I noticed the test Lusso is one of the "newer" versions. There are some changes that have showed up in the Lussos in the past few months, most noticably: the pressure gauge is different, there is more play in the lever and the plastic shield protecting the interior wiring and pressurestat is smaller for easier removal. I am wondering if there are any further differences that might skew the results between the two machines, ie. pre vs. post Millennum La Pavonis. Several contributors to this thread are comparing your Lusso results to their Lusso results.

Fullsack wrote:I noticed the test Lusso is one of the "newer" versions. There are some changes that have showed up in the Lussos in the past few months, most notably: the pressure gauge is different, there is more play in the lever and the plastic shield protecting the interior wiring and pressurestat is smaller for easier removal. I am wondering if there are any other differences that might skew the results between the two machines, ie. pre vs. post Millennum La Pavonis. Several contributors to this thread are comparing your Lusso results to their Lusso results.

If the group comes to temperature without a purging flush on the newer Lussos, I suspect the vapor-lock issue in the thermosyphon has been addressed.

Regards
Timo

HB wrote:Just another day at the office....

In this picture of the latte art foreground, Lusso main left flanked by grinders on the right, what is the pressure-gauge reading?

HB wrote:Greg Scace, creator of the famous thermofilter, plans to machine one specifically for the Lusso. Once it's done, we will create plots of the Lusso's pressure profile with it. I expect it to look like this:

<image>
From Olympia Cremina 2002: The evolution of design

Though I'm not sure about the height of the peaks. The piston is much smaller than the Microcasa, but the spring seems to pack about the same punch. It should put out more brew pressure. I'm not willing to pop THAT spring out of the group, the end isn't a bolt-in like the Microcasa! I'll have to ask Jim if he minds me tapping a hole in the side of the Microcasa's group to plot the brew pressure. I've always wanted to do that...

The PV's group design does not allow for the exchange of water above and below the piston, like the Elektra and Cremina groups do. I don't really understand how the flow of water above and below the piston works in conjunction with the flow of water from the boiler on the MCaL and Cremina groups, but I do know that with the PV group, there must actually be negative pressure at the group on the (piston's) upstroke, so I would imagine zero would not be the bottom point on the actual pressure graph. What makes this interesting to me is that the way you make the second pull will affect the shape of the valley - for example, two short strokes that minimize the travel of the piston beyond the boiler fill hole in the group versus two strokes that allow the piston to travel its full range. In the first case, I would imagine that the puck would be disturbed less by the shorter duration of the negative pressure.

Does the water exchange between the top and bottom of the piston change the duration of the negative pressure in the MCaL and Cremina groups, or are all three of these groups similar in the way the upstroke creates negative pressure?

HB wrote:Correction: The Lusso and the Microcasa don't have water above the piston; instead they have a "breather" hole like on a bicycle pump to allow air above the piston to escape during the upstroke.

There's an old thread that has a photo of the inside of the MCaL's group, which clearly shows 3 holes - one very near each end of the group, and one that is more central. I can guess that the more central hole is the boiler fill hole, but if the MCaL does not have water above and below, what is the purpose of the other 2 holes?

The Gaggia Achille does have water above the piston. The water above the piston moves through a one way valve in the shaft/piston on the upstroke. On the down stroke the one way in the piston closes. On the down stroke a negative pressure is created above the piston which opens another one way valve in the heat exchanger and allows water to flow into the piston chamber above the group.

More on that in the Buyer's Guide to the Gaggia Achille.

HB wrote:Sorry, I know the photo you're referring to and it's of my Microcasa (Steve borrowed it for the Elektra/Pavoni side-by-side). There's only two holes. You had me going for a minute... I just removed the piston and rechecked. There's still only two holes.

Dan, thank-you for straightening me out on the MCaL group. About all I can offer in my own defence is the photo about which we are talking:





Whatever it is just above the screen at around the 1 o'clock position looks like a hole. It must be something else. I'm actually pleased to hear how similar the PV and MCaL groups are.

Dave, thanks for clarifying the valve on the Gaggia. The Cremina, however, does exchange water, but does not have a 1-way valve...is that right?

