[xnor]

The following table is based on measurements, not manufacturer specs.
 
Target SPL is 110 dB SPL.
The source is assumed to output 2 V. The amp is assumed to be a voltage source (0 ohm output impedance).
Voltage, current, power are RMS figures.
 
What do the columns mean?
S@1V is the sensitivity with 1 V, 500 Hz sine wave input in dB SPL.
Z is the impedance at 500 Hz in Ω.
Voltage is the required voltage to reach the target SPL.
Current is the required current to reach the target SPL in milliamperes.
Power is the required power to reach the target SPL in milliwatts.
Gain is the gain the headphone amplifier theoretically needs to reach the target SPL without excess gain. If needed you can add a few dB excess gain (suggestion: 3 to 9 dB).
Notes:

1. 1 kHz: the measurement was done at 1 kHz instead of 500 Hz
2. specs: based on specifications provided by the manufacturer, not independent measurements
3. nc: noise canceling enabled

 
 
There is no guarantee that the data is 100% correct. The sensitivity of some headphones can vary as much as +/- 3 dB (some manufacturers even specify this explicitly).
 
 

Manufacturer	Model	S@1V [dB SPL]	Z [Ω]	Voltage [V]	Current [mA]	Power [mW]	Gain [dB]	Notes
AKG	K240 Studio	103	64	2.239	34.98	78.311	1
AKG	K271 MK II	106	65	1.585	24.383	38.644	-2
AKG	K272 HD	110	65	1	15.385	15.385	-6
AKG	K550	115	35	0.562	16.067	9.035	-11
AKG	K601	99	131	3.548	27.085	96.101	5
AKG	K701	105	65	1.778	27.358	48.65	-1
Audeze	LCD-2	108	45	1.259	27.976	35.22	-4
Audeze	LCD-3	102	48	2.512	52.331	131.449	2
Audio Technica	ATH-AD700	113	35	0.708	20.227	14.32	-9
Audio Technica	ATH-AD900	114	37	0.631	17.053	10.76	-10
Audio Technica	ATH-AD900X	114	38	0.631	16.604	10.477	-10	1kHz, specs
Audio Technica	ATH-ANC7B	118	305	0.398	1.305	0.52	-14	nc
Audio Technica	ATH-ANC9	109	100	1.122	11.22	12.589	-5	nc
Audio Technica	ATH-M50	115	38	0.562	14.798	8.322	-11
Beats by Dr. Dre	Pro	117	18	0.447	24.816	11.085	-13
Beats by Dr. Dre	Studio	121	216	0.282	1.305	0.368	-17	nc
Beyerdynamic	Custom One Pro	116	18	0.501	27.844	13.955	-12
Beyerdynamic	DT770 Pro	98	251	3.981	15.861	63.143	6	1kHz
Beyerdynamic	DT770-32	111	32	0.891	27.852	24.823	-7
Beyerdynamic	DT770-600	100	557	3.162	5.677	17.953	4
Beyerdynamic	T1	99	750	3.548	4.731	16.786	5
Beyerdynamic	T5p	116	41	0.501	12.224	6.127	-12
Beyerdynamic	T70	110	380	1	2.632	2.632	-6
Beyerdynamic	T90	102	308	2.512	8.155	20.486	2
Bose	AE2	112	36	0.794	22.065	17.527	-8
Bose	QC15	113	4800	0.708	0.147	0.104	-9	nc
Bowers & Wilkins	P5	117	27	0.447	16.544	7.39	-13
Denon	AD-D2000	115	25	0.562	22.494	12.649	-11
Denon	AH-D1001	112	31	0.794	25.623	20.353	-8
Denon	AH-D7000	114	25	0.631	25.238	15.924	-10
Denon	AH-D7100	108	30	1.259	41.964	52.83	-4
Fischer Audio	FA-003	117	75	0.447	5.956	2.66	-13
Fostex	T50RP	107	54	1.413	26.158	36.949	-3
Fostex	T7	113	80	0.708	8.849	6.265	-9
Fostex	TH900	108	25	1.259	50.357	63.396	-4
Grado Labs	SR60i to 325i	111	34	0.891	26.213	23.363	-7
Hifiman	HE-4	90	63	10	158.73	1587.302	14
Hifiman	HE-500	102	34	2.512	73.879	185.576	2
Hifiman	HE-6	89	43	11.22	260.935	2927.734	15
Hifiman	Re0	118	60	0.398	6.635	2.641	-14
KRK Systems	KNS6400	110	34	1	29.412	29.412	-6
KRK Systems	KNS8400	106	35	1.585	45.283	71.768	-2
Sennheiser	Amperior	113	22	0.708	32.179	22.781	-9
Sennheiser	CX880	120	34	0.316	9.301	2.941	-16
Sennheiser	HD202	119	34	0.355	10.436	3.703	-15
Sennheiser	HD280 Pro	114	73	0.631	8.643	5.454	-10
Sennheiser	HD555/595	114	72	0.631	8.763	5.529	-10
Sennheiser	HD558/598	112	70	0.794	11.348	9.014	-8
Sennheiser	HD600	105	322	1.778	5.523	9.821	-1
Sennheiser	HD650	104	333	1.995	5.992	11.955	0
Sennheiser	HD700	105	199	1.778	8.936	15.891	-1
Sennheiser	HD800	103	430	2.239	5.206	11.656	1
Sennheiser	IE800	125	18	0.178	9.879	1.757	-21
Sennheiser	PX100 II	114	34	0.631	18.558	11.709	-10
Sennheiser	PX200 II	115	38	0.562	14.798	8.322	-11	1kHz
Shure	SE215	126	18	0.158	8.805	1.395	-22
Shure	SE535	133	36	0.071	1.967	0.139	-29
Shure	SRH1440	107	38	1.413	37.172	52.507	-3
Shure	SRH1840	102	66	2.512	38.059	95.6	2
Shure	SRH440	116	41	0.501	12.224	6.127	-12
Shure	SRH750	113	39	0.708	18.152	12.851	-9
Shure	SRH840	116	44	0.501	11.391	5.709	-12
Shure	SRH940	113	40	0.708	17.699	12.53	-9
Skullcandy	Aviator	118	36	0.398	11.059	4.402	-14
Skullcandy	Crusher	114	32	0.631	19.717	12.441	-10	1kHz, specs
Skullcandy	Mix Master	119	20	0.355	17.741	6.295	-15
Sol Republic	Tracks	118	60	0.398	6.635	2.641	-14	1kHz
Somic	MH463	106	45	1.585	35.22	55.82	-2	1kHz, specs
Sony	MDR-MA900	111	15	0.891	59.417	52.955	-7
Sony	MDR-XB1000	115	27	0.562	20.827	11.712	-11
Sony	MDR-XB500	123	43	0.224	5.206	1.166	-19
Sony	MDR-XB700	115	28	0.562	20.084	11.294	-11
Superlux	HD668b	108	61	1.259	20.638	25.982	-4
Superlux	HD669	110	62	1	16.129	16.129	-6
Takstar	HI2050	104	60	1.995	33.254	66.351	0	1kHz, specs
Ultrasone	Edition 8	115	34	0.562	16.539	9.301	-11
Ultrasone	HFI580	115	36	0.562	15.621	8.784	-11
Ultrasone	HFI680	115	75	0.562	7.498	4.216	-11
Ultrasone	HFI780	116	40	0.501	12.53	6.28	-12
Ultrasone	Pro550	117	65	0.447	6.872	3.07	-13
Ultrasone	PRO750	114	41	0.631	15.389	9.71	-10
Ultrasone	PRO900	108	43	1.259	29.277	36.858	-4
V-Moda	Crossfade M100	115	36	0.562	15.621	8.784	-11
Yamaha	PRO 300	116	58	0.501	8.641	4.331	-12

