[terry j]

thank you john, must say I've never noticed the c to -1 before!! Brilliant. Sometimes had 'sensible' measurements, others not.

Thanks shez, not sure you're analysis of the purple trace is correct. Is an interesting one tho isn't it! That trace was 1/12th octave each measurement, took around 18 mins to do! Left it and went and worked elsewhere. It was done outdoors, nearest object is about 4m away ( except for the ground ), even then was on a stool so almost 2m off the ground. But I suppose you could be right, those conditions certainly qualify as 'slightly delayed'.

But Johns 'troubleshooting' is certainly the way forward for tomorrow, will let y'all know how it goes.

lots of love

terry.