Massive Audio DB8000 Manuel d'utilisateur télécharger pdf (Page 53)

it

+11

° R12

RI

b

ú°b

o4ct+

0

? sir

o-

R13

Rll

óQ

:cs b b c

b

11°'_.

°-

Ri

R5 p...

R3

-°

Cl

b + o

ó

?

°°f

c4

Rs

R4

ó

12

C42

óC3

bó

gate results in

a

higher

drain -source

resistance,

and

this,

in

turn, acts

to re-

duce the bypassing

action of C5 and

limit

the gain of

Q2. Thus,

as the signal

level

at the

collector of Q2 tries

to

in-

crease, the control

circuit acts to

reduce

the gain to its original value.

Figure

2

shows,

graphically, the result

of this action.

The

gain

of

the circuit

increases

only a

few

dB although the

signal

input level may be increasing by

as

much

as

20

dB

-about 10

times!

Construction.

The

entire Audio

Lev-

eler

circuit

can be assembled on a

11/,"

x

31/2" printed circuit board or

phenolic

Parts

identification

of

the

fully

assembled printed circuit board

includes input A,

output B, and

+12

-volt supply connection point.

C8

514

\

R12

Fig.

3.

Actual

-size

photo

shows

toil

side

of

printed

circuit board

(up-

per left); component side

of

board

is

below it. Observe

polarity

mark-

ings when installing

diodes and

electrolytic capacitors. Also, po-

sition the transistors as

shown.

circuit

board.

An etched and

drilled

fiberglass printed circuit board (Fig.

3)

is

available

(see

Parts

List)

.

The

board

comes marked with

the location of all

components, and

it is only

necessary for

the builder to

insert the parts in the

marked

positions

and

solder

the leads to

the copper foil.

When installing the

parts on

the

PC

board, be sure to position the flat sides

of

Q1 through Q4 as shown in Fig. 3.

Also,

the

locating tab on Q5 must

be

oriented as indicated.

The

ground lead

of this transistor

(Fig. 4) must

be cut

off since it

is not

used.

And

be sure

to

observe

the proper polarity

when in-

C6

RIO

Q4

Q3

55

R1

C5

R7 I

C4

R3

Q2

Cl

--- C2

R15

D2

D1

C9

R13

B) \ C7 R8

C3

R11 R9

R6

R4 R2

February, 1967

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