I understand why preinfusion is desirable, but I was under the impression that the slower pressure ramp-up of a vibratory pump, like that in a Vivaldi II mini, made preinfusion unnecessary.

If that isn't the case, and preinfusion DOES help even with a vibe pump, does the preinfusion option for the Mini actually make a difference? How do we know? Anyone instrumented it? Is the pressure ramp-up actually slower?

Does the difference prove out in the cup?

Thanks,

Rick

The Vivaldi obsessives have a whole forum section devoted to this topic: http://s1cafe.com/.

These threads should answer your questions: http://s1cafe.com/viewforum.php?f=45

From my experience with the rotary pump Vivaldi, preinfusion does help with the "forgiveness" factor. As for the Mini, judging from these excerpts from s1cafe and this forum, the jury is still out:

Niko wrote:It's totally worth it
The effort is pretty minimal for what you'll get out of your machine.

Weska wrote:Yes, I second Niko on this. The pre-infusion has cut short my worrying about channeling. Not that you can't get it still, but it takes some effort to have jets of channeling after the puck is soaked by the pre-infusion system.

TruthBrew wrote:As for whether it's worth it.... I've only played with it for 2 days but I haven't seen much difference in performance. I think it is now slightly more forgiving, so perhaps less chance of sink shots, but otherwise not much difference in the cup. It's certainly no worse than it was, but time will reveal any improvements.

mgwolf wrote:I wouldn't waste your money up front for the preinfuser either. I got one and haven't noticed much of a difference and will probably take it off. Michael

I didn't notice a huge difference. Still, can't hurt if you're willing to shell out the $80.

You can see the pressure ramp-up on my video:

Marshall wrote:The Vivaldi obsessives have a whole forum section devoted to this topic: http://s1cafe.com/.

Thanks, Marshall. I didn't know about this forum.

Rick

It is in my mind a contentious issue, but I feel that pre-infusion is insufficiently explained as a simple pressure ramp-up mechanism. Perhaps more importantly, small changes in the flow rate during the distribution of dry particulate grounds in the basket lead unavoidably to diagonal semi-planar solid-solid interfaces. These semi-conical surfaces act as channels.

In experiments actually designed to analyze this problem for the laying of foundations for houses etc. it has been demonstrated that placing the particles in a liquid suspension eliminates this problem creating an equal distribution of particles. Pre-infusion likely acts in a similar way by partially removing these interfaces, thus reducing channeling.

My own experiments with introducing the coffee grounds as a semi-liquid suspension bear out this theory, although the exposure of coffee grounds to liquid results in washing (i.e. extraction) which is undesirable, as it cannot be realistically controlled with much rigor. Thus, pre-infusion seems to be a good compromise, reducing but not eliminating channeling, while only minimally impacting the extraction.

Adrian