Refurbishing KF750s

Right now I'm running stock drivers on mid/hi and B&C 12NDL88 in the lows.
I was advised by EAW NOT to change drivers in the mid/hi because it would mess with the focusing algorithms.

The 12NDL88 is a really close match to the original driver spec vise, but it's deeper so you'll need a thick gasket to mount it.

Power is provided by a Powersoft X8 DSP running greyboxes.
 
Great work!
Couldn't help notice two of the boxes seemed to have slightly different ports - were there different versions/generations of the cabinet or was there some other reason please?
Cheers,
David.
 
Great work!
Couldn't help notice two of the boxes seemed to have slightly different ports - were there different versions/generations of the cabinet or was there some other reason please?
Cheers,
David.

I don't know, I guess you have to ask EAW about that.

I'm uncertain if this has any effect, the front grille is solid and will cover part of that "hole" anyway. I haven't measured them to see if they're similar, but it looks like the difference is only in the opening towards the grill.
My idea is to run them with subs anyway, so the port loading shouldn't be a huge issue, I think.

Maybe someone else can elaborate on this?
 
I'm not sure, but I did a test with one box where I covered the horn exterior with some rubber sound dampening sheets designed for car stereo use, it made a difference. So I'm planning to do that on all the boxes.

I had some of the early 750's - I eventually did some testing with some accelerometers and discover the resonance issue, wrote a paper and sent it off to EAW. They then made some calcium load horns that fixed the problem. Latter an improved cover for the 10" driver was release. There were a bunch of errors with some of the original GF settings (that took some arguing to get fixed)...and ...and ... eventually they got the box to working really well, but by then it had a bit of a bad name and Line-arrays were becoming the trend. Fundamentally even by today's standards its a great design and can sound absolutely fantastic.

Just out of interest a friend of mine was using the Beyma HF driver used in the 750's in their boxes. There was a resonance issue caused by a cavity inside the driver near the VC. It was causing a bit of a dip in the response. He actually made a mathematical model of the drivers internals and recommended a design change that I think Beyma implemented.

Good luck with these Helge :)
 
Helge, how have you been finishing these cabinets? The paint job is absolutely stellar and I'm honestly feeling a bit ashamed of what I'm able to accomplish.

Cabinets were sanded down, washed with denatured alcohol and painted with Warnex.
I had a guy do this part, didn't have the time nor space to do it myself.
I believe he used a textured roller when he applied the paint.