Okay,

I am amazed you have time for this with your new arrival!

Firstly, l can simulate for you the voltage drives of your hybrid in Leap 5 to evaluate the overall network phase and voltage drives and compare with the vanilla 3155 network. I might be able to look at this over the weekend.

I have the 4344mk11 network so l am familiar with its operation.

Secondly, Looking at the drivers sensitivity of the Beyma slot looks identical but the impedance curve may not be the same as the 2405? In your post you mention a 2 db drop off @ 10 Khertz? Are you referring to the horn only or the slot only or the overall response with the Lpads full?

If you can please provide clarity?

If this comment relates to the level of the Beyma only we can then focus on the adjustment range of the L pad.

If the drop off relates to a notch in the response please advise?

Some commentary of why you think this is a phase issue would assist in evaluating the situation.

The thing to understand with a 4 way is setting up the levels for each driver can be a challenge as can the phase of each driver. It's easy to wire up one of the driver. As l recall the mid, hf and uhf should all be in phase. I assume you have previously checked this? The polarity convention of the Beyma slot maybe different to the 2405.