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Tips on how to choose a suitable amplifier for your beloved headphone

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2014-10-28
Post time 2014-11-27 15:46:19 |Show all posts |
Edited by FiiO at 2015-10-12 14:28

By one way or another, we have been acknowledged that many users are haunted with one question: which FiiO amplifier would go perfectly with one certain headphone or earplug.

Generally speaking, we should take the timbre and the power into consideration when speaking of the match of amplifier with headphone. As is known to us all, the match of timbre is kind of complicated. For those who possess headphone in somewhat “cold sound”, all he needs is a “warmsound” amplifier to balance it out. Due to the subjectivity of timbre, it can’tbe quantized or described with specific numeral data which then results in” Eachone thinks in his way.”Therefore, here we may mainly focus on the explanationon the matching from the aspect of the power.

First of all, we should have a clear definition here. In term of the sound reduction merely, different people would have different expectations of the sound according to different using environment, personalized listening curve and individualized loved music type.  Therefore, we need to do a simple classification regarding the headphone sound.

A. Standard sound pressure (95dB): Under normal application environment, we define the sound pressure of the headphone as standard level when enjoying popular music. Considering the theoretic dynamic range of CD being 96dB, whereas the minimum sound pressure that human ear can hear out of 1KHz is 0 dB, then the dynamic range for the maximum sound pressure of 95dB is 95dB as well. As a result, we define the maximum sound pressure of 95dB as the basic needs of enjoying common music.

B. Favorable sound pressure (105dB): As a matter of fact, 95dB sound pressure is far from satisfactory in enjoying high quality music. Normally speaking, in terms of thelive show of symphonic music, rock concertand other sort of high dynamic music forms, the maximum sound pressure can reach 105dB. Therefore, we define 105dB sound pressure as favorable sound pressure.

C. Excellent sound pressure (120dB): 105dB sound pressure, is it enough? In reality, thesound of the nature is far above 105dB, like the sound of the thunderstorm, the sound felt towards a plane flying nearby whose maximum sound would hit above 120dB. Also, the record of SACD format music can reach 120dB as well. That’s why we regard 120dB as excellent sound pressure.
With the help of this quantized sound pressure levels, we can calculate how much power it needs to boost one specific headphone according to the theoretical computational formula.

The procedure and formula of the calculation are as follows:

1. Usually, each headphone would be given with one sensitivity data which is tested under the environment of below 1mW power.
2. Based on the required sound pressure, work out the corresponding power(P for short).

Assuming the maximum required sound pressure as B, and A as the rated sensitivity of the headphone, then the computational formula would be P=10^ ((B-A)/10).

3. In line with the power requirements, figure out the required maximum voltage and current.
The reason why we should calculate the maximum voltage and current is because
P=I(current)*U(voltage).

As to the fixed output power of one certain amplifier, it may thanks to the high output voltage or because of the high output current.

Take the Beyerdynamic DT990 for example, while in different headphone impedance with one version at 32Ohm and one at 250Ohm, in order to get 120dB sound pressure, they both require for 251.19mW power due to the same sensitivity. However, the required maximum current of the 32Ohm version is 88.60mA which is far above the 31.70mAof the version with 250Ohm.

To the contrary, the demanded amplitude peak in boosting the voltage of the DT990 with 250Omh impedance would be 22.41V whichis far above the 8.02V of the version with 32Ohm. This tells us that power rateis not the only thing we should consider. To a headphone with low impedance, high current and low voltage is what it requires, while high voltage and low current would be the target of headphone at high impedance. That’s why we need to work out the corresponding output voltage and current in order to select suitable amplifier.

One more thing we need to be aware of is that the impedance and the sensitivity of the headphone is not a fixed figure which might vary with the headphone input signal’s response. Generally speaking, the maximum impedance of the headphone is higher than the rated one, which even can be 3 folds higher. So does the minimum impedance and the rated one. Thus, the data result from the formula should be regarded as a merely reference.

To sum up, in accordance with corresponding power and high dynamic peak voltage required by 120dB sound pressure and the current demanded by high dynamic, the chosen amplifier would basically meet some kind of high level ofsound effect. If take the power storage into consideration, we can also get it doubled or tripled based on the related power of 120dB.

You can feel free to visit our official website at www.fiio.net to get the related information about the maximum output power, peak voltage of high dynamic and the current of high dynamic in terms of all the amplifiers and amplifiers with decode function. You are warmly welcome to select the suitable amplifier to your own headphone based on the listed information.

