您的声音工具分贝( dB )知多少
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S e r v i c e | R e v i e w |M u s i c W o w | C o n n e c t U s| H o m e
( dB ) ?________________________________________
, ( dB )
( decibel ) dB
( ) (decibel dB )
Alexander Graham Bell ( 1847 - 1922 )
1876
Bell
dBm
dBm , ( Audio Signal Level ) . ( decibel ) 1 Milliwat t . dBm m (milliwatt)
600Ω. 0.775 V , RMS ,
0 dBm 0.775 V 600Ω 1mW . :
1 Milliwatt = 0.775V = 0 dBm / 600Ω.
dBm m m, 1 mW( milliwatt ). ( Z ) .
dBm , 600
dBm = 10 log ( P / 0.001 W )
P = 0.001 × 10 ( dBm / 10 )
P Power , Watts.
0 dBm 600 ( 600 ),
0.001 W .
P = E × I = E2/ R 0.001 = E2/ 600
E= √0.001 × 600 = 0.775V
0.775 V 600 . 0 dBm , 600 , dBm
dBm = 20 log ( E / 0.775 )
E .
dBv and dBu
v u ,
v u ,
dBv dBu , ( Audio Signal Level ) .
(decibel) , 0.775 V RMS , dBm , dBu dBv, dBv dBV,
dBv dBV . dBu , dBv . ?
dBv dBu v u , , , 0.775 V ,
, 600Ω ,( , .)
, , , ,
dBv or dBu . dB , .
,
dBm = 20 log ( E / 0.775 ),
dBv = 20 log ( E / 0.775 ),
dBm 0.775V 600 .
dBv 0.775V 600 ,
E , .
dBm = dBv or dBu dBv . ?
, , , ,
, .
dBV
dBV , ( Audio Signal Level ) .
( decibel ) 1 V RMS . .
,dBV dBv( dBu ) , V 1 ( ), , .
,dBV ?
10 dBV ( Unbalanced ) or (High Impedance) ,
, 10, dBV ,
( ). dBv or dBu ,
, . dBV ,
,
.
dBW
, 1 W ,
dBW W Watt . dBm .
dBm , , (Line Level) , dBm
.dBm or dBv or dBu .
dBW . .
, dBW. dBW dBm ,
0 dBW=1W,
100W=10log(100W/1)=20 dBW
1000W=30 dBW
dBW dBm
1W= dBm
dBm=10log(1W/1mW)=10log(1/0.001)=30 dBm
1W= 0 dBW=30 dBm
dBW = -30 dBm 30 dBm = 0 dBW.
dBW Watts ,
1 , 10 dB , 10 .
dBr
dBr , , .
. dBr . 20~20k.
0 dBr . 0 dBr = 1.23 Vrms = + 4dBv .
dBr ( Level ) .
dBFS
.
” ” or .
( " digital clipping" ).
0 dBFS .
0dBFS + 24dBu . + 18dBu . dBA dBB dBC
2~3
20~55 dB SPL A .
55~85 dB SPL B .
85~140 dB SPL C .
B
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