Preinfusion on the La Marzocco GS3 - Page 2

[chelseacoffee]

So I've just received my GS/3 and Mazzer Mini (yay!) - and basically we are pretty sure we have the grind, tamping pressure and the flow right - but we're wondering about the temperature and the preinfusion and how that would affect everything - we are using a central and south american blend of beans, which my friend uses in her coffee bar with a faema due, with great success - on our machine though the shots range from slightly flat, some ashy, other a bit zingy - nothing spectacular, a couple close - shots were originally a little sour but we bumped the temperature up to 203 (from the 197.6 the machine was set to), and we're back down to 201 - 201.5. The water we are using is bottles "natural spring water" as our tapwater is ultra hard with somewhat dangerous levels of uranium!

We would appreciate any advice re the preinfusion - length of time on and off for a single and double shot - and the temperature for this type of bean. I've read many of the posts elsewhere, but would appreciate any advice.

Incidentally, the PID setting is 20F - is this anything to be concerned about - assumed its just the factory setting.

Thanks (in advance), Jonathan & Cindi

[HB]

We would appreciate any advice re the preinfusion - length of time on and off for a single and double shot - and the temperature for this type of bean. I've read many of the posts elsewhere, but would appreciate any advice.

The effectiveness of the GS3's preinfusion has been questioned a few times, most recently on CoffeeGeek GS3 and Pre Infusion. My own brief experience echoes roblumba's report - not a big deal. As for temperature, 201F is a good starting point, then adjust to taste. The range of taste defects you report (flat, ashy, a little sour, etc.) suggests you're too early in your experimentation to really offer concrete suggestions other than "keep trying" and "check the how tos" (especially The Home Barista's Guide to Espresso).