In 2020, Asahi Kasei Microdevices Corporation (AKM) expanded its lineup of premium audio Digital-to-Analog converters (DACs) with the development of a two-chip solution that separates the digital aspect from the analog. While conventional DACs use a single chip to convert signals from digital to analog, the new AKM approach splits the conversion process between a delta-sigma modulator chip and a separate DAC, providing additional design flexibility for audio manufacturers. This two-chip solution was unfortunately held back by the tragic destruction of AKM's Nobeoka semiconductor factory due to a fire, in October 2020.
Earlier in 2022, AKM resumed sample shipments and select production of its Velvet Sound DAC/ADC products. In February 2022, AKM confirmed that it totally redesigned its range of 2-channel premium converters under the Velvet Sound brand - launched subsequently as part of a new generation of improved devices targeting high quality audio applications. At the end of 2022, the Japanese manufacturer released to production the new flagship stereo DAC, AK4499EX, alongside the AK4191 Digital Filter and ΔΣ Modulator, finally completing the two-chip solution.
Given that this two-chip topology allows designers to improve performance with completely independent digital and analog circuitry, the original AK4499EX chip (S/N: 135dB, THD: -124dB) has been selected for high-quality, ultra-high-resolution DACs and was embraced in multiple audio designs already in the market. (See Orchard Audio PecanPi+ Streamer Premium)
Now, AKM announced the new AK4498EXVQ, which also offers a complete two-chip DAC solution that isolates the processing intensive digital signal, handled by the same AK4191 digital filter and ΔΣ modulator device, from the analog. As AKM has proven, this partitioning significantly reduces digital noise interference within the analog conversion process, with benefits in sonic transparency. In conjunction with the AK4191, the AK4498EX supports ultra-high-resolution audio formats up to 64-bit/1536kHz PCM or DSD1024.
With a similar 129dB of signal to noise ratio (A-weighted) and -117dB THD+N measured on the analog output as the recently announced AK4497SVQ stereo DAC, the new AK4498EXVQ also leverages advanced Velvet Sound technology. As AKM details, the AK4498EXVQ uses a Switched Capacitor Filter block (1st-order) that converts MBD7-2 data from the DWA (Data Weighted Averaging) output to analog voltage signal, with a cut-off frequency that is proportional to 128fs or 256fs over sampling rate.
The new DAC also uses the DWA routing technology from the flagship AK4499EX DAC, which minimizes the effects of conversion element variation, resulting in improved analog characteristics. Likewise, the AK4498EX benefits from the AK4191's Automatic D/A Conversion Mode Switching Function, which enables seamless transitions between audio formats (PCM, DSD). The integrated asynchronous operation mode further allows for dedicated clock supply to the AK4498EX, facilitating precise D/A conversion with minimal jitter.
Targeting applications in new network audio and USB DACs as well as wireless speakers, the new AK4498EXVQ Stereo Premium DAC is now sampling, with mass production slated to begin in April 2025. Packaging is the same HTQFP 64-pins as the AK4499EXEQ and AK4191EQ.
www.akm.com
