[bcwang]

Prompted by the higher than expected sensitivity of the HD800, I spent some time creating a spreadsheet of headphones output power required at different level, using their official sensitivity spec to scale with. I thought it was quite interesting after looking at the results, so I'm going to share.

The list of values is based on:

-Power required to reach 120db. (Note, some headphones cannot actually reach this level because it exceeds their max power capability. This is just theoretical.)

-nominal impedance value. (some headphones change impedance depending on frequency, so it wouldn't be accurate in those cases. example: HD800 goes from 300 to almost 650 ohm, so the voltage required to hit the required power output is over 11v in that case, not just the 7 something in the list)


Ordered by Power Required:
HE5 - 1995 mw - 282 ma - 7.06v rms
K204DF - 1585 mw - 51ma - 30.84v rms
K701 - 510 mw - 91 ma - 5.62v rms
HD800 - 210 mw - 26 ma - 7.94v rms
HD600 - 199 mw - 26 ma - 7.74v rms
HD650 - 167 mw - 24 ma - 7.08v rms
RS1 - 158 mw - 70 ma - 2.25v rms
ER4S - 100 mw - 32 ma - 3.16v rms
RE0 - 100 mw - 39 ma - 2.53v rms
T1 - 63mw - 10 ma - 6.15v rms
SRH840 - 63 mw - 38 ma - 1.67v rms
Westone3 - 20 mw - 26 ma - 0.77v rms
E4C - 13 mw - 21 ma - 0.60v rms
GR8 - 1.6 mw - 3.6 ma - 0.44v rms
UE-18 Pro - 2.7 mw - 11 ma - 0.24v rms
Triple-Fi 10 - 2 mw - 7.9 ma - 0.25v rms
SE530 - 1.3 mw - 6 ma - 0.213v rms
ES3X/UM3X - 0.4 mw - 2.7 ma - 0.15v rms

Ordered by Current Required:
HE5 - 1995 mw - 282 ma - 7.06v rms
K204DF - 1585 mw - 51ma - 30.84v rms
K701 - 510 mw - 91 ma - 5.62v rms
RS1 - 158 mw - 70 ma - 2.25v rms
RE0 - 100 mw - 39 ma - 2.53v rms
SRH840 - 63 mw - 38 ma - 1.67v rms
ER4S - 100 mw - 32 ma - 3.16v rms
HD600 - 199 mw - 26 ma - 7.74v rms
HD800 - 210 mw - 26 ma - 7.94v rms
Westone3 - 20 mw - 26 ma - 0.77v rms
HD650 - 167 mw - 24 ma - 7.08v rms
E4C - 13 mw - 21 ma - 0.60v rms
UE-18 Pro - 2.7 mw - 11 ma - 0.24v rms
T1 - 63mw - 10 ma - 6.15v rms
Triple-Fi 10 - 2 mw - 7.9 ma - 0.25v rms
SE530 - 1.3 mw - 6 ma - 0.213v rms
GR8 - 1.6 mw - 3.6 ma - 0.44v rms
ES3X/UM3X - 0.4 mw - 2.7 ma - 0.15v rms

Ordered by Voltage Required:
K204DF - 1585 mw - 51ma - 30.84v rms
HD800 - 210 mw - 26 ma - 7.94v rms
HD600 - 199 mw - 26 ma - 7.74v rms
HD650 - 167 mw - 24 ma - 7.08v rms
HE5 - 1995 mw - 282 ma - 7.06v rms
T1 - 63mw - 10 ma - 6.15v rms
K701 - 510 mw - 91 ma - 5.62v rms
ER4S - 100 mw - 32 ma - 3.16v rms
RE0 - 100 mw - 39 ma - 2.53v rms
RS1 - 158 mw - 70 ma - 2.25v rms
SRH840 - 63 mw - 38 ma - 1.67v rms
Westone3 - 20 mw - 26 ma - 0.77v rms
E4C - 13 mw - 21 ma - 0.60v rms
GR8 - 1.6 mw - 3.6 ma - 0.44v rms
Triple-Fi 10 - 2 mw - 7.9 ma - 0.25v rms
UE-18 Pro - 2.7 mw - 11 ma - 0.24v rms
SE530 - 1.3 mw - 6 ma - 0.213v rms
ES3X/UM3X - 0.4 mw - 2.7 ma - 0.15v rms

