继续补充 SONY MDR 7506 测量值 — 麦文学看图说话系列
继续补充 SONY MDR 7506 测量值 — 麦文学看图说话系列
不少拥有 SONY MDR 7506 这个重新发现的神器的读者， 也许会好奇一些关键点。
比如：
SONY MDR 7506 的 1000 Hz 赫兹 的失真 THD 在什么电平会超过 0.1%
图中就是这个转折点的电压 100mV RMS， 100 毫伏有效值（1000Hz）以后 SONY MDR 7506 的 THD 就会明显上升。
如果希望测试结果好看， 可以参考俺上一篇散文：麦文学：有图有真相？耳机测试结果如何造假举例 — 麦文学看图说话系列zhuanlan.zhihu.com
。
这个转折点的电压 100mV RMS （100 毫伏有效值） 有啥意义呢？
这又会牵涉到 “推力” 这个几十年来争议不断的话题， 俺就不在这里扯 “推力”了。感兴趣的同学敬请参考另一篇散文：麦文学：推力单位的诞生（上） — 麦文学ver猪.2019 我读书少您别耍我系列zhuanlan.zhihu.com
。
一般来说， 烧友希望自己的耳机失真越少越好， 即便人类只能侦测到 0.3%.
100mV RMS （100 毫伏有效值）的时候, SONY MDR 7506 典型的THD不到 0.1%.麦文学：现在的音量相当于多少分贝？– 麦文学看图说话系列zhuanlan.zhihu.com
麦文学：再次转发WHO的新闻 （全球）11亿人面临听力损失风险 当然也因为耳机zhuanlan.zhihu.com
您觉得这个听音的电平合适吗？
世界卫生组织也就是 WHO (谁？) 了， 推荐的听音声压最好不要超过 85dB SPL re 20uPa.
当然， 祖国的噪音保护条例也许为了照顾烧友，宽松了许多， 推荐值是不要超过 90dB.
好了， 那 90dB SPL re 20uPa 的时候， 失真又是多少呢？ 请看图
。
开心不开心，意外不意外， 惊喜不惊喜？
听音电平降低一点， 更高保真了。
好了， 也许有同学纠结 SONY MDR7506 的阻抗-频率 (Impedance vs Frequency) 的变化关系。 俺也测了一下， 欢迎大家踊跃点赞， 踊跃赞赏。
看到了吧， 最大值不超过 120 OHM, 最小值不低于 70 OHM.
详细结果如下
Impedance values for 479 frequencies
Frequency(Hz) Magnitude(ohms) Phase(deg)
19.958 78.298 12.756
20.325 78.629 12.969
20.691 78.935 13.183
21.057 79.356 13.322
21.423 79.591 13.478
21.790 80.032 13.659
22.156 80.311 13.758
22.522 80.742 13.935
22.888 81.056 14.144
23.254 81.481 14.339
23.621 81.886 14.478
23.987 82.345 14.538
24.353 82.631 14.703
24.719 83.123 14.838
25.085 83.492 15.022
25.452 83.979 15.090
25.818 84.389 15.186
26.184 84.754 15.307
26.550 85.260 15.466
26.917 85.626 15.501
27.283 86.233 15.563
27.649 86.775 15.715
28.015 87.172 15.735
28.381 87.606 15.862
28.748 88.040 15.915
29.114 88.608 15.931
29.480 89.132 15.966
29.846 89.534 16.048
30.212 90.302 16.103
30.579 90.717 16.083
30.945 91.172 16.126
31.311 91.700 16.160
31.677 92.334 16.199
32.227 93.198 16.121
32.776 93.871 16.087
33.325 94.832 16.021
33.875 95.559 15.980
34.424 96.496 15.872
34.973 97.327 15.865
35.522 98.283 15.726
36.072 99.123 15.550
36.621 99.930 15.360
37.170 100.800 15.213
37.720 101.752 15.002
38.269 102.601 14.817
38.818 103.379 14.582
39.368 104.277 14.300
39.917 105.069 14.114
40.466 105.833 13.786
41.016 106.764 13.530
41.565 107.525 13.248
42.114 108.293 12.895
42.664 109.078 12.500
43.213 109.727 12.236
43.762 110.418 11.849
44.312 111.320 11.419
45.044 112.101 10.933
45.776 112.840 10.413
46.509 113.593 9.875
47.241 114.381 9.237
47.974 115.023 8.676
48.706 115.715 8.123
49.438 116.214 7.552
50.171 116.707 6.898
50.903 117.148 6.385
51.636 117.493 5.660
52.368 117.624 5.107
53.101 118.072 4.519
53.833 118.142 3.981
54.565 118.386 3.307
55.298 118.453 2.803
56.030 118.632 2.191
56.763 118.564 1.680
57.678 118.396 1.058
58.594 118.601 0.347
59.509 118.362 -0.335
60.425 118.342 -1.022
61.340 117.783 -1.723
62.256 117.509 -2.217
63.171 117.076 -2.986
64.087 116.794 -3.439
65.002 116.249 -4.028
65.918 115.666 -4.525
66.833 115.091 -5.002
67.749 114.524 -5.486
68.665 113.932 -5.953
69.580 113.374 -6.339
