ben8jam wrote:The thing that drives me nuts is Intelligentsia Black Cat tastes really good! But SO's taste like dirt. And both of those roasts taste almost exactly the same. Which they obviously should not.
Coupled with this:
ben8jam wrote:I have varied temp 5 degrees.
Leads me to a couple thoughts and suggestions:
While I haven't tried Black Cat, and I know it is not the dark comfort blend that it perhaps once was, I find it unlikely that the temperature required to make a tasty shot of Black Cat would be anywhere near warm enough to bring out the sweetness of a lightly roasted SO.
Have you asked the cafes where you get good SO shots what temperature they use? Have you determined the required temperature offset for your machine; do you know what temperature you actually get at the group when you dial in a temp of say 203°F?
I have a commercial HX machine, and manage brew temp every shot. I don't nail the temperature every time; far from it. But I can
nail the temp regularly. I bring this up because of the profound impact the right temperature has on the flavor of a single origin. While most folks figure too cool will be one dimensional and sour (they certainly can be), I have found that there is a non-dimensional blandness accompanied by maybe some astringent properties when the temperature is close, but not quite there. Going from my go-to SO roasts to a comfort blend, I flush about 7-9 seconds more, which is theoretically 7 to 9 degrees between what's good for a darker chocolate-colored bean with a couple spots of oily skin and what shines for a light-medium roasted single origin on my machine.
I would keep bumping the temperature up until your machine hisses out the group with a quick flush and try again and report back. I don't think a 5 degree swing is necessarily enough to go from good Black Cat to good light-roasted SO.