Summary:
This list gives the trend that headphones that we know improve greatly with an amp are near the top of at least one, if not all lists. It also shows that a great amp must be able to at least both deliver high current and high voltage. Otherwise there are headphones that cannot reach their potential. That HE5 is a monster to drive!

On the other side of the spectrum, you can see IEMs so sensitive to the slightest voltage, thus picking up all kinds of noise in the system. And you can clearly see how the ER4S and RE0 behave much like full size headphones, probably devoid of "hiss" problems other IEMs suffer through. This also shows how they don't work so well in headphone jacks of portable players, they do require much power capabilities than other IEMs.

 

[12345142]

Nice work. I was expecting the GR8 to be harder to drive because of the 120-ohm impedance, but it doesn't seem to be the case.

 

[JohnFerrier]

It's interesting to see an up-to-date version of something like the following:

HeadWize - Technical Paper: Understanding Headphone Power Requirements by Dennis Bohn

-

It looks to me that there is about a 37 dB difference from top to bottom.


.

 

[bcwang]

Added e4c as it was in my spreadsheet but missing from this chart.  I wonder why most of the high end IEMs are so sensitive, for me it makes them difficult use due to hiss and volume control issues. 

 

[Danz03]

Thanks for posting, it's a very interesting chart. I guess most IEMs are designed to be used with iPods or MP3 players so they can give a higher listening level. In fact, it's more of a disadvantage using my UM3Xs and UE-18 Pros with some amps because of the hiss issue, even when there's nothing playing and the volume is set to 0.

 

[Kevin Brown]

Hi bcwang- Could you add the AKG K240DF's to your list?
 
In another thread, there was a discussion about whether the DF's or the K701's were harder to drive.  Here are the specs:
 
AKG K240DF:  88 dB/mW sens,  600 ohm imped
 
Thanks !!

 

[bcwang]

Quote:

Hi bcwang- Could you add the AKG K240DF's to your list?
 
In another thread, there was a discussion about whether the DF's or the K701's were harder to drive.  Here are the specs:
 
AKG K240DF:  88 dB/mW sens,  600 ohm imped
 
Thanks !!

 
Done... wow, that headphone is crazy.  Due to it's power handling limits you can't exceed 111db.  And to even get to that limit you need lots of voltage, more than most amps can deliver.
 

 

[Kevin Brown]

Thanks, that's what I thought: harder to drive than the K701's. 
 
(Oh, "K240DF" for your table.  Is the order correct in the power and V and I tables?)
 
If I can get you some other specs, would you add those too?
 
I'm thinking of the K501's, K601's, the Sextetts, and then I just got a pair of Ultrasone Pro 2500's that are surprising me by being a fair amount harder to drive than the MS2i's I'm currently using.
 
Thanks !!

 

[latenlazy]

I wonder what the Audeze LCD2 or the HE-500s need (given that they are the more sensitive orthos out there)?

 

[Quadfather]

Prompted by the higher than expected sensitivity of the HD800, I spent some time creating a spreadsheet of headphones output power required at different level, using their official sensitivity spec to scale with. I thought it was quite interesting after looking at the results, so I'm going to share.

The list of values is based on:

-Power required to reach 120db. (Note, some headphones cannot actually reach this level because it exceeds their max power capability. This is just theoretical.)