70.679 112.466 -6.787
71.777 112.086 -7.283
72.876 111.161 -7.653
73.975 110.474 -8.018
75.073 109.929 -8.342
76.172 109.072 -8.720
77.271 108.449 -9.011
78.369 107.474 -9.308
79.468 106.988 -9.620
80.566 106.227 -9.900
81.665 105.596 -10.053
82.764 104.841 -10.255
84.045 104.042 -10.528
85.327 103.483 -10.660
86.609 102.703 -10.915
87.891 102.010 -11.001
89.172 101.244 -11.207
90.454 100.699 -11.248
91.736 99.943 -11.429
93.018 99.346 -11.493
94.299 98.682 -11.615
95.581 98.200 -11.623
97.046 97.489 -11.728
98.511 96.936 -11.783
99.976 96.429 -11.852
101.440 95.806 -11.911
102.905 95.210 -11.903
104.370 94.689 -11.927
105.835 94.239 -11.883
107.300 93.571 -12.010
108.948 93.177 -11.954
110.596 92.675 -11.940
112.244 92.116 -12.018
113.892 91.609 -11.894
115.540 91.121 -11.921
117.188 90.762 -11.868
118.835 90.240 -11.860
120.483 89.888 -11.821
122.314 89.445 -11.704
124.146 89.040 -11.681
125.977 88.570 -11.635
127.808 88.228 -11.583
129.639 87.920 -11.519
131.470 87.487 -11.499
133.301 87.105 -11.372
135.315 86.771 -11.283
137.329 86.442 -11.187
139.343 86.078 -11.122
141.357 85.820 -11.036
143.372 85.410 -10.992
145.386 85.042 -10.861
147.583 84.795 -10.829
149.780 84.469 -10.658
151.978 84.233 -10.579
154.175 83.959 -10.502
156.372 83.725 -10.413
158.569 83.430 -10.323
160.950 83.129 -10.201
163.330 82.925 -10.107
165.710 82.659 -9.930
168.091 82.413 -9.836
170.471 82.263 -9.656
173.035 81.970 -9.617
175.598 81.717 -9.457
178.162 81.589 -9.380
180.725 81.347 -9.218
183.289 81.168 -9.144
186.035 80.939 -8.994
188.782 80.774 -8.888
191.528 80.657 -8.695
194.275 80.384 -8.588
197.021 80.321 -8.508
199.951 80.171 -8.330
202.881 80.030 -8.188
205.811 79.889 -7.989
208.740 79.829 -7.825
211.853 79.730 -7.692
214.966 79.701 -7.517
218.079 79.725 -7.377
221.191 79.608 -7.266
224.487 79.645 -7.191
227.783 79.764 -7.071
231.079 79.742 -7.084
234.375 79.745 -6.942
237.854 79.820 -6.974
241.333 79.822 -6.985
244.812 79.774 -6.978
248.291 79.726 -7.037
251.953 79.601 -7.116
255.615 79.530 -7.151
259.277 79.410 -7.165
263.123 79.310 -7.226
266.968 78.992 -7.250
270.813 78.793 -7.232
274.841 78.611 -7.184
278.870 78.367 -7.188
282.898 78.026 -7.116
286.926 77.901 -6.993
291.138 77.717 -6.900
295.349 77.487 -6.780
299.561 77.432 -6.724
303.955 77.234 -6.660
308.350 77.099 -6.508
312.744 76.953 -6.418
317.322 76.788 -6.307
321.899 76.697 -6.199
326.660 76.609 -6.131
331.421 76.495 -6.034
336.182 76.423 -5.850
341.125 76.266 -5.820
346.069 76.139 -5.741
351.013 76.104 -5.559
356.140 76.074 -5.509
361.267 75.871 -5.387
366.577 75.845 -5.260
371.887 75.811 -5.224
377.380 75.716 -5.071
382.874 75.549 -4.998
388.367 75.453 -4.882
394.043 75.411 -4.863
399.719 75.350 -4.659
405.579 75.296 -4.632
411.438 75.213 -4.578
417.480 75.167 -4.406
423.523 75.114 -4.294
429.749 75.086 -4.216
435.974 75.029 -4.141
442.383 74.965 -4.060
448.792 74.868 -3.910
455.383 74.895 -3.825
461.975 74.759 -3.744
468.750 74.762 -3.739
