[sdiy] Matching transistors in "diode ladder" filters

[Aaron Lanterman]

One of my students is working on building a variant of the Roland 100  
VCF:

http://fa.utfs.org/diy/roland100/101_op27.jpg

See lower half, 3rd "block" from the left.

I've heard that in the Moog ladder, it's important to match the top  
transistors and the bottom transistors, but the ones in the middle  
aren't so important to match (and some schematics of various Moogs  
bears this out.)

Does anyone have advice of what is important to match in a "diode  
ladder" filter? We're doing the Roland 100, but I the same question  
could apply to TB-303, EMS, and Sonic V (IIRC).

I told my student to use CA3046s to get some cheap pairs (since I have  
a bunch), but if he could use garden variety diodes for some that  
would be convenient.

- Aaron