Based on this formula, we have worked out the power, voltage and current for some popular headphones.
In order to get the best sound effect, you can refer to the power required by 120dB sound pressure and peak voltage required by high dynamic.

  
     Brand
  
  
Unit
  
Model
Impedance
Sensitivity
Power required by
95dB sound pressure
Power required by
105dB sound pressure
Power required by
120dB sound pressure
Peak voltage required
by high dynamic
Current required  
by high dynamic

  
Omh
dB/mW
mW
mW
mW
Vp-p
mA
Koss
A250
60
98
0.50
5.01
158.49
8.72
51.40
Koss
PP
60
118
0.25
2.51
79.43
6.17
36.39
Koss
KSC35
60
101
0.25
2.51
79.43
6.17
36.39
Audio-technica
ATH-A1000
40
103
0.16
1.58
50.12
4.00
35.40
Audio-technica
ATH-A700
64
102
0.20
2.00
63.10
5.68
31.40
Audio-technica
ATH-A900
40
101
0.25
2.51
79.43
5.04
44.56
Audio-technica
ATH-AD700
32
98
0.50
5.01
158.49
6.37
70.38
Audio-technica
ATH-A2000X
42
101
0.25
2.51
79.43
5.17
43.49
Audio-technica
ATH-CM7
16
100
0.32
3.16
100.00
3.58
79.06
Audio-technica
ATH-EM7
32
109
0.04
0.40
12.59
1.79
19.83
Audio-technica
ATH-EW9
29
105
0.10
1.00
31.62
2.71
33.02
Audio-technica
ATH-L3000
48
104
0.13
1.26
39.81
3.91
28.80
Audio-technica
ATH-W100
48
100
0.32
3.16
100.00
6.20
45.64
Audio-technica
ATH-W1000
40
101
0.25
2.51
79.43
5.04
44.56
Audio-technica
ATH-ON300
32
102
0.20
2.00
63.10
4.02
44.40
Audio-technica
CK100

