A Little Angel Corus. Made for my niece for her 14th birthday.
I used the birthday edition, which includes:
1. Latch up fix. The PT2399 chip, on which the Little Angel is based, is known to lock up. This small circuit takes care of the problem. However, I have some chips that keeps locking up no matter what. If you are struggling with this – try to find another batch of PT2399s.
2. Capacitors between pins 9-16 are increased (3- to 10-fold). I used the original 1 and 10 nF initially, but got a nasty distorition and hiss. Increasing the values solved this issue, but the wet signal was also a bit darker.
I also made some small modifications:
1. Decreased R18 (10K from pin 14) to 4.7K to have a bit more wet signal in the mix.
2. Pots decreased to 100K and 50K for depth and speed respectively. This gave, in my opinion, more control and a more useful range.
3. A chorus/vibe switch. Cutting the dry signal gives a vibe-sound, although a bit dark (as mentioned above).
The PT2399 chip is known to have some lock up issue. I included mictesters fix for this, but it didn’t solve the problem. Waiting for new chips, which might be a solution.