Aletheia dac-1 Development

The fundamental design topology of the dac-1 took maybe two years to evolve. The key elements in all the modules were tested and refined many times. We improved our anti-vibration techniques and learned how to best minimise RFI interaction. We experimented with layout of the modules and wiring routing. We refined our modifications to the Paul Hynes voltage regulators and optimised the construction of the passive output I to V conversion. We made sure that everything was sturdily built for long reliability.

And we listened as we went along. And because we had so much experience with all elements of systematic interactions from our 15 years work with the Vertex AQ products, we knew what we were aiming for. And of course we were also supported with our work with Acuity Products, building our understanding of the benefits of time domain thinking. Our aim was simply to get the system-of-systems within the DAC to perform impeccably both individually and as a whole, to make sure that nothing was causing any time-domain smearing.

Key Features

As the development progressed, several critically important features emerged:

  • It became essential to use an over-specified mains transformer of considerable robustness to prevent it from buzzing and thus becoming a vibration generator. It was also essential to have the output windings in ‘balanced mode’ which lowered noise considerably. We now have our own bespoke transformers specially wound in the UK to meet our requirements.
  • The use of Paul Hynes discrete component regulators. An over specified first-stage voltage regulator and then four second stage voltage regulators which feed all the DAC functions proved essential to the sound quality we required.
  • The use of specialised resistors in the critical output I to V conversion circuit. In the dac-1 we found that the Vishay non-inductive thick film resistors were a great cost/performance balance, and because of their metal exposed heat-sink construction they respond very well to direct anti-microphony techniques.
  • The quality of the output stage that we were aiming for also dictated the use of the Mundorf metallised polypropylene silver/gold in oil capacitors. Again these have a very good cost/performance balance and they respond excellently to anti-microphony treatment.

Sound Quality

Most digital replay gets blurred and confused when playing complex material, mixing and intermodulating the musical programme in a very obvious way. With the dac-1, the complex threads and intertwining harmonic ‘fibers’ of dense passages remain clearly separated and accurate. As the intensity of the music increases, you hear a dazzling display of performance and emotion, deep into the mix, thats incredibly easy to follow. This ability regularly reveals things you never previously heard in your recordings.

Another clear indication of the lack of systematic distortion is the way music from the dac-1 images, and remains detached from the speakers. To explain a bit more, if you play a string quartet piece, well recorded in a nice ambient environment, the image should be spread well around behind the plane of the speakers. When the dac-1 plays the piece, the sound is clearly in the soundstage, and remains there. With lesser sources, parts of the music (particularly with lots of treble content like strings) collapse back onto the face of the speakers.

The next huge advantage with the dac-1 is the vibrancy and richness of the midband, and a total lack of harshness in the treble. You get a completely realistic sense of the body of instruments – nothing sounds thin or washed-out. And sounds clearly stop and start in a totally incisive, yet completely smooth manner.

And finally there is a significant improvement in the way the dac-1 conveys the energy envelope. Most D to A processing seems to accentuate quieter passages, making them seem artificially spotlit, then as the music builds, it gets to a certain level then won’t go any further (and with quite an obvious increase in distortion levels). With the dac-1 the music scales up and down over a huge range, and remains stable and listenable over its whole output.

If you are wondering what the press think of the dac-1, you might like to check out these reviews: Aletheia dac-1 review by Alan Sircom, HiFi Plus issue 85 and Aletheia dac-1 review by Paul Messenger, HIFICritic 2012. Also HIFICRITIC have a sound quality rating system and you can see how well the Aletheia dac-1 compares to the competition here. And an explanation of how the scoring is derived is here.

Aletheia rear 1Rear panel dac-1.0