Specifications
INITIAL ADJUSTMENT
Plug
in
the
EL-34's
(see
pictorial)
and
the
7199
tube.
Do
not
plug
in
the
GZ-34/5AR4
rectifier yet.
If
an
ohmmeter
is
available
measure
the
resistance
from
capacitor
lug
#2
to
ground
(chassis).
This
should
be
in
excess of
one
hundred
thousand
ohms.
Inspect
wir-
ing to
make
sure
that
all
joints
are
soldered
and
that
no
parts
are
shorting
together.
Plug
line
cord
into
117
volt
AC
outlet
and
turn
on
switch.
While
tubes
are
warming
up,
set
the
bias
potentiometer
to
the
ap-
proximate
center
of
its
rotation.
This
setting
is
only
approximate
and
the
amplifier
should
not
be
run
without
following
the
directions
below.
Your
Dynakit
includes
Dyna
Biaset
(patent
pend-'
ing) which
greatly
simplifies
setting
of
the
bias volt-
age.
This
can be
done
with
the
most
simple
and
inex-
pensive types of
DC
meters
as
long
as
they
have
a
If
in
the
course
of
bias
setting
it
is found
that
the
control
range
of
the
potentiometer
is insufficient to
obtain
the
correct
setting,
do
not
operate
the
ampli-
fier
until
the
cause
of
the
difficul
ty
is
determined.
Operation
with
incorrect
bias
can
lead to
damage
of
the
output
tubes
andlor
other
components.
Note
that
the
use
of
pin
#8
as
directed
in
the
wir-
ing
instructions
means
that
this
pin
may
not
be
used
as
a
connection
for power takeoff for preamplifiers.
Most
preamplifiers
do
not
require
the
use
of
this
pin;
however if use
of
pin
#8
is
indicated
for
your
particu-
lar
preamplifier,
another
unused
pin
must
be chosen
for a bias voltage check point.
If
this is
not
possible,
the
connection
from
the
output
tube
pin
#8
to
the
power takeoff
socket
must
be
omitted;
the
bias volt-
age
meter
reading
may
then
be
made
directly
at
the
#8
pin
of
either
output
tube.
PREAMPLIFIERS
The
Dynakit
Mark
IV
can
be used
with
any
con-
ventional
preamplifier
in
monophonic
or
stereo
sys-
tems.
Preamplifiers
which
are
self powered
are
con-
nected
by
simply
plugging
the
signal
or
audio
cable
into
the
input
socket
of
the
Mark
IV.
Preamplifiers
which
are
dependent
on
a power
amplifier
for
their
power
source
are
readily
connected
to
the
preamp
power takeoff octal
socket
on
the
Mark
IV.
The
Mark
IV
wiring
instructions
include
the
correct
power take-
off
connections
for
both
the
DYNAKIT
PAM-l
pre-
....
rating
of ]
000
ohms
per
volt
or
higher.
The
correct
setting
of
the
bias provides a total
cathode
current
of
115
MA
for
the
pair
of EL-34's.
This
current
through
the
precision 13.5
ohm
resistor
produces
a
voltage
drop
of
exactly
1.56 volts
DC,
and
this
voltage
can
be
checked
at
pin
#8
of
the
preamplifier
power takeoff
socket. 1.56 volts is
the
voltage
reading
of
a
new
type
D flashlight cell.
Thus
any
fresh
type
D cell
may
be
used for
an
accurate
reference for
the
bias voltage
setting.
The
procedure
for
"etting
the
bias voltage is to
measure
the
voltage of a fresh
type
D cell
and
note
the
meter
indication.
Then
insert
the
positive
meter
probe
in
the
pin
#8
hole of the
preamp
takeoff socket.
(Note
that
outside
the
chassis
the
pin
numbers
are
counted
counter-clockwise from
the
key.)
The
nega-
tive
meter
probe
should
be
applied
to
the
chassis.
Plug
in
the
GZ-3415AR4 rectifier tube,
and
in
about
ten
seconds
there
will be a
current
flow
which will
cause
an
indication
on
your
meter.
The
bias poten-
tio'
..
rieter
should
be
adjusted
until
the
meter
indicates
the
same
voltage
as
did
the
type
D cell.
There
may
be
a
slight
drifting
of
the
voltage
indication
as
the
new
amplifier warms
up
for
approximately
the
first
15
minutes,
after
which
the
bias control
may
be read-
justed.
Thel'€after
slight
variations
may
be
caused
by
small
changes
in
the
supplied
line voltage.
These
variations
will
neither
affect
the
performanc(~
of
the
unit,
nor
will
it
be
necessary
to
readjust
the
bias
set-
ting.
The
bias
setting
is a
semi-permanent
one
and
need
only
be reset
upon
replacement
of
the
output
tubes
or
at
such
time
as
other
repairs
or
maintenance
might
be
required. A recheck
at
the
time
of
mainten-
ance,
or
after
a
year
or
more
of
heavy
usage, will
hP.lp
preserve
peak
performance
and
keep
distortion
to
an
absolute
minimum.
Connect
one
end
of
a 7" wire to lug
#4
of
the
four screw
terminal
strip
(8).
Con-
nect
the
other
end
to
eyelet
#3
(8
l.
Connect
one
end
of a 1000
ohm
(brown-
black-red)
resistor
to
eyelet
#9
(8).
Con-
nect
the
other
end
to
pin
#5
of
socket
V3
(8)
.
40
38
37
34
33
32
35
36
Connect
one
end
of a 3
1
h"
wire to lug
#2
of
the
bias
potentiometer
(8).
Connect
the
other
end
to
eyelet
#11
(S).
Connect
one
end
of
a 1000
ohm
(brown-
black-red)
resistor to lug
#5
of V2
(8).
Connect
the
other
end
to
eyelet
# 10
(8).
Connect
one
end
of
a 3
1
/
2
"
wire
to
pin
#4
of V3
(8).
Connect
the
other
end
to eye-
let
#7
(8
l.
Connect
one
end
of
a 6800
ohm
(blue-
gray-red)
resistor to lug
#2
of
the
quad
filter
capacitor
(8).
Connect
the
other
end
to
lug
#4
of
the
filter
capacitor.
Connect
one
end
of a 10" wire to lug
#4
of
the
filter
capacitor
(8).
Connect
the
other
end
to
eyelet
#8
(8).
Connect
one
end
of
an
11" wire
to'lug
#3
of
the
filter
capaci
tor
(8
l.
Connect
the
other
end
to
eyelet
#6
(8).
Separate
the
two
conductors
of
the
line
cord
for
about
2
1
/
2
".
Cut
about
1" from
one
of
the
conductors,
then
strip
and
tin
both.
Insert
the
line
cord
through
the
grommet
from
the
outside
and
push
enough
through
to
tie
a
knot
about
4"
from
the
end.
Pull
the
cord
back
until
the
knot
is
snug
against
the
grommet.
Connect
the
short
lead
to lug A
of
the
fuse
post
(8).
Connect
the
other
lead to
lug #1 of
the
slide
switch
(8).
It
is wise to go
back
and
check
all
connections
for
correctness
and
for good soldering. All
hardware
should
also
be checked for tightness.
The
fuse
can
now be
installed
in
the
fuse post.
The
rubber
feet
should
be
installed
in
the
proper
holes
in
the
bottom
of
the
bottom
plate.
6