another_jim wrote:The Ulka pump is just 55 watts or so, so a dimmer for the pump alone does not to be expensive. Doing the lower pressure preinfusion "by ear" is somewhat hit or miss. The alternative is to cut the dose without changing the grind, so the espresso starts flowing at lower pressure. Once you see flow, lift the lever slighty (or move it to the right) to cut the pump and finish the preinfusion by holding it there for a few seconds
I cut the pump once I see coffee coming out from the basket. Even I hold the lever there, the flow has started nonetheless. So the preinfusion I have, if I can call it a preinfusion, is one with the shot already started.