M14s: I may have a pair

[Alien_Shore]

Why not mount the 908 on the Manta..This will give you the opportunity to examine the 902 to see what is wrong with it.

Good thinking, AB...did just that very thing. In fact, I toyed around with several drivers on some spare MR horns. Also, I rebuilt the prototype XO, using the inductor and L-pads from the 9842 XO, and all new caps - playing around a bit with the values.





This is getting much better now. The prototype left channel is now sounding better than the stock right channel. Progress!
I need to get a measuring program for my laptop. Any suggestions out there for something that is accurate but doesn't cost an arm/leg?

[aditya]

This is getting much better now. The prototype left channel is now sounding better than the stock right channel. Progress!
I need to get a measuring program for my laptop. Any suggestions out there for something that is accurate but doesn't cost an arm/leg?

Congratulations on your progress

I use a db-meter, and the free version of ARTA for my measurement work. The free version can do everything except saving a graph, and is not fussy about the sound card also.

ARTA Download

[Alien_Shore]

After a couple attempts at getting an L/C meter that would work accurately with these multi-layer coils, I have some fairly reliable measurements of the coil in the Model 14 crossover. So here's the updated schematic. I'll measure some of the other crossovers I have later this week.


For what it's worth, the 4 crossovers I have all measure a bit differently, but that's predictable given the tolerances of these devices. I'm feeling pretty good about the 0.21 mH being the average across the ones I have.

[Alien_Shore]

So in the process of updating these crossovers, I decided to test the woofers. Here's the comparison of the two:

This first one is looking and sounding pretty good.



Something is off with this one. The Re is low, and a big difference in the impedance plots.


Anyone got any insights? I think the second one may need a trip to OKC...

[Alien_Shore]

Here are the original 2 M14 woofers (before reconing) as tested in Aug, 2012:



Maybe I'll drag out the testing gear and see if I can get some updated graphs...