rendered paste body [15:21:28] <leeeeee> R1 is placed in series with the speaker and is used to
[15:21:28] <leeeeee> attenuate the output.
[15:21:28] <leeeeee> R2 is placed in parallel with the amp output and is
[15:21:28] <leeeeee> used to correct the attenuator impedance.
[15:21:28] <leeeeee> Rsp is the nominal speaker impedance.
[15:21:30] <leeeeee> R1 = (Rsp/SQR(Pout/Patt)) - Rsp
[15:21:32] <leeeeee> Where Patt/Pout is the output ratio e.g 1/10th, 1/4 etc
[15:21:34] <leeeeee> R2 = 1/( (1/Rsp) - (1/(R1 + Rsp)) )
[15:22:20] <leeeeee> 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] <Excelsior> Er, no transistors, Just resistors. All values +- 5
Ohms acceptable: (R == Ohm) , 24.75R, 54R << Are the component values I
need
[05:48:31] <Excelsior> (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