Pioneer | Classic Receivers

This Pioneer SM-B201 Stereophonic Amplifier was built in the early 1960's. It has FM and AM tuners and produces 14 watts per channel.

In the pre-MPX days of AM-FM simulcast stereo one channel was on AM and the other on FM. Two broadcast towers were required for stereo. In other words, FM was broadcast on one tower and AM on another. The user of the SM-B201 would have to tune both dials to the correct frequencies to get stereo. Of course, not many stations wanted to build two towers to broadcast in stereo so the design was short lived. The Fisher 800 was another example of simulcast stereo.

The Pioneer SM-B201 has a strange symmetric front because of its dual tuning dials and "magic eye" tubes.

The controls include separate Bass and Treble as well as a Whistle and Loudness switch.

On the back panel there are outputs for 4, 8 and 16 Ohm speakers. There are phono inputs for both ceramic and magnetic cartridges of 3mV or more. There's also a Tape In and Out, Aux in and FM/MPX out.

The SM-B201 has 19 tubes including the two 6E5 eye tubes. 12AX7's are in each channel driving a pair of 6BM8 (ECL82) output tubes. There is also a 5AR4 rectifier tube.

The early Pioneers were built like tanks but age takes a toll on them. The magic eye tubes in the SM-B201 are usually dead and the gray capacitors are usually leaking. With a little servicing you can have a nice amp and a great conversation piece.

These early receivers are somewhat rare but not impossible to find. They are not as popular as the later 1970's Pioneers. A nice SM-B201 will run anywhere from $200 to $400 depending upon condition.

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In 1980 Pioneer introduced the Pioneer SX-D7000 and made a statement that it was heading into the digital future. It's similar in many ways to the SX-3900 except that Pioneer did away with nearly all of the knobs - replacing them with push buttons. There are no analog meter or dials either as Pioneer utilized their Fluroscan technology for the power meter and digital tuning display. The SX-D7000 retailed for about $800.

Aesthetically it's a beautiful receiver. It has a modern, clean look to it and the symmetrical layout of the controls give it balance to the eye. It's rated at 120 watts per channel and 0.005% total harmonic distortion.

The power output and tuning meters are Fluroscan and the Treble and Bass controls are adjusted via sliders with 11 click stops. The Adaptor switch allows the user to patch in a signal processor such as a graphic equalizer or reverb unit.

The SX-D7000 was the bigger brother to the Pioneer SX-D5000 and was slightly bigger and a little heavier. Pioneer also added a C speaker switch, Tone on/off control, a display dimmer and a second phono input. The SX-D7000 was one of the first receivers to incorporate a preamp section that could handle both a moving magnet and a moving coil cartridge. The user could switch between cartridges with the push of a button just to the right of the volume knob. Switching to the MC position boosts the phono gain by 20dB and reduces the impedance to 100 ohms.

The SX-D7000 also features:

Non-switching DC power amp design
Quartz PLL Synthesizer Tuner
6 FM and 6 AM station memory for easy tuning
High Gain FET phono equalizer
Attenuator type master volume control

To set the memory for a station you tune to the station using either the autoscan or manual scan and then push the memory along with one of the station call buttons.

Pioneer SX-D7000 Ad

The power amp is a Direct Current configuration. Coupling capacitors are used at the input of the amp to safeguard the circuits and speaker systems. Ultra-low-frequency signals which might be picked up from a warped record can cause annoying Doppler distortion in drivers, adversely modulating the audible frequencies. Pioneer's DC configuration removes signal-delaying capacitors from the negative feedback loops to reduce phase distortion. This contributes to a "sharp and densely-textured sonic imagery in the final reproduction".

Pioneer avoided the problems associated with Class A or Class B amps by designing a special circuit they called Vari-Bias. According to them it is:

"An inspired breakthrough that led to the Pioneer Vari-Bias circuit, which constantly monitors the amplitude of incoming signal, then automatically controls the amount of bias fed to the power transistors. While they 'rest' during no-signal periods they get only a trickle - just enough to keep them from switching off. Actually, this circuit is so simple it does not limit the transient response of the transistors in any way."

The Pioneer SX-D7000 has three power transformers. One is toroidal, for the non-switching power amp, and the other two are of conventional design.

It has three speaker outputs as well as two Phono inputs and one Aux input. It even has an AM Stereo out.

The SX-D7000 is the beginning of the end for silver faced receivers. It wasn't long after its introduction that audio manufacturers, including Pioneer, moved toward cheaper black plastic components. The receiver has a distinct look to it that some like and some don't. It's still very popular for its performance level can usually be bought for a reasonable price. In good serviced condition they will sell for $500 to $600.