[15:21:28] R1 is placed in series with the speaker and is used to [15:21:28] attenuate the output. [15:21:28] R2 is placed in parallel with the amp output and is [15:21:28] used to correct the attenuator impedance. [15:21:28] Rsp is the nominal speaker impedance. [15:21:30] R1 = (Rsp/SQR(Pout/Patt)) - Rsp [15:21:32] Where Patt/Pout is the output ratio e.g 1/10th, 1/4 etc [15:21:34] R2 = 1/( (1/Rsp) - (1/(R1 + Rsp)) ) [15:22:20] SQR(n) is the square root of n R1 = (Rsp/SQR(Pout/Patt)) - Rsp R2 = 1/( (1/Rsp) - (1/(R1 + Rsp)) ) RSP = 16 --- 1/8 R1 = (16/sqrt (1/8))-16 R1 = 29.254833995939 R2 = 1/((1/16) - (1/(29.254833995939 + 16))) R2= 24.7506905708484 --- 1/4 R1 = (16/sqrt (1/4))-16 R1 = 16 R2 = 1/((1/16) - (1/(16 + 16))) R2 = 32 --- 1/2 R1 = (16/sqrt (1/2))-16 R1 = 6.62741699796951 R2 = 1/((1/16) - (1/(6.62741699796951 + 16))) R2 = 54.6274169979696 --- 1/1 R1=0 R2=infiniti [IGNORE] Digikey Only: -1/8- 30R (50W) = 6.25000 25R (25W) = 4.89000 -1/4- 16R (50W) = 6.25000 30R (50W) = 6.25000 -1/2- 7.5R (25W) = 4.66000 50R (50W) = 5.21000 Total: $33.51 ---------------------- [/IGNORE] Ebay only: $1.83 $5.2 $1.15 $2.5 $5 $7.73 $23.4 What I bought: 10x 45R (25W) 10x 100R (50W) 10x 20R (25W) 1x 25R (50W) [05:47:54] Er, no transistors, Just resistors. All values +- 5 Ohms acceptable: (R == Ohm) , 24.75R, 54R << Are the component values I need [05:48:31] (10) 20R resistors, (10) 45R resistors, (5) 100R Resistors is what I have. 31.034R (100 || 45) 31.034R (100 || 45) 16.66R ( 100 || 20 ) 8.188R ( 20 || 20 || 45) 50R (100 || 100) 25R Left (5) 20R resistors, (4) 45R resistors, (10) 100R Resistors is what I have left now. --- -1/2- R1: 8.188R ( 20 || 20 || 45) R2: 50R (100 || 100) -1/4- R1: 16.66R ( 100 || 20 ) R2: 31.034R (100 || 45) -1/8- R1: 31.034R (100 || 45) R2: 25R 0.9022=(30^2)/r --- 1/8 R1 = (16/sqrt (1/8))-16 R1 = 29.254833995939 R2 = 1/((1/16) - (1/(29.254833995939 + 16))) R2= 24.7506905708484 ][ 31.034 = (16/sqrt (1/x))-16 x=8.6413951 Real attenuation:1/8.6413951 ][ --- 1/4 R1 = (16/sqrt (1/4))-16 R1 = 16 R2 = 1/((1/16) - (1/(16 + 16))) R2 = 32 ][ 16.66 = (16/sqrt (1/x))-16 x=4.1667016 Real attenuation: 1/4.1667016 ][ --- 1/2 R1 = (16/sqrt (1/2))-16 R1 = 6.62741699796951 R2 = 1/((1/16) - (1/(6.62741699A796951 + 16))) R2 = 54.6274169979696 ][ 8.188 = (16/sqrt (1/x))-16 x=2.2853881 1/2.2843881 ][ --- V = SQR(W*R1) X---X 1/2 R1: 8.188R ( 20 || 20 || 45) R2: 50R (100 || 100) Speaker power: 50 * 1/2.2843881 = 21.887 R2 power: 28.3^2/50= 16.0178 W Dissipation for r1: 50 - 21.887 - 16.0178 = 12.0952W [R1] V=9.951 p=v^2/R 9.951^2/20= R1(20): 4.951W R1(20): 4.951W R1(45): 2.192W [R1] [R2] 100R: 8.0089W 100R: 8.0089W [R2] x---x 1/4 R1: 16.66R ( 100 || 20 ) R2: 31.034R (100 || 45) r1 values: 16.66R for R1, R2: 31.034 Speaker power: 50 * 1/4.1667016 = 11.999W R2 Power: 28.3^2/31.04 = 25.801 50 - 11.999 - 25.801 = 12.2W For R1's power [R1] 12.2w 16.66R ( 100 || 20 ) v=14.230 14.230^2/100 R1(100): 2.02W R1(20): 10.124W [R1] [R2] 31.034R 28.3^2/45= R2(45): 17.797 W R2(100): 8.0089W [R2] x----x 1/8 R1: 31.034R (100 || 45) R2: 25R ( 45 || 45 || 45 + 20 || 20) 50 * 1/8.6413951 = 5.7861W R2 Power: 28.3^2/25 = 32.0356 W R1 Power: 50 - 5.786 - 32.0356 = 12.1784W [R1] R1: 31.034R (100 || 45) v=19.44 p=19.44^2/R R1(100): 3.779W R1(45): 8.399W [R1] [R2] R2:25R 50W R2(25): 32.0356W [R2] x----x R1(20): 4.951W R1(20): 4.951W R1(20): 10.124W R2(100): 8.0089W R1(100): 3.779W R1(100): 2.02W 100R: 8.0089W 100R: 8.0089W R1(45): 2.192W R1(45): 8.399W R2(45): 17.797W R2(25): 32.0356W ----- C1A C2A C3A L1A L1B L1C