DAC TRANSDUCER – HEART OF THE MODERN AUDIO SYSTEM
The DAC (Digital to Analog Converter), which converts digital signals to analog signals, is one of the basic elements of an audio system. Integrating the DAC in the amplifier can bring many benefits – primarily reducing the costs of the entire system and positively affecting signal quality at the device output.
Essentially all recordings are currently made in digital form. And although microphones and analog amplifiers of various types are still used in the studio or concert hall, ultimately individual signals are recorded in digital form. They are digitally edited and combined into the musical piece, which eventually is published in digital form on CDs, DVDs, as well as in online streaming services.
Digital signals are resistant to interference and their repeated playback does not degrade the carrier. However, they need to be transformed back into an analog form that matches the instantaneous speed of the acoustic wave reaching the human ear. And this operation is performed in the DAC.
The quality of digital-to-analog processing is crucial!
Digital-to-analog processing is a fairly demanding and complicated process. The operation involves converting a string of numbers that contains the instantaneous amplitude into a continuous signal containing only original components of the recorded signal. Due to the limited capacity, i.e. carrier bandwidth, audio signals are usually sampled with the minimum technically viable frequency. As a result of the above, it is necessary to perform a number of consecutive operations in order to properly reproduce the analog signal:
interpolation (the process of adjusting sampling frequency to match the transducer),
digital filtering equalising the processing characteristics,
the digital-to-analog processing proper,
analog filtering to suppress components from outside the acoustic band.
It is also important to synchronise the digital signal at the input with the processing. The consequence of shortcomings that may occur in this respect is the introduction of additional, unpleasant listening distortions (this is the so-called jitter). Each of these operations is demanding in mathematical and performance terms. It is necessary to have a thorough understanding of the individual processes and to select the right means to perform them. High computing power and advanced digital signal processing algorithms are essential for the system. Due to the complexity and difficulty of the issue, most DACs introduce significant phase distortions and their processing characteristics are non-stationary as a function of signal change rate. This translates directly to deterioration of the listening properties of the entire audio system.
Amplifier-Integrated or Standalone DAC?
Initially, when digital recordings were only available on CDs, DACs were fitted in CD players. Currently, when almost all sound sources (CDs, TVs, PCs, consoles, streamers, etc.) play digital signals, it is more justified to integrate a single high-end DAC in the amplifier. This solution provides much better signal parameters, e.g. because tonal level control operations can be performed on the digital signal. No additional distortions and noises are introduced, as is typical of analog pre-amplifier systems. In addition, an amplifier with built-in DAC allows for greater control of the device, because by analysing the received signal in a digital system and knowing the current volume level, it is possible to prevent clipping - which can lead to speaker damage - even before the signal is played. Another benefit of integrating the DAC is the you can very accurately match its sound properties to the amplifier itself.
When to Choose an Integrated DAC?
To summarise, the DAC is a key part of the modern audio system. Its integration in the power amplifier can bring additional benefits, provided that the amplifier can perform tone adjustment, loudness compensation, etc. in the digital domain. If you're using a budget source, use the high-quality DAC integrated in the amplifier. Connect the source to a digital interface and you will find that signal quality at the output of such a configured system is much higher. However, in general, signal quality at the DAC output depends on the converter’s quality; if you can fit it in your budget, the DAC in a separate housing will probably allow you to get the best sound quality. However, if your funds for the audio system are limited, then an integrated DAC will be a better solution, allowing you to save on the additional housing and cabling. It is worth noting here that the integrated circuits of the DAC do not determine the final sound of the entire device because the digital-analog processing process is complex and involves more than just converting the instantaneous value of the signal into analog form! On the market there are expensive yet poor quality stand-alone converters as well as high-end integrated ones. When picking a solution, pay attention that in addition to an expensive integrated circuit, the manufacturer should also declare that the device uses DSP processing, as it is indispensable if the process of translating the digital signal to analog is to be performed correctly. Ultimately, it is always worth following your own ear.