-nominal impedance value. (some headphones change impedance depending on frequency, so it wouldn't be accurate in those cases. example: HD800 goes from 300 to almost 650 ohm, so the voltage required to hit the required power output is over 11v in that case, not just the 7 something in the list)


Ordered by Power Required:
HE5 - 1995 mw - 282 ma - 7.06v rms
K204DF - 1585 mw - 51ma - 30.84v rms
K701 - 510 mw - 91 ma - 5.62v rms
HD800 - 210 mw - 26 ma - 7.94v rms
HD600 - 199 mw - 26 ma - 7.74v rms
HD650 - 167 mw - 24 ma - 7.08v rms
RS1 - 158 mw - 70 ma - 2.25v rms
ER4S - 100 mw - 32 ma - 3.16v rms
RE0 - 100 mw - 39 ma - 2.53v rms
T1 - 63mw - 10 ma - 6.15v rms
SRH840 - 63 mw - 38 ma - 1.67v rms
Westone3 - 20 mw - 26 ma - 0.77v rms
E4C - 13 mw - 21 ma - 0.60v rms
GR8 - 1.6 mw - 3.6 ma - 0.44v rms
UE-18 Pro - 2.7 mw - 11 ma - 0.24v rms
Triple-Fi 10 - 2 mw - 7.9 ma - 0.25v rms
SE530 - 1.3 mw - 6 ma - 0.213v rms
ES3X/UM3X - 0.4 mw - 2.7 ma - 0.15v rms

Ordered by Current Required:
HE5 - 1995 mw - 282 ma - 7.06v rms
K204DF - 1585 mw - 51ma - 30.84v rms
K701 - 510 mw - 91 ma - 5.62v rms
RS1 - 158 mw - 70 ma - 2.25v rms
RE0 - 100 mw - 39 ma - 2.53v rms
SRH840 - 63 mw - 38 ma - 1.67v rms
ER4S - 100 mw - 32 ma - 3.16v rms
HD600 - 199 mw - 26 ma - 7.74v rms
HD800 - 210 mw - 26 ma - 7.94v rms
Westone3 - 20 mw - 26 ma - 0.77v rms
HD650 - 167 mw - 24 ma - 7.08v rms
E4C - 13 mw - 21 ma - 0.60v rms
UE-18 Pro - 2.7 mw - 11 ma - 0.24v rms
T1 - 63mw - 10 ma - 6.15v rms
Triple-Fi 10 - 2 mw - 7.9 ma - 0.25v rms
SE530 - 1.3 mw - 6 ma - 0.213v rms
GR8 - 1.6 mw - 3.6 ma - 0.44v rms
ES3X/UM3X - 0.4 mw - 2.7 ma - 0.15v rms

Ordered by Voltage Required:
K204DF - 1585 mw - 51ma - 30.84v rms
HD800 - 210 mw - 26 ma - 7.94v rms
HD600 - 199 mw - 26 ma - 7.74v rms
HD650 - 167 mw - 24 ma - 7.08v rms
HE5 - 1995 mw - 282 ma - 7.06v rms
T1 - 63mw - 10 ma - 6.15v rms
K701 - 510 mw - 91 ma - 5.62v rms
ER4S - 100 mw - 32 ma - 3.16v rms
RE0 - 100 mw - 39 ma - 2.53v rms
RS1 - 158 mw - 70 ma - 2.25v rms
SRH840 - 63 mw - 38 ma - 1.67v rms
Westone3 - 20 mw - 26 ma - 0.77v rms
E4C - 13 mw - 21 ma - 0.60v rms
GR8 - 1.6 mw - 3.6 ma - 0.44v rms
Triple-Fi 10 - 2 mw - 7.9 ma - 0.25v rms
UE-18 Pro - 2.7 mw - 11 ma - 0.24v rms
SE530 - 1.3 mw - 6 ma - 0.213v rms
ES3X/UM3X - 0.4 mw - 2.7 ma - 0.15v rms

Summary:
This list gives the trend that headphones that we know improve greatly with an amp are near the top of at least one, if not all lists. It also shows that a great amp must be able to at least both deliver high current and high voltage. Otherwise there are headphones that cannot reach their potential. That HE5 is a monster to drive!