113
0.02
0.16
5.01
0.00
#DIV/0!
Beyerdynamic
DT231
32
96
0.79
7.94
251.19
8.02
88.60
Beyerdynamic
DTX501p
32
104
0.13
1.26
39.81
3.19
35.27
Beyerdynamic
DT860
32
97
0.63
6.31
199.53
7.15
78.96
Beyerdynamic
DT880
250
96
0.79
7.94
251.19
22.41
31.70
Beyerdynamic
DT990
32
96
0.79
7.94
251.19
8.02
88.60
Beyerdynamic
DT990
250
96
0.79
7.94
251.19
22.41
31.70
Beyerdynamic
DTX800
32
105
0.10
1.00
31.62
2.84
31.44
Beyerdynamic
DTX900
32
108
0.05
0.50
15.85
2.01
22.25
Beyerdynamic
DT1350
80
109
0.04
0.40
12.59
2.84
12.54
Beyerdynamic
T1
600
102
0.20
2.00
63.10
17.40
10.25
Beyerdynamic
T70
250
104
0.13
1.26
39.81
8.92
12.62
Beyerdynamic
MMX100
12
102
0.20
2.00
63.10
2.46
72.51
SHURE
E2C
16
105
0.10
1.00
31.62
2.01
44.46
SHURE
E3C
26
115
0.01
0.10
3.16
0.81
11.03
SHURE
E4C
29
109
0.04
0.40
12.59
1.71
20.84
SHURE
E5C
110
122
0.00
0.02
0.63
0.75
2.39
SHURE
SE530
36
119
0.00
0.04
1.26
0.60
5.91
SHURE
SE535
36
119
0.00
0.04
1.26
0.60
5.91
SHURE
SE215
20
107
0.06
0.63
19.95
1.79
31.59
SHURE
SE215
20
107
0.06
0.63
19.95
1.79
31.59
SHURE
SE315
27
116
0.01
0.08
2.51
0.74
9.65
SHURE
SRH940
42
100
0.32
3.16
100.00
5.80
48.80
SHURE
SRH840
44
102
0.20
2.00
63.10
4.71
37.87
SHURE
SRH44
44
105
0.10
1.00
31.62
3.34
26.81
SHURE
SRH240
38
105
0.10
1.00
31.62
3.10
28.85
SHURE
SRH750DJ
32
106
0.08
0.79
25.12
2.54
28.02
SHURE
SRH1840
65
96
0.79
7.94
251.19
11.43
62.16
SHURE
SRH1440
37
101
0.25
2.51
79.43
4.85
46.33
SHURE
SE115
16
105
0.10
1.00
31.62
2.01
44.46
SONY
MDR-E888LP
16
108
0.05
0.50
15.85
1.42
31.47
SONY
MDR-EX1000
32
108
0.05
0.50
15.85
2.01
22.25
SONY
MDR-EX600
32
107
0.06
0.63
19.95
2.26
24.97
SONY
MDR-EX310SL
16
105
0.10
1.00
31.62
2.01
44.46
SONY
MDR-EX210B
16
104
0.13
1.26
39.81
2.26
49.88
SONY
R10
40
100
0.32
3.16
100.00
5.66
50.00
SONY
XBA-10
24
102
0.20
2.00
63.10
3.48
51.27
SONY
XBA-20
48
102
0.20
2.00
63.10
4.92
36.26
SONY
XBA-30
48
102
0.20
2.00
63.10
4.92
36.26
SONY
XBA-40
16
102
0.20
2.00
63.10
2.84
62.80
SONY
MDR-1R
24
105
0.10
1.00
31.62
2.46
36.30
SONY
MDR-XB200
24
100
0.32
3.16
100.00
4.38
64.55
SONY
MDR-XB30EX
16
105
0.10
1.00
31.62
2.01
44.46
SONY
MDR-XB900
24
106
0.08
0.79
25.12
2.20
32.35
SONY
MDR-XB90EX
16
106
0.08
0.79
25.12
1.79
39.62
SONY
MDR-XB60EX
16
105
0.10
1.00
31.62
2.01
44.46
SONY
MDR-XB600
40
104
0.13
1.26
39.81
3.57
31.55
SONY
MDR-XB1000
24
106
0.08
0.79
25.12
2.20
32.35
SONY
MDR-XB41EX
16
105
0.10
1.00
31.62
2.01
44.46
SONY
MDR-XB21EX
16
103
0.16
1.58
50.12
2.53
55.97
ER4P
ER4P
37
102
0.20
2.00
63.10
4.32
41.30
ER4P
ER4B
100
108
0.05
0.50
15.85
3.56
12.59
ER4P
ER6
48
108
0.05
0.50
15.85
2.47
18.17
ER4P
ER6i
16
108
0.05
0.50
15.85
1.42
31.47
Sennheiser
HD200
64
106
0.08
0.79
25.12
3.59
19.81
Sennheiser
HD201
24
108
0.05
0.50
15.85
1.74
25.70
Sennheiser
HD202
32
115
0.01
0.10
3.16
0.90
9.94
Sennheiser
HD212pro
32
112
0.02
0.20
6.31
1.27
14.04
Sennheiser
HD215
32
109
0.04
0.40
12.59
1.79
19.83
Sennheiser
HD25SP
85
109
0.04
0.40
12.59
2.93
12.17
Sennheiser
HD270
64
106
0.08
0.79
25.12
3.59
19.81
Sennheiser
HD280pro
64
113
0.02
0.16
5.01
1.60
8.85
Sennheiser
HD437
32
115
0.01
0.10
3.16
0.90
9.94
Sennheiser
HD457
32
114
0.01
0.13
3.98
1.01
11.15
Sennheiser
HD465
32
110
0.03
0.32
10.00
1.60
17.68
Sennheiser
HD477
32
109
0.04
0.40
12.59
1.79
19.83
Sennheiser
HD485
32
110
0.03
0.32
10.00
1.60
17.68
Sennheiser
HD497
32
112
0.02
0.20
6.31
1.27
14.04
Sennheiser
HD500
32
105
0.10
1.00
31.62
2.84
31.44
Sennheiser
HD515
50
105
0.10
1.00
31.62
3.56
25.15
Sennheiser
HD555
50
112
0.02
0.20
6.31
1.59
11.23
Sennheiser
HD570
64
102
0.20
2.00
63.10
5.68
31.40
Sennheiser
HD580
300
97
0.63
6.31
199.53
21.88
25.79
Sennheiser
HD590
120
103
0.16
1.58
50.12
6.94
20.44
Sennheiser
HD595
120
112
0.02
0.20
6.31
2.46
7.25
Sennheiser
HD598
50
112
0.02
0.20
6.31
1.59
11.23
Sennheiser
HD600
300
97
0.63
6.31
199.53
21.88
25.79
Sennheiser
HD650
300
98
0.50
5.01
158.49
19.50
22.98
Sennheiser
HD700
150
105
0.10
1.00
31.62
6.16
14.52
Sennheiser
HD800
300
102
0.20
2.00
63.10
12.30
14.50
Sennheiser
MX500
32
125
0.00
0.01
0.32
0.28
3.14
