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product review . . . PrismSound dScope Series III Audio Test System The dScope Series III is a complete audio system which works in both the digital and analog domains. Its inbuilt generator produces a wide range of analog and digital test signals and its analyser then produces a performance analysis of the equipment under test. T he big advance of the dScope is that it is completely under the control of your PC, using either Windows 2000 or Windows 98. In fact, clicking on the dScope shortcut even turns the machine on! Our previous experience with complete audio analysers has been largely confined to our own Audio Precision test set although we are briefly familiar with the notable Tektronix 700 audio analyser. Our Audio Precision machine is DOS-controlled although Windows upgrades are available. However, the dScope is the most completely Windows-controlled audio test set we have come across. Another big advantage over the esteemed Audio Precision test set is that the dScope does not require a large custom card to be installed in the PC which for the AP set means that it is permanently tethered to one particular PC. Instead, the dScope links to any PC, laptop or whatever, via a USB (Universal Serial Bus) cable. That means you 86  Silicon Chip can use it with any machine that has the software loaded. Hardware required is a Pentium 200 (or above) PC or laptop with 24MB of free memory, running Windows 98 or 2000, CD-ROM drive and USB port. The software comes on CD-ROM and auto-runs as soon as you slot it into the drive (provided you have auto-play enabled). Once the software is loaded, you can start the machine just by clicking on the desktop short-cut. The machine itself is quite compact and has seven XLR sockets on the front panel, for the Generator and Analyser inputs and outputs. As well, there are BNC sockets for unbalanced inputs and outputs and for monitor (external oscilloscope, AC millivoltmeter, etc) outputs. Optical (TOS) sockets are also provided for the digital inputs and outputs. There is also a headphone socket and volume control, for monitoring the signals. . . . by Leo Simpson can be easily varied from the various windows. We have taken some screen grabs to demonstrate some of the operations. Apart from being entirely controlled under Windows (the only panel control is the headphone volume knob), the Prism dScope is a highly specced audio test set. Its analog audio generator operates from 1Hz to 86kHz. THD + noise over the range from 20Hz to 20kHz (for sinewaves) is -105dB (<.0006%). Output waveforms can be sinewave, square, ramp, burst, white noise, pink noise, MLS, pulse, twin-tone and arbitrary. The digital generator can produce the same waveforms as the analog with frequency range from 1Hz to 96kHz (fs/2). Dither is applied as white TPDF or plain truncation. DC resolution is 48 bits. A large range of digital carriers are supported, including AES3(XLR), S/PDIF and TOS (optical). On the analyser side, the analog amplitude range Setting up the dScope is done under Windows. A separate window is opened for each function. In this case there are six windows displayed, with the active window having a green title bar. While the software is claimed to be intuitive (the same claim is made for virtually all Windows software), we found that there is quite a learning curve as you build familiarity with all the operating features. Most of these are brought into play by the toolbar at the top of the screen or in the various windows brought up as you select a feature or operating mode. These toolbars are quite complex and we found all the little symbols anything but intuitive at first – “inscrutable” would be a better word. However, perseverance pays off and you soon begin to appreciate how all the parameters and operating modes dScope can display Generator and Analyser waveforms and again, the timebase and other settings are controlled by opening separate windows. dScope can operate in both the frequency and time domain, as indicated by this screen which has a window for the time domain detector. The drops down menu shows some of the measurements which can be made. is large, ranging from the residual noise of 1.1µV up to the maximum peak input of 159V RMS (-116dBu to +46dBu; ie, referred to 1mW into 600Ω). Residual THD + noise for 20Hz to 20kHz is -108dB (.0004%). As you would expect, both the analog and digital analysers fully complement the analog and digital generators and the whole system can fully check both channels of a stereo system, driving both channels simultaneously, in balanced or unbalanced mode. All in all, the Prism dScope Series III is a very impressive instrument. Further technical information can be obtained from the PrismSound website at www. prismsound.com The Australian distributor for PrismSound products is Control Devices, 1/150 William Street, East Sydney, NSW SC 2011. Phone (02) 9356 1943. July 2001  87