The Toshiba SA-7150 was a high-quality stereo receiver that was released in 1978, during the era of powerful “Monster Receivers”. It produces 150 watts per channel and retailed for a hefty $1100 at the time. Despite being a lesser known brand than the likes of Marantz and Pioneer, the SA-7150 featured excellent build quality and superb stereo performance that rivaled or exceeded the major brands.
The SA-7150 had innovative features like the world’s first quartz-locked digital synthesizer tuner. Toshiba was able to produce high quality components for their receivers since they were already manufacturing quality parts for other major high end brands. In fact, the SA-7150 offered comparable quality to top models from Marantz, Pioneer and Sansui.
However, Toshiba’s smaller dealer network meant the SA-7150 was not as widely marketed. As a result, the excellent SA-7150 tends to be rarer and more obscure today compared to vintage receivers from the bigger brands. But for those in the know, the Toshiba SA-7150 represents an underrated high performance stereo receiver from the late 1970s.
Front Panel
The SA-7150’s cabinet is about one third vinyl covered wood and two thirds metal. The face plate is brushed aluminum and there is a retractable hinged door that covers a number of controls.
The SA-7150 has controls for bass and treble, with turnover frequency switches, tone defeat, low and high filters, -20 dB audio muting, two-way tape dubbing and monitoring, mode switch, and an input selector. The large volume knob has detents and a corresponding numbered outer ring for precision.
It also has built-in Dolby FM (no module needed), a multipath switch, switchable IF Bandwidth (wide/narrow), a Hi-Blend switch and even an Air Check switch (a white noise generator) for setting recording levels.
The tuning display is digital and there are a number of colored LED indicators, including six for the station presets. The signal level meter is also LED and to the right of it are two analog peak power meters. A strange mix of digital and analog.
Tuner
The Toshiba SA-7150 was revolutionary for being the first receiver to integrate a digitally synthesized tuner. Toshiba called it “Synthetune” and it enabled features that were unprecedented for the late 1970s.
The digital frequency readout displays tuned stations in bright green LED numerals. The auto scan function can search the entire AM/FM band, automatically stopping on each listenable station. With its six station memory buttons, the Synthetune tuner allowed easy push-button access to preset stations. No longer did listeners have to manually tune dials to find their favorite stations.
The Synthetune tuner uses a quartz crystal oscillator to lock onto broadcast frequencies with extreme precision, eliminating station drift. Toshiba claimed tuning accuracy was so precise that a center tuning meter was unnecessary. The SA-7150 brought digitally synthesized, drift-free, push-button tuning to high fidelity receivers for the first time. This pioneering technology made tuning radio stations incredibly precise and convenient.
SA-7150 vs SA-7100
What are the differences between the Toshiba SA-7100 and the SA-7150? The later SA-7150 improved upon the SA-7100 with higher power output, lower distortion, larger filtering capacitors, and a digital tuner. But both Toshiba models share high-end design elements like dual independent power supplies. Here are the basic differences:
- Power Output: The SA-7100 is rated at 110 watts per channel into 8 ohms or 4 ohms. The SA-7150 has higher power output at 150 watts per channel into 8 ohms, or 230 watts per channel into 4 ohms.
- Distortion: The SA-7100 has 0.08% total harmonic distortion. The SA-7150 improves on this spec with 0.05% distortion.
- Power Supply: Both models utilize dual independent power supplies to isolate the preamp and power amp sections. This prevents distortion.
- Capacitors: The SA-7100 has 2 22,000μF 63V capacitors. The SA-7150 upgrades this to 4 15,000μF 80V capacitors, totaling 30,000μF.
- Tuner: The SA-7150 has a quartz-locked digital tuner, versus the SA-7100’s analog tuner.
- Weight: The SA-7100 weighs 38.6 lbs (17.5 kg). The SA-7150 is much heavier at 59.5 lbs (27 kg ).
Toshiba was somewhat late to the monster receiver competition and didn’t push the SA-7150 very hard. As a result there are not many around today.
Specifications
- Power output: 150 watts per channel into 8Ω (stereo)
- Frequency response: 10Hz to 50kHz
- Total harmonic distortion: 0.05%
- Damping factor: 50
- Input sensitivity: 2.5mV (MM), 150mV (DIN), 150mV (line)
- Signal to noise ratio: 80dB (MM), 95dB (DIN), 95dB (line)
- Output: 150mV (line), 30mV (DIN), 1V (Pre out)
- Dimensions: 21.7″ W x 7.9″ H x 19.7″ D (550 x 200 x 500mm)
- Weight: 59 lbs. 6 oz. (27kg)
- Digitally synthesized tuner section
- Dolby FM
- Selectable cartridge loads
- Dual power supplies
Despite the poor marketing Toshiba’s engineers produced an excellent receiver that could easily compete with the best of the other popular brands.
There are a few minor downsides to the SA-7150 however. As mentioned above, the cabinet is vinyl covered which tends to peel over the years. The front panel door doesn’t seem to have any real purpose and can break. Some complain about it being too heavily sprung as well. Another complaint is that the heat sinks are interior mounted which results in heat build up inside the cabinet. This is in contrast to receivers such as the Pioneer SX-1250 which has the heat sinks mounted outside the cabinet. At least there is venting on both sides of the SA-7150 cabinet.
Amplifier
A core feature of the Toshiba SA-7150’s amplifier section is the OCL circuitry which eliminates the need for output capacitors and results in enhanced audio quality. Coupled with a toroidal power transformer, this setup ensures efficient and reliable power delivery.
The power supply system of the SA-7150 is divided into distinct sections for the preamp and power amplifier stages. This separation allows for customized power supply to each stage. The power amplifier supply is segmented into independent left and right power supplies, employing high-grade heavy-duty electrolytic capacitors and a substantial toroidal transformer.
In terms of power output, the SA-7150’s amplifier boasts a significant reserve of power with minimal distortion. The first-stage differential amplifier incorporates low-noise dual transistors, specifically developed for Toshiba audio equipment. In the power stage, parallel push-pull connected power transistors generate 150 watts of power per channel (both channels driven) into 8 ohms, maintaining a low total harmonic distortion (THD) of no more than 0.05% from 20 to 20 kHz.
Internally, the SA-7150 incorporates components mostly sourced from Toshiba, ensuring compatibility and synergy among the receiver’s internal parts.
Rear Panel
The rear panel of the SA-7150 has connections for two turntables, two tape decks and an auxiliary device. Preamp in and main amp out connections are very useful too. Just below the antenna is a phono cartridge load switch.
There are three AC outlets on the rear panel, two of which are un-switched and one that is switched. The SA-7150 can operate three sets of speakers. If you’re only running one pair of speakers then the amp can handle 4-16 ohm speaker loads. If you’re running two pair at a time then only 8-16 ohm speaker loads
The Toshiba SA-7150 is a true monster receiver. It has tons of power and its FM tuner is far above average. In fact, its performance is second to none when compared against similar receivers. It is also rarer than most other monster receivers. If you want a unique receiver to add to your collection you surely won’t be disappointed with the SA-7150.
