Philosopher Senior Member Joined: 13 Feb 2007 Posts: 188 Location: Australia Expertise: I like coffee
Espresso: Silvia Grinder: Rocky
Posted Thu Mar 8, 2007, 6:19pm Subject: Re: Awesome Article, but two points...
MarkPrince Said:
but I have to echo the first posters' comments - I disagree with the conclusion that the Silvia is as consistent as a HX machine. I've put several machines head ot head with the Silvia myself, in some pretty intense testing, and where all other things are equal (volume of grinds, tamp, baskets used, etc), it has a hard time matching the shot performance of some of the HX machines that are just as "dialed in" as the Silvia is (ie, temperature surfing, flushing the grouphead, knowing the cycles, etc).
Alan makes an interesting conjecture attempting to debunk the myth of temp surfing the Sylvia
To quote
"often repeated in online forums that "the Rancilio Silvia is a difficult and finicky machine make good espresso with." Actually, I find it easier to make good espresso with a Silvia (given, of course, a decent grinder) than with any comparable machine.
You read a lot about boiler temperature variations and the need for PID electronic control, but again, I've never found it necessary. To prove to myself that I'm not imagining things I recently conducted a set of three straight runs of 6 double shots (18 shots in all), measuring the temperature of the shots in the glass as soon as they were pulled. The coolest shot I got was 67ºC, the hottest was 69ºC, and all the shots tasted basically identical. During the process I simply ignored what the boiler was doing and just kept on grinding, tamping and brewing. There are people out there who claim to be able to detect a 1ºC or less variation by taste; I'm obviously not one of them."
Coming from an experienced barista, this seemed surprising until I thought about the premise of temp surfing.
There is a belief that the temperature of the water in the boiler correlates in linear fashion with the measured temperature outside the boiler. However, Alan certainly notes that the water temperature exiting the portafilter varies vary little regardless of when he makes his pour.
This is not surprising in a machine which contains a lot of thermal mass e.g. heavy duty brewgroup and portafilter.
Thermal mass acts like a thermal 'flywheel' which has a tendency to even out temperature fluctuations. It buffers marked temperature variations of the surrounding environment despite changing heating inputs.
We are going to build an environmentally-friendly house based on this premise which will keep the house warmer at night during winter and cooler during the day in summer.
Once the Silvia has reached operating temperatures - all components warmed up to a stable level then you should expect much less temperature variations and hence this observation.
Worldman Senior Member Joined: 16 Nov 2004 Posts: 1,790 Location: Pittsburgh, PA, USA Expertise: Professional
Espresso: Expobar Office Control Grinder: Cimbali 6/S
Posted Wed Aug 8, 2007, 3:52am Subject: Re: Up at the Sharp End by Alan Frew
Alan,
A nice article...thanks.
As far as the Expobar p-stat, mine has one and always did as you can clearly see in the picture. (You can also clearly see that mine has had some modifications, but the addition of a p-stat was NOT one of them.)
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