BD34301EKV, a 32bit D/A converter IC designed for Hi-Fi audio equipment White Paper

1

Introduction

Since the invention of the phonograph, musicians and engineers alike have combined their talents

in order to capture the dynamic range of musical instruments and translate them seamlessly into

a format to be recorded and replayed. This, however, comes with major challenges (even in the

21st century) where optimizing digital signal quality parameters such as sampling rate, resolution,

signal-to-noise ratio (SNR), and total harmonic distortion plus noise (THD + N) requires close

attention in all stages of production from circuit design to wafer fabrication and packaging. Since

the 1970s, ROHM has been steadily developing audio ICs, optimizing devices with a low distortion

and high resolution to adequately capture and reproduce the sound image (effects), timbre

(natural sound without coloring), and low-noise characteristics of acoustic instruments in the

ambient experience of a concert hall.

This whitepaper dives into the qualities and features of ROHMs latest musical IC ― the MUS-

IC™ BD34301EKV, a high-resolution audio digital-to-analog converter (DAC). This component,

along with an array of others (including a high-fidelity power supply and sound processor), offers

the basic building blocks of a Hi-Fi audio device.

BD34301EKV developed with three critical elements for classical music

To improve the listening experience of classical music, ROHM introduced a development concept

that ultimately emphasizes three major elements in the BD34301 audio DAC. (see Figure 1 on

the next page):

● Spatial reverberation

● Quietness

● Dynamic range

Spatial reverberation refers to the attenuation of sound pressure waves as they are emitted from

the source and reflected off a multitude of surfaces within a facility. While this may seem like a

simple natural phenomenon, in fact, it is a complex interaction that is critical for high-quality sound.

Large concert halls must mitigate this decay of sound pressure waves in order to create a “fuller”

sound and grant the audience a more immersive experience. On the other hand, orators would

require a more rapid decay in sound energy for the speech to remain intelligible and not muddled.

For instance, in a large gothic cathedral, sound energy can take up to 9 seconds to decay ― this

is massive compared to the rapid decay found in small offices/conference rooms. Concert halls

will almost exclusively leverage hard surfaces to reflect the sound, while soft surfaces (such as

the seating and curtains) would absorb these sound waves.

Typically, classical music is meant to be experienced for extended periods of time, with periods

quiet (decrescendo) and loud (crescendo). This is further complicated by the fact that each

acoustic instrument picked out from any musical family exhibits a timbre (i.e., a distinct musical

sound/tone color). In order to capture the unique overtones of each instrument, as well as the full

experience of multiple instruments playing loudly, the DAC must have a high dynamic range, high

signal-to-noise ratio (SNR), and low distortion. This way, the audio is natural and flat across the

sound spectrum, easing the experience for the listener over extended periods of time.