The ST 1500(A) is an versatile piece of audio test equipment that although designed for tape recorder (and turntable) testing can be of more general use.
It incorporates a low distortion sine wave generator that can output a signal from 20hz to 40Khz (up to 2 VRMS). Older machines can measure 2nd and 3rd harmonic distortion (HD) at 1Khz only - newer machines can measure HD at 315, 333, 400 or 1000hz. It can measure noise and channel separation to better than 90dB. Of course various weighting contours are available when making noise measurements. The spectrum analysis option adds third-octave distortion component display capability.
For tape recorder analysis the machine incorporates a unique 3-tone azimuth measurement, along with flutter and noise measurement (with the optional third-octave display). A very useful feature is that it can display record/play distortion while automatically "stepping thru" input levels from +10 to -20dB.
ST also supplied a "TR150 test record" LP for testing and setting up cartridges and turntables. You'll NEVER find that.
Now the somewhat bad news: to fully utilize the machines capability you need the accompanying test tape especially for playback setup. It has the level set tone, azimuth adjust and synchronized frequency response sweep(s). Fortunately, Magnetic Reference Labs (MRL) can supply the tapes. Unfortunately they are expensive, around $100, and are offered for only one speed and equalization (NAB/IEC). I had them make me up a single tape with reference and sweep tones for 15 and 7 1/2 ips, NAB and IEC. Wasn't very expensive at all considering it replaced four separate tapes.
Now the real bad news. If the machine is broken or breaks, FORGET trying to repair it. It is all microprocessor-based and even getting to the cards is tough. It also appears that ST is "out of business" - for all intents. The monitor on my 1500 broke and ST doesn't seem to want to respond to Emails. Their website indicate that they will repair 1500's for a fixed charge of upwards of 1kilobuck depending on how long ago it was serviced. I fixed mine by substituting a unit from a baby monitor.
If you find a 1500 don't buy it unless it passes the built-in self-test function (generator output must be manually set to 2 VRMS prior to running the test). If not, you have a(n expensive) collection of spare parts.
Charles
