[sdiy] twilight zone solved

[Jason Proctor]

i swapped out the tl072s for lm358s and the whole thing works fine. 
ken had warned me about some 358s being really bad, looks like i got 
lucky.

ftr i think the best chip to use in this situation is the lt1013. 
paul uses it for CV mixing, which is a top recommendation in and of 
itself.

thanks everyone, particularly mike irwin, for all the help you gave 
me with this 'zone. now onto the next one... actually i think i'll 
take a break and build an MOTM kit...