What is stereo?

There are now two system of high fidelity, monophonic (monaural) and stereophonic. Monophonic is a system that starts from one microphone and is fed through a single high fidelity set. Stereophonic is a double system. Two separate microphones are placed at different sides of the orchestra and two different systems are used to keep the two signals or channels separated. Two separate speakers are used, placed on different sides of you room. Stereo is much like 3-D photography, two slightly different sound reach your ears giving you a new dimension in sound.

H.H. Scott '59

Pioneer SX-1250 (1976)

Because it enables you to enjoy both the joys of records and of the numerous musical programmes broadcast on the air in mono and stereo, the receiver is by far the most convenient piece of hi-fi equipment. It is no coincidence that Pioneer is particulary reputed for this type of equipment, the refinement, performance and sturdiness of Pioneer receivers is almost legendary. Ask one of the thousands of audiophiles already equipped with even an old Pioneer receiver and you'll be convincend. The range of Pioneer receivers is particulary wide. As many 12 models, including the two quadraphonics, from 2 x 15 watts for the SX-450 up to the extraordinary SX-1250 with a record 2 x 160 watts.

Pioneer The Uncompromising Demand Of Quality

There is no bottom line in Pioneer and the least powerful, the SX-450 presents a total harmonic distortion of only 0,5%, which reaches 0,1% when you get to the SX-750. As for its sensitivity, it's already 11.2 dBf on the SX-450 and reaches 8.7 dBf on the SX-1250.

To achieve this quality, Pioneer carefully choses the components and the circuitry so that the quality of each FM, AM, preamp, and amp section is beyond reproach regardless of the model you select.

Multiplex (MPX) Circuit

Its function is to separate the right and left channels from the stereo FM signal. This is a very complex operation and often influenced by temperature and air humidity. The phase lock loop integrated circuits (PLL) automatically control the stability of this separation. They are standard on all Pioneer equipment from the SX-450 to the SX-1250.

FM Front End And FM IF Section

The quality of these two sections is decisive for sensitivity, enabling you to get stations whose signals are weak or weakended by distance or obstacles and for selectivity which rejects undesirable stations. This is why Pioneer uses field-effect transistors (FET and MOS-FET) for the first section and variable capacitors with a minimum of 3 gangs (SX-450 to SX-650) and up to 5 gangs (SX-1250). Multipath switch ensures accurate antenna mouting for optimum reception (SX-1050 and Sx-1250).

FM Muting

A built-in muting circuit effetively eliminates irritating pop and interstation noises during tuning and detuning on all Pioneer receivers.

AM (Long ANd Medium Wave) Reception

AM reception is often a neglected point on many receivers, and the poor quality of the sound drivers you back to FM eben when you want to listen to an interesting program on AM. Not on a Pioneer, thanks to the use of LSI (Large Scale Integrated Circuits), ceramic filters (SX-450,550, 650, LX-434,550) and two or three gang capacitors (SX-750 to SX-1250)

Hign Class Equalizer And Control Preamplifier

The quality signal produced by the FM section must be as carefully treated as the signals from the turntable, the tape recorder, or the cassette deck.

For records the direct coupled 3 or 4 stage preamplifier equalizers give an RIAA correction always within ±0.3 dB, and input tolerances of 150 mV (SX-450) to 500 mV (SX-1250) assuring good rstitution of the high and low frequencies and a god dynamics range.

The control preamp using field effect transistors and integrated circuits (CR type) allows very delicate control. Starting with the SX-750 there is double effect and twin tone control system.

Power Supply and Protection Of Power Amplifier

The power of the Pioneer receivers is a real power, always indicated from 20 to 20,000 Hz with the corresponding maximum distortion. Direct coupled PNP, NPN circuits (up to SX-950) and Darlington transistorized circuits (SX-1050, SX-1250) assure this succes.So that this power can be supplied, Pioneer chose oversize transformers and electrolytic capacitors to provide all the energy necessary for the lowest frequencies.

Refined Design and Operation Features

The presentation of the Pioneer receivers SX-450 to SX-1250 is of a remarkable quality. Pioneer styling is also legendary, touch the button of a Pioneer and compare to others. Such production precision is almost incredible.

Finally, it's the power and the variety of possibilities which will enable you to choose.

Specifications SX-1250

Audio Section

Continuous power:

2 x 200 W (both channel driven at 20 Hz - 20 kHz, 4Ω)

2 x 160 W (both channel driven at 20 Hz - 20 KHz, 8Ω)

THD at rated output power (DIN), 8Ω: 0,1%

Power bandwidth (DIN) both channel driven 8Ω: 5 Hz - 40 kHz

Frequency response at AUX input (DIN): 10 Hz - 50 kHz (+0 dB, -1 dB)

Input sensitivity impedance:

Phono: 2,5 mV/50 kΩ

Microphone: 6,5 mV/50 kΩ

Tape monitor, Tuner, Aux: 150 mV/100 kΩ

Bass control (100 Hz): ±10 dB

Treble control (10 kHz): ±10 dB

FM Section (87,5 to 108 Hz)

Sensitivity (DIN):

Mono (26 dB S/N ratio): 1,3 μV

Stereo (46 dB/S/N ratio): 35μV

Capture ratio: 1 dB

Selectivity (±400 kHz): 83 dB

S/N ratio (IHF): 80 dB

THD (stereo) 1kHz (DIN): <0,2%

Frequency response (DIN): 30 Hz - 15 kHz (+0,2 dB, -2 dB)

Stereo separation 1 kHz (DIN): 50 dB

Subcarrier suppression: 74 dB

AM Section (525 - 1605 kHz)

Sensitivity (IHF): 15 μV/m

Selectivity: 40 dB

Dimensions (W x H x D): 556 x 186 x 464 mm

Weight: 29,2 kg

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