strange (and frustrating) OA effect

[Phorhas]

Hello.

I breadborded an OA based circuit. I tried to connect the resistor/cap from the FB loop to Vref, but the sound was kinda weak and didn't clip well (gain off 116 with two BtB Si diodes). when I connected them to ground the sound was powerfll as I anticpated it would be. I 've built many TSs, which has a similar gain stage and never had this weak FB loop problem before. any thoughts of what it might be?