Sennheiser
MX550
16
123
0.00
0.02
0.50
0.25
5.60
Sennheiser
PX100
32
114
0.01
0.13
3.98
1.01
11.15
Sennheiser
PX200
32
100
0.32
3.16
100.00
5.06
55.90
Sennheiser
MX375
32
122
0.00
0.02
0.63
0.40
4.44
Sennheiser
MX760
32
114
0.01
0.13
3.98
1.01
11.15
Sennheiser
MX880
16
120
0.00
0.03
1.00
0.36
7.91
Sennheiser
MX980
16
120
0.00
0.03
1.00
0.36
7.91
Sennheiser
MX985
16
120
0.00
0.03
1.00
0.36
7.91
Sennheiser
MOMENTUM
18
110
0.03
0.32
10.00
1.20
23.57
Sennheiser
IE8
16
125
0.00
0.01
0.32
0.20
4.45
Sennheiser
IE80
16
125
0.00
0.01
0.32
0.20
4.45
Sennheiser
IE800
16
125
0.00
0.01
0.32
0.20
4.45
Sennheiser
IE6
16
115
0.01
0.10
3.16
0.64
14.06
Sennheiser
IE60
16
115
0.01
0.10
3.16
0.64
14.06
Sennheiser
CX980
32
115
0.01
0.10
3.16
0.90
9.94
AKG
K1000
120
74
125.89
1258.93
39810.72
195.47
575.98
AKG
K141
55
101
0.25
2.51
79.43
5.91
38.00
AKG
K141S
55
101
0.25
2.51
79.43
5.91
38.00
AKG
K171
55
94
1.26
12.59
398.11
13.23
85.08
AKG
K240df
600
88
5.01
50.12
1584.89
87.21
51.40
AKG
k240M
55
91
2.51
25.12
794.33
18.69
120.18
AKG
k240S
55
91
2.51
25.12
794.33
18.69
120.18
AKG
k24P
32
125
0.00
0.01
0.32
0.28
3.14
AKG
k26P
32
125
0.00
0.01
0.32
0.28
3.14
AKG
K271S
55
91
2.51
25.12
794.33
18.69
120.18
AKG
K301
55
102
0.20
2.00
63.10
5.27
33.87
AKG
K301XTRA
55
102
0.20
2.00
63.10
5.27
33.87
AKG
K401
120
94
1.26
12.59
398.11
19.55
57.60
AKG
K401
120
94
1.26
12.59
398.11
19.55
57.60
AKG
K420
32
125
0.00
0.01
0.32
0.28
3.14
AKG
K450
32
126
0.00
0.01
0.25
0.25
2.80
AKG
Q460
32
125
0.00
0.01
0.32
0.28
3.14
AKG
Q350
16
121
0.00
0.03
0.79
0.32
7.05
AKG
K374
28
120
0.00
0.03
1.00
0.47
5.98
AKG
K55
32
114
0.01
0.13
3.98
1.01
11.15
AKG
K501
120
94
1.26
12.59
398.11
19.55
57.60
AKG
K550
32
120
0.00
0.03
1.00
0.51
5.59
AKG
K601
120
101
0.25
2.51
79.43
8.73
25.73
AKG
K66
32
96
0.79
7.94
251.19
8.02
88.60
AKG
K701
62
105
0.10
1.00
31.62
3.96
22.58
AKG
K702
62
102
0.20
2.00
63.10
5.59
31.90
AKG
Q701
62
105
0.10
1.00
31.62
3.96
22.58
AKG
K71
19
100
0.32
3.16
100.00
3.90
72.55
AKG
K3003
8
125
0.00
0.01
0.32
0.14
6.29
AILISI
M1
32
100
0.32
3.16
100.00
5.06
55.90
GARDO
RS1
32
98
0.50
5.01
158.49
6.37
70.38
GARDO
SR325
32
98
0.50
5.01
158.49
6.37
70.38
GARDO
SR80
32
98
0.50
5.01
158.49
6.37
70.38
GARDO
SR125
32
98
0.50
5.01
158.49
6.37
70.38
GARDO
SR225
32
98
0.50
5.01
158.49
6.37
70.38
GARDO
ps500
32
98
0.50
5.01
158.49
6.37
70.38
GARDO
rs1i
96
98
0.50
5.01
158.49
11.03
40.63
GARDO
GR8
120
118
0.01
0.05
1.58
1.23
3.63
Astrotec
AS200HD
32
115
0.01
0.10
3.16
0.90
9.94
Astrotec
ax7
32
108
0.05
0.50
15.85
2.01
22.25
Astrotec
AM90
25
109
0.04
0.40
12.59
1.59
22.44
Logitech
UE 900
30
101
0.25
2.51
79.43
4.37
51.46
Logitech
TF10
32
117
0.01
0.06
2.00
0.71
7.90
Logitech
TF15
32
117
0.01
0.06
2.00
0.71
7.90
Edifier
H180
32
100
0.32
3.16
100.00
5.06
55.90
Edifier
K550
32
91
2.51
25.12
794.33
14.26
157.55
Philips
Fidelio X1
30
100
0.32
3.16
100.00
4.90
57.74
DENON
AH-D1100
32
101
0.25
2.51
79.43
4.51
49.82
DENON
AH-D7000
25
108
0.05
0.50
15.85
1.78
25.18
DENON
AH-D7100
24
110
0.03
0.32
10.00
1.39
20.41
STAX
stax SR009
145
100
0.32
3.16
100.00
10.77
26.26
Westone
UM1
24
114
0.01
0.13
3.98
0.87
12.88
Westone
UM2
27
119
0.00
0.04
1.26
0.52
6.83
Westone
UM3
27
119
0.00
0.04
1.26
0.52
6.83
Westone
W1
27
122
0.00
0.02
0.63
0.37
4.83
Westone
W2
33
117
0.01
0.06
2.00
0.73
7.78
Westone
W3
30
107
0.06
0.63
19.95
2.19
25.79
Westone
W4R
31
118
0.01
0.05
1.58
0.63
7.15
Klipsch
X10
50
110
0.03
0.32
10.00
2.00
14.14
JVC
HA-FX700
16
104
0.13
1.26
39.81
2.26
49.88
JVC
HA-S500
32
106
0.08
0.79
25.12
2.54
28.02
ECCI
PR200MKII
16
105
0.10
1.00
31.62
2.01
44.46
CREATIVE
Aurvana In-Ear2
42
110
0.03
0.32
10.00
1.83
15.43
CREATIVE
Aurvana In-Ear3
28
112
0.02
0.20
6.31
1.19
15.01
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Post time 2015-6-20 10:46:06 from mobile |Show all posts |
Can you please suggest for AUDIOTECHNICA
MSR-7. & Bose QC15
Thanks
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Post time 2015-10-30 22:01:24 |Show all posts |
Edited by alphire at 2015-10-30 22:47

