Okay, my work has a La Spaziale S5 three group. Standard 53mm basket for the spaz's. I've noticed that the dwell time (as in, the time it takes from pump on to espresso coming from the spouts) is 2-3 seconds. No matter what i try i can't get this to change. Is this normal for 53mm baskets? The shots don't taste too bad but they're nothing compared to what i can get at home. I lowered the pump pressure yesterday from 10.5-11 bar to 9ish (took me a while to get permission to open her up ) and that didn't help.

Im sure there's no channeling, my technique is pretty solid and very consistent but this is stumping me. The mediocre coffee im producing could be the beans them self but i want to rule out this dwell time issue first.

edit: forgot to add that with the short dwell times im still getting good looking pours and getting 30ml~ in 27 seconds. thats all fine. however im not sure how these guidelines apply to the smaller baskets. everything seems to be written for 58mm basket sizes.

I don't know this machine; but dwell time has little to do with basket diameter. It depends how much space there is in the group above the puck that has to fill with water, and how quickly that space fills. You can increase the space by dosing less, using a deeper basket, or going to a thinner dispersion disk if La Spaz makes them; you can decrease the speed by going to a smaller gicleur if La Spaz makes those.

Longer dwell times are typical for preinfusing E61 groups. I see similar short dwell times (3-4s) on my Spaz S1V1 (rotary pump, no preinfusion), even with the thinner dispersion disk and relatively large headroom. There is a mechanical aftermarket P/I device for the Vivaldi (available here) that increases dwell time, but I'm not convinced that it always improves the extraction.

Zaneus wrote:The mediocre coffee im producing could be the beans them self but i want to rule out this dwell time issue first.

edit: forgot to add that with the short dwell times im still getting good looking pours and getting 30ml~ in 27 seconds. thats all fine.

Mediocre coffee is likely the cause of your uninspiring results. Also, consider specifying your dose and extracted liquid by weight (see brew ratios). 30ml really doesn't tell us much.

dosing 18g-18.5g and getting a ~35g double. Even on machines without preinfusion my dwell times are much higher. My silvia at home is typically around 5-7 seconds and i've had the same with an older three group Rancilio and similar results with a synesso i've played around with. I'm only getting these really short dwell times with the la spaziale.

I doubt it's a headroom issue, i've played around with the dose taking it as low as 15g and the dwell time barely changes at all

Vibe pumps take a lot longer to build pressure. Most of the machines you are talking about use rotary pumps.

yes. The pump on the synesso is a rotary. the pump on the silvia is a vibe, right? Both of them have similar dwell times. The pump on the spaz is also a rotary and i have the issue. So the pump should be a non issue. Especially after i changed the pressure

I used a La Spaziale New EK for about 4 years, so I had a similar machine. One of the things it is known for is an inability to gracefully handle an updose. In general I was limited to between 15.5 and 16 grams maximum before the hex screw holding the dispersion screen would cause center channeling. If you have a very light impression of the screw in the center of the spent puck you have pretty much reached its limit. If you would like a higher dose, they do sell a thinner dispersion block, but I believe it is a special order from the factory. You could also go bottomless and buy the triple baskets.

Using the machine as it