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For those who cannot get enough details, I've included my research findings in the next three sections. The final sections cover the more mundane considerations like dimensions, capacities, materials, and so on.
Temperature Performance and Management
The usual heat exchanger temperature management rules apply to the Elektra, with one twist. The HX water is overheated, but the group cools when idling. You can actually pull two shots in the proper temperature range without any flushing, although the temperature on these is constantly rising. By the third shot, the group overheats and you absolutely need to flush. The heat exchanger is very efficient, and the water boils even when the prior shot ended only 20 seconds previously. So don't worry about shot intervals, just flush the same way before every shot.
When flushing, the water will run for about three to four seconds without boiling, then another two to four boiling. You get the proper temperature range, hot to cool, by going two to four seconds past the point when the boiling stops, about 2 to 2.5 ounces in all.
Flushing will get consistent starting temperatures, but not consistent finishing ones. The overall temperature profile is very bowed, and to keep the temperature at the end of shots curving the same way shot to shot, you should open the steam valve for a second or two immediately as the shot begins. This forces the boiler pressure and heating into the same state for every shot. However, in typical Elektra fashion, this last wrinkle may improve the temperature plot, but does not seem to improve the taste one whit.
Graph of shot temperatures
Brew Pressure Performance
The Elektra has no overpressure valve (OPV); so its pressure cannot be adjusted independently of the flow rate, and singles extract at 13 to 14 bar. Quite frankly, a properly adjusted OPV should be on a machine at this price. There is sufficient room in the base and the waste water can be fed directly back into the pump, so a second hose is not required. However, that being said, the missing OPV, quite amazingly, does not affect the quality of the espresso. Machines without OPVs generally make very poor singles, whereas the Elektra's are among the best espresso I've ever tasted.
Out of curiosity, I did add an OPV, set to 11 bar after some experimentation, and a needle valve to increase the dwell time from around two seconds to around four. This did not improve the taste of the shots, except on coffees roasted very light for cupping. However, it did make the machine more forgiving on packing doubles, and widened the range of acceptable extractions. Since retrofitting a valve properly is a job requiring some skill, I don't recommend it as a do-it-yourself project. However, I do urge Elektra to add one in their new production, and to reduce the group jet from 0.9mm to 0.6mm or 0.5mm to achieve reasonable dwell times.
Why is the Elektra Semiautomatica So Good?
The consensus of North American espresso experts since Schomer is that the quality of a machine is mostly determined by how stable and adjustable its temperature and pressure are. My experience with the Semiautomatica convinces me that this is not even close to the whole story. It is not particularly stable on temperature and way off on pressure, yet it produces shots that spank many machines with far better temperature and pressure performance. Moreover, after I added pressure controls and got very painstaking on temperature, the shots did not improve, although it allowed for more latitude. Finally, I get interesting and tasty flavor variations by changing dose and grind. In contrast, changing any of the variables on many other machines reveals that the shots are lousy outside of a tight "sweetspot" range.
The conclusion to this is obvious. There is a factor to espresso extraction that we are hardly aware of, and that the Semiautomatica does a lot better than most other machines on the market.
What is this factor? One thing stands out when looking at the Semiautomatica's water path from pump to puck. The water goes through two dispersion blocks and a shower screen which are elaborately engineered to provide straight down, ultra-even water distribution over the entire puck.
Diagram of group
Suddenly, the light bulb comes on:
- All the Elektra commercial groups use the same system, other companies' pump groups don't even comes close, and Dan has found that the Elektra A3, a beautiful, but technologically plain vanilla commercial HX machine, also pulls incredible shots.
- Lever machines have a similar straight down and wide water path and also produce ultra-clear shots despite non-existent temperature and pressure controls. Joel Klein, a friend of mine who owns a Brewtus and an Elektra Microcasa a Leva always insisted that it was the simple water path of the levers that made the Leva's shots taste so good. I think he's nearly right; groups perform better if the water enters straight down over the entire puck surface, rather than entering in a narrow area or oblique angle, then dispersing turbulently in the gap between the shower screen and puck.
