USB Audio Optimization
When connected to the computer, the USBPre is a highly integrated part of the PC that relies on the host (computer) to handle data traffic in and out of its hardware. With late model computers there is sufficient processing power to handle all of the tasks of computing along with audio. The performance of the USBPre with your system is dependent on three major factors - the hardware configuration, operating system configuration, and the audio software configuration. To obtain the best performance from the USBPre optimization of each of these factors is recommended.
Assuming that the computer system meets the minimum requirements outlined in this documentation there are other areas that can be optimized.
Memory
Sufficient RAM is important for audio applications. Since a system with insufficient RAM must access the hard drive as virtual memory, the data flow is slowed greatly in and out of the processor. 128 MB of RAM or more is highly recommended for most audio applications.
Hard Disk
Multi-track audio recording is a hard disk intensive activity. As an audio production increases its track count, the demands on the disk drive increase. In general, higher rpm drives have greater sustained throughput than low speed drives. High sustained transfer rates are more important than high burst rates when comparing hard drives for audio (and video) applications. SCSI drives typically have higher sustained throughputs than IDE drives, although newer IDE implementations have sufficient data rates for audio. Depending on the computer system, increased hard disk activity can interfere with (interrupt) the USB bus, resulting in audio dropouts. In general, disk drives with fast sustained data rates and large memory caches perform best for multi-track audio.
Buffer Adjustment
Many audio applications have selections to adjust playback and record
buffer sizes. These adjustments change how much audio data is retained in RAM.
With too small of a buffer, audio hardware runs out of audio data before it
can be read from the hard drive. Typically, larger buffer sizes improve
stability of audio applications at the expense of program responsiveness.
Refer to you software documentation for guidance in adjusting buffer sizes.
Power Management
Power conservation is a significant issue for notebook computer designers and is becoming more popular on newer desktop computers. Most computers are shipped from the factory with some power management applied. Audio applications and USB audio work best when all power management is deactivated. Power management can spin down hard disks, slow processor and bus speeds, and shut down displays. Often, when recording long programs, the computer keyboard and mouse are not touched. The computer thinks that it is idle and goes into standby mode. The change in state can cause audible artifacts when recording and playing.
Notebook Computers (Windows)
Many notebook computers share IRQ's between the display adapter or other devices and the USB controller. This causes additional traffic on the USB's interrupt. To check for this condition, follow Start>Settings>System and select the Device Manager tab, select Computer and click on Properties. This reveals the list of system interrupts. If any device (except for "PCI steering") shares an IRQ with the USB Host Controller, try removing any unused hardware devices to free up IRQs and turn off hardware acceleration to improve USB audio performance. To turn off hardware acceleration follow
Start>Settings>Control Panel>Display, select the Settings tab, click "Advanced..", select the Performance tab and slide the control to the None position.
|