LOW FREQUENCY  RESONANCE

Pickup arms have a lower subsonic limit (i.e. below 20Hz) imposed by the resonance of arm mass against cartridge compliance. Ideally, it should be around 12Hz. Much lower and the arm will read warps rather than ride over them; much higher and low audio frequencies will receive noticeable boost. Frequency will be low if the arm is heavy (high effective mass) or the cartridge very compliant. Another factor here is cartridge weight, which at 8gms or more approaches the effective mass of a modern arm at 12gms or so.

Adjust+ measures low frequency response using a frequency sweep from 8Hz up to 40Hz. Usually, there will be a resonant peak of 4dB or more and you can see this in our graph showing behaviour of a Goldring 1012GX cartridge in an SME M2-10 arm. Adjust+ neatly identifies the peak and measures both its frequency and amplitude,

Low frequency arm resonance. Adjust+ graphs it and identifies frequency and amplitude, in

this case the 7Hz and +8dB result of a Goldring 1012GX cartridge in an SME M2-10

There's not so much you can do about the LF resonance, because, if it is low, using lighter headshell screws or abandoning the finger lift will make little difference. If it is high, when an incompliant Moving Coil cartridge is used in a lightweight arm say, mass can be added to the headshell. However, these days lightweight arms don't exist; most are medium mass. So measuring LF resonance is interesting, but it doesn't facilitate system tuning.

CONCLUSION

All in all then, the Adjust+ test LP is accurate and gives a reliable set of measurements, in conjunction with a computer and soundcard, plus Adjust+ software. The system is superb value at 249 Euros, allowing a cartridge to be aligned with great accuracy, and a wide range of test data to be gleaned about turntable behaviour. It is perhaps a bit complicated, as such an ambitious system inevitably will be, but it works well and is mightily impressive. Nothing like it has ever appeared before, to my knowledge, so it moves the art of LP playing forward by a significant step.

ADJUST+   LP TRACK LIST

TRACK CONTENT PURPOSE

SIDE A

1 Sinewave 3150Hz                                        wow and flutter

2 Sinewave 1kHz,                                           lateral/left/right headshell tilt

3 Pink Noise                                                    lateral/left/right frequency response

4 Sinewave 1kHz,                                           lateral/left/right headshell tilt

5 Sine Sweep 3Hz-40Hz                                 lateral arm resonance

6 Sine Sweep 3Hz-40Hz                                 vertical arm resonance

SIDE B

1 Sweep 20Hz-20kHz                                      lateral/left/right frequency response

2 Sweep 20Hz-20kHz                                      lateral slow frequency response

3 Sinewave 3150Hz wow and flutter

4 Sinewave 1kHz,                                           vertical VTA distortion

4 Sine bursts 315Hz                                        left/right/lateral tracking

5 Sine bursts 1kHz                                          left/right/lateral tracking

6 Sine bursts 3.15kHz                                     left/right/lateral tracking

7 Sine bursts 10kHz                                        left/right/lateral tracking

8 Twin tone 3150Hz + 1850Hz                       1:1 intermodulation

9 Twin tone 315Hz + 3150Hz                         4:1 intermodulation

10 Sweep 30Hz-500Hz ..................................arm tube resonance

11 Silent groove ............................................rumble