Pioneer a 6 service manual

Page 2

CIRCUIT DESCRIPTIONS

The Model A-5 and A-6 are integrated amplifiers
belonging to the same series. The table shown
below lists and compares the major circuits and

The general circuit configuration for Model A-6
is shown by block diagram in Fig. 1; Fig. 2 shows
Model A-5. The circuit description will be based
on Model A-6.

performance characteristics of both models.

Circuit-Performance Comparison

Circuit

Modal A-G

Model A5

Equalizer Amp

Amplifier section uses a dual FET differential
input amp and operational amp IC.

OCL and ICL configuration obtained by using DC
servocontrol circuit. MM and MC cartridge
compatibility.

Uses operational amp [0.
MM cartridge only.

Hum and Noise
(IHF, short circuited A network)
PHONO MM
PHONO MC .
Overload Level
(T.H.D. 0.002%,1KH2)
PHONO MM ............. 15UmV
PHONO MC .............. 15mV
Frequency Response

(RIAA Equalization)

.......... 20H2 7 20kHz 20.2dB

Hum and Noise
(IHF, short circuited A network)
PHONO MM .............. 70dB

Overload Level
(T.H,D.0,004%,1kHz)
PHONO MM .............. 140mV

Frequency Response
(RIAA Equalization)
.......... ZOHZ - 20kHz LOSdB

Power Amp

Nonswitching Amp using high speed bias servo-
control circuit in power stage. OCL and ICL con-
figuration obtained by using dual FET differen-
tial input amp and DC servo-control circuit.

Non-switching type power amp using high speed
bias servo-control circuit in power stage.

Continuous Power Output
(both channel driven)
20Hz - 20 kHz ............ 60w+60W
(T.H.D. 0.008%)
Tonal Harmonic Distortion
(20H2 - 20kHz, 89, from AUX)
Continuous rated power output
.......... No more than 0.008%
30W per channel power output
.......... No more than 0.006%
Frequency Response

.......... 5H2 - 100kHz :g dB

Continuous Power Output
(both channel driven)
20H! e 20kHz ............. 35W+35W
(T.H.D, 0.009%)
Total Harmonic Distortion
(20Hz - 20kHz, 80, from AUX)
Continuous rated power output
.......... No more than 0.009%
17.5w per channel power output
.......... No more than 0.007%
Frequency Response

.......... 5H2 e lOOkHz :2 dB

Tone Control Circuit

Constructed within the NFB circuit of power amp.
Tone switch tunrs circuit ONIOFF.

Same as Model A-6

Protection Circuit

Senses DC voltage and overload in output of
power amp, activating relay to disconnect speaker
system from power amp output. Also functions as
transient killing muting circuit when power switch
turned ONIOFF.

Same as Model A-6

Power Meter
Cirou it

IC (TA731BP) functions to compress and rectify
power amp output signal, and drives 7»point LED
meter module, Signal peak value displayed.

Not featured in Model A-5