475.525 74.743 -3.566
482.483 74.659 -3.456
489.441 74.608 -3.363
496.582 74.589 -3.275
503.723 74.442 -3.194
511.047 74.546 -3.098
518.555 74.387 -3.024
526.062 74.333 -2.909
533.752 74.366 -2.834
541.443 74.276 -2.726
549.316 74.244 -2.610
557.373 74.273 -2.580
565.430 74.216 -2.469
573.669 74.148 -2.391
582.092 74.092 -2.284
590.515 74.116 -2.188
599.121 74.050 -2.141
607.910 74.057 -2.040
616.699 73.913 -1.976
625.671 74.029 -1.856
634.827 73.913 -1.746
643.982 73.882 -1.655
653.320 73.954 -1.603
662.842 73.885 -1.488
672.546 73.864 -1.404
682.251 73.816 -1.308
692.139 73.875 -1.175
702.209 73.818 -1.155
712.463 73.814 -1.010
722.900 73.734 -0.909
733.337 73.831 -0.889
743.958 73.734 -0.784
754.761 73.767 -0.687
765.747 73.861 -0.497
776.917 73.723 -0.464
788.269 73.791 -0.420
799.805 73.757 -0.269
811.523 73.799 -0.092
823.242 73.762 -0.135
835.144 73.804 -0.018
847.229 73.817 0.056
859.497 73.782 0.142
871.948 73.802 0.304
884.583 73.846 0.383
897.400 73.812 0.426
910.400 73.825 0.538
923.584 73.821 0.570
936.951 73.785 0.701
950.500 73.781 0.828
964.417 73.828 0.879
978.516 73.851 0.968
992.798 73.789 1.096
1007.263 73.887 1.228
1021.912 73.974 1.318
1036.743 73.992 1.361
1051.758 73.921 1.489
1067.139 73.977 1.541
1082.703 74.035 1.649
1098.450 74.100 1.743
1114.380 74.123 1.858
1130.676 74.194 1.941
1147.156 74.259 1.979
1163.818 74.369 2.084
1180.664 74.377 2.172
1197.876 74.351 2.239
1215.271 74.450 2.302
1233.032 74.425 2.359
1250.977 74.368 2.436
1269.104 74.331 2.493
1287.598 74.342 2.661
1306.274 74.410 2.766
1325.317 74.505 2.933
1344.543 74.518 3.020
1364.136 74.622 3.105
1383.911 74.690 3.187
1404.053 74.696 3.285
1424.561 74.791 3.325
1445.251 74.835 3.470
1466.309 74.909 3.613
1487.549 74.923 3.709
1509.155 75.098 3.778
1531.128 75.050 3.883
1553.467 75.110 3.967
1575.989 75.233 4.084
1598.877 75.327 4.302
1622.131 75.371 4.307
1645.752 75.497 4.434
1669.739 75.561 4.540
1694.092 75.522 4.611
1718.811 75.691 4.760
1743.896 75.797 4.890
1769.348 75.914 4.973
1795.166 76.035 5.101
1821.350 76.201 5.224
1847.900 76.291 5.344
1874.817 76.429 5.448
1902.100 76.561 5.523
1929.749 76.742 5.661
1957.764 76.927 5.829
1986.328 77.062 5.864
2015.259 77.292 5.995
2044.556 77.501 6.055
2074.219 77.689 6.142
2104.431 77.952 6.223
2135.010 78.012 6.294
2166.138 78.244 6.314
2197.632 78.345 6.371
2229.675 78.607 6.487
2262.085 78.913 6.512
2295.044 79.133 6.602
2328.369 79.246 6.642
2362.244 79.518 6.706
2396.667 79.736 6.823
2431.458 80.100 6.889
2466.797 80.383 6.936
2502.686 80.714 6.989
2539.124 81.076 7.022
2576.111 81.424 6.980
2613.647 81.858 6.972
2651.733 82.237 6.938
2690.369 82.615 6.873
2729.553 83.012 6.823
2769.287 83.462 6.657
2809.570 83.760 6.474
2850.403 84.185 6.297
2891.785 84.533 6.029
2933.899 84.820 5.752
2976.563 85.098 5.545
3019.775 85.243 5.187
3063.721 85.432 4.785
3108.215 85.224 4.307
3153.442 84.672 3.796
3199.402 81.855 6.031
3245.911 86.334 4.536
