Quad II Schematic

QUAD II Power Amplifier

R

C

HT and

heaters to

Control unit

socket

SK

1

h h

4

2

56

3

1

Input

R

1

1.5MΩ

1

R

1MΩ

R

1MΩ

2

3

2
3

1

110V 0.22mA

C

1

0.1µF

110V

0.22mA

V

EF86

2.2V

V

EF86

4

1

h h

R

680Ω

h h

2

1.2mA

4

115V

1.2mA

R

100Ω

115V

10

10

R

180kΩ

R

6

180kΩ

11

7
8
9

12

5
6

2

6543

T

V

5

SK

SK

C

16µF

450V

GZ32

C6 and C4 are in the

2

large square can. C

plain foil) and has

3

rating, C4 is marked

6

+E (for etched foil)

and is more like a

standard electrolytic

h

h

is marked +P (for

the higher ripple

capacitor

330V

17mA

L

h h

h h

65mA

65mA

R

12

180Ω

3W

1

For 15Ω speakers link S to

R as shown, for 8Ω link S

Y

Z

U

26V

V

W

X

C

25µF

50V

C

2

0.1µF

350V

5

680kΩ

2.7kΩ

680kΩ

C

0.1µF

350V

R

7

R

8

R

9

3

C

16µF

450V

14mA

V

3

KT66

V

4

KT66

4

147mA

to T and Q toR

T

1

5

340V

T

S

R

Q

Output

310V

rms

310V

rms

5V rms

6.3V rms

HT

HT

5V

5V

6.3V

6.3V

E

Note: The original capacitors for C

6

which were connected to ground, the
small capacitance to ground controls

the open loop frequency response and

change these capacitors with caution!

2

240V or 130V

220V or 115V

200V or 100V

com

F

1
2A 200-250V
3A 100-130V

PL

1

a.c. mains from QUAD 22

control unit

and C3 had insulated metal bodies

thus the stability with feedback;

2

R

470Ω

11

QUAD II Power Amplifier Schematic Drawing 11175 iss.1 Redrawn in original style by

Keith Snook

d.c.~daylight ltd.

1994