bolojm Senior Member Joined: 11 Jun 2004 Posts: 417 Location: Indianapolis, IN Expertise: I love coffee
Espresso: Isomac Amica (PIDed) Grinder: Mazzer Mini Vac Pot: none Drip: French Press, on occasion Roaster: I-roast, unassembled SC/CO
Posted Tue Nov 8, 2005, 5:55pm Subject: Re: Introducing the La Marzocco GS3
MarkPrince Said:
... but soon I will be setting up a few "open houses" (hope to get Rick to one of them!) where I'll be doing some blind tasting comparisons with one or two other machines. I'm working on the questionaire this week for it.
Coffees used will most likely be Black Cat and Kidd-O. But I may arrange to get a few other top notch espresso blends to toss into the mix.
If Vancouver were a days drive from Indy, I would happily make the trek, with my Amica in tow (for comparison purposes), as well as a few pounds of Metropolis Redline and Paradise Espresso Classico.
Did, way up in this thread ;) But to repeat the details - this prototype (not all of them tho) is dual-PID'ed, a PID for the brew boiler, and a PID for the steam boiler. This was done to see if setting up the steam boiler with PID will improve performance in the economy mode of this machine (if it's set to 10AMP service, so you can have a grinder, ice cream maker, whatever on the same circuit).
When in economy mode, the machine operates in brew boiler priority - if the brew boiler needs some chargin', the steam boiler gets no power. But because of the way PID works, pulsing on and off, I'm testing the machine to see what recovery times are like while running in economy mode - the thought is it will be more effective.
MOSFET Senior Member Joined: 31 Dec 2003 Posts: 376 Location: Long Island, NY Expertise: I like coffee
Espresso: Linea Grinder: Mazzer Mini Vac Pot: Hoover Drip: Post-nasal Roaster: Perdue Oven-Stuffer
Posted Wed Nov 9, 2005, 6:12am Subject: Re: Introducing the La Marzocco GS3
A clever approach, and maybe they did this, would be to make on-cycles of one heating element coincide with off cycles of the other. On my insulated Linea boiler I only need a duty cycle of 11% to maintain 203F. Maybe a steam boiler would require 20% to 30%. Then you'd limit the peak current draw and have room to spare for recovery purposes.
AndyS Senior Member Joined: 10 May 2003 Posts: 494 Location: NY
Espresso: Tricked-out Silvia Grinder: Robur, M3, Mazzer Mini Vac Pot: Yama Drip: no, I don't have a Clover... Roaster: PIDed Popper
Posted Wed Nov 9, 2005, 7:19pm Subject: Re: Introducing the La Marzocco GS3
Rick Said:
I'm not aware of anyone except Jim and Ken who have posted a rotary vs. vibe blind (sort of) taste test in which the brew pressure, water debit and brew temperature have been equalized on both machines. The results of such tests would help to clarify whether there is a real difference in espresso quality produced by rotary vs. vibe machines. Does anyone have a link to such a test?
It's not hard to show that a casual swap of vibe vs rotary machines makes a difference. It's a totally different matter to carefully match a vibe pump installation to a rotary pump installation so that the pressure profiles are truly comparable. Very few of the people who note these flavor differences have sweated the details to make their test one that can be used to draw universal conclusions.
Also, it's a serious oversimplification to glibly compare "vibe" vs. "rotary" pumps. Rotary vane pump oscillation patterns vary tremendously. To wit: the waveform is different if you are running it at 50 hz (in Europe) or 60 hz (over here). The waveform is different if you're drawing water from a static tank at 0 psi or from the mains. If from the mains, the waveform is different if your inlet pressure regulator is set to 10 psi, 20 psi, 40 psi, or whatever. If your rotary has one sticky vane (or two, or three), the waveform will change. Etc, etc....
MarkPrince Moderator Joined: 19 Dec 2001 Posts: 4,700 Location: Vancouver Expertise: Professional
Espresso: Frankenstein'ed LM Linea Grinder: Anfim Super Caimano Vac Pot: 1922 Silex Drip: Krups Moka Brew Roaster: Hottop
Posted Sat Nov 12, 2005, 3:02pm Subject: Vibe vs. rotary.
Since I've been accused elsewhere of trying to stifle this thread :D, I figured I'd bring it back up with a new thought on the off track topic - vibe vs. rotary.
I can't explain why I didn't bring this up before... but there's one major factor that I think contributes to vibe's lower quality shots vs a rotary pump that really should be discussed.
I think part of the reason why vibe performs less is because (at least in every single vibe equipped machine I've tested in a HX machine, and even in some single boiler machines) is that they are not and can not handle multi tasking.
Situation: you're brewing a shot. You've flushed the E61, you've watched the timing on the cycle on the steam boiler, and all signs point to go. You start brewing. Midway through the brew, the machine's brainbox says "wait, I need to autofill the steam boiler" and it kicks in. Wallah, your pressure at the group is reduced, and many times visibly. Affects the shot and extraction.
Also, most of these machines designed for Europower-spec can't even handle a cycle during a brew - the pump loses pressure. You can see it in the espresso flow, and you can hear it in the sound of the vibe. Three notable machines (out of many) I've noticed this in:
- FF!! X1 with it's super tiny deadband, will cycle 2, 3 or 4 times during a shot pour, and you can see the output volume per second change. - Isomac Millenium - minor reduction in pressure during a cycle, medium reduction during autofill, major reduction during cycle / autofill. - Expobar Office - ditto to the Millenium, but a bit more even (less pressure loss).
Rotary pumps, on the other hand, seem to handle multitasking much better. I'm not saying by any stretch that there's no reduction or change in pump pressure when the pump is called to multitask or similar, but in eveyr machine I've ever tested with a rotary pump, I've never seen even the slightest visual indication of a change in pump pressure at the spouts.
If you're brewing at 9BAR or 10.5BAR (what a lot of the HX machines seem to brew at!) and all of a sudden the pressure goes down to 7BAR or less, it's going to affect extraction quality.
AndyS Senior Member Joined: 10 May 2003 Posts: 494 Location: NY
Espresso: Tricked-out Silvia Grinder: Robur, M3, Mazzer Mini Vac Pot: Yama Drip: no, I don't have a Clover... Roaster: PIDed Popper
Posted Sun Nov 13, 2005, 5:16am Subject: Re: Vibe vs. rotary.
MarkPrince Said:
there's one major factor that I think contributes to vibe's lower quality shots vs a rotary pump that really should be discussed.
I think part of the reason why vibe performs less is because (at least in every single vibe equipped machine I've tested in a HX machine, and even in some single boiler machines) is that they are not and can not handle multi tasking.
<snip>
Rotary pumps, on the other hand, seem to handle multitasking much better. I'm not saying by any stretch that there's no reduction or change in pump pressure when the pump is called to multitask or similar, but in eveyr machine I've ever tested with a rotary pump, I've never seen even the slightest visual indication of a change in pump pressure at the spouts.
If you're brewing at 9BAR or 10.5BAR (what a lot of the HX machines seem to brew at!) and all of a sudden the pressure goes down to 7BAR or less, it's going to affect extraction quality.
You're correct, of course. Rotaries are generally operating at only a fraction of their capacity when pulling a shot. Cycling of the heat element on and off is going to have little or no effect on their delivered pressure. Refill of the steam boiler during an extraction will have less of an effect than with a vibe pump.
Conscientious machine designers have all kinds of tools at their disposal to prevent the negative effects of boiler refill and/or heat element cycling during an extraction. Often the manufacturers are just too cheap and too lazy to do so.
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