oda v2.1 schematic
DESCRIPTION
freeTRANSCRIPT
CLC Filter for audioband noise in bothdirections
transformer secondary ringingsnubber from Hagerman
Power jack and power on/off switch
Low drop-out low-noise adjustablevoltage regulators
Pre-regulator for inputvoltage reduction andripple reduction
Gain section bypass capsand amplifier section rail clamp diodes
post-regulator stabilitycaps and diode rail clamps
Dual rail power readyLEDs
Ground jumperrequired bylayout
RF filter for 3.5mminput jack Gain stage with optional
bass boost
Volume pot with attenuation resistorsand DC blockingcoupling caps
Variable gain rotary switch
6 parallel high current buffer chips. 70mA each, for a total of around375mA per channel maximum.
Output relay control circuit
1K LinearBourns Pro Audio 9mm
1%
1%
35Vdcsolid tantalumESR = 1.3R
5mA
+14.35V (+/-0.5Vdc) or+18.49V (+/-0.5Vdc)
+12.52Vdc (+/-0.1Vdc) or+15.0Vdc (+/-0.1Vdc)
+17.24Vdc or+ 13.25Vdc
1N40
04
35Vdcsolid tantalumESR = 2R
1.21Vdc
-1.22Vdc
CO
G/N
POM
LCC
50V
CO
G/N
POM
LCC
50V
16Vac for +/-12.5Vdc power rails2.4A secondary
main on/off switch
5% MLCC C0G100V
10% MLCC X7R100V
1%
Attenuation1K with 1K pot for 50%
Attenuation1K with 1K pot for 50%
Dual half wave rectifier
-14.5V (+/-0.5Vdc) or-18.54V (+/-0.5Vdc)
Relay circuit voltage regulator.24V for +/-12.5V rails48v for +/-15V rails
Op amp groundreturn resistors
Output stage op ampground return resistor1.5Hz high pass filter
Clipping detect circuit
Clipping detectindicator LED
6 parallel high current buffer chips. 70mA each, for a total of around375mA per channel maximum.
Output relay
Output jacks andaccessory output.3.5mm and 1/4".
0.1%
250
mW
0.1%
250
mW
0.1%
250
mW
0.1%
250
mW
35Vdcsolid tantalumESR = 2R
-17.29Vdc
Less than +39.0Vdcpeak
Less than -39.0Vdcpeak
V+ takeoff
-V power rail takeoff
-12.52Vdc (+/- 0.1Vdc) or-15.0Vdc (+/-0.1Vdc)
35Vdcsolid tantalumESR = 1.3R 14.3Vdc max
20Vgs 2N7000 are OK 14.3Vdc max20Vgs 2N7000 are OK
1N4004
1N4004
All gain switch resistors 0.1% 1/8W or greater
Pre-regulator voltage test point
Pre-regulator voltage test point
LDO-regulator voltage test point
LDO-regulator voltage test point
EVER
LIG
HTM
V546
4MP4
BEV
ERLI
GHT
MV5
464M
P4B
IC5
IC2
IC1 GAIN STAGERIGHT CHANNELTEST POINT
GAIN STAGELEFT CHANNELTEST POINT
Optional Zobel Network.Leave R86, R87, C60, C61UNPOPULATED unlessoscillation trouble.
Optional Zobel Networkfor use when poweringPC speakers instead ofheadphones.
Optional attenuation resistsorsand EMI filter. Short (jumper) R80 & R81 for no attenuation.
Jumper (short) dampingresistor positions R88 & R89 for no dammping (the usualway to build the amp)
Optional EMIfilter
RIGHT
RIGHT
RIGHT
RIGHT
RIGHT
RIGHT
LEFT
LEFT
LEFT
LEFT
RIGHT
LEFT
LEFT
LEFT
PRE-AMP OUT BUFFER / AMPFor 1x voltage gain buffer remove R45, R46 = 1.5kC46 = 220pF. For gain, use the formula gain = (1 + R46 / R45).
PRE-AMP OUT BUFFER / AMPFor 1x voltage gain buffer remove R43, R44 = 1.5kC56 = 220pF. For gain, use the formula gain = (1 + R46 / R43).
