Heathkit W-5M User Manual

One
of
the
outstanding features
of the
W-5M
is
the remarkable low frequency power response .
Observe that the
0.25 watt
curve
extends smoothly
to 3
cps
and
is
only
down 3 db at this point
.
Also,
note
that it is
possible
to obtain
20
watts
of power at 20 cps
without overloading.
In con-
ventional
amplifiers, low
frequency response at low
levels
has
been sadly
lacking.
At
high
levels
these amplifiers
tend
to go
into overload and block
on heavy bass
passages.
Because
of
the unique
output
transformer design
featured in the
W-5M,
low
frequency
power
response is
greatly im-
proved.
Special
attention has been
given
to the problem
of overload
recovery. (See
"Overload
Recovery” on
Page
7.
)
FREQUENCY RESPONSE:
See
Figure 2 below. This
curve
was
taken
at 1
watt reference output and
may
be
considered as
the voltage
response
of the
amplifier
I CPS
10 CPS
IOO CPS
1KC 10 KC
100
KC
Figure 2
HEATHKIT
W-5M
FREQUENCY
RESPONSE
(
1
WATT
OUTPUT
)
An
outstanding
characteristic of
the
W-5M
amplifier
is
the
complete
absence
of the
rising
res-
ponse
at
the
low and high
limits
of
the pass
band
which
has been
considered a
necessary
evil
up to
the
present
time.
Although
outside
the
audible
range, such
humps
add to
the
instability
of the
amplifier
and tend
to
create
distortion
in the
audio
range. This
happens when
low
frequency
trans-
ients,
such as
turntable
rumble,
line
voltage
surges
or
tuning thumps,
drive
the
amplifier
into
low-frequency
overload. In
the
W-5M,
these
transients
cannot
create
any
audible
distortion
and
no
hangover or
"breathing"
conditions
are
evident.
The
curve
in
Figure
2,
taken
at 1
watt
output
and
the
5 watt
curve in
Figure
1,
represent
aver-
age
room
listening
levels.
In
this
amplifier, a
minimum
of
500%
reserve
power is
available
to
accomodate
heavy
bass
passages
and
to make
up
for
the
relative
inefficiency
of less
expensive
speaker
systems.
HARMONIC
DISTORTION:
Figure
3
below
gives five
curves
which
relate
the
total
harmonic
distortion
to
power
output
throughout
the
frequency
range.
From
these
curves
it becomes
evident
that
specifying
total
har-
monic
distortion
at
any
power
level
without
designating
the
test
frequency
can
be
very
misleading.
)
Competent
authorities
seem
to
agree
that a
total
of
2%
harmonic
distortion is
tolerable
for mus-
ical
reproduction
through
wide-range
audio
equipment.
Harmonic
distortion
below
0.7%
is
com-
pletely
imperceptible,
even
to
highly
trained
critical
observers.
Curves
showing
the
output
ob-
tainable at these
distortion
levels
throughout
the
frequency
range
have
been
included above.
Figure
4
indicates
the
distortion
versus
frequency
curves
for several
power levels.
Page
4
Figure
4
HEATHKIT
W-5M
TOTAL
HARMONIC
DISTORTION
(
DETERMINANT:
POWER
OUTPUT
)

Heathkit W-5M Specifications

General

Brand	Heathkit
Model	W-5M
Category	Amplifier
Language	English