 
 
 
Some have raised concerns with 110 dB SPL being too loud. Well, that is just the absolute highest SPL you can reach with a full-scale 500 Hz tone and the volume set to max.
Music has a higher crest factor than sine tones, which means that the RMS value will be much lower.
 
The following graphic shows a volume control with a 15A taper pot as found in many heapdhone amps. Ideal range should be somewhere between 10 and 2 o'clock.
The inner labels show the attenuation of the pot at each full hour. So 110 becomes 95 dB SPL at 12 o'clock.
The outer blue/red labels show the overall perceived SPL of an uncompressed classical track and a heavily compressed metal track respectively. Loudness was calculated using an EBU R128 compliant scanner.
 
Obviously, you can really hurt your hearing if you listen to highly compressed music and turn up the volume. With less compressed music overall levels will be a lower but there can still be very loud passages or short peaks in SPL.
 
So turn the volume down - better be safe than sorry. Don't rely on calculations only. Use a sound level meter.
 
 
 

 
 
Please let me know if you find that some values are completely off or want some headphones added.

 

[Greenleaf7]

Thanks for the great work. Could you also include these models from beyerdynamic? I've provided the links below so you won't have to go searching for it.
 
T 70 - http://europe.beyerdynamic.com/shop/hah/headphones-and-headsets/at-home/music-pleasure/t-70.html
T1    - http://europe.beyerdynamic.com/shop/hah/headphones-and-headsets/at-home/music-pleasure/t-1.html
T5p  - http://europe.beyerdynamic.com/shop/hah/headphones-and-headsets/at-home/music-pleasure/t-5-p.html
T 90 - http://europe.beyerdynamic.com/shop/hah/headphones-and-headsets/at-home/music-pleasure/t-90.html
 
Thanks in advance.

 

[HalidePisces]

Audio Technica ATH-AD700
Sony MDR-MA900

For fun, you could do a "marketing headphone" (Beats, SOL Republic, etc.).

