1500 series has some nice features.
The azimuth test actually tests / measures 4 frequencies (2.8, 5.7, 11.8 and 15.8 Khz) SIMULTANEOUSLY and you can discern phase better than 5 degrees of arc. The frequency response can be displayed with 10 db per division, or in "expand" 2 db, so its very easy to see "flatness" down to a quarter of a dB or so - over the full range of 40hz to 40kHz! Beats spot tones right out of the gate. If you have the spectrum analysis option, you can measure the actual level / frequency of the flutter components. - same with noise. The distortion function works nicely in record - produces a selectable sine wave in 1dB steps that decrease from +20 to -10dB and simultaneously displays either the 2nd or 3rd (you select) harmonic distortion as the level decreases - useful for setting the bias "right on".
Of course to use the level, azimuth and frequency response sweep capability, you need the appropriate test tapes- which are still available from MRL. As I indicated in a previous post, they made me up an "all in one" tape with level, Azimuth and frequency sweeps (both NAB and IEC) for 15, 7.5 and 3.75 for not a lot of money.
Charles
Charles