Hi, thanks for your post. However, I don't quite agree with your volume assessment (95dB is really loud). Also you've mistaken VRMS for Vp-p. You cannot use Vp-p in Ohm's Law formula. Those 22.41V would kill the headphones for sure. That's 2003mW for 250Ohm.

There are some mistakes in your chart as well:
For AKG K701 you have probably mistaken dBV for dB/mW. They're in fact 93dB/mW, which is 105dB/V.
K702, Q701 share the same driver, so their values has to be the same.

Same for K240 series. All of them are same efficiency - 89dB/mW, they differ only in impedance:
600Ohm - K240 Monitor, K240 DF
55Ohm - K240 Studio, K240 MKII
Only exception are K240 Sextetts, those are 600Ohm and 94dB/mW
K240M = K240 Monitor which are 600Ohm

K141 are made in two variants - vintage and MK2. Again, share same sensitivity (100dB/mW), but vintage are 600Ohm

Beyers DT770 - 990 are made in many variants, but all share the same efficiency (96dB/mW):
Edition 2005:
32Ohm
250Ohm
600Ohm
Pro version:
80Ohm
250Ohm

Some less experienced users might have problems converting peak-to-peak voltage to real RMS value. Maybe consider changing Vp-p values for V RMS at 1kHz, since miliamps are connected to RMS values rather than peak.
What is also useful to know is maximum power rating specified by the headphone manufacturer. For example DT880 600Ohm are rated maximum 100mW per channel, which equals to 116dB, 7.75VRMS at 12.92mA. Forcing them all the way to 120dB (threshold of pain!!!) might damage the drivers, and more importantly our ears too.  
I'll be covering advantages of high impedance in separate article.
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