PLEASE NOTE: This article pertains only to the AudioBox VSL products, Legacy VSL drivers, older PC computers and older versions of Windows. Current drivers and systems do not apply.
Intel’s CPU and USB design changes to its Core i-Series processors have affected compatibility with the AudioBox 22VSL, 44VSL, and 1818VSL. Differences in USB chipset design and implementation, power management, and USB 3.0 implementation have caused problems for both Mac and PC users. This is an industry-wide issue and PreSonus has investigated these issues, is providing solutions and has recommendations for possible workarounds.
PLEASE NOTE: The topics covered here are limited to the Intel Core i-Series first-, second-, third-, and fourth-generation processors. We’ve had reports that users of AMD and older Intel Core 2 Duo and Core 2 Quad series systems have less-frequent or no such issues.
Intel’s line of Core i-Series multi-core processors conserve energy by putting processing power where the processor “thinks” it’s most needed. This dynamic process throttles the CPU down to a very low speed and then ramps the speed back up when more processing power is needed. CPU cores are throttled individually in a process known as Core Parking. This dynamic shifting in clock speed and core power state impacts audio performance. The issue is more prevalent on the Windows platform than on the Mac.
What to do about Core Parking / CPU Throttling
There are two methods that can be attempted to disable the Intel CPU power-management features. The first option is to turn off or disable the following feature options in your system's BIOS setup utility. Before making changes, consult your motherboard or system manual about how to access these settings.
Intel SpeedStep (sometimes labeled EIST)
C1E Power State
Some manufacturers don’t provide a control setting for some or all of these features, so the second option is to use third-party software that is successful in disabling core parking on many computers. The only utility that we have successfully tested is Park Control. The Web site linked below has an informative explanation of what core parking does and explains how manual methods can be used to control the way Windows manages CPU power use.
USB Controller Performance
Intel's USB 2.0 controller implementation shares the bandwidth of the USB ports with other, often slower onboard devices, which creates problems for USB audio devices. Using a specific kind of USB hub called a “Multi-Transaction Translator USB Hub” (Multi-TT USB 2.0 Hub) can eliminate the pops and clicks and provide better overall performance.
Using a Multi-TT USB Hub provides a way of fixing the communication between Intel’s internal USB hub in the computer and the AudioBox VSL interface. Not all USB hubs are created equal, and the Multi-Transaction Translation Hub is not found in every USB hub available at your local computer store or retail outlet. It’s best to find one that states Multi-TT specifically in the product description.
One that we have successfully tested is the Manhattan Products 7-Port USB 2.0 Ultra Hub (Part #161039)
One that we have had a successful report from a customer with an 1818VSL is the 'LinXcel UH-BSC4-US USB 2.0 4-Port Multi TT Hub' (Part #BPC3-HUBUHBSC4US)
There are others; just be sure that the hub description says “Multi-TT” or “Multi-Transaction Translation.” A simple search in your favorite search engine will turn up different places to purchase this from.
USB 3.0 Compatibility
Last year we released a report with information on USB 3.0 compatibility
AudioBox 22VSL & 44VSL:
We have learned that the incompatibility issue with USB 3.0 on Mac OS X Mavericks 10.9, 10.9.1, and 10.9.2 late model MacBook Pro, MacBook Air, iMac and Mac Pro systems released in late 2013 is an issue with Apple. We have tested and confirmed that this distortion issue is resolved with pre-release builds of 10.9.3. 10.9.3 was released on May 15th, 2014, and 10.9.4 was released on June 30th, 2014. You should update to the latest Mac OS X to ensure that this issue no longer occurs.
We also learned of a problem of an incompatibility between the AudioBox VSL series on late model PC’s with the Intel USB 3.0 Chipset running with 4th Generation Haswell Intel Processors.
UPDATE: July 21, 2014 - Our Engineering Team has resolved this issue. We have a new family driver available. The updated release for Mac OS X and Windows are ready. To download it, please access it through your http://my.presonus.com account. Your AudioBox will need to be registered.
Please contact PreSonus Technical Support by creating a Support Ticket at My.PreSonus.com for further assistance.