Ken Fox wrote:There is only one single advantage that rotary pumps have over vibe pumps, and that is that it is easier to make a machine that is quiet with a rotary pump, than it is with a vibe pump.
On a related note, one of our new sponsors is Olympic Express and their US importer,
Swiss Coffee Products. Why am I bothering you with this tidbit, other than the excuse to plug the wares? Well, I took this opportunity to ask them for a loaner Olympia Maximatic to get to know their product line better. It's an HX espresso machine similar in footprint to their Olympia Cremina and sports a vibratory pump.
After a few days of using it, two noteworthy points related to this thread come to mind:
- Vibe pumps aren't noisy, it's the casing - the Maximatic may be nosier than a rotary pump, but I would need a sound meter to confirm. It makes less noise than my electric razor, demonstrating that vibratory pumps don't have to be noisy if their vibration is properly isolated
- HX rules of engagement vary dramatically - similar to the Elektra Semiautomatica and the Gaggia Achille, the Olympia Maximatic has no thermal memory. So although you do have to flush, it's the same whether the last shot was 2 minutes, 5 minutes, or 20 minutes ago.
That said, Timo raised a good point earlier in this thread: No matter how simple the HX's flush routine, it won't have the same range as twiddling a dial on a double boiler. If you want to pull shots at 185F one day and 203F the next, an HX espresso machine isn't a good fit. They're quite capable within a narrow range of 4-6 degrees F, especially for "on the fly" within that range, but they're not well suited to the wide range of brew temperatures double boilers can deliver with ease (*).
Marshall wrote:But [the Appia] is very different in design, performance and cost from the Aurelia, which is almost in a class by itself among HX machines.
Indeed, I've been hoping that designs similar to the Aurelia would trickle down to the 1 groups. I like the idea of a no flush, easily adjustable HX espresso. That is, all the convenience of a double boiler without the extra cost.
(*) Yes, I am aware that some HX owners have added PIDs for the purpose of extending the brew temperature range and simplifying the flush routine. My point above speaks to the typical unmodified HX espresso machine available on today's market.