Bang & Olufsen Beomaster 1000 (1968)

Overview

The Bang & Olufsen Beomaster 1000 came out in 1968. It was a compact all-transistor hi-fi receiver, low-profile and built to fit into a modern living space, not the big tube sets of the era. Inside is a circuit board of discrete components, including the original AD149 output transistors and AC127/AC132 driver pairs. Onboard safety circuits protect it, and they need precise alignment during servicing. Maintenance is not simple. The parts are proprietary and the mechanics are complex, so it takes a specialist. The market is split: working, serviced examples command high prices, and non-functional units are good-looking paperweights.

Power is modest, approximately 2 × 15 watts RMS into 4-8 ohms. The Beomaster 1000 was about tonal balance, clarity and integration, not brute force. After repair, the sound is described as "really impressive," offering "a beautifully colorful, warm sound with a good foundation." The output stage is capacitor-coupled, which avoids the DC offset issues common in direct-coupled designs. Forum discussions note that some units still develop DC offset problems over time, likely from aging components or bias instability. The design prioritizes reliability and serviceability in theory. In practice, decades of oxidation, capacitor drift and fragile crimp connections have made fully functional units increasingly rare.

Specifications

Manufacturer	Bang & Olufsen
Product type	stereo receiver / amplifier
Production years	1968
Technology	all-transistor
Power output	2×15 watts RMS
Power output	approx. 2 × 15 watts RMS into 4–8 ohms
Power consumption	120 watts
Original price	approx.: 995 DM
Original price	£82
Inputs	Phono 1: 25 mV, 500 kOhm. phono 2: 200 mV, 47 kOhm.
Technology	capacitor coupled output

Key Features

Compact All-Transistor Hi-Fi Design

The Beomaster 1000 was part of Bang & Olufsen's push into solid-state audio during the late 1960s, a shift from tube-based systems to more reliable, cooler-running transistorized circuits. It is described as a "compact all-transistor hi-fi." The layout is dense but logical, with an emphasis on thermal stability and long-term operation. The metal case holds a large gray capacitor in the secondary supply next to the transformer, and a precise biasing network that keeps the output stage in check.

AD149 Output Transistors with Crimp Connections

The original output/power stage transistors are AD149 types, mounted with crimp connections rather than solder. That allowed easier replacement in theory. In practice, the crimps loosen and oxidize over time. Collectors note that loose and oxidized crimp connections on the AD149 transistors can lead to higher current consumption and eventual transistor failure. It is a common failure mode, so inspect carefully during restoration. AD149 transistors were still available at the time of one repair report, but sourcing NOS or suitable substitutes today takes patience.

NTC Resistor-Based Bias Setting with 100 Ohm Trimming Potentiometers

Bias stability is handled by an NTC (negative temperature coefficient) resistor, meant to compensate automatically for thermal drift in the output stage. Over decades these NTC resistors can fail and develop a steeper characteristic curve, which disrupts the bias point. The system includes 100 ohm trimming potentiometers for manual adjustment, but repairers caution that if the NTC is defective, the bias will drift regardless. Some technicians recommend replacing the NTC with fixed resistors as a permanent fix. Purists may frown on the modification.

Protective Circuits Requiring Service Manual Alignment

Unlike simpler receivers of the era, the Beomaster 1000 includes protective circuits to safeguard the output stage and speakers. They are not set-and-forget. They need alignment and testing according to the official service manual, which adds complexity to servicing and calls for specialized knowledge. Owners attempting DIY repairs without the manual risk misalignment, instability, or even damage to connected speakers.

3000uF Output Capacitors and Secondary Supply Components

The output stage uses 3000uF capacitors to couple the audio signal and block DC. These electrolytic capacitors, like others in the unit, are prone to aging, showing oxidation points and increased ESR (equivalent series resistance) over time. The large gray capacitor in the secondary supply, near the transformer, is another aging point. A measurable change in capacity often indicates it needs replacement. Given the unit's age, a full capacitor refresh is typically recommended before powering it up after long storage.

Collectibility & Value

The Beomaster 1000 is increasingly sought after for its Danish mid-century modern design, but its collectibility hinges entirely on functionality. Common problems include oxidation and verdigris on transformer fuse holders (rated at 800 mA on the secondary side), oxidation of contacts on potentiometers and switches, and dust inside the chassis. The 2 amp fuse in the power amplifier stage often blows as a symptom of deeper issues, typically failed output transistors or shorted capacitors. Plastic parts, such as the power switch housing, can become brittle or slightly torn with age, and switches often develop a yellowed patina.

Repair paths exist: the AC187/AC188 transistor pair is a known replacement for the original AC127/AC132 drivers, offering better heatsinking capability. Contact cleaning with specialized products is recommended, as is careful dust removal using brushes and low-pressure air. Despite these challenges, a fully serviced unit delivers a listening experience that owners describe as rich and engaging—proof that, when working, the Beomaster 1000 is more than just a design artifact. However, without service history or recent restoration, buyers should assume a non-working unit and price accordingly.