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Upcoming Seminar:
"Loudspeaker
Measurement"
Lone Star Audio Fest
May 2-4, Dallas TX
Details
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The Woofer Tester 2 in Windows
The Woofer Tester appears to Windows as a generic sound device and can be managed like any other USB sound card. The
difference is that the input is a special purpose current trans-impedance drive and sense circuit. The 1/8 inch mini-jack output is a
line-level output that is normally connected to an external amplifier for woofer break in. A simple test to determine if the WT2 is
installed and working properly is to connect a pair of headphones to the 1/8" jack and configure Windows to use the WT2
as its default sound output (and input) device. This is done from the control panels Sound and Multimedia Device tab.
IRQ Settings
Some PCs will have IRQ setting problems where the normal operation of 'Plug and Play' has inappropriately assigned an IRQ.
Quite often, the entire USB system will be having trouble, so this is really not an issue with the WT2. The problem is that the IRQ
that is normally reserved for PCI/ISA plug in sound card operation has also been assigned to the USB controller. This is often
fixed by disabling the plug-in sound card; but with care the IRQ's can be reassigned and both sound cards can be used.
You can use the device manager to view and adjust these IRQ's.
OEM PC's or PC's Setup by an IT Group
Pre built PCs and the software that drives them are often stripped to a bare minimum. This means that although the newer version
of Windows is loaded and should support generic devices like USB Sound Devices, those drivers may not come preloaded. If this
happens to be your case, you will need to find the OS installation disk that came with your PC, get the driver from the
manufacturer or from Microsoft.
Discontinuities and Dropouts
Though great care has been taken to minimize the CPU requirements, the software does rely on the PC to perform all user
interface and signal processing computations. Ultimately this makes the tester sensitive to other things that may be going on
in the PC. If you are having trouble with consistency, it is advisable to shut down as many running processes as possible
when performing critical tests. The bare minimum for usability is a 450 MHz Pentium class machine running Win98Se and 650 MHz
for WinXP and Win2K. A fast properly configured video card also helps. If dropouts do occur, there can be several other reasons.
First off, other Windows multimedia programs can consume a large amount of processor bandwidth. The bandwidth usage,
however, comes in bursts as Windows prefers to process data in large chunks rather than on a sample by sample basis. This
means that there could be large gaps where data gets clogged up. Not surprisingly, this leads to large delays as well.
The tester, being a Windows multimedia type of application, also falls into this category. The solution is to increase the
number of buffers and the size of each buffer at the expense of update rate. If you have a speedy machine without much other
stuff contending for resources you can decrease these settings for a faster update.
Video Cards
The Woofer Tester's graphical output is updated on each input/output buffer boundary, making graphical performance important
if the buffer size is small. If you double the buffer size, this will slow the tester's response time by factor of two a
but half the overall CPU and video processor loading on the system. This can have a big impact if your PC is boarderline.
Video card settings can also play a large role in overall system performance. You will need to consult your video card manual.
SpyWare
SpyWare applications are the new bane of the Internet. We are often unaware that these demonic creations are lurking inside
our PCs. These crafty little programs get loaded and from time to time send information about what we are doing to their
masters. And, if not properly written, they clog up the machine and more than the Internet connection gets bogged down.
If you want (or need) to rid your PC of these abominations, check out Ad-Aware or
SpyBot.
Other Audio Programs Using the Tester
Not surprisingly, it is possible for other programs or the operating system to use the Woofer Tester 2 for audio input and
output. In general, the tester should not be set as the default audio device for the system. This will cause disruptions
in the tester's data stream and sounds from the operating system will not be heard.
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