During that process I realised I had possibly made a mistake by positioning the resistor network BEFORE the filter cell, rather than AFTER as per diagram above, which is more "textbook" if you like.
This topology gives the ouput of the cell a more stable impedance and make it easier to tune the cut off frequency of each cell.. We tried various iterations of this topology, swapping the resistor values to adjust the relative levels of the midrange and tweeter, and I guess I confused Perry quite a lot in the process, without necessarily getting a better result on listening tests.
But a few days later, we had a breakthrough, actually two...but let's start with the cruncher!
Perry had spotted on eBay another pair of Integrales for sale in Canada, and I think at one point he may have been tempted to buy them...but in his infinite wisdom, he had the genius idea to ask the seller for a photo of HIS crossover and the seller kindly agreed!
The other good thing about this photo is that the filter has not been tampered with and is obviously as per the original design. So, then I spent some time decrypting it and came up with a new schematic - see below:
Here are the corresponding measurements: We have not quite figured out why there is so much difference between the two speakers, but one suggestion is that one speaker is positioned in a corner of the room where the other one is not.
Now I promised you that there was a final twist in the story...well I will keep that for our next and last episode 7, next week! Stay tuned...