Bang & Olufsen Beogram 1200
The Beogram 1200 is not the most advanced record player – but it may be the most stylish. Jacob Jensen designed it in 1969. It is part of the design collection of the Museum of Modern Art.
Dual 1229 – the last idler-wheel record player from Dual
The German company Dual had a long history of idler-wheel record players. Many manufacturers introduced belt drive record players in the mid of the last century, but some companies still produced idler-wheel drives. Dual was the last big company building idler-wheel turntables. Dual produced the 1229 model during the years 1972 – 1974. It was mostly based on the Dual 1219.
Phonoclone
This project is based on the circuit published by RJM Audio. Compared to the costs, this is a really excellent RIAA preamp.
Universal smoothing and rectification PCB
You will find a lot of preamplifier power supply PCBs on the market. Some use only a few capacitors and a following voltage regulator, others use lots of capacitors first. Sometimes people put capacities in the smoothing section that would be enough for a power amplifier. This PCB looks like the second type, but has some advantages over “use as much capacitors as you can find” design. The capacitors are grouped into 3 sections. Between 2 sections you can place inductors. This limits not only the peak current draw from the transformer, but also adds extra smoothing.
The basic concept of this PCB is:
- Rectification (dual Graetz bridge)
- Current limiting (by using a resistor)
- C-L-C-L-C smoothing
You can replace the inductors by resistors or leave it out completely. For a complete preamp power supply you need extra voltage regulators behind this circuit. The voltage regulator should be placed near the load while the rectifier and smoothing section is places best near the power transformer.
Another difference of this PCB to others is the possibility to use different kinds of capacitors. There are 3 sizes of capacitors that can be used:
- 28x diameter 13mm
- 16x diameter 16mm
- 12x diameter 18mm
Use whatever fits best for your application.
Downloads
- unisieb-1.1.brd Cadsoft Eagle .brd file