timo888 wrote:Again, the second half of a pump machine's extraction (if it is dosed moderately) will be duller and thinner than the first half's product. (Or do you disagree?)
Agreed. While I haven't compared them closely side-by-side, the second pull of a lever espresso reminds me of the taste of the last third of a pump extraction. In other words, the first and second stroke are reminiscent of the first half and last third of a pump extraction. If you want to get more precise, I recommend Andy's EvaluSpromatic:
Schecter EvaluSpromatic; photo courtesy Mark Prince (flickr)
At some point after the holidays I'll give this a try.
timo888 wrote:This is not a feature peculiar to the lever machine
I disagree. As Steve shows, a pressure profile with a "valley" in the middle is indeed unique to multi-pull levers:
I understand Greg can program his Linea to produce this pressure profile; it would be interesting to see how it affects the extraction, though technically they're not the same since the lever produces negative pressure on the upstroke and his setup cannot.
timo888 wrote:You only get a fracture on the upstroke when you have tamped so hard that you truly have a "puck" rather than a deformable medium.
One can argue that the "brew pressure valley" has minimal negative effects, but judging from the split espresso's appearance, taste, and mouthfeel, it's hard to argue that it's a benefit.
This discussion has been split from Lever Espresso Machines Smackdown by the moderator...