I would like to add a constant current sink to my next amplifier project,current mirror seems to be a good choice,but I have no experience on this,so doing some experiment and try to familiar with it first,is just a experiment,trying to learn something from it.
So you learned that your modification doesn't do what you expected.
Are you trying to improve the mirror's characteristics?
If so you might look at a Wilson current-mirror which adds a transistor to greatly reduce its variation in output current with output voltage.
Hi, the link below is an interesting read, part 7 is about current mirrors, and there is a schematic similar to your second one but the third transistor is in a slightly different place:
**broken link removed**
I recommend the web in general, if you haven't seen it, in my opinion it's really informative.