External Input. RemoveR1 and R2 to use.
48Vdc (+/-2Vdc) with +/-15Vdc rails or24Vdc (+/-2Vdc) with +/-12.5Vdc rails
Aluminum Electrolytic
Aluminum Electrolytic
Aluminum Electrolytic
Aluminum Electrolytic
Alum
inum
Ele
ctro
lytic
1N40
04
LM337
A version of an O2 Desktop Amplifier (ODA)agdr, 2013 - 2014V 2.0
wall transformer AC input jack
ESR
= .1
2mR
ESR
= .1
2mR
Connect JP8 to JP10with wire
Connect JP9 to JP11with wire
0.01uF 5mm 100V COG/NPO MLCCcapacitors soldered across C11 pins under the PC board
0.01uF 5mm 100V COG/NPO MLCCcapacitors soldered across C12 pinsunder the PC board
-5m
A
ESR
= .1
2mR
ESR
= .1
2mR
System starground point
JP18-1 & JP18-2 arepower disconnects
JP19-1 & JP19-2 arepower disconnects
RF filter
3.5mm input jack withswitch for grounding
RCA input jack
Input select switch withJP7 switch output tap
Output DC offsetnulling circuit
Output DC offsetnulling circuit
Pre-amp output RCA jackson front panel
1/4" output jackon front panel
3.5mm output jackon front panel
off-board outputconnection holes
Relay voltage regulatortest point, +48Vdc +/-2with repsect to thenegative rail, JP9. for the +/-12.5Vdc build. +24Vdcotherwise.
(1.30K 0.1% 1/8W if +15Vdc rail)
(1.30K 0.1% 1/8W if -15Vdc rail)
(86.6R 0.1% 1/8W if +15Vdc rail)
(100R 0.1% 1/8W if -15Vdc rail)
24Vd
c co
il fo
r +/-1
2.5V
dc b
uild
48Vd
c co
il fo
r +/-1
5Vdc
bui
ld
(3.4
K 0.
1% 1
/8W
if +
18.5
Vdc
rail)
24Vac for +/-15Vdc power rails1A - 2.4A secondarydepending on amplifier load
30V
oper
atin
g bi
late
ral
trans
ient
sup
pres
sion
2.5A picofuse2.8mm x 7mmslow blow
rela
y ci
rcui
t con
tact
Powerline transienttransorb
2 wires connect theCRC filter section tovoltage regulators
Heatsink Used
Relay reverse EMItransient suppression
Relay circuit voltagetest point
GND
35RAPC4BV4
Output
SR10010F-0205-20F0B-C7-N
220pF
220pF
4.99
k
0.1%
1/8
W
4.7uF
4.7uF
560uF
20%
org
anic
pol
ymer
20V
dc
560uF
20%
org
anic
pol
ymer
20V
dc
150p
F
5% MLCC COG 100V
150p
F
5% MLCC COG 100V
1000uF20% 50V low Z
1000uF20% 50V low Z
820uF20% 50V low Z
820uF20% 50V low Z
0.5R
1% 4
00m
W
0.5R
1% 4
00m
W
0.5R
1% 4
00m
W
0.5R
1% 4
00m
W
0.5R
1% 4
00m
W
0.5R
1% 4
00m
W
0.5R
1% 4
00m
W
0.5R
1% 4
00m
W
LT1963AET
2.61
k
1N58
19-T
1N58
19-T
0.1%
1/4
W40
.2k
red
2N3904TO92-INLINE
560uF
20%
org
anic
pol
ymer
20V
dc
560uF
20%
org
anic
pol
ymer
20V
dc
GND
BAT41
BAT41
BAT41
BAT41
4.7uF
4.7uF
gree
ngr
een
2N7000G2N7000G
10uF
25V
20%
ele
ctro
0.1u
F0.
