TOSHIBA A1943/C5200 DX-AMP High Quality DX Amplifier

November 10, 2011 amplifier, circuit diagram, diy

TOSHIBA A1943/C5200 DX-AMP High Quality DX Amplifier

The DX Amplifier is based on the old amplifier designs from the eighties. This choice was made because of their good sonics, but equally important was to make an amplifier that was simple to construct, and cheap.

TOSHIBA A1943/C5200 DX-AMP Power amplifier Kit 2-CH. This is a kit,you need solder it by yourself. DX AMP is DIYAudio on the “destroyer X” by the launch of the Amplifier.

The machine is based on the traditional bootstrap circuit – known in the classic lines of a good sound, There are three characteristics: 1, very good sound; 2, the device is easy to find, easy to make; 3, are not expensive. Also has these three characteristics, it is worth a try.

36V power supply with positive and negative power supply, the whole can be achieved under the 8ohm speaker 50W power, 4ohm speakers up to 100W power next.

Using imported high-power tube 2SA1943 2SC5200 Toshiba one pair per channel

TOSHIBA A1943/C5200 DX-AMP High Quality DX Amplifier PCB Trace

Carlos Eugenio Mergulhão, AKA Destroyer X on the www.diyaudio.com forum, has been constructing amplifiers since the ’60s, when he was only 9 years old. He has constructed more than 4,000 amplifiers from circuits published in magazines. A large number of them exploded, some worked fine, but only about 8 amplifiers sounded really good.

After years of research, he finally decided to make his own. His first design choice was to use bootstrap technology, a technology he knew sounded very nice. The amplifier was based on simple circuitry with a small number of easy to find parts. The parts used are cheap generic parts, not the hard to find, expensive audiophile components. Thus, the DX amplifier was born, then developed a little with cooperation from guys like Graham Maynard, Greg Erskine, Klaas Veenstra, Daniel Mustran and suggestions from other diyaudio forum friends.

TOSHIBA A1943/C5200 DX-AMP High Quality DX Amplifier Layout Component

The prototype art work and boards were prepared by Greg Erskine based on Carlos’s initial working amplifiers. The first professional looking schematic and kind support came from Daniel Mustran from Croatia. Klaas Veenstra from Nederland was the first pioneer to construct and test the DX amplifier.

You will notice some the sub-circuits and parts have been removed from the old reference designs. For example, the emitter resistors have been removed and the fuses have been removed to avoid the sonic problems related to these annoying resistances, thus increases the sonic impact. Of course, you can include fuses, especially a speaker fuse, but double check for resistances and for bad electrical contacts.

TOSHIBA A1943/C5200 DX-AMP High Quality DX Amplifier Schematic

A single 350 to 400 watts symmetrical supply with plus and minus 35 volts is recommended. You will need to use a 10,000uF electrolytic condenser on each rail for filtering. If you want to use two 200 watts supplies instead, you can get away with a 4,700uf electrolytic condenser for each rail. The amplifier design can tolerate higher voltage supplies, but you will need to include more output transistors and add a 0.22 ohms emitter resistor for each of the output transistors.

The amplifier is rated to 100 watts rms into a 4 ohms load and 50 watts rms into 8 ohms load. In reality, it produces much more power than that, but it is rated this way because distortion is quite low at these levels. By increasing the rail voltages, 300 watts rms would not be difficult to produce using this same schematic but with the modifications described above.

The unit can work without thermal compensation if you use a very large heatsink. If you prefer to use a smaller heatsink, you can use 3 diodes in series in the bias circuit. These diodes need to be in close contact with the heatsink so they can follow the temperature changes. This effectively adjusts the bias to protecting the amplifier.

Another option is a Vbe multiplier. More details about this option can be found in the DX Amplifier thread on diyaudio. The marks A, B, and C are provided in the schematic and PCB for connection the 3 diode or Vbe multiplier circuits.