Okay, I finished out the pair and completed some extensive testing. There is good and bad with a few surprises.
First here are a few pics. Good looking stands...
The mirrored pair allows the amps to be on the inside.
Front on view.
Looking down at them from the back.
Back side.
The idea was that the open back would allow cancellation and have a null that would minimize front wall gains. In actuality the slotted opening in the back was so narrow that it acted more like an open port. Measuring all the way around it from front to back showed a slight decrease in output at a 90 degree angle or dead on with a side where it was 6 to 8db down across the lower range. In the rear it had just as much output as from the front and it had a little bit of a peak at 250Hz on the back side indicating that might be the tuning range of the slotted opening.
So I then tried some listening tests with the single LGK desk top speakers sitting on them.
Here is an in room response measurement. Note this is a 5db scale. So getting an in room response this smooth is almost unheard of.
I have various filters like these on hand for pulling the lows off of the LGK's. I had some .047uF, some .033uF, and some .022uF values to test with. I settled on the .022uF values for them. That pulled enough of the lows off of the LGK's for me to play them pretty hard with no issues.
Here is another set of measurements that I took with the stands turned around backwards.
Okay, the listening tested reveals good and bad.
The good was that it sounded unbelievable. It was clearly full range just like the measurements showed. The bass was very clear and tight as one would expect from servo subs. And they matched well with the LGK's. It was a stunning combination. You'd never know a little 3" driver was handling so much.
Okay the bad part was this was with the highest extension filter and damping setting. Yes, it was flat to 20Hz on the highest setting. The other two settings let it drop deep into the teens. The problem with the lower settings is that when playing music with really low notes it let them run out of X-Max in a hurry. Even on the highest setting the X-Max became a limiting factor on deep notes. We are going to have to re-visit extension filters and come up with some ways to limit the low end extension to bring SPL levels up.
I also tried these with a pair of the N1's.
Again I went with the .022uF filter to remove the lows from them. It removed a LOT of the low end from the N-1's. The woofers hardly moved even with good bass notes. It did make the mid-range much cleaner as well. The servo woofers blended easily with them.
I flipped the phase control all the way around on this reading. If I would have played with it a little I am sure I could have gotten a better response. They weren't perfectly in phase at 200Hz. But man, did these things sound great! All of the great imaging of a mini-monitor and the full range sound of a big speaker. It was great top to bottom. But again, really low notes over worked the woofers pretty easily. So this thing is clearly going to need some tweaking.
