Yes, I remember the discussions. I think we can be very happy with this result. Your original idea was to use a front chamber of 50 litres which would have caused a reasonably big dip. I think now the 12pi response is very nice.Still I would like to know if the dip around 40Hz is just as big as with 1W as with 1600W. If that is the case there is no limitation due to x-max in this 12pi design.
Best regards,
Walt