How much gain do I need?

There is a constant question of microphone gain. And here is the microphone Gainstrolabe, an ancient device (this is humor) to answer this question depending on how loud you speak.

This Gainstrolabe (chart) shows the amount of vocal preamplifier gain required to target 100% on a common, 1.228V VU analog meter (at 1000Hz,) typical on analog recording gear. This with common conversational speech levels of 60dB(A) measured at one meter distance, and interpolated to more useful recording distances.

1.228V 100% dBVU is an agreed upon standard, and although there are multiple conflicting standards for digital and digital equivalency, this 0dBVU at 1000Hz signal should result in -18dB on a dBFS digital console meter or in recording software. A common digital voice recording target.

Most microphone preamps provide at least 50dB gain, with some providing 60 and a few, 70dB. So 70dB is a realistic maximum. A few ribbon microphone preamps offer 80dB of gain, but are not computer interfaces.

Your microphone specification hopefully has something that looks like this:

18mV/Pa

Find the most similar number along the left side of this chart. To the immediate right is the amount of gain required at a few common distances.

You may have to turn mobile devices horizontally for the chart to display properly

mV/Pa1″3″6″Examples
76.8
68.4
60.9
54.3
48.3
43.1
38.4
34.2
30.5
27.1
24.2
21.5
19.2
17.1
15.2
13.6
12.1
10.8
9.59
8.55
7.61
6.78
6.04
5.38
4.8
4.27
3.81
3.39
3.02
2.69
2.4
2.14
1.9
1.7
1.51
1.35
1.2
1.07		26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63		35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72		41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78		sE DCM6 with boost

sE DCM8 with boost


Vanguard V14
Soyuz 017 FET, MKH800
RODE NT1 4th, Blue Spark SL
sE X1s, RODE NTG3, KSM44, Sanken CU51
U87Ai, Lewitt LCT 440 PURE
sE 2200, NT1 5th, 416, MKH50, TLM103, Sony C800
Blue SONA, AT2035, Samson C01
AKG P220, sE7, ETHOS, Sanken CU44
AT 4047, Schoeps MK4
KSM32, MXL 990, V67G, Sony C100, RODE K2
KSM141, R122
Violet Finger

Warm Audio WA47jr

E914
Sanken CU41
AKG C1000, RODE M2
SM81



SM94
SM86, e614, M88, KSM9, R121
KSM8, AKG D5, e835, Beta57, Beta58, VP64A
SM87, sE DCM3 , sE DCM6
MD431 II
sE V7, SM58, sE DCM8, e945, Sony C-37A, Beta87A
SM57, MV7, Procaster, MD441U, KSM313, Naked Eye
RE20, Stedman N90
SM48
Beyerdynamic M201
SM7B

Of course, you can record with less gain than needed and try to boost later or use a lifter/booster. You would simply subtract the cloud lifter/booster gain to see the remaining requirement from the preamp. there are advantages and disadvantages of this but the booster discussion is a different subject entirely.

Example USB interface with 70dB gain:
MOTU UltraLite MK5

Example USB interfaces with 60dB gain:
RME BabyFace
Presonus STUDIO 26c
SSL2

Example USB interfaces with 50dB gain:
Behringer UM2
Behringer UMC204HD/404HD
MOTU M2
Steinberg UR22C