What Is a Digital Amplifier?

By Ezmeralda Lee

Digital amplifiers are a new revolution in the technology of the audio industry. They allow the audio signal to remain in its true digital form, from the beginning of the audio signal until it is reproduced. This enhances the audio quality greatly.


Ever since the invention of the phonograph, sound has been amplified. In the old days, the sound that was reproduced was subject to much interference and sound distortion, thus resulting in very poor sound quality. If you have ever listened to an old Victrola machine, you will know what I mean. In later years of development, with one of the first converters having been built in 1950 by D.H. Wilkinson, sound was modified and reproduced with the use of Analog to Digital converters This provided for much improvement in sound quality, but one could still hear background noise from the tape used in the original recordings. Early analog to digital conversion still lacked the clear sound quality we have today. Recordings often sounded high-pitched and "chirpy," often due to poor quality materials and off timed converters.


In the beginning, true digital sound was only possible in very expensive audio systems or in the laboratory setting, because of the great number of computer chips that was required for the digital audio signal to be transferred consistently from point A (the origin) to point B (the speakers). Recently, technology has been able to reduce the number of chips required to just a few, thus keeping costs to a minimum and allowing for digital amplification to be incorporated into a vast number of products.

How it Works

A digital amplifier receives a digital input from its source, which is usually in a linear pulse code format and digitally converts it to a Pulse Width Modulation (PWM) format. The Pulse Width Modulator then produces a high voltage signal which is filtered to replicate the original audio signal. For this to be accurate, both the timing and the alignment of the signal must be maintained throughout the transfer. The actual output signal is actually synthesized on the speaker terminals themselves, allowing for further reduction in background and machine noise.


Because of the recent advancement in sound technology, it is now possible to purchase a true digital amplifier at a reasonable cost. The use of only a few microprocessor chips allows the product to be mass produced without sacrificing the quality of the product.


When purchasing a digital amplifier, be sure to check the label carefully as not all amplifiers that are labeled “digital” are true digital amplifiers. Look carefully at the fine print on the label for the words “analog input” as digital amplifiers that only use analog input are not true digital amplifiers, but really analog-to-digital converters With this type product, you will not get true digital sound, as this type of conductor allows for significant background noise and vibration.