the Utopia. It simply doesn’t need a whole lot to get pumping.  

So with a headphone that has a 105dB of Sensitivity, only 2.5mW of power is required to reach optimal loudness (110dB SPL). Easy right?

Sensitivity is measured in either dB/mV (decibels per millivolt), while efficiency is measured in dB/mW or dB/W (decibels per milliwatt/watt).


Amps and Impedance


Essentially, a headphone’s Impedance, Sensitivity, and resulting Efficiency will help you determine if it requires an amp to reach a listenable level.

Listenable simply means loud enough. Peak loudness. It doesn’t just mean “I can hear the music.”

If you were to plug an HD600 into your phone without an amp you’d wonder what all the fuss was about.

It doesn’t sound good at all and is much too quiet to actually enjoy.

Generally speaking:

  • Higher Impedance headphones need more power from the amp.
  • Lower Impedance headphones need less power from the amp.

Impedance is simply the resistance that the headphones present to the amp as an electrical load.

We discussed briefly the power requirements of the HD600.

Again, all you really need to know before buying an amp is the Impedance and Sensitivity of the headphones. Both are very important.

  • The HD600 absolutely needs an amp because it has both a low Sensitivity and high Impedance.
  • Something like the Samson SR850 doesn’t need an amp because it has both High Sensitivity and Low Impedance. This basically means that it can achieve a loud sound with hardly any power.
  • A lot of Planar Magnetic offerings such as my beloved HE400i have a very low Sensitivity (93dB) but also a low impedance. So it needs quite a bit of current, but also a lot of power from the Amp to reach an acceptable level; somewhere between 39-79 mW.
  • Even some really cheap open backs like the venerable AKG K240 have extremely low Sensitivity (91dB) and must be paired with an amp.

That said, it’s also important to take a gander at the spec sheet of the Amp/DAC in question as well!

For instance, my Oppo HA-2 provides 30mW of power into 300 Ohm. It just makes the cut for my HD600s. Anything over 300 Ohms is not recommended.

An amp like the Magni 3 provides 430mW into 300 Ohms.

This is why it works so well with a variety of headphones. It becomes an all-purpose tool.

The ATOM from JDS Labs is similar.

JDS ATOM HEVI Review

It pumps out an insane amount of power for all impedance levels and does fantastic with every headphone I’ve tried with it.

Clean and neutral!

One of the best tools at your disposal is a simple spec sheet from the manufacturer when looking at amps.

If it doesn’t clearly indicate power outputs at various Impedance loads, you should probably next it. Lol.

A good example of a company I trust is JDS Labs.

They always provide concrete numbers so there’s no confusion, their amps are some of the best around, and they’re extremely affordable. I’ve tried their cMoy, ATOM, Objective 2, and Element. They’re all top-notch and provide an insane amount of power into any Impedance rating.

Let’s take a look:

The Objective 2

  • Max Output (33 Ohms): 613 mW
  • Max Output (150 Ohms): 355 mW
  • Max Output (600 Ohms): 88 mW.

The Element

  • Max Continuous Output, 600Ω 140 mW (9.4VRMS)
  • Max Continuous Output, 150Ω 505 mW
  • Max Continuous Output, 32Ω 1.1 W
  • Peak Output Power, 32Ω 1.5W

The Element is definitely more powerful than the Objective 2, but both amps sound fantastic. I did a neat comparison on the two if you were interested: JDS Labs Element vs. Objective 2! Check it out if you fancy 🙂

With that, let’s wrap this thing up!


Final Word


Sensitivity in headphones is a tricky subject, but shouldn’t have to be all that complicated.

Generally, a headphone with around 97dB or below isn’t that efficient.

Most headphones below this threshold tend to be planar magnetics like HIFIMAN, Audeze, etc.

Some like the K240 are also extremely low and that’s why it’s important to know these things before you buy!

A headphone that’s around 100dB and greater is very efficient and usually doesn’t need any sort of amplification to sound good.

The internal amp in your mobile device should suffice in most cases, but it’s never set in stone.

My top option for a headphone around the threshold of 97dB is of course my beloved HD600.

Learn More:

 

My top option for a higher Sensitivity headphone that doesn’t need a lot of power is most certainly the Sony MDR-7506 @ 106dB. It’s been a quintessential studio headphone for decades and still can be had for a great price.


