Do you guys think the E61 group head is outdated? What other options are there for dual boiler espresso machines? Just curious to see what you all think. Sorry if this is the wrong forum.

No, not outdated.

Consider the Breville Dual Boiler...great features for the price, some compromises. The majority of owners are quite happy with them.

Here's the thing with the e61- it is a 'known quantity' and a workhorse.

I started with a Lelit (with a 57mm basket!), moved up to the Breville 900/920, and landed on the Vesuvius (dual boiler, e61 with pressure profiling).

Here's what I do NOT like about the e-61:
- There's a 7# (or was that 7kg?) chunk of chromed metal radiating 201°F into the room when it's on. I haven't burned myself on it, that just doesn't sound like a good design particularly when you live in a place that's warm most of the year. Sure, I leave a bar towel on it when not in use but still.
- The design REALLY pushes the group out which puts it at the front edge of the drip tray on most machines.
- This is more about me, but taking the screen / gasket out without scratching the hell out of it takes some learning. It's more annoying when you buy an expensive IMS screen for it and scratch it's fine mesh up with lines that look like what a 3 yr old does with crayons on a clean wall.
- You have to start / stop shots with a mechanical lever. Not a real dis-like for me but something to be aware of.

Things that are great about it:
- TONS of parts still available. Might be a downside too as there are some cheaply made parts out there too I guess.
- As a continuation of that last mention- customizable parts are out there, change flow rates, screens, gaskets, etc. Silicon gaskets are available which are a buy once and forget it part (unless you rip them up taking the out / putting them in).
- This thing lasts a LONG time if you have decent quality parts.
- Plenty of guides online to taking it apart, cleaning, lubing, troubleshooting.
- In the case of the Vesuvius the group does a great job in producing repeatable espresso shots.

I believe the thinking behind having a LARGE chunk of metal for the brew chamber is temp stability. Spring lever machines have 14# (or was that kg?) groups for the same reason. Now-er-days we have PID controlled stuff that SHOULD be good at keeping temps stable from shot to shot without so much metal. That's the Breville design. The result is much lighter weight and probably a quicker warm up time.

I don't know how much a comparable LM group weighs, but that's a good example of a more modern group I guess. Seems like LM embraced PID controls a while ago now.

In a lot of ways I miss the Breville 920, it'll tell you when to clean it, when the drip tray is full, when it needs water (the Vesuvius does this as well but it's annoying and you can't see it coming like the Breville). It has a cleaning cycle you can run instead of doing the hokey-pokey of backflushing.

My current feeling is I would have been better off with a Londinium L-R at this point, but that's another species and you didn't ask about spring levers. Talk about out old tech that's re-purposed! There are even spring levers with PID controlled boilers now.

Perhaps I've grown to see the ridiculousness of buying a profiling machine only to leave it on a spring lever pressure profile all the time. Sure, the Vesuvius can do much more but that's where I leave it

Sorry, on my third coffee and rambling. Let me sum up by quoting sweaner- no, not outdated. Old, proven big heavy tech that can still be used with new tech.

-Richard

This seems like an area where a 'good' design doesn't become obsolete. If your priority is the in-cup result, you simply want temperature stability. How you achieve that doesn't matter and the E-61 does a good job of it. Newer group designs may have aesthetic appeal (no protruding metal, slick paddle to slide, etc). However, if they don't have some element of improved temp stability during brewing they don't change the espresso product.

Exactly (what spearfish25 said). I will say that the term 'temp stable' appeals to me, however that term may be misleading and a drop or increase of temp during a pour may produce good stuff. The thing *I* want is that my machine is consistent in they way it pulls shots so this isn't something I have to manage. So if the temp drops during a shot I want it to drop the same way each time, as an example.

I would add this- a machine having the e61 group doesn't automatically mean it's temp stable. I certainly don't have experience with enough machines to say that. The trick is to understand how (whichever machine you get) works so you can get consistency out of it. There's more to a machine than the group.

The Breville 920 will warn you if you get ahead of it's ability to keep your water up to temp, as an example of the user friendliness that can be brought to you via newer tech.

I guess an e61 means it's durable, maintainable, and certainly NOT a weak link in the chain that makes good espresso. However it's not a 'oh, this is an e61 machine so it MUST be good' detail.

