The problem is that my espresso shots are consistently bitter and harsh. There are good tastes in the shot, but I cannot seem to make the harshness go away. Here's some background information. Eight months ago I bought a Silvia / Rocky doserless combination. Silvia has had the OPV pressure reduced to 8.5 bar and Rocky has the Teflon tape mod. I brew freshly roasted Black Cat, use the WDT, and underdose slightly (around 14g in a ridgeless double basket) using a convexly cut credit card. Tamp is around 30lb. I reverse temperature surf, brewing 45-60 sec after the boiler light goes off. I set the grind to mostly fill my Illy espresso cup in 25-30 sec. This is at seven or eight clicks above true zero. Crema is good. I rarely have obvious channeling issues, e.g. jets from the naked portafilter. I have experimented with the variables above but the harshness remains.
Here's the complication. I recently took a barista training class at Intelligentsia. By the way, the two trainers, Matt Riddle and Andy Carey, were great. It is humbling to see great latte art prepared so effortlessly, but I digress. The best part was that I got to play with two and three group Linea machines and Robur grinders. My "problem" is that almost every shot I pulled was better than anything I have ever pulled at home. Not just a little better. Order of magnitude better. And I was working fast, trying not to display my dorky home technique: no WDT, just grind, use finger to make small mound, tamp, brew. Now I know that I have the capability to pull a shot in the same class as what I've had at Intelligentsia, Ritual Roasters, etc.
The question I'd like to pose is how to proceed from here. I'm beginning to think that I am equipment-limited. I've thought about some things I might try:
- If temperature management issue: Do more temp surfing experiments on Silvia. Buy or make a portafilter thermometer. Install a PID. Upgrade the machine.
If other issue with Silvia: Upgrade the machine.
If grind quality issue: Upgrade the grinder as the Teflon tape mod is the only thing I know to try and I've done it already.
Technique issue: ?
Thanks again for the wonderful site.