Espresso shots taste bad when they are over or under extracted or both. I think a wide, straight down water path makes machines very resistant to over and underextraction, so they don't have a narrow sweetspot, but can operate well over a wide range of extraction conditions. This I believe is the secret of the Elektra's great shots.
While this theory for the Elektra's prowess remains to be proven, it is always important to consider how well different machines stack up when one varies grind, dose, packing techniques, shot times or shot volumes. In other words, how friendly to "mano," the barista's art, are different machines?
I think one can tease out two dimensions here. The Forgiveness Factor, that is, the degree to which machines require baristas to be painstaking when tamping and distributing, or how far they forgive small mistakes here. And the Workability Factor, that is, the degree to which they allow the barista to shape the taste of the shot with small adjustments to grind, dose, and shot timing
The Forgiveness Factor Unlike any machine I've used, singles are easier on the Elektra than doubles. Singles can be difficult because the puck tends to disintegrate over the course of the shot. The very good water dispersion on the Elektra stops this from happening. However, it runs at high pressure, up to 14 bar, and double baskets, with their straight sides, are more prone to side channeling than the sloped sides of singles. You can make good doubles by paying particular attention to the edges of the puck when distributing the grinds. A convex tamper or an NSEW (Staub) tamp also helps. Overall, the machine is less forgiving on doubles than E61s, but more forgiving than old style La Marzoccos or Cimbalis. Singles are easier than on any other machine I've tried.
The Workability Factor If a machine has little tolerance for longer or shorter shot times, lower or higher doses of coffee, or lower and higher water volumes in shots, then it will be a nightmare for beginners, since they usually are fairly inaccurate in these matters. It will also be boring to experts, since they can't do much to manipulate the shot's taste but have to stick with one grind, dose, and shot time. The Silvia and the Livia have the reputation among amateurs, perhaps undeserved, of being in this first, unforgiving class.
If a machine is insensitive to the Mano variations, it's forgiving for beginners, but still not workable for experts. Pros tend to think of E61s in this way, again perhaps with little justification.
The ideal "Mano machine" is one that produces distinctly different tasting shots when one varies grind, dose and volume, but with all variations tasting good. Such a machine is useful to both beginners and experts. The La Marzocco and Synesso have earned the pros' love for being like this. I'm no pro, but I've found the Semiautomatica to be in this third "Mano machine" class for singles; I could vary dose, flow and timing, and get very different tasting, but equally good, shots from the same coffee. For doubles, I found the range of variation a lot narrower; one can vary dose, but should keep the volume on the ristretto side. The one reservation is that shots running longer than about 30 seconds can get an overextracted aftertaste, due to the high pump pressure. The addition of an OPV (see below), while not doing much of anything else, eliminates this constraint.
WARNING: THE FOLLOWING HAS BEEN DESCRIBED FOR INFORMATIONAL PURPOSES ONLY, BECAUSE ESPRESSO HOBBYISTS AND PROFESSIONALS HAVE EXPRESSED AN INTEREST IN IT. DO NOT ATTEMPT THESE MODIFICATIONS YOURSELF; SEEK THE ASSISTANCE OF A CERTIFIED ESPRESSO MACHINE TECHNICIAN. ANY ONE OF THE MODIFICATIONS DESCRIBED HERE WILL VOID YOUR WARRANTY. THESE MODIFICATIONS REQUIRE TAMPERING WITH CONTROLS AND CONDUITS FOR ELECTRICITY, VERY HOT WATER, STEAM AND HIGH WATER PRESSURE. ATTEMPTING THESE MODIFICATIONS OR ANY PART OF IT YOURSELF COULD RESULT IN SERIOUS INJURY OR DEATH TO YOURSELF AND TO OTHERS AND THE DESTRUCTION OF PROPERTY BY FIRE AND OTHER CAUSES. THE AUTHOR AND WEBSITE OWNER ACCEPT NO RESPONSIBILITY FOR ANY INJURIES OR LOSSES RESULTING FROM ANY ATTEMPT TO PERFORM THESE MODIFICATIONS.
It is not necessary to add pressure controls to the Semiautomatica, and as stated before, it will not improve overall shot quality. However, there are some minor improvements: singles that take longer than about 30 seconds can have an overextracted note in the aftertaste, while doubles not perfectly packed will have an extraction biased towards the edges. Pressure control eliminates this, and makes the machine more forgiving than it is stock.
