Judging by your response, your "twang" could very well be attributed to fermentation temps getting too high during initial fermentation. I can't stress enough how controlling that one factor dramatically improved my brews. I was pretty frustrated with some batches, as well, when the rest of my process seemed pretty solid - except for controlled ferm-temps. If you can get your hands on a cheap chest cooler/fridge and a temp controller, it makes life -- and beer - much better. Or, if you stick with water bath/swamp cooler, just monitor temps carefully the first few days and adjust as needed with frozen water bottles to keep below 70, mid to low 60's even better for many ale strains (I love WLP 007 for several styles). Also be sure to check each yeast strains' specific temp range. Some, like Belgians, do particularly well at slightly warmer temps, so might be more forgiving with your setup. Regardless, from my limited experience, the low end of the published temp range seems to produce the cleanest beer, with less yeast-produced off flavors. Other culprits could be ph or water chemistry - but I can't comment on either of those possibilities, as store bought ozarka water seems to have done me ok at this point, so I haven't dabbled much with changing those factors. Good luck!
