Thrax Maximinus

Universal DSP controlled discrete resistor ladder 32bit/384kHz audio DAC

Maximinus frt 500px1
This is the simplest DAC concept with the most sophisticated front end. Maximinus uses a concept called R2R ladder. This is a resistor matrix that is switched for the various output levels outputting a fraction of an internal reference (much like a volume control). This concept was introduced to audio by Philips with the TDA1540 and the first CD players. It was followed by further developments that reached culmination with the sign magnitude Burr Brown PCM 1704 chip. All new development chips currently used by high end DAC manufacturers are delta sigma modulators. They use very sophisticated techniques to achieve very good parameters. Unfortunately never being able to match the sound quality of the multi-bit convertors mostly due to the inherent problems in the single-bit concept itself, forcing the use of filters following the DAC output.

In order to bring the performance of multibit DAC’s toThrax Dac2 new levels the only solution is to build them from discrete components as there are no off the shelf chips good enough. This involves the selection of ultra precision resistors, thermally coupling them and building a very fast and sophisticated switching logic to control them. This comes at a substantial cost as one such resistor costs more than 12Euro!! , but the result is an order of magnitude better performance than what is achievable by IC based dac's.

To take advantage of the available resolution and bandwidth we had to implement a state of the art digital pre-processing. This is a suite of algorithms that would apply digital filtering and up sampling to the incoming data stream. After processing a 16bit 44.1kHz CD data stream it is converted to 32bit 352.8kHZ data fed directly to the DAC. This greatly improves low-level resolution and the sense of space. The processing is all user controllable and defeat able for purist non-oversampling use mostly used with high-resolution source files.

Thrax Dac3Apart from taking the uncompromising approach of using discrete ladder technology we have taken exceptional care with the construction and operation of each circuit within the DAC. We use transformer or optical decoupling of all I/O ports, meaning that contaminated ground and other interfering signals don’t make it to the inside of the unit.

We have no output buffer or filter at the DAC output providing the cleanest possible output signal. We also use separate power supplies for (not separate regulators but physically separate transformers and all) the Converters, Clock, DSP and Control logic all with floating ground planes and our unique constant current regulator technology.

Then the whole assembly is mounted in a solid aluminum case for vibration damping and EMI/RFI screening following the same construction concept as our preamplifiers.

It’s a different league from all currently available high end DAC’s hence the name Maximinus.