Layout and Internal Configuration
The product description gives some information about the hardware components covered by the protective armor:
- Audio Processor: ASUS AV200 High-Definition Sound Processor (Max. 192kHz/24bit)
- 24-bit D-A Converter: Burr-Brown PCM1796*4 (123dB SNR, Max. 192kHz/24bit)
- 24-bit A-D Converter: Cirrus Logic CS5381*1 (120dB SNR, Max. 192kHz/24bit)
The rest can be seen if the casing is removed: original squares of film capacitors (I have not seen them before in any mass-produced sound card) in DAC filters, solid-state electrolytic capacitors, a handful of electromagnetic relays (more than on the Creative X-Fi Elite Pro), four voltage regulators at the right edge of the PCB, and a huge number of operation amplifiers.
The DACs employed on the card, like most top-class chips of this type, have balanced current outputs. It means the signal must be converted into voltage before the low-pass filter, which triples the amount of necessary opamps.
Cheap dual-channel 4580 amplifiers from Texas Instruments are used on three out of the four output channels. The front output uses more expensive NJM2114 (at the I/U conversion step) and LM4562 (in the low-pass filter) amplifiers. Besides, two RC4580 are installed on the front output as a buffer for connecting the headphones directly to the sound card. This solution was used before for the headset output on the M-Audio Revolution 5.1 and Audiotrak Prodigy HD2 cards.
The ADC filters are based on the NJM5532 but the RC4580 is used as the inverter for the DAC’s balanced inputs. These various opamps indicate the developer’s effort to optimize the product’s price/quality ratio. Let’s see what is different between these chips.
The four models are all recommended by their manufacturers for the use in sound devices, and three of them have similar specs. All the chips feature good tolerance to variations in the supply voltages and the ground as well as a low level of harmonics in the audio range. The LM4562 differs from this group with its response and distortions, provoking some questions to the developer.
You can learn about the advantages of the LM4562 over other opamps (including the NJM2114) by the example of the Creative X-Fi Elite Pro in our previous review. I/U-conversion opamps are used in inverting circuits, and the LM4562 would work well in this cascade, too. The combination of it with the NJM2114 looks strange as it has a narrower pass band and introduces more distortions. Moreover, the RC4580-based output buffer is good for headphones but nearly negates all the advantages of the LM4562 when working with a high-resistance load. Added to that, the film capacitors in the filters’ feedback circuit work together with ceramic capacitors in the feedback circuit of the I/U conversion cascade. So, the subunits of the card’s analog section seem to have been developed by different engineers who didn’t collaborate.