E-MU 20K is the commercial name for a line of audio chips by

Creative Technology Creative Technology Ltd., or Creative Labs Pte Ltd., is a Singaporean multinational electronics company mainly dealing with Audio equipment, audio technologies and products such as speakers, headphones, sound cards and other digital media. Foun ...

, commercially known as the

Sound Blaster X-Fi Sound Blaster X-Fi is a lineup of sound cards in Creative Technology's Sound Blaster series. History The series was launched in August 2005 as a lineup of PCI sound cards, which served as the introduction for their X-Fi audio processing chip, ...

chipset. The series comprises the E-MU 20K1 (CA20K1) and E-MU 20K2 (CA20K2) audio chips. The 20K1 chip was launched in August 2005, and ever since it has been used in a variety of audio solutions from Creative, and more recently third-party manufacturers, such as Auzentech and Audiotrak. The audio processor on X-Fi was the most powerful at its time of release, offering an extremely robust sample rate conversion ( SRC) engine in addition to enhanced internal sound channel routing options and greater 3D audio enhancement capabilities. A significant portion of the audio processing unit was devoted to this resampling engine. The SRC engine was far more capable than previous Creative sound card offerings, a limitation that had been a major thorn in Creative's side. Most digital audio is

sampled Sample or samples may refer to: * Sample (graphics), an intersection of a color channel and a pixel * Sample (material), a specimen or small quantity of something * Sample (signal), a digital discrete sample of a continuous analog signal * Sample ...

at 44.1 kHz, a standard no doubt related to

CD-DA Compact Disc Digital Audio (CDDA or CD-DA), also known as Digital Audio Compact Disc or simply as Audio CD, is the standardization, standard format for audio compact discs. The standard is defined in the ''Rainbow Books, Red Book'' technical s ...

, while sound cards were often designed to process audio at 48 kHz. So, the 44.1 kHz audio must be resampled to 48 kHz (Creative's previous cards' DSPs operated at 48 kHz) for the audio DSP to be able to process and affect it. A poor resampling implementation introduces artifacts into the audio which can be heard, and measured as higher

intermodulation distortion Intermodulation (IM) or intermodulation distortion (IMD) is the amplitude modulation of signals containing two or more different frequencies, caused by nonlinearities or time variance in a system. The intermodulation between frequency compo ...

, within higher frequencies (generally 16 kHz and up). X-Fi's resampling engine produces a near-lossless-quality result, far exceeding any known audio card DSP available at the time of release. This functionality is used not only for simple audio playback, but for several other features of the card such as the "", a technology that claims to improve the clarity of digital music through digital analysis (supported by all X-Fi models, including the Xtreme Audio and X-Mod). The X-Fi name has also been applied to cards based on the CA0106 and CA0110 chips, which belong to the previous generation Live!/Audigy series.

Specifications

The 130 nm, 51 million

transistor A transistor is a semiconductor device used to Electronic amplifier, amplify or electronic switch, switch electrical signals and electric power, power. It is one of the basic building blocks of modern electronics. It is composed of semicondu ...

s audio processor operates at 400

MHz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), often described as being equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose formal expression in terms of SI base u ...

and its computational power is estimated at 10,000 MIPS, which is about 24 times higher than the estimated performance of its predecessor – the Audigy processor. E-MU 20K features the ''Quartet DSP'', a set of 4 identical

digital signal processor A digital signal processor (DSP) is a specialized microprocessor chip, with its architecture optimized for the operational needs of digital signal processing. DSPs are fabricated on metal–oxide–semiconductor (MOS) integrated circuit chips. ...

s interconnected with a wide ring bus. The CA20K1 chip is a slave processor which requires a host CPU to control it. The CA20K2 adds an embedded RISC processor which controls the audio part; this configuration safeguards against the

audio latency Latency refers to a short period of delay (usually measured in milliseconds) between when an audio signal enters a system, and when it emerges. Potential contributors to latency in an audio system include analog-to-digital conversion, buffering, ...

of its PCI Express interface. 20K2 also has more I/O ports, a DDR SDRAM memory interface, and a built-in Universal Audio Architecture component. A big improvement in the X-Fi DSP over the previous Audigy design, is the complete overhaul of the resampling engine on the card. The previous Audigy cards had their DSPs locked at 48 kHz/16-bit, meaning any content that didn't match this format had to be resampled on the card in hardware, which resulted in serious intermodulation distortion. For the X-Fi, Creative completely rewrote the resampling engine and dedicated more than half of the power of the DSP to the process, resulting in a very clean resample. In addition, X-Fi on the PCI bus can operate at a frequency of 44.1 kHz, in all modes of operation of the card, and X-Fi on the PCI-E bus can operate in the "Audio Creation Mode" mode at any of the frequencies (44.1, 48, 88.2, 96 kHz), and in the modes "Game Mode" and "Entertainment Mode" are only on frequencies (88.2, 96 kHz), since disabling the frequency multiplier on X-Fi PCI-E is blocked by the manufacturer, moreover, the 88.2 kHz frequency has been removed from the Windows mixer, but is supported in ASIO and the device as a whole.

Applications

Sound Blaster X-Fi series

Third party

* Auzentech mentions only the DAC's ideal theoretical SNR being 120 dB (AKM AK-4396).

References

External links