I recommend an added OPV be set to 11 bar blind pressure, and an added needle valve to reduce the water debit to 50mL in ten seconds and increase the dwell time to 3.5 to 4 seconds. This setting does not interfere with the excellent taste profile of the machine, and does the job of widening the boundaries of acceptable extractions. The unmodified machine starts with a squirt of espresso, followed by an almost complete cessation of flow, since the 13 to 14 bar pressure packs the fines very densely. The pressure mod to 11 bar and 50mL in 10 seconds debit changes this to a more conventional flow pattern, and also allows for the finest possible grind setting.
The existing pump has a 1/8 inch BSPP female outlet connected to a hose with the same gauge male connector mated to a flare fitting. I added the OPV and needle valve with parts in the following order: Existing pump -> new braided flexible hose -> OPV -> needle valve -> existing braided flexible hose. The waste water from the OPV is fed back to the pump intake via a silicone hose and a tee junction into the existing hose line from tank to pump intake. Flare connectors on the hoses, and BSPP pipe fittings do not leak; NPT threads require Loktite 565, an NSF rated Teflon thread sealer, to seal properly.
However, using off-the-shelf parts made for a shoehorned fit and added noise. Since the improvement is so small, I advise against making this change unless you enlist the aid of a trained repair technician with the know-how to custom cut pipe or hose, and solidly mount the added hardware to ensure everything fits easily and without added vibration. Finally, the ideal position for the needle valve is downstream of the boiler refill solenoid. Putting it there is a harder job, since it's a short pipe run from the solenoid's tee junction to the spot the feed to the HX comes out of the base. If the valve is installed as described, upstream from the solenoid, open it to restore full flow whenever the boiler is drained, so that it will refill rapidly.
This modification should only be considered by certifified espresso machine repair technicians who understand they are voiding the machine warranty and assuming all risks.
A note for those who would like the Semiautomatica more convenient and can modify their kitchen. This is a relatively easy machine to convert to a plumbed in rotary pump that's located in a cabinet below the machine. The base plate and drip tray base are plastic, and can easily be drilled for the pump and drain lines. The depression in the case holding the driptray has no components underneath it, and is brass, so it can also be drilled easily. The Ulka pump is connected to a braided hose which has plenty of slack and can be run through a notch in the base, through a hole in the counter, down to the pump located in the cabinet below. The Ulka would have to be disconnected, and the wiring extended to the rotary. The wiring to the Ulka uses quick connectors. With the wiring, pump and drain lines run through the base, the conversion would be invisible.
Again, this modification should only be considered by certifified espresso machine repair technicians who understand they are voiding the machine warranty and assuming all risks.
Appendix C: Machine Specifications
- 10 inches round at base; 14 inches deep with portafilter attached
- 21 to 23 inches high
- 25lbs empty, 32lbs filled
- Size: 2 liters with heat exchanger
- steam wand with 90 degree turn valve and knob,
- sight glass,
- boiler pressure gauge,
- no water tap
- Manual Fill Push Button
- Safety Valve,
- Vacuum Breaker,
- Safety Thermostat, bulb type, manual reset.
- Heat: 800 Watts
- Power Consumption: 120 watt-hours per hour idling
- Size: 58mm Commercial
- 3 way valve: Yes, solenoid driven
- Group Heating: Directly bolted to boiler and HX
- Baskets: 10 gram single, 18 gram double, E61 style
- Brew Control: Combination Push and On/off Button
- Group Jet: Yes, 9mm with sieve
- Water path: Straight down, double dispersion block covering entire puck
- Pump: 52 watt Ulka without overpressure valve, 15 bar max.
- Tank: 2 liters, 1.9 usable
- Cup Warmer: None
- Drip Tray: 0.175 liters
Brass/Copper or Chrome Plated Brass, both with clear-coat finish
- Materials Quality:
- Superior Commercial: none
- Standard Commercial:
- brass group, boiler, piping, fittings, & valves
- braided metal hose
- harnessed wiring
- bulb safety stat
- Mater pressurestat
- Ulka brass head pump
- Domestic: none