3293.152 85.939 3.831
3341.125 85.605 3.449
3389.648 85.211 3.177
3438.904 84.878 2.969
3488.892 84.490 2.758
3539.612 84.244 2.725
3591.064 83.954 2.599
3643.250 83.720 2.642
3696.167 83.446 2.664
3750.000 83.374 2.720
3804.565 83.274 2.753
3859.863 83.292 2.904
3916.077 83.344 2.907
3973.022 83.604 2.879
4030.884 83.875 2.895
4089.478 84.165 2.685
4148.987 84.566 2.363
4209.412 84.784 1.940
4270.569 84.752 1.309
4332.642 84.261 0.666
4395.630 83.508 0.159
4459.534 82.474 -0.250
4524.353 81.504 -0.393
4590.088 80.540 -0.247
4656.921 79.686 -0.140
4724.670 79.021 0.147
4793.335 78.441 0.539
4863.098 77.870 0.860
4933.777 77.576 1.226
5005.554 77.286 1.541
5078.430 77.078 1.844
5152.222 76.917 2.222
5227.112 76.728 2.484
5303.101 76.733 2.762
5380.188 76.616 3.053
5458.374 76.507 3.295
5537.842 76.562 3.437
5618.408 76.398 3.730
5700.073 76.301 3.895
5783.020 76.217 4.103
5867.065 76.177 4.298
5952.393 76.098 4.495
6039.001 75.969 4.730
6126.892 75.945 4.878
6216.064 75.908 5.138
6306.519 75.727 5.408
6398.254 75.690 5.738
6491.272 75.697 5.900
6585.754 75.590 6.149
6681.519 75.618 6.465
6778.748 75.642 6.663
6877.258 75.630 6.918
6977.234 75.673 7.197
7078.674 75.684 7.475
7181.580 75.739 7.702
7285.950 75.776 7.928
7391.968 75.869 8.229
7499.451 75.908 8.370
7608.582 76.097 8.643
7719.177 76.146 8.854
7831.421 76.209 9.070
7945.313 76.325 9.254
8060.852 76.408 9.495
8178.040 76.444 9.770
8297.059 76.589 9.934
8417.725 76.630 10.193
8540.223 76.705 10.502
8664.367 76.817 10.659
8790.344 77.032 10.968
8918.152 77.252 11.130
9047.791 77.451 11.410
9179.443 77.697 11.607
9312.928 77.953 11.783
9448.426 78.147 11.910
9585.938 78.423 12.068
9725.281 78.562 12.155
9866.821 78.814 12.264
10010.376 78.828 12.340
10155.945 78.984 12.472
10303.711 79.056 12.534
10453.491 79.233 12.547
10605.469 79.178 12.638
10759.644 79.224 12.760
10916.199 79.158 12.858
11074.951 79.089 12.981
11236.084 78.967 13.247
11399.598 78.903 13.465
11565.490 78.802 13.798
11733.765 78.848 14.053
11904.419 78.853 14.331
12077.637 79.063 14.632
12253.234 79.151 14.905
12431.396 79.225 15.235
12612.305 79.450 15.524
12795.776 79.572 15.830
12981.812 79.781 16.072
13170.594 79.911 16.320
13362.121 80.111 16.546
13556.396 80.333 16.812
13753.602 80.503 17.073
13953.735 80.783 17.300
14156.616 80.821 17.516
14362.609 81.049 17.731
14571.533 81.230 17.990
14783.569 81.349 18.289
14998.535 81.584 18.523
15216.613 81.709 18.716
15437.988 81.905 18.968
15662.476 81.993 19.305
15890.259 82.328 19.535
16121.338 82.385 19.798
16355.896 82.751 20.150
16593.750 83.025 20.420
16835.082 83.119 20.692
17079.895 83.468 20.952
17328.369 83.762 21.194
17580.506 84.049 21.546
17836.305 84.279 21.712
18095.764 84.544 21.928
18358.887 84.761 22.295
18625.855 84.983 22.546
18896.852 85.252 22.805
19171.691 85.599 23.093
19450.563 85.916 23.368
19733.459 86.262 23.734
20020.568 86.532 23.960
=====================================================
【待续】
【待续】
