Pioneer A-757 MK II specifications

Category : Integrated amplifier

Brand : Pioneer

General

Connections

Technical data

Special equipment

Other models of the same series:

Previous model:

Successor model:

External differences to the A-757: minor Rotary knobs have been replaced by cylindrical versions similar to the large knobs. Golden dot only on the volume potentiometer. Inside: still horizontal boards, but already no honeycomb housing around the volume potentiometer at the back right of the device. No more copper flooring!

manufacturer: Pioneer
model: A-757 MK II
year of construction: 1990 - 1991
Made in Japan
color: Black
remote control: no
power consumption: 820 watts (max)
dimensions: 420 x 162 x 435 mm (WxHxD)
weight: 19.5 kg
factory price approx.: 1.000,- DM

number of inputs: 8
- Phono MM/MC 2.5 mV/50 kOhm or 0.2 mV/100 Ohm s
- DAT /TAPE 1, TAPE 2, ADAPTER1/ TAPE3, ADAPTER 2, CD (gold plated), TUNER, LINE 150 mV/50 K-ohms
number of outputs: 5
- 2x Rec Out 150 mV/2.2 K-ohms
- 2x speaker
- headphones

Phono MM/MC 2.5 mV/50 kOhm or 0.2 mV/100 Ohm s
DAT /TAPE 1, TAPE 2, ADAPTER1/ TAPE3, ADAPTER 2, CD (gold plated), TUNER, LINE 150 mV/50 K-ohms

2x Rec Out 150 mV/2.2 K-ohms
2x speaker
headphones

the duration of the performance (total harmonic distortion)
- 8 Ohm : 2x 95 watts / 0,003 %, 100 Watt DIN
- 4 Ohm : 2x 140 Watt / 0,005 %, 150 Watt DIN
- 2 Ohm : 2x 200 watts
dynamic performance
- 8 Ohm : 2x 150 Watt
- 4 Ohm : 2x 200 watts
- 2 Ohm : 2 x 300 watts
total harmonic distortion: 0,003% (20Hz - 20 kHz, 95W, 8 Ohm )
damping factor:
frequency response: 1 Hz - 150 kHz 0 dB/- 3 dB
signal-to-noise ratio: 95/77/110 dB (Phono MM, Phono MC, high-level)
stereo channel separation:
control:
- Bass: ± Straight, 8 dB at 100 Hz
- treble: ± 8 dB at 10 kHz
Loudness: Yes
High Filter : no
Low Filter (Subsonic): Yes, only Phono, 17 Hz/12 dB
Mute: Yes
Direct/Line: Yes

8 Ohm : 2x 95 watts / 0,003 %, 100 Watt DIN
4 Ohm : 2x 140 Watt / 0,005 %, 150 Watt DIN
2 Ohm : 2x 200 watts

8 Ohm : 2x 150 Watt
4 Ohm : 2x 200 watts
2 Ohm : 2 x 300 watts

Bass: ± 8 dB at 100 Hz
height: ± 8 dB at 10 kHz

recording selector switch
pairs of Speakers and headphones via Relay
metal front plate
Phono input with possibility to choose MM/MM subsonic Filter /MC/MC subsonic Filter
Switchable Phono pre-amplifier
auftrennbare in Front of switched - and power amplifier
shortened signal paths possible clean sound
separate levels: Reduced interference
resonance-absorbing construction: honeycomb-shaped reinforced frame, heat sink, and a damper to prevent microphonic effects
powerful, niedrigimpedantes power supply: 2 power transformers and ribbed solid cast housings have a high capacity
good resonance damping and clean magnetic shielding
"Non-Switching" type III secure: The elimination of the switching distortion and improved stability at low impedances

A-227
A-337
A-447
A-656 MK II
A-757 MK II
A-858

A-757

A-777

Pioneer was launched at the time, starting from the A-717, a whole series of amplifiers of the same basic design: Solid design with consistently sized components, which was reflected in the weight low. The durability is enormous, so that most of the amplifiers that are still available used today usually work perfectly. In particular, the typical scratching of old switches and potentiometers is rather rare here. From 7x7 the amplifiers have two transformers in the power supply. However, these do not serve as usual for the separate supply of the two stereo channels, but supply the alternating current which is then converted on the one hand into the positive and on the other hand into the negative operating voltage of the output stages.

Although the amplifiers have two connection pairs on the back, which are each connected by a wire bridge, they do not have separable preamps and power amplifiers. Rather, this so-called adapter connection is located in front of the volume control and tone control stage in order to connect an equalizer, for example. That's why you can use the Pioneer amplifiers as power amplifiers for other preamps, but you can't connect the Pioneer preamps to other power amplifiers. Without these bridges, the tone control stage will not work.

The sound of these amplifiers can be described as warm, powerful and precise compared to similar amplifiers from other manufacturers, although perhaps the last bit of precision is missing compared to devices that are several times more expensive. The devices must be certified as having an excellent price - performance ratio, especially with the used ones available today, which are technically always in new condition.

The amplifiers of the A-656 to A-757 series, possibly also later models, have a more common weak point: a capacitor in the protection and power-on delay circuit breaks, after which the speaker relays turn on with a delay and then buzz for a while. The repair should cost about € 50 in a specialist company, plus 80 cents in material costs. Another rather rare weak point are the IC's PA0016 from Pioneer , which control the quiescent currents of the power amplifiers. If errors occur here, the complete power amplifier is usually extensively broken and the IC is difficult to get in the original.