Kingman asked me for this the other day via email and now ataudio on the forum, so here is my take on the Dennis Murphy engineered mod turned up a notch or two.
Parts List from Parts Express:
(2) Vifa tweeters #264-1040
(2) Jantzen 0.50mH inductors #255-036
(2) Jantzen 1.5mH inductors #255-260
(1) Sonic Barrier 1/2" thick #260-520
(1) #6 x 3/4" screws #081-435
Instead of using the stock low pass 1.0mH inductor and adding a 0.50mH 20 AWG to it, I replaced it with the Jantzen 1.5mH 18 AWG with a DCR of 0.67 ohm.
Optional: I replaced the stock binding posts with #260-309. You will need to remove the binding posts from that part and install them on the stock binding post plate because you need the 4 plastic posts to support the new board. The reason I did this is because the connectors on the back of the stock posts are not gold plated and already looked like they had oxidation.
Optional #2: I upgraded the stock 20 ga. chassis wire from the board to the drivers with 16 ga. If you do this you will need to get new female disconnects from PE.
(1) .205" #095-282
(1) .110" #095-286
Parts List from Sonic Craft:
(2) Sonicap Gen I 3.9uF 200V (they only have 4uF, which will be fine)
(4) Sonicap Gen I 2.2uF 200V
(2) Sonicap Gen I 10uF 200V
(2) Mills .33 ohm/12 watt resistor
(2) Mills 6.8 ohm/12 watt resistor
Instead of using the existing 2.2uF in the high pass I replaced it with the Sonicap Gen I. Also, instead of using the stock 10uF in the low pass I replaced it with the Sonicap Gen I. Again, instead of using the stock resistors they were replaced with Mills 12 watt.
The new Vifa tweeter requires you to enlarge the notch at the bottom of the tweeter mounting flange and make a new notch at the top to accommodate the terminals.
I get my black FR4 from
www.AmericanEpoxy.com and use the .094" thickness. They have a $25.00 minimum, so if you order a 12" x 24" sheet that will meet the minimum. The shipping cost will run $18 to $20 I guess. You will need to cut 2 sheets, size 2 7/8" x 5 1/2", so plenty of leftover. Cutting this stuff is best done with a wet tile cutter to keep the dust down, but a table saw or band saw will work too. Do NOT breath the dust.
Here's the thread on AK where a guy talks about cutting the Sonic Barrier to size and has the new schematic posted.
http://www.audiokarma.org/forums/showthread.php?t=610820 A few other things you will need, 3M VHB tape to help secure the parts to the board and plastic zip ties to further secure them. You will note in my photos a screw at the top of the board when installed. I wasn't happy with the board unsupported up there, you may feel differently. I used nylon spacers and a 2 1/2" long round head wood screw shimmed up on the top side of the board making the screw length 2 1/4" otherwise it will go through the back of the cabinet. You'll probably find it easier to install all of this by using a sharp chisel to shave off an 1/8" from the bottom edge of the binding post opening.