"Peter Larsen"
see http://muyiovatki.dk/yorkville/
comments appreciated, is the 4 Ohm box broken?
** From your graphs, the woofers seem close in level but there is something
fishy going on with the other two drivers.
Like you, I would expect the 4 ohm version to be about 3 dB louder in your
test - that it is not suggests to me that the drivers are non original in
the 4 ohm box. The crossovers may be faulty or modified too.
You will have to do an investigation and use an ohm meter to compare the
resistances of each driver in each box.
At a guess, the woofer is an 8 ohm replacement, the horn driver is 16 ohms
and the tweeter is burnt out.
..... Phil