They are starting to come alive now after about 20 hours. At first there was no center image at all. But it is starting to focus now.
I listened to my newest Julia Fischer album about 5 times yesterday, over and over. Wow, the detail on the strings is awesome. Percussion too. Basically the tweeter with this huge coil is a MONSTER. But totally inoffensive, since it is a soft dome.
Mono recordings make a center image strong enough to perceive while I am reading or typing, not even concentrating or looking at the speakers. Imaging was a disaster at first.
The woofer coils are about 200 feet of 10ga magnet wire. Remembering back to the first set of speaker wires I had, Anticable which were 8ga magnet wire, I was worried that if 8 feet of the stuff is THAT bad, then 200feet might not be so great either. But I went on faith that so many good opinions of North Creek big coils are the best available. I don't hear the copper ringing or trashing noise of the Anticable at all. But breaking in all that dielectric probably takes a little extra while than 10 feet of 18ga steel lam coil that came with the kit.
One problem that is becoming more obvious as the focus improves is that I am hearing a little bit of stuffiness in the low midrange. Some possible reasons for this:
1. Steel mounting bolts in the center of the woofer coils are adding hysteresis. Not sure if that would be audible, but the resolution of these drivers with these 10ga coils is unbelievable, so maybe. I am replacing the steel bolts and buts with nylon bolts and thread inserts. Parts ordered and on the way.
2. Binding post holes. The boxes are sealed, no ports. The posts I am using are Electratubes, which are basically just plastic bushings with conductors through them. After I do the wood finishing I will press them in to seal up the 7/16" holes. But for now I am running the wires out through the holes and clamping the bare wires in some brass posts to connect them to my bananas. On high volume tunes I can feel air through the open holes. At normal listening levels I can't feel any air motion, so I don't know if these small holes might have an audible effect. Today I will solder on the electratubes and push them into the holes just enough to plug them, not all the way in. twss
3. Too much stuffing. I am also hearing a slight softness to midrange instruments, so I think I need to pull out some stuffing. I don't think this would blur the low midrange, though. If anything, it should make them even tighter by increased damping of the driver motion.
4. The 17 liter box is supposed to be Qts ~ .7. Maybe Q is higher due to smaller box than expected or variation of driver Q. This would give a bass bump and some looseness at the bump.
5. It could be cabinet vibration. I am using all kitty corner bracing which links adjacent walls and reaches in about 3 inches to the 1/3rd width of the cabinet. The box is pretty solid to knock test. But on high volume bass heavy songs I can feel vibration on the sides. I can add a couple cross braces inside the box to link the sides together against internal pressure. This might be the most likely cause.
EDIT, or it could be that 20 hours is not enough break in time... That's my bad habit of thinking too much before break in is finished.
Any other opinions on what can cause minor low mid blur in a small bookshelf? Most audible on acoustic bass and deep male voice. Probably 60-100Hz. Thanks
Rich
