8
ABOUT
POWER
OUTPUT
PLACEMENT OF
AMPLIFIER
About Power Output
This unit is provided with 2
toroïdal power transformers with
the least leakage and high heat ef
ficiency in combination with 4
giantic
electrolytic
capacitors
( 15,000µF), which makes it possible
to ensure perfect independence of
both right and leh channels at the
power supply source fed to the out
put stage of parallel push-pull con
figuration. Therefore one channel
is kept immune from the influence
given by the other and you can get
without difficulty the rated output
power of 100W/ch into 8 ohms
loads.
With this unit such circuit that
restricts the power output is not
employed, because this gives an
unfavorable influence on the play
back sound from electrostatic loud
speakers etc.
The output power of 1 OOW per
channel (into 8 ohms) is not small,
but rather classified into the
category of high-powered amplifier.
As far as this is used at the do
mestic listening room, it is not
always required to have such loud·
speaker systems
·
whose maximum
input exceeds 100W.
Speaking about the overload
handling capability, loudspeakers in
general accept the instantaneous in
put power exceeding 5 times of the
specified maximum input. Also
when the input voltage into the
power amp is reduced by half, the
actual output power becomes one
quarter. Therefore you can use
loudspeakers of relatively low input
capability. Select the loudspeakers
that reproduce your favorable
sound rather than care about the
input overload characteristics.
The 5M21 is equipped with 2
large VU meters to show the
average output level. If you want
to monitor the instantaneous peak
output, it is recommended to
purchase the 5E24 peak indicator
unit of our Laboratory Reference
Series. The following table shows
the correlation between the meter's
indication level and the power out·
put. (only for the 5M21)
AMS vs. output level (dB) (only for the 5M21)
.,,.,
..
me1er ,en1,111v1ty Ott8
1ndic,i1ton
output
8ohm IOld
voltoc,eCVI
IWI
♦
3d8
40
200
♦
2d8
35.7
160
♦
ld8
31.6
125
OdB
28.3
100
-
1d8
25.2
80
-
3d8
20
50
-
6d8
14,2
25
8d8
11.3
16
-
IOdB
9
10
-20d8
2.8
1
-30d8
0.9
0.1
Placement of Amplifier
The 5M21(5M20) is a high power
output amplifier of DC-amp con
figuration, adopting class "AB"
operation in the output stage.
Therefore, it is necessary to choose
such location that effective heat
radiation is possible.
ln the case of transistorized
power amplifier, most of elecrric
power is consumed in power
transistors and the heat-sink con
tributes to radiate heat. The heat·
sink of the 5M21 (5M20) is placed to
0
4onm lood
IWI
400
320
250
200
160
100
50
32
20
2
0.2
tnettf Sitnltl1Ylt\f• 10d8
ou1pu1
8ohm 106d
4ohm IOld
voltoc,eCVI
IWI
IWI
12.7
20
40
11,3
16
32
10
12.5
25
9
10
20
8
8
16
6.3
5
10
4,5
2.5
5
3.6
1,6
3.2
2.8
1
2
0.9
0.1
0.2
0.3
0.01
0.02
the back side, where good venti·
lation is indispensable, otherwise
temperature inside of the unit
increases to give decisive damage to
the components. Therefore the
thermal protector is provided to
sense the temperature of heat sink
when it exceeds 90
°
C, and terminate
the operation of amplifier.
ldeally the back-side should be
thoroughly free, and at least be
careful so that heat-radiation is
done smoothly.
0
X
