I am an extract brewer and I have been struggling with an unknown off flavor lately, kind of bitter/astringent and it has me rather discouraged. As a result, I have been examining my procedure looking for things that may need improvement. I shared some at a recent brewclub meeting and they were unable to difiniatevely determine the source of the problem. Some speculations were that it may be a mild infection/contaminated yeast. I used rehydrated Nottingham for all of the batches with the problem. I am thinking that if it is a contamination/yeast problem the first action would be to quit using nottingham. The other thing I am considering is maybe my lag time is too long (usually about 48 hours). I am thinking that I can decrease my lag time by waiting to chill the beer to fermentation temp. I currently ferment in a glass carboy with blowoff tube in a swamp cooler. My pitching temp is 68-70 degrees, and my fermentation temp in the swamp cooler is 65-60 degrees. I pitch my yeast and then immediately place in the swamp cooler. My question is should I wait until I see visible signs of fermentation before I place it in the cooler? It seems as this would decrease lag time, but I am afraid of off flavors from warm fermentation. What should I do?