 

[Steve Eddy]

Quote:

The source is assumed to output 2 V.

 
RMS I presume?
 
se

 

[xnor]

Yes, 2 Vrms.
 
Obviously the target SPL with that gain is only reached with a full-scale 500 Hz tone. But depending on the frequency response the headphone will produce a couple dB more at other frequencies.

 

[xnor]

Added some more headphones. SOL Republic Tracks has a terrible dip at 400 Hz, which is the only headphone so far that has such a problem near 500 Hz, so I chose 1 kHz instead.

 

[Greenleaf7]

Thanks for the added information. I have a question regarding how the calculations work. Take for instance the Beyerdynamic T1, which is rated at 600 ohms. Why did you base the calculations on a 730 ohm impedance?

 

[00940]

I might be wrong but... looks like the value in mA are based on the RMS voltage. They should be based on the peak voltage.

 

[xnor]

@Greenleaf7: That's because manufacturers provide nominal impedance in the specs. That number is just an approximation anyway.
 
The measurements of T1's I've seen never reach 600 Ohm. The minimum at 2 to 4 kHz is somewhere around 630 Ohm. It has a very broad impedance peak at about 80 Hz, so the impedance at 500 Hz is higher.

 

[xnor]

@00949: Numbers are based on RMS power. P = Vrms^2 / R = Vrms * Irms.

 

[00940]

Irms is almost never used, datasheets and specification sheets usually use Ipeak and that's what is assumed when giving values in mA. If you use it, you should specify it (as you did for V).

 

[xnor]

Added some more headphones, added manufacturer column.
 
Interestingly, with just 3 dB excess gain more than 70% of the headphones listed require no more than unity gain (0 dB).
 
Even with a 1 V source like an iPod the SE535 would be fine with 20 to 14 dB of attenuation due to their high efficiency.
 
And to the DIYers and reviewers: If you have a DAP or amp that is free of hiss with the SE535 it is very likely going to be fine with any other earphone or headphone.

 

[xnor]

As we know, ideally the volume control pot should spend most of its time between 10 and 2 o'clock.
 
Assuming the pot ranges from 7:00 to 17:00 and has a 15A resistance taper we get an attenuation of about 22 to 9 dB at those positions.
With the 110 dB SPL target and no excess gain that results in 88 dB to 101 dB SPL with the 500 Hz full-scale tone.
 
Using an EBU R-128 loudness scanner I looked at some completely uncompressed classical / hypercompressed metal tracks.
The perceived overall loudness of those tracks, which may have soft and loud passages, is up to 20 dB / 6 dB quieter compared to a full-scale 500 Hz tone.
 
 
What does this all mean?
 
Example:
110 dB SPL target with a 2 V source as used in #1
Sennheiser HD800 => amp with 0 dB gain
no excess gain
 
1) volume control at 10 o'clock
perceived overall loudness:
a) classical recording: 68 dB SPL
b) compressed track: 82 dB SPL
 
2) volume control at 2 o'clock
perceived overall loudness:
a) classical recording: 81 dB SPL
b) compressed track: 95 dB SPL
 
3) volume control at max
perceived overall loudness:
a) classical recording: 90 dB SPL
b) compressed track: 104 dB SPL
 
 
(EBU R128 uses Loudness Units instead of dB but I used plain old decibels to avoid [even more] confusion.)
 
 
edit: will have to do some measurements to see how big the error is using a 500 Hz tone as reference

 

[ab initio]

Couple quick thoughts
 
1) First and foremost, thank you for this reference! 

This is extremely helpful (see below) and *should* be linked to very very often in the future.
 
2) If you are from an english-speaking country:

 sed '/[0-9]\,/s/\,/./g'

 I spent 20 minutes trying to figure out how the heck the HE-6s needed 3 kW to reach 110 dB!!!
I knew they were inefficient, but I didn't think they were that bad!

 
4) there is no number 3.
 
5) This data is super helpful for guiding people who are considering new headphones or amplifiers and are unsure whether or not their amp-cans combination will work. If they have cans A and are considering cans B, they can compare the sensitivities, current requirements, and voltage requirements and weigh the differences against their amp's capability to source that current and voltage. 
 
6) I think 110 dB is a little bit high for a reference loudness, especially since 90dB is the typical threshold for hearing damage. Because this data is especially useful for guiding newer enthusiast in their search for headphone nirvana, I think it's a little dangerous to give the impression that they should be listening at 110dB SPL with any regularity. Perhaps you could put a disclaimer in the original post warning against prolonged exposure to  >= 110 dB. Of course I'm just picking nits here.
 
 
+1 rep
 
Cheers!

 

[KamijoIsMyHero]

Quote:

As we know, ideally the volume control pot should spend most of its time between 10 and 2 o'clock.

 
why? I never heard of this ideal placement for a volume pot