i've had many successful brews, but the couple of times i've made dark beers, they haven't come out right.
this last one was the newcastle clone in our recipe section.
i tasted it at bottling and it was delicious.
i tasted it last night (3 weeks) and it had the same off-flavor as a porter i made (the first beer i ever made - i chalked the problem up to inexperience at the time). the best way i can describe the flavor is that it makes the beer sharp. i suppose the off flavor would be astringency, although i'm not that good at labeling particular off-flavors.
with this beer i used 1099 whitbread. the other was nottingham. i noticed the whitbread fermented fast down to target FG but i still had a few floaties after 3 weeks but bottled anyways. this one was a partial mash with four pounds of grain. i mashed around 152, sparged around 170. the other was extract with steeping grains, steeped around 160 (hot). with my last, the off-flavor remained even after 6 weeks in the bottle.
so anyhow this exact same flavor i've only noticed in two beers i've made, and they were both dark beers.
i've looked into my water quality, and cincinnati's is actually quite good for brewing, both per Dan Listermann and based on the published data, which puts the pH right in the target range.
oh, the good news is, i finally got a good cold break and have a nice clear beer. i didn't even use a wort chiller