I just ordered two new GPA diaphragms.

They were a bit hesitant to sell them to me, assuming I did not like the 288 character. Kudos to that attitude, wich I think is a good customer relation is all about!
In hindsight I think reports on people not liking the 288-k has more to with faulty diaphragms than with an alnico or a circumferential-slotted phaseplug preference. Those will matter in the end, but are in the realm of "288-k ok, good but not my thing" rather than "dude switch off immediately".

Which brings me to an offer to you. i will off course measure again with the new dias but I wondered is there anyone who would like to measure my distortion makers in their units?

There is off course a tiny risk that the new dias don't work out and the cause is elsewere....

Coen