Pioneer A-858 specifications

Amplifier derived from the A-757 (and thus from the A-717) with even larger transformers and even more power in the housing with oversize, successor of the A-88X, very similar to the analog part of the A-90D /A-91D. However, introduced only at the same time as the A-757 and A-656, therefore smaller rotary knobs already made of plastic and plugged instead of screwed.

General

Connections

Technical data

Special equipment

Manufacturer: Pioneer
Type: Integrated Amplifier
Years of construction: 1989 - 1991
Manufactured in: Japan
Color: Black
Power consumption: 1000W (max)
Dimensions: 420 x 172 x 474 mm (WxHxD)
Weight: 24.5 kg

Number of inputs: 8
- Phono
- Tuner
- CD/DVD
- Line/Aux
- Tape-1/DAT
- Tape-2
- Tape-3
- Adaptor In-Out / Pre- Out
Number of outputs:
- list the outputs here (with level/impedance)

Phono

Tuner

CD/DVD

Line/Aux

Tape-1/DAT

Tape- 2

Tape-3

Adaptor In-Out / Pre-Out

list the outputs here (with level/impedance)

Continuous power (with total harmonic distortion)
- 8 ohms: 2 x 105 W / 0.03%
- 4 Ohm s: 2 x 160 W / 0.05%
Dynamic power
- 4 Ohm : 2 x 230 W
- 2 Ohm : 2 x 350 W
Total harmonic distortion: 0.03%
Damping factor 1kHz/20Hz ~ 20kHz, 8 Ohm : 200/70
Bandwidth power 0.05%, 8 Ohm : 5 - 60,000 Hz
Signal-to-noise ratio Phono MM: 74dB
Signal-to-noise ratio CD, Tuner, Line, Tape: 92dB
Stereo channel separation:
Tone control:
- Bass: +-8dB (100Hz)
- Treble : +-8dB(10kHz)
Loudness: Yes, Button Volume -40dB Position +5dB(100Hz) +3dB(10kHz)
High Filter :
Low Filter (Subsonic): Yes, button 17Hz (12db/oct.)
Mute: Yes, Button
Direct/Line-Straight: Yes

8 Ohm s: 2 x 105 W / 0.03%
4 Ohm s: 2 x 160 W / 0.05%

4 Ohm s: 2 x 230 W
2 Ohm s: 2 x 350 W

Bass: +-8dB (100Hz)
Treble: +-8dB (10kHz)

Elaborate and solid workmanship
Extremely high output power (immense current resistance)
Adapter loop (through bridge connector on the back)
Direct switch : For direct connection to the volume control
Phono switch for MM and MC pickups + subsonic
Transformers in solid cast housings for protection against resonances and magnetic interference
Honeycomb rib-reinforced chassis and honeycomb-structured heat sink (resonance and vibration-damping)
Robust power supply for stable supply at peak loads
Spatially separated stages, therefore elimination of mutual interference
Gold-plated connection sockets for phono and CD

Predecessor model:
Pioneer A-8 8X

Successor model:
Pioneer A-8 78

Other models of the same series :
Pioneer A-22 7
Pioneer A-33 7
Pioneer A-44 7
3498f73c37688adb1a96fc0533245fad 56 MK II
Pioneer A-7 57 MK II
Pioneer A-8 58

Picture: Pioneer A-8 58

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At that time, starting from the A-717, Pioneer had launched a whole series of amplifiers of the same basic concept: solid construction with consistently oversized components, which was reflected in the weight. The durability is enormous, so that most of the amplifiers that are still available used today work absolutely flawlessly. 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 provide the positive and the negative operating voltage of the output stages.

Although the amplifiers have two connection pairs on the back, each connected by a wire bridge, they have none on separable pre- and power amplifiers. Rather, this so-called adapter connection is located in front of the volume control and tone control stage. 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.

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 only one real weak point: a capacitor in the protection and turn-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.

Pioneer A-858