coffeeOnTheBrain wrote:I have installes the Matrix in my E61 heat exchanger and the puck looks like nothing else, but I have an issue hearing how long I need too flush. Basically I can't hear it anymore. This leaves me guessing timing instead of just hearing when to stop the flush. Is that an issue for anyone else?

I ran into the same thing with my Profitec Pro 500. I only make espresso for myself and it could be 2 hours between shots, so I need to flush some water to get past the flash boiling which was easy to determine with a normal screen but impossible to tell with the Matrix.

While my pucks came out drier, the increased difficulty in keeping the Matrix clean and the fact that I couldn't really taste any difference (my taste buds are probably fried), I felt that for me, the IMS E61 PRECISION Shower Screen (non Nanocoated) was good enough for me, so I switched back.

I like good espresso, but I'm a lazy sod.

kaptain_zero wrote: felt that for me, the IMS E61 PRECISION Shower Screen (non Nanocoated) was good enough for me, so I switched back.

I like good espresso, but I'm a lazy sod.

PM me if you want to sell it. I'd like to try one out.

Well, this arrived really fast, thankfully before the upcoming Canada Customs strike. Blank shots sure look different ... Not sure what to make of it - maybe I will get out the Scace. I have to roast more decaf before I pull out the refractometer ...

baldheadracing wrote:Well, this arrived really fast, thankfully before the upcoming Canada Customs strike. Blank shots sure look different ...
video
video
Not sure what to make of it - maybe I will get out the Scace. I have to roast more decaf before I pull out the refractometer ...

If I was going just by appearance from those videos, I would have picked the IMS.

Me too.

I wonder about the impact of these screens in the closed, semi-pressurised, pressurised group environment.
I can visualise how a paper filter sitting on a puck of coffee can help even out the pressure across the entire puck but what occurs when a filter sits a mm or two above the puck surface?

I think that a couple big advantages for the Matrix are the advertised drier pucks and that there's no way for coffee grounds to get sucked back into the group by the 3-way valve/solenoid. However, there's no 3-way with a lever group .

I did a little test today on the (lever group) Strega - I made six single luongos and tasted them blinded and controlled for temperature. Three with the Matrix shower; three with the Cafelat IMS 200. Upon tasting, the shots split into two groups of, coincidentally, three each. There was little difference between the top three but I did pick one as best-tasting by a hair over the other two, which tied. There was a little more difference in the bottom three; two tied, and there was one at the bottom. Upon unblinding, the bottom espresso was revealed as the (only) pour that had a spritz (naked portafilter; the spritz didn't make it into the cup) - so some user error.

Note:
- The Cafelat IMS Competition 200 shower screen has holes all over the screen for a lever group, unlike a proper E-61 screen.
- The Strega is not an E-61. The temperature profile, pressure profile, flow profile, and pre-infusion behaviour are all different. Results are not applicable to an E-61 - or even other lever machines.
- Coffee and roast: My roast of Aida Batlle Selection: Washed Kilimanjaro
- Pull: 7.5g in VST-7 basket, maximum 2 bar pre-infusion for about 15 seconds, extraction for another 15 or so seconds; target 20g out (1:2.7 brew ratio).
- 98F taste temperature.
- Extraction yield is not comparable outside of this test as no filters were used. Total dissolved solids were measured after tasting and ranking.


Edit to answer a few questions:
1. So is there a difference or not?
There are two possible conclusions from an experiment designed like this: Either a) The two baskets taste different; or b) The experiment wasn't big enough/broad enough to find the taste difference. The conclusion from this experiment was b), i.e., more testing is needed to find the difference (larger sample sizes, multiple machines, multiple coffees, etc.).

2. Was I just tasting differences in Extraction Yield?
That's certainly possible. However, I didn't design the experiment to test if there were differences in extraction yield between the two shower screens.

3. How were the temperatures equalized?
For more complicated experiments I use a sous-vide stick, but in this case I just used a water bath. After every shot, the jar was sealed and placed in a pot. The bath was at 110F for the Matrix pulls, and had cooled to 105F for the Cafelat pulls that followed. I then waited about 20 minutes until the bath was at 98F before tasting. That was long enough to equalize the temperature of all of the espressos. I have found in the past that temperature of the espresso is highly correlated with taste.

Did you measure the pull time for the 6 shots?

Was there a difference between the IMS and the sintered screen? I ask since if the sintered screen drops a bar or more that would affect timing. If you raise the upstream pressure to compensate how would that affect the pull (not sure that is possible on a Strega).

I had a timer running but didn't record times. I don't recall any notable difference in time to the bottom of the portafilter basket wetting, or overall shot times.

However, the Strega, and other commercial lever groups that I've used, do not flow like pump machines. The Strega fills the headspace immediately once the lever is pulled down, a.k.a. a "wall of water" of very high water debit. Thus pressure will be equalized above and below the screen pretty much immediately - so that feature of the Matrix shouldn't have a noticeable effect.

I did notice when I was doing the videos that the Matrix exerted force on the screen as I had to re-torque the shower fully in place between shots with a portafilter.

slybarman wrote:If I was going just by appearance from those videos, I would have picked the IMS.

Really? The first sneeze from IMS was terrible (it may channel after it). Did not happen in my setup with multiple screens.

They both did that which I assume was steam blowing out. Probably too hot for an actual shot?