You would think it’s a question that your average audiophile would know the answer to – but you’d be surprised at how often that question arises on the day-t0-day, even with our most regular of regular customers. What the bloody hell is a DAC? Frankly, if you’re not already a streaming aficionado, or know a great deal about digital music, you probably hadn’t given much thought to the matter. But despite DACs being present ever since the digital revolution began – and was intrinsic to its longevity.
There are a number of different DACs, all of which serve different functions. But their primary principle is always the same – the conversion of a digital signal into an analogue one. In terms
“A DAC, or digital to analogue converter, is a device that translates digitally stored information from a laptop, iPod or other such device into analogue signals, improving the quality of the sound and upping the volume in the process”
Signal Types
In order to fully understand – and appreciate what a DAC is (and does), you first have to understand the difference between an analogue and a digital signal.
An analogue signal is smooth and resembles a sound wave- in fact, that’s its exact purpose. While the vast majority of modern audio signals, certain (more archaic) formats such as vinyl records and cassette tapes store data as an analog signal. The grooves on the record or magnetic signals on the tape would work by increasing and decrease to decry the shape of the sound wave it is emulating.
The more common method of audio storage is the digital system. This works by taking snapshots of a continuous process and numbering each segment.A compact disc takes roughly 22,000 snapshots of an electric signal describing a sound wave every second and records the voltage of that signal, known as a ‘sampling rate’ – a higher sampling rate makes for a higher quality of ‘recording’ . And this is where a DAC comes in! A digital-to-analog converter turns those snapshots back into a continuous ‘analogue’ sound wave, ready for amplification and driving though the speakers.
Enter the DAC
The vast majority of units which produce a digital signal will have an inbuilt digital to analogue signal converter, with is relevent to the playback of digital files.
It works by reading the digital data in a file and recreating a copy of the original analog signal recorded, with a three step checklist:
- Amplitude: creating an analogue voltage equivalent to the numeric value read from the binary digital file
- Timing: creates the above analogue voltage at the right level and at the right time
- Blanks: due to the nature of a digitally replicated analogue file, there will be data missing between each sample. That, and that the original ‘level’ may differ slightly from the level recorded. The DACs final role is to fill in those blanks in relation to the data it already has, by reading both the past and future data, and making an estimation as to how the wave would fit the data, were it analogue.
While a rudimentary inbuilt DAC will only do a basic job (in order to enable the audio to be amplified and driven), a separate DAC will work harder to improve the quality of the analogue wave, henceforth improving the quality of the sound. A separate, hi-fi quality DAC will improve upon all three of its main jobs:
- Amplitude: a more accurate reading of the numeric value of the digital file, and a more faithful recreation of the analogue voltage
- Timing: the accuracy of the ‘clock’ (a device which creates a pulse at a fixed interval or time) and the amount of clock jitter, used to create these voltage levels is vital – the higher end the DAC, the more accurate the clock.
- Blanks: the digital filter that a DAC uses is where the science ends and the art of the DAC begins. A smooth ‘life like’ analogue wave, as close to the original as possible, is the ideal. The higher end the DAC, the smoother (and closer to the original analogue wave) the replicated wave will be.
Even though any one DAC will do the same job as another, it is always worth remembering that the audio quality of any digitally replicated audio is almost entirely dependent on the DAC, and how well it fills in those all important blanks. When you’re passionate about audio – and about hi-fi, the investment in a separate DAC should not be overlooked.
That is pretty much as simple as we can make it. As we said before, there are several different types of DACs, for several different purposes – but all of that is a subject for another blog and another time.
We’ll leave you with this thought: if it weren’t for the simple DAC – the music (and indeed any electronic) industry would have remained in the analogue days. Some may well say they prefer it that way, but most would agree that the presence of the DAC has had a profound and largely – if not wholly – positive effect on the audio industry.
When you take apart the technology that shapes our lives, you will often find it is the most humble of items that make the biggest changes. The DAC is a perfect example of this. Without it and its older sibling the ADC (the analogue to digital converter – mostly used for the purposes of recording), the music industry as it is today simply would not exist.