Over the past week I have continued to use both the Elektra and Gaggia. My previous impressions of the machines still stand. The Elektra produces an amazingly clear and clean cup. The acidity is accentuated with the deep earthy tones being moved to the background. The fruity sweet flavors are accentuated but not overpowering. You would think a machine that accentuates these flavors would pull harsh and extreme cups when using bright blends or single origin coffees but it does not.

I have been trying different dose/tamp/pull techniques. More detailed information can be read in the Lever Multiple Pull Techniques thread. I still find that I prefer a single lever pull extraction from the Elektra Microcasa Leva when making a straight shot. For cappuccinos I will use a pull and a half. I allow the lever to travel around a half stroke or until the first drops fall from the portafilter. I then re-cock the lever and let it run its full stroke.

I was using Counter Culture's Twin Cities Express espresso. The Microcasa makes the berry and citrus in the cup stand out while producing a nice sweetness. The toasted nut took a background note. It produces a very nice cup, it would be a shame to cover it up with milk.

[gvideo]http://video.google.com/videoplay?docid=9039134583762475714&hl=en[/gvideo]

Time to pop the hood on La Pavoni.

Looking down inside the boiler, there's not much to see other than a heating coil at the bottom, a tube that supplies brewing water to the grouphead, and openings for the steam and overpressure wands.

Sorry for the lousy image quality. The flash on my little digital camera doesn't do chrome very well.

To access the innards, you have to remove a screw...

...infamously located underneath the drip tray.

In addition to its unfortunate location, this is a tamper-resistant screw requiring a Torx security bit.

Sigh. Another trip to the hardware store.

In general, manual lever espresso machines are far simpler in design than pump machines. La Pavoni is no exception. Besides the electrical wiring inside the base, there appears to be a resettable thermal cutoff switch in the center of the boiler, and an adjustable pressurestat at bottom center. That's about it.

Hard to get much simpler than this! No wonder these machines can last for decades.

FWIW, the screw location ain't a big deal. There's nothing underneath it except the plastic bottom of the machine. All the electronics are at the other end.

Ponte Vecchio Lusso 2 group (PVL). I had posted earlier that the left & right group released water at different lever positions. Not sure when the change actually occurred but today while flushing the groups water started dripping out of the dispersion screens at approximately the same lever position. About 90 degrees from their resting upright position. Not sure what the cause was or why things have evened up.

Now that both groups are behaving more or less the same "experimented" with a pseudo-no tamp vs. #30 tamp. Several limitations to the "experiment". My digital scale accuracy is only to within 1gm. Figure in the accuracy assuming a high degree of precision in the scale (probably not) the doses could be as much as 2 grams different. Significant in relative and absolute terms. The "no-tamp" was just resting the tamper to level the grind. Brew ratios were in the 50-60% range. The sink-to-drink ratio increased today. Adjusting the grinder wasted a number of shots. When finally getting the grind correct I only repeated the pull once. So the results reflect on a total of 2 shots per tamp pressure. For the acceptable pulls I could not really conclude that the no vs traditional tamp made a difference in regard to overall quality. It will be interesting when the naked portafilter arrives to see any visual differences. But the bottomline is taste.

My general impressions with the PVL are that it's very capable of pulling acceptable shots in the moderate (50-60%) brew ratios and it has the ability to be consistent shot to shot. Simple improvements that I would like to see are a larger in surface area drip tray, a drip tray surface that doesn't pool, an access hole to the pstat and thermofuse and a easier to remove casing. Insulated boiler would be nice. The only modification I have done was to insulate the boiler. Reduces the heating cycling by a magnitude. Based on the current price and if the machine lasts it is IMO a good value. Not the beauty and build of a Elektra MicroCasa a Leva, but very functional.

narc wrote:My general impressions with the PVL are that it's very capable of pulling acceptable shots in the moderate (50-60%) brew ratios and it has the ability to be consistent shot to shot.

I used to brew all my shots to this ratio on my Export. Doing so, I came to the conclusion that the PV group was great for lighter roasts or many SO's, but was not the best for the thick sweet (Black Cat) style dark roasts. I recently started to brew doubles using a generous Fellini and then a single pull. This results in shots that weigh 17-18gm using 12-14gm of coffee (ie. brew ratios ranging from 60%-75%), and suddenly found that those dark roasts are intensely sweet and creamy. I even brew sumatras now with tremendous results. I would be proud to serve these shots to anyone! I really have to agree with Peacecup that the PV group can be a very versatile brewer.

