Before I can begin to pick and choose the best components for a high-end two-channel desktop audio system I must define the physical parameters of a desktop environment. What does my desktop listening environment look like? Let us take an imaginary stroll around my neighborhood.
The World is Flat
From a sonic point of view this desktop delivers a mixed set of attributes. On the positive side of the ledger, unlike a hollow core door, it takes a very high SPL level to excite any sympathetic resonances. My tabletop also offers a rigid surface for transducers, but it has a large expanse of hard surface to reflect mid and high frequencies that interfere with the primary information from speakers. The ideal surface would be both physically rigid and sonically absorbent. How can we achieve this?
That Felt Good
After cutting the piece to fit my desktop I was left with several good-sized scraps to use for another sonic purpose that I'll mention a little later. I now had a working surface that is still rigid, but sonically absorbent. If you regularly test incendiary devices at your desk, smoke, or have a penchant for devotive candles, I must warn you that standard industrial felt is not fire-resistant. It will catch fire if you place it in intimate contact with a flame. Even without a felt-covered desktop I strongly suggest you keep a working fire extinguisher in your office space in case your computer or monitor decides to self immolate.
Consider this a legally sanctioned warning INDUSTRIAL FELT IS FLAMMABLE -- USE EXTREME CAUTION AROUND FLAME AND HIGH TEMPERATURES. If you have any doubts about the pyrotechnic security of your desktop environment, do not use felt that has not been fireproofed. Fireproof felt is available by special order, but is far more expensive and due to the nature of retardant impregnation offers less sonic advantage than untreated felt.
Back To Your Desks
My own desktop sits in front of a large 72" by 50" window, with the back of the desk about 2" from the window ledge. My left wall is 30" from the edge of my desk, and a large industrial-grade 60" high metal file cabinet resides 8" to the right side of my desk. The rear wall of my office is 118" from the back of my office chair. Given their distances, both the left and rear walls of office offer little in the way of negative sonic reflections, so they have not required any sonic treatments, but the front and right side of my desktop environment have needed some attention.
I use two 15" by 15" 2" thick foam sound absorbing panels from Markertek on either side of my 19" CRT color monitor to absorb early reflections from the back of any transducers on my desktop. I also use a triple-pleated Hunter Douglas window covering to reduce reflections from the window itself. A half-inch thick corkboard reduces problems from the side of the metal file cabinet to the right of my desktop.
Screening the Screen
Common sense, which is often in short supply on office environments, indicates that the industrial felt should be placed so it does not impede your monitor's ability to circulate cooling air properly or the monitor's working life will be reduced. In a worst case scenario felt could cause your monitor's internal temperatures to approach hazardous levels.
Note: Do not block the circulation vents on your monitor.
Little Boxes On The Hillside
Obviously a desktop environment imposes certain physical limitations on the size of the speakers in your system. Using anything bigger than a smallish bookshelf speaker creates both ergonomic and sonic problems. While a bigger t desktop allows larger maximum speaker, three-way floor-standing transducers will never find their way comfortably into a desktop environment. In a conventional room-based two-channel system the general rule of thumb is that you should use the largest speaker a room will properly support, but with a desktop system the trick is to use the smallest speaker that will still give you adequate dynamic impact and integration with your subwoofer. Even mid-sized bookshelf speakers can impose placement, diffraction, and driver geometry issues that can noticeably degrade their desktop performance. On a computer desktop you must remember that small is beautiful.
The Lay Of The Land
Next month I'll begin to look at individual components in my desktop system and begin to establish some basic performance benchmarks. See you then.