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Detailed comparison - EM6910 vs Silvia

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  • Detailed comparison - EM6910 vs Silvia

    Hi guys,

    The recent thread Silvia eye and hand cast over Sunbeam EM6910 was a brief overview of the 6910.

    Ive now posted a detailed comparison at http://www.coffeetamper.com.au/kb/reviews/sunbeam-silvia/

    Enjoy (now I can get to bed!)
    Greg

  • #2
    Re: Detailed comparison - EM6910 vs Silvia

    Excellent write up there Greg. Very balanced and a lot of time obvsiously gone into it.

    I assume that you cranked the Steam temp on the EM up by 10 degrees - you didnt say in the review - you mentioned the pump recovery time in terms of wetness/dryness.

    I terms of the water temp appearing low on the EM on the thermo tests, I think some of the people on here mentioned a while ago that the thermoblock by design requires the correct flow rate (that can only be achieved by the puck inhibiting flow it seems) to get the water to the correct temp. So that might explain why on thermocouple testing it seems low, but the coffee still tasts good - ie like coffee that has hit over 90 degrees C. But the graph of consistency over the shot would still tend to be an accurate representation you would expect, but I dont know.

    Again, well done and a great write up. Now would be buyers of either machine can get a comprehensive write up with videos and photos and a neat summary table of pros and cons in a one stop kind of way.

    CHEERS

    Comment


    • #3
      Re: Detailed comparison - EM6910 vs Silvia

      Greg

      Great review... and I believe a very detailed and accurate comparison of the two machines......

      [smiley=tekst-toppie.gif]

      Is there a clear winner? Well that depends on what you want..... Until you get into the $1500+ category - Ive always said its all about compromise.... giving the potential purchaser the maximum "bang per buck" at that price point.... And the purchaser must prioritise what is wanted and choose a machine which satisfies as many of their highest priorities as is possible.

      Is there a place for both machines in the Snob world- definitely (unlike the 6900- "boat anchor")..... and what is best for one member wont be the best for another - but I have no doubt Gregs review will help you decide which is for you.

      Good one Greg!

      Comment


      • #4
        Re: Detailed comparison - EM6910 vs Silvia

        Yep steam was at +10; this is the middle bullet point just above the Brewing section.

        Yes the water temp out of the thermoblock would vary with flow rate which is one problem with them, and the 6910 is better than most TB machines in this regard. Its really no different to the idea of a heat exchanger though (water heated by being passed through a hotter surround), so there must be some differences - perhaps its to do with whether the excess pressure is recycled through an over-pressure valve (OPV) or if its just left to sit in the thermoblock as pressure and superheat. I suspect cheaper iterations may do the latter. Still, the 6910s fighting an uphill battle without much thermal mass to fall back on, which is what gets the Silvia over the line I think.

        Absolutely JavaB; you cant expect something for nothing. I remember Luca once said that in fact every machine no matter what the price is about which list of compromises you can best put up with (even Synessos!). I think in the early days of Silvia vs Sunbeam discussion there was a tendency to flame whichever machine you didnt have; running this review highlighted to me that a snob can be a snob with either machine, its just a matter of which category you fit.

        Comment


        • #5
          Re: Detailed comparison - EM6910 vs Silvia

          Great work Greg ;D

          Comment


          • #6
            Re: Detailed comparison - EM6910 vs Silvia

            ...gotcha Greg - I was reading a bit quick...so keen to see the results!!.

            Again great job mate.

            Cheers

            Comment


            • #7
              Re: Detailed comparison - EM6910 vs Silvia

              Very good review...

              I think what Greg pointed out and I do agree.. both machines are excellent but are different and really only share the same price bracket...

              The Water/\/espresso temp suprised me.. the Sunbeam temp was too low for my liking... even set at 96deg... TB tech still has some work to do I feel... Boiler over TB for steam will always be I feel....

              Comment


              • #8
                Re: Detailed comparison - EM6910 vs Silvia

                Flow must be one of the taste factors - too quick (for eg. from insufficient coffee/coarse grind or insufficient tamp) and the brew temp will be down accross the pour - get it right (as we should be doing as SNOBS) and the flow rate will be correct and the brew temp will be up at the correct temp for the duration of the pour. So the secret of the EM, as with any machine though one would expect (but perhaps more critical with the TB machines) is get the grind, dose and tamp right and your on a good cuppa.

                Cheers

                Comment


                • #9
                  Re: Detailed comparison - EM6910 vs Silvia

                  Agreed ozscott, but the graphs were based on the right grind giving a drip to slow stream pour, and the similarities between the slow and fast pour graphs indicates the temps inherently lower and a bit bumpier. But the right pour rate will certainly minimise the affect of those variations.