Also, I always thought it looks like a large, metal nose with nostrils flared. Like a really pissed off tin man.

-Richard

Personally I think everything should be either saturated group or temperature controlled. Let E61 (and HX) die as imprecise relics of the past.

The E61 hits a unique balance of performance, price, design, and reliability.

CwD wrote:Personally I think everything should be either saturated group or temperature controlled. Let E61 (and HX) die as imprecise relics of the past.

Yes, I can see that. But per my earlier post, there is then a trade off with price, reliability, and (subjectively) design.

At some point it still being around becomes the driving force of keeping other things expensive. Stop making new machines with the old tech and prosumer manufacturers would be forced to develop a new group for that price bracket, at which point they may as well use a saturated design.

Hopefully Decent Espresso turns out to be a good option for a halfway ok group without the durability issues of the BDB or expense of the current saturated designs.

Contrary to what's being stated above here the E61's weak point is temperature stability as compared with other techniques available today. And with that it's technically outdated. Can't argue about looks and general appeal off course since that's subjective.

I've made this case before here on HB, let me elaborate.

Before closed loop control (PID) became available the way to achieve thermal stability was thermal mass. This can be achieved with large boilers and at the grouphead either with a big hunk of metal (E-61, Bosco for Levers) or with a traditional saturated group setup (i.e. LM Linea, GS/3) with a large volume of heated water which is circulated trough a hollow grouphead.

Brass which is the metal of choice in E61 groups has quite good thermal conductivity (about 6 times better than stainless steel) and also compares well to alluminium and copper with it's thermal properties (conductivity, specific heat).

In times of electronic control this makes the design less suited however. Since E-61 almost solely relies on thermal conductivity for heat distribution (disregarding the siphon with which heat is supplied) the geometry of the group introduces temperature differences (The large surface radiating into the room that some also in this thread cover up with a towel when not in use: it actually serves to introduce a temperature difference and ensure good heat transfer and circulation in the siphon. The design is very well thought out!). This can be mitigated by calibration which is done for almost all DB E-61 machines under standard conditions.

However, bring any change in room temperature, usage scenario etc. and the validity of the calibration decreases. Also a thermal lattency will occur since the temperature probes for the PID can only be placed at the base of the group more than 10cm from the portafilter (heat transfer takes time!) which increases the possible resonse time of an open loop system making it less accurate.

It even worsens precision as compared to i.e. a PID'd Silvia where ithe electronic controller only controls boiler temperature and the group itself is not heated. This is because the E-61 group actually affects the temperature after the control system has regulated it precisely in the boiler. It is as if you you would have a very nice linear amplifier and source in a hifi setup, and then speakers with lots of distortion...

This is where the saturated group comes into play. Specific heat (heat capacity of water per mass) of water is very high. One of the highest available. Discounting for the higher density of brass this means heat capacity of water per volume is in between 1.5-2.0 times as high.

More traditional satured group designs relied on constant heat circulation to the boiler (of which a Linea Classic, GS/3 group basicaly is an extended part) for good heat distribution. But more recent developments see a smaller body of water around the group head (LM Linea Mini that I went for, or the ring groups around the portafilter on the Brevilles with an even smaller body of water).

The great advantage when using electronic control in this setup is that it allows placement of the temperature probes very close to the pf and that the flow of water trough the grouphead ensures very good temperature distribution.

This then allows for a more compact design with better temperature control. And also it allows the use of stainless steel and less mechanical parts instead of brass and the mechanical parts in the assembly of the E-61. This is a big advantage in keeping the machine clean since brass has the tendacy to stain from oils in the coffee and the O-rings used in E-61s mechanical lever system are prone to wear when cleaning chemically often.

Let it be said though that the E-61 group is a very clever design from a time whe no electronic control and good pressure regulation with pumps was possible (also this can be done electronicaly now, as with the Vesuvius which omits the spring lever mechanism in it's E-61 group off course). A solid HX at a good price point without electronic control still makes sense today in that respect I think. Bolting on lots of technology in an expensive machine with E-61 does not however IMHO.

BTW I didn't investigate all this stuff just for the sake of buying an espresso machine. I also happen to teach thermodynamics at an applied university. I'm actually contemplating building a machine with students one day to put some more of this theory into practice