Mark

RapidCoffee wrote:To access the innards, you have to remove a screw...infamously located underneath the drip tray.
FWIW, the screw location ain't a big deal. There's nothing underneath it except the plastic bottom of the machine. All the electronics are at the other end.

Just a quick note for those who are considering buying a La Pavoni Millenium model. While the Europiccola and the Professionals both still have the screw in the drip tray, the new Stradivari models of both types do not. They are a bit more expensive, but can be found near the same prices with some digging. Mine was a similar price to the Professional.

Edit: As far as the screw in the drip tray being an issue, it really isn't going to be a problem for an owner who cleans up after themselves.

narc wrote: ... a drip tray surface that doesn't pool ...

On the two-group Lusso, it would also be interesting to have a way of restricting/opening the thermosyphon flow on each group, so that you could pull cooler shots on one side and hotter shots on the other.

Regards
Timo

gscace wrote:This is probably as good a time as any to say that I just don't get why the piston displacement is so small. It's very apparent to me when using a bottomless portafilter that recocking the lever plays hell with the extraction. The art practiced here is in figuring out how to mitigate the problems resulting from the recock, and make the best of what I view as a design flaw. Maybe all of the home machines share similar miniaturization, but it would seem to me that lever groups should be designed to produce an excess of water volume, with the idea that the barista would remove the cup from the flow of coffee when the extraction was deemed complete, allowing the post-extraction effluent to drain into the tray.

This is consistent with my experience of the Lusso lever recock, any type multiple pull shows up poorly in the cup. That being said, I am getting terrific 13 gram, 1 ounce ristrettos with a single pull on the Lusso, (medium-hard tamp).

The 45-mm piston on the Ponte Vecchio is not a "design flaw". It was designed to be that size, and, without knowing more about the desingers we can only guess why they did so. Several possible reasons suggest themselves:

1) One very probable reason is that small-volumes of espresso were the norm when the group was designed.

2) Another possible reason is that the surface-to-volume ratio of the tall, narrow group provides a much more efficient heat sink than does a shorter, wider group. Anyone who has compared a La Pavoni to a PV Export can tell you that the PV group overheats far less quickly. In fact overheating can be entirely managed on the Export simply by sponging the group with cool water, at least at lower pressurestat settings. I doubt this can be done with the La Pavoni, or even the Cremina.

3) The designers may have thought that the relatively tall, narrow basket shape would yield a better extraction than would a shallower, wider basket. The puck is less likely to be fractured all the way through, if at all. This has considerable bearing on multiple lever pulls (see below).

4) A fourth reason that comes to mind is simply cost-saving (less brass).

Fullsack wrote:This is consistent with my experience of the Lusso lever recock, any type multiple pull shows up poorly in the cup. That being said, I am getting terrific 13 gram, 1 ounce ristrettos with a single pull on the Lusso, (medium-hard tamp).

I have consistently noted that good-quality espresso can be achieved using multiple pulls on the Ponte Vecchio. I believe this is in part due to the 45-mm group shape. Regardless of why, I think it is important that potential buyers be aware that it is possible, because many are concerned that the small group size will be a limitation. Needless to say the 45-mm group is not the best for pulling 20g, 2-oz. espressos. But it works well for up to ~1.5 oz shots. Fullsack's 13-g, one pull shots are an example of one very good way to use the PV, but there are others.

A couple of pages back on this thread I posted some photos and a brief description of taste tests between pulls one and two using the double basket. These are 14-15-g, 1-1.5 oz shots. They nearly fill the double basket, which I believe helps to keep the puck intact during the second pull. They are also ground slightly coarser, and tamped slightly harder than a 13-g shot.

PC

Why such a small water draw?

The size of the spring, and so the length of the lever, required to attain 6+ bar on a piston with a larger diameter than the Lusso's would have exceeded domestic scale. To have attempted a larger water draw with the same diameter piston cylinder would have meant a longer piston travel, increasing the length of the arc the lever would have to traverse, which would then have required significant changes to the group fulcrum ratios, the machine's center of gravity, its weight, etc etc.

Regards
Timo