                  Comment


                  • #10
                    Re: Detailed comparison - EM6910 vs Silvia

                    Originally posted by Greg Pullman link=1177174323/0#8 date=1177313754
                    Agreed ozscott, but the graphs were based on the right grind giving a drip to slow stream pour, and the similarities between the slow and fast pour graphs indicates the temps inherently lower and a bit bumpier. But the right pour rate will certainly minimise the affect of those variations.
                    what kind of temp surfing was done on the silvia prior to the temp logging, ie was it after a flush? a few minutes after after the themostat going off? etc

                    Comment


                    • #11
                      Re: Detailed comparison - EM6910 vs Silvia

                      Excellent review, Greg, very thorough as usual, with plenty of detailed comparisons to allow honest appraisal of the two machines by readers.

                      -Robusto

                      Comment


                      • #12
                        Re: Detailed comparison - EM6910 vs Silvia

                        Gotcha Greg - you were very thorough then. Thanks again.

                        Comment


                        • #13
                          Re: Detailed comparison - EM6910 vs Silvia

                          None specifically. This was because theres no indication on the Sunbeam when its heating and when its not unless youre able to decode the morse code produced by the thermostats, so it didnt seem fair to give the Silvia the advantage of brewing straight after the heating cycle. As I mentioned, once Silvia was stable it would heat for about 50 seconds and then sit idle for about 17 minutes, so the brews would have taken place during the idle period. The Sunbeam cycles much more regularly so I would expect almost identical results regardless of what timing was used.

                          Comment


                          • #14
                            Re: Detailed comparison - EM6910 vs Silvia


                            A very nice review Greg. Im still not happy with the thermal mass arguement, though. Aluminium is superior to brass in the thermal characteristics that count. For a given volume, aluminium and brass hold about the same amount of heat (al is slightly better -dependent on alloy), but brass is much denser, so weighs more. So heft doesnt equate to more thermal mass. In fact al is more thermally conductive, and so responds faster than brass to fluctuating temperatures.

                            In short there is no simple arguement. The devil is in the detail. Thats why a La Marzocco saturated group isnt the same as an Imat Mokita boiler/group even though in principle they appear quite similar.

                            Id also like to see a thermofilter graph of the intra-shot temperature, rather than a TC up the spout. I have the thermofilter, I just need a volunteer with an EM6910 and a naked PF.

                            I agree with the overall findings though and I think Sunbeam would too. I think they have achieved their marketing objectives.

                            Cheers,

                            Mark.

                            BTW: Id only take Silvia with a PID controlled boiler and an adjustable brew pressure.

                            Comment


                            • #15
                              Re: Detailed comparison - EM6910 vs Silvia

                              Send it down to Melbourne Sparky...Id be more than happy to do it. I have a naked, 6910 and datalogging DMM. This will put to rest all the bs everyone is talking.

                              I agree with you on the aluminium argument there. Im currently studying a mech engineering unit called heat transfer and thermodynamics (boy is it hard) and cannot fault the "In fact al is more thermally conductive, and so responds faster than brass to fluctuating temperatures." The heat transfer rate through Al will be greater than in brass. But maybe having the a boiler respond slower to thermal gradients is a good thing(?) [smiley=undecided.gif] Sort of like a thermal lag that allows the boiler to maintain temperature without much energy needed to keep it there. What it does mean though is that the thermoblock will respond to a re-programmed brew temp a lot faster than a boiler. 2 distinct advantages of each technology.

                              My premise for this argument is this. We all know the conservation of energy law....basically its the 1st law of thermodynamics and states that "for all adiabatic processes between 2 specified states of a closed system, the net work done is the same regardless of the nature of the closed system and the details of the process". So in essence, the 1st law is a simple energy balance. {Total E in} - {Total E out} = {Change in E total of system}

                              Aluminium as discussed above is a better conductor of heat. Applying Fouriers Law for conduction we have q" = -k dT/dx.
                              Thermal conductivity [k{brass}] of Brass is 109 W/mK. Thermal conductivity [k{A}] of Aluminium is 250 W/mK.

                              Take an instant in time where the rate of change of temperature with respect to the x-direction perpendicular to the direction of heat transfer does not change (i.e. dT/dx = same for Brass and Aluminium), it is easy to see the heat flux {q"} of the Aluminium is much larger than that of Brass. Which proves Sparkys point that Aluminium has superior thermal characteristics. Actually I really didnt need to go through all that to prove that point. All I needed to do was compare their k values (thermal conductivity values).

                              But it sets up my next point. I discussed above the 1st law of thermo. If Aluminium is quick to heat and quick to cool compared to brass, it then requires more energy to keep it in thermal equilibrium (heat flux). The advantage of having a brass boiler is that the silvia element doesnt need to work as hard. There is a "thermal lag" or as explained above the heat flux of brass is lower....meaning it takes longer to heat up and longer to cool down. Aluminium is suited to tasks such as being heat sinks where the higher thermal conductivity is desired.

                              Thermoblocks and boilers are two totally different things, so the two really cannot be compared.

                              The test with the thermofilter will either confirm or deny Sunbeam is the shit or a piece of shit and:
                              • runs at programmed temp
                              • has good intrashot thermal stability
                              • has good inter-shot recovery


                              Would be very interesting to see how the Sunbeam stacks up against a PIDd Silvia in all the above points. My prediction is that it will fail test 1, do well in test 2 and even better in test 3.

                              Comment

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