1uF
0.22
uF
0.22uF
0.22uF
50V
10%
sta
cked
film
GND
GND
1% 1
/2W
16.9
K
1% 1
/2W
16.9
K
4.7u
F
63V
10%
sta
cked
film
LM317
249R
10uF
22uF
22k
1% 1
/8W
100k1% 1/8W
2.2k1% 1/8W
10k
10k
0.51R1% 2W
051R1% 2W
0.1%
1/4
W
15.8
K
0.1uF
0.1uF
CON-KYCON-RCA-VERT
2.61
k
249R
10uF
0.5R
1% 4
00m
W
0.5R
1% 4
00m
W
0.5R
1% 4
00m
W
0.5R
1% 4
00m
W
GND
J10M
M
G6A
-234
P
22uF
4.7uF
4.7uF
4.7uF
GND
R-US-3PIN
R-US-3PIN
15k
1k
499R
301R
4.7uF
4.7uF
0.01uF
0.068uf
1% 1
/4W
53.2
R
0.1%
1/4
W1.
65k
15k
1k
220pF
220pF
274R
1% 2
W20
R
0.05
6uF
GND
1% 2
W20
R
0.05
6uF
GND
0.22uF
50V
10%
sta
cked
film
50V
10%
sta
cked
film
0.22uF
GND
GND
22uF
20V
orga
nic
poly
GND
20V
orga
nic
poly
mer
22uF
GND
301R
499R
10%
50V
sta
cked
film
0.22uF
4.99
k
0.1%
1/8
W
0.22uF
63V
10%
sta
cked
film
1% 1
/4W
499k
1N40
04
1N47
55A
43Vd
c 1W
0.1%
1/4
W1.
65k
0.1%
250
mW
15.8
K
0.1% 1/8W
3K
0.1% 1/8W3K 0.22uF
50V
10%
sta
cked
film
0.22uF
50V
10%
sta
cked
film
GND
0.22uF
50V
10%
sta
cked
film
0.22uF
50V
10%
sta
cked
film
GND
0.22uF
50V
10%
sta
cked
film
0.22uF
50V
10%
sta
cked
film
274R
5% 1/4W0R
5% 1/4W0R
JP0E
JP0E
J7MM
0.22uF
JP0E
JP0E
GND
3K 1% 1/2W
R-US-3PIN
CON-KYCON-RCA-VERT
4.7u
F
63V
10%
sta
cked
film
GND
GND
0R
0R0R
JP0E
15k
0.1%
1/8
W
2.49
k
1% 1
25m
W
2.49
k
1% 1
25m
W
GNDGND
0.1%
1/8
W40
.2R
10R
25 tu
rn 1
/2W
2k
1% 1/8W
TZX2
V4B
2.4V
dc 1
/2W
5%
GND
10R
25 tu
rn 1
/2W
5.49K
1% 1/8W
2k
1% 1
/8W
TZX2
V4B
2.4V
dc 1
/2W
5%5.49K
1% 1/8W
4.7uF
5.49K
0.1% 1/4W
5.49K
0.1% 1/4W
1K
0.1%
330
mW
GND
GND
1K
0.1%
330
m8W
1K
1K
169R
1% 1
/4W
JP0E
1N5404
1N5404
1% 1
/4W
499k
GND
22uf
35V
20%
low
ESR
22uf35
V 20
% lo
w E
SR
JP0E0.
