In 1989, we acquired an Audio Preicsion System One test system, upgraded to dual domain status in 1991. This piece had given sterling service over the years, but as I write in the forthcoming December issue, I was approached by Audio Precision earlier in the year about trying their new System 2722, which offers significant increases in dynamic range and bandwidth, as well as using a Windows XP interface rather than System One's antique DOS program, which has required me maintaining a stable of older PCs. I am therefore gradually migrating the test regime for amplifiers and digital components over to the System 2722, and am currently performing duplicate tests using both systems.
Shown in the photo, taken in the test lab in the basement of my house (this used to be a dentist's office, and my lab is in the old dentist's lab) are (from top to bottom): 1995-vintage laptop running DOS, used to control the 8-bit Heath storage oscilloscope beneath it; Hitachi 20MHz analog 'scope used to minitor test and analyzer signals; 2007-vintage Audio Precision System 2722, controlled by dual-core PC not in photo; 1989-vintage Audio Precision System One. The screen on the right is displaying the DOS control panel for the System One. You can also see a Musical Fidelity X-24K D/A, which is the unit I use to develop and check out digital performance tests. (I use a 1978-vintage pair of Rogers LS3/5as for the same purpose in my speaker tests). You can just see the AC strip on the wall: I installed a dedicated 20A circuit for the test gear.
Other gear used for the magazine's measurement regime are: DRA Labs' MLSSA hardware/software suite and SMUGsoftware's Fuzzmeasure program for measuring loudspeakers, in conjunction with an Outline speaker turntable and calibrated Earthworks, Mitey Mike, and DPA microphones; Miller Audio Research Jitter Analyzer and QC Suite (both based on National Intruments PC cards); Fluke 87 multimeter; Neutrik portable signal generator; AudioControl SA305A spectrum analyzer; Old Colony inverse-RIAA adaptor; Heathkit oscilloscope calibrator; and Prismsound DScope II digital-domain analyzer.