On the other side of the spectrum, you can see IEMs so sensitive to the slightest voltage, thus picking up all kinds of noise in the system. And you can clearly see how the ER4S and RE0 behave much like full size headphones, probably devoid of "hiss" problems other IEMs suffer through. This also shows how they don't work so well in headphone jacks of portable players, they do require much power capabilities than other IEMs.

I have a Lotoo Paw Gold Diana, and it is powering the Sennheiser HD650 headphones to loud volumes. Do you still recommend an amp or do you think the staff has enough power to drive them? I was possibly thinking Bottlehead Crack with the 1.1 speedball modification...

 

[Quadfather]

Prompted by the higher than expected sensitivity of the HD800, I spent some time creating a spreadsheet of headphones output power required at different level, using their official sensitivity spec to scale with. I thought it was quite interesting after looking at the results, so I'm going to share.

The list of values is based on:

-Power required to reach 120db. (Note, some headphones cannot actually reach this level because it exceeds their max power capability. This is just theoretical.)

-nominal impedance value. (some headphones change impedance depending on frequency, so it wouldn't be accurate in those cases. example: HD800 goes from 300 to almost 650 ohm, so the voltage required to hit the required power output is over 11v in that case, not just the 7 something in the list)


Ordered by Power Required:
HE5 - 1995 mw - 282 ma - 7.06v rms
K204DF - 1585 mw - 51ma - 30.84v rms
K701 - 510 mw - 91 ma - 5.62v rms
HD800 - 210 mw - 26 ma - 7.94v rms
HD600 - 199 mw - 26 ma - 7.74v rms
HD650 - 167 mw - 24 ma - 7.08v rms
RS1 - 158 mw - 70 ma - 2.25v rms
ER4S - 100 mw - 32 ma - 3.16v rms
RE0 - 100 mw - 39 ma - 2.53v rms
T1 - 63mw - 10 ma - 6.15v rms
SRH840 - 63 mw - 38 ma - 1.67v rms
Westone3 - 20 mw - 26 ma - 0.77v rms
E4C - 13 mw - 21 ma - 0.60v rms
GR8 - 1.6 mw - 3.6 ma - 0.44v rms
UE-18 Pro - 2.7 mw - 11 ma - 0.24v rms
Triple-Fi 10 - 2 mw - 7.9 ma - 0.25v rms
SE530 - 1.3 mw - 6 ma - 0.213v rms
ES3X/UM3X - 0.4 mw - 2.7 ma - 0.15v rms

Ordered by Current Required:
HE5 - 1995 mw - 282 ma - 7.06v rms
K204DF - 1585 mw - 51ma - 30.84v rms
K701 - 510 mw - 91 ma - 5.62v rms
RS1 - 158 mw - 70 ma - 2.25v rms
RE0 - 100 mw - 39 ma - 2.53v rms
SRH840 - 63 mw - 38 ma - 1.67v rms
ER4S - 100 mw - 32 ma - 3.16v rms
HD600 - 199 mw - 26 ma - 7.74v rms
HD800 - 210 mw - 26 ma - 7.94v rms
Westone3 - 20 mw - 26 ma - 0.77v rms
HD650 - 167 mw - 24 ma - 7.08v rms
E4C - 13 mw - 21 ma - 0.60v rms
UE-18 Pro - 2.7 mw - 11 ma - 0.24v rms
T1 - 63mw - 10 ma - 6.15v rms
Triple-Fi 10 - 2 mw - 7.9 ma - 0.25v rms
SE530 - 1.3 mw - 6 ma - 0.213v rms
GR8 - 1.6 mw - 3.6 ma - 0.44v rms
ES3X/UM3X - 0.4 mw - 2.7 ma - 0.15v rms