1% 1
/4W
60.4
R
0.51R1% 2W
0.51R1% 2W
TL783TSTL783
4.7uF
20%
63V
Hig
h-Z
3.01
K1%
1W
0R1%
1/2
W0.01uF
100V
5%
MLC
C C
OG
0.01uF
100V
5%
MLC
C C
OG
1% 1/2W3K
JP0E
274R
274R
JP0E
JP0E
1% 1
/4W
200k
1% 1
/4W
200k
4,7uF
100V
10%
X7R
PICOFUSE-VPICO-V
1N58
19-T
1N58
19-T
J2
SHIELD1
TIP2
RING-SWITCH3 RING4
TIP-SWITCH5
JP22123
REA
R1
6
REA
R2
7
REA
R3
8
REA
R4
9
REA
R_W
IPER
10
FRO
NT_
WIP
ER1
FRO
NT1
2
FRO
NT2
3
FRO
NT3
4
FRO
NT4
5
S3
C4
C3
FRONT-RIGHTF1
FRONT-WIPERF2
FRONT-LEFTF3
BOTTOM-RIGHTR1
BOTTOM-WIPERR2
BOTTOM-LEFTR3
VR1
R43
C27
C30
SHIELD 1
TIP 2
RING 4
C57
C58
CATHODE1
ANODE2
CATHODE1
ANODE2
C14
C13
C7
C8
C11
C12
A-OUTPUT1
A-INV-INPUT2
A-NON-INV-INPUT3
V-4
B=NON-INV-INPUT5
B-INV-INPUT6
B-OUTPUT7
V=8
A-OUTPUT1
A-INV-INPUT2
A-NON-INV-INPUT3
V-4
B=NON-INV-INPUT5
B-INV-INPUT6
B-OUTPUT7
V=8
R66
R68
R77
R81
A-OUTPUT1
A-INV-INPUT2
A-NON-INV-INPUT3
V-4
B=NON-INV-INPUT5
B-INV-INPUT6
B-OUTPUT7
V=8
A-OUTPUT1
A-INV-INPUT2
A-NON-INV-INPUT3
V-4
B=NON-INV-INPUT5
B-INV-INPUT6
B-OUTPUT7
V=8
R65
R67
R76
R80
GND
IN2 OUT 4
SHDN1 SENSE 5
3IC6
R26
D12
D13
R28 CATHODE1
ANODE2
Q1
C38
C39
1OUT1
1IN-2
1IN+3
VCC+4
2IN+5
2IN-6
2OUT7 3OUT 8
3IN- 9
3IN+ 10
VCC- 11
4IN+ 12
4IN- 13
4OUT 14
D7
D9
D10
D8
CENTER-PIN3
SWITCH2
OUTER1
C28
C31
LED
1LE
D2
Q2Q3
C37
C16
C15
JP13
12JP
121 2
INV2
NON-INV3
V-4
OUT 6
V+7
INV2
NON-INV3
V-4
OUT 6V+7
C10
C19
C59
R61
R60
C42
ADJIN OUT
IC3
R29
C17
C20
R41
R40R39
R17
R16
R18
R19
D5
GND
IN3 OUT 5
SHDN1SENSE/ADJ 4
2 R38
C23
C22
2TOP 2
1SHIELD 1
3BOTTOM 3
J1
ADJIN OUT
IC4
R27
R30
C18
A-OUTPUT1
A-INV-INPUT2
A-NON-INV-INPUT3
V-4
B=NON-INV-INPUT5
B-INV-INPUT6
B-OUTPUT7
V=8
R72
R74
A-OUTPUT1
A-INV-INPUT2
A-NON-INV-INPUT3
V-4
B=NON-INV-INPUT5
B-INV-INPUT6
B-OUTPUT7
V=8
R73
R75
JPR
11
2
K1
16 1
K1 O1
S1
P1
K1 O2
S2
P2
C21
C26
C29
C25
R32
R31
R10
R9
R8
R7
C33
C34
22
11
55
44
S1S1
C5
C6
R13
R88
R89
D6
R35
SWA11 SWA22 SWA33
SWB14 SWB25 SWB36
S2GND17
GND28
R15
R14
C1
C2
R6
R86
C60
R87
C61
JP18
-11 2 JP
18-2
3 412
JP19
-1
34
JP19
-2
12
JP6-
134
JP6-
2
C45
C46
C47
C48
R11
R12
C44
R42
C24
R82
D15
D16
R34
R37
R22
R23C51
C52
C55
C56
C53
C54
R5
D3
D4
R64
R63
JP16
1
JP17
1
JPR21 2
C9
JP141
JP15
1
R25
2TOP2
1SHIELD1
3BOTTOM3
J5
2
31
84
6
57
C40
JP21123
R56
R55
R52
R49
C41
C43
JP20123
R90
JP712
R1R2
JP312
JP21
R44
R84
R85
R33
13
2
R46
R51
D11
13
2
R53
R54
R59
D14
R58
C32
R47 R48
R45
R50
R57
R62
R71
JP111
D1
D2
R78
C35
C36
JP101
R36
R20
R21
J6
S
RT
ADJIN OUT
IC11
C49
R70
R69
C62
C63
R24
JP23
1
R3
R4
JP91
JP81
D17
JP1123
R79
R83
C50
F1
D18
D19