Well, that’s about it for today my friend! I hope I’ve answered your question of What is Sensitivity in Headphones?

Questions? Comments? Requests? Did I miss the mark on something? Looking for something else? Please let me know down below or Contact me!!

How did I do? I would love to hear from you. Until next time…

All the best and God bless,

 

 

-Stu

[Xtr@Ba$eHitZ]

Can’t decide which headphones to purchase? Interested in a complete buyers guide outlining over 40 of the best options on the market? Click on over to the best audiophile headphones to learn more!!

Be sure to also check out my Reviews and Resources page for more helpful and informative articles!

 

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8 comments

Jamiro Hazel December 28, 2018 - 11:23 pm

I had no idea what Sensitivity in headphones was, but this article helped me understand the concept a little better. It says that Sensitivity is the amount of current that a headphone requires. In other words it measures efficiency of the headphones. But when you buy headphones, they don’t talk about the efficiency. I want to know why it’s so vital to know the Sensitivity of my headphones? And how can that be measured? 

Reply
Stuart Charles Black December 30, 2018 - 6:15 pm

Hey Jamiro!

Normally audiophile type headphones will supply that number, but most big named companies may or may not; it just depends. Bose and Beats for example don’t, but to be fair their headphones have never needed separate amplification.

It’s vital because it indicates how much power is going to be required from an amplifier to reach acceptable listening levels.

So if you drop $300 on a headphone but didn’t check the Impedance and Sensitivity, you may be frustrated to know that you’ll have to spend more money on An amp that will enable it to sound loud enough.

Many people who buy these types of headphones leave negative reviews online stating “It’s not loud enough” without understanding what these numbers mean and why they’re important. 

Thanks for stopping by!

Reply
Babsie Wagner December 28, 2018 - 11:23 pm

I honestly never really knew any of this information when it came to headphones, but I can tell you a good set from a bad set and I’m actually just a little tired of always getting bad sets. I can’t stand it when they aren’t comfortable or I just can’t hear what I want to hear in a clear, clean, loud enough way, you know? I am so happy I stumbled upon your website. The information is clear and concise and is really helping me to learn all the information I need to make an informed decision instead of believing some ad that says how great they are! Thanks for your hard work in putting this together!

Reply
Stuart Charles Black December 30, 2018 - 12:53 am

Thanks Babsie!

Let me know if you ever need a hand in deciding on something 🙂

Reply
Bex December 28, 2018 - 11:24 pm

Wow! I really enjoyed reading your detailed and insightful post. I LOVE learning and absorbing knowledge and I was completely ignorant about the fact that sensitivity in headphones is actually a thing and a very interesting and important factor in considering when tuning into sound. It seems to me that you have taken the complexities of what is entailed in generating an optimal sound experience and laid it out in a simple and easily understandable manner. Thank you so much! I will check out more posts! Great content!

Reply
Stuart Charles Black December 29, 2018 - 4:05 pm

Thanks Bex!

I agree; Sensitivity is an important metric and perhaps more important than Impedance in my opinion. I appreciate your comment as well because I always try to write in a way that makes sense for the majority of people. I know that I myself appreciate when something is laid out simply, so I attempt to do that for my readers as well. 

Don’t hesitate to reach out if you ever need a hand!

-Stu

Reply
Felix December 6, 2023 - 11:22 am

I bought a DT 900 80ohms headphone which has a sensitivity of 96 dB. What kinda amp do you recommend ? How much of output impedence should the amp have in order to drive my headphone ?

Reply
Stuart Charles Black December 8, 2023 - 5:32 pm

Felix,

Thank you for the comment! Generally speaking, if you’re wanting the amplifier in question to portray the headphone’s sound signature as accurate and true as possible, go with an amp with a lower output impedance. Typically anything below 1 is good, but I should caution you that very very low numbers, as in the case of the Hugo 2, aren’t all that ideal as the sound can actually become a bit too sterile/cold/lifeless. Something like the JDS ATOM is great because it’s neutral (0.7 Ohm) without coming across as soulless.

The ATOM, as well as amps like the K5 Pro/K7 provide plenty of power to drive the DT900 with a good amount of headroom left over.

I should also mention that the ATOM is an amp only and will need to be paired with a DAC (JDS’ ATOM DAC is great), while the K5 Pro/K7 are amp/dac combos.

Hope that helps! Please keep me posted with questions.

-Stu

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