Ordered by Voltage Required:
K204DF - 1585 mw - 51ma - 30.84v rms
HD800 - 210 mw - 26 ma - 7.94v rms
HD600 - 199 mw - 26 ma - 7.74v rms
HD650 - 167 mw - 24 ma - 7.08v rms
HE5 - 1995 mw - 282 ma - 7.06v rms
T1 - 63mw - 10 ma - 6.15v rms
K701 - 510 mw - 91 ma - 5.62v rms
ER4S - 100 mw - 32 ma - 3.16v rms
RE0 - 100 mw - 39 ma - 2.53v rms
RS1 - 158 mw - 70 ma - 2.25v rms
SRH840 - 63 mw - 38 ma - 1.67v rms
Westone3 - 20 mw - 26 ma - 0.77v rms
E4C - 13 mw - 21 ma - 0.60v rms
GR8 - 1.6 mw - 3.6 ma - 0.44v rms
Triple-Fi 10 - 2 mw - 7.9 ma - 0.25v rms
UE-18 Pro - 2.7 mw - 11 ma - 0.24v rms
SE530 - 1.3 mw - 6 ma - 0.213v rms
ES3X/UM3X - 0.4 mw - 2.7 ma - 0.15v rms

Summary:
This list gives the trend that headphones that we know improve greatly with an amp are near the top of at least one, if not all lists. It also shows that a great amp must be able to at least both deliver high current and high voltage. Otherwise there are headphones that cannot reach their potential. That HE5 is a monster to drive!

On the other side of the spectrum, you can see IEMs so sensitive to the slightest voltage, thus picking up all kinds of noise in the system. And you can clearly see how the ER4S and RE0 behave much like full size headphones, probably devoid of "hiss" problems other IEMs suffer through. This also shows how they don't work so well in headphone jacks of portable players, they do require much power capabilities than other IEMs.

I am getting 500 mw/32 ohms, 27 ma, 7.6 volts from LPG 2017 for my HD650s. Is the mw figure into 32 ohms?

 

[Quadfather]

How about Shure SRH1540?

 

[Eagle_Driver]

How about Shure SRH1540?

Calculated using the parameters based on the first post:

SRH1540 - 126 mW - 52 mA - 2.41V RMS

 

[Quadfather]

Calculated using the parameters based on the first post:

SRH1540 - 126 mW - 52 mA - 2.41V RMS

Thank you. My NW-WM1A and NW-WM1Z seem to drive them well from balanced output.

 

[Eagle_Driver]

For the record, based solely on the published specs on my headphones that I tried with my new iFi Hip DAC/amp, here are my calculations:

Sorted by Power Required:
DT 990 Pro (250 Ohm) - 251 mW - 32 mA - 7.92V RMS
ATH-M50X - 126 mW - 58 mA - 2.19V RMS
MDR-7506 - 25 mW - 20 mA - 1.26V RMS
MDR-7509 (Old version, not HD) - 20 mW - 29 mA - 0.69V RMS

Sorted by Current Required:
ATH-M50X - 126 mW - 58 mA - 2.18V RMS
DT 990 Pro (250 Ohm) - 251 mW - 32 mA - 7.92V RMS
MDR-7509 (Old version, not HD) - 20 mW - 29 mA - 0.69V RMS
MDR-7506 - 25 mW - 20 mA - 1.26V RMS

Sorted by Voltage Required:
DT 990 Pro (250 Ohm) - 251 mW - 32 mA - 7.92V RMS
ATH-M50X - 126 mW - 58 mA - 2.19V RMS
MDR-7506 - 25 mW - 20 mA - 1.26V RMS
MDR-7509 (Old version, not HD) - 20 mW - 29 mA - 0.69V RMS

No wonder why my old MDR-7509 sounded the way it did, especially when amped: It sounded honky and boxy due to a combination of highly resonant earcups and a poor damping factor. Using the MDR-7509 out of a gutless portable device's headphone out mitigates that problem but still doesn't make it sound good. The MDR-7506, on the other hand, is one of the few headphones that I have had that sounded reasonably good on almost anything, and that amping it didn't improve the sound quality all that much.