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| Pioneer M-22 |
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| 120,000yen(around the 1980 time) |
Class-A stereo power amplifier which adopted the chassis made from
die-casting as the radiator made from die-casting.
The Class-A operation
is adopted as a whole page.
The Class-A operation sends many idle currents
through the transistor also in the time of a non-signal, and is a scheme which
uses only operating range with the sufficient linearity of a transistor.
Although a Class-A operation has a low electrical-power utilization factor
and calorific value also increases, in order that the upper and lower sides may
be amplified by the same wave and may obtain a synthetic output, with B class
amplifier, switching distortion or crossover distortion which are not avoided do
not generate two transistors of a push pull.
The Class-A operation circuitry of M-22 has DC amplifier composition which
removed the capacitor of the NFB circuitry. The time constant formation
of the NFB loop was lost by this DC-ization, and the stable NFB operation
is realized.
A whole page Class-A
operation and this DC amplifier stream composition have realized the mid-high
range without a distorted feeling, and the outstanding low-pass property.
The large-sized transformer of a L/R independency and the capacitor of
33,000 micro Fx4 are adopted as a power-source part.
The construction of
the whole included amplifier is used as a symmetrical form, and the power relay
of a protection network is also using the power-source part by two L/R
independencies. Furthermore, attention is paid to leading about of an internal
wiring etc. and the cross interferencee between channels is eliminated.
The pure-copper board is adopted as the earth line from an electrolytic
capacitor to a speaker termination.
In order to protect a speaker and a
transistor even against an emergency outage, the reliable protection network
constituted from a quick electronic circuitry of a power relay and a response is
built in.
A power relay carries out parallel connection of the two contacts, and is improving the robustness.
|
| Form |
Stereo power amplifier |
| Circuit system |
Two steps of differentials, PP drive,
two-step Darlington, parallel PP,
Pure complimentary OCL (a Class-A
operation, DC amplifier stream composition) |
| Effective output (both channel drive) |
30W+30W (10Hz - 30kHz, 8ohm) |
THD
(10Hz - 30kHz, 8ohm) |
At the time of an effective output: 0.01%
At the time of 15W output: 0.005%
At the time of 1W output: 0.005%
|
Cross modulation distortion
(50Hz : 7kHz = 4:1 or 8ohm) |
At the time of an effective output: 0.005%
At the time of 15W output: 0.003%
At the time of 1W output: 0.003%
|
| Output bandwidth (IHF, both channel drive) |
5Hz - 100kHz (distortion 0.01%)
|
| Frequency characteristic |
2Hz-150kHz+0 -1dB (at the time of 1W output)
|
| Input terminal |
Input: 1V/50kohm |
| Output-terminal |
Speaker: 8ohm |
| Dumping factor |
60 (20Hz - 20kHz, 8ohm) |
SN ratio (IHF, A network)
Short circuit
|
106dB |
| The semiconductor used |
Transistor: 44 pieces
Diode, other:62
piece |
| Supply voltage |
100V, 50Hz/60Hz |
| Power consumption |
240W (Electrical Appliance and Material
Control Law) |
| Dimensions |
Width 420x height 153x depth of 370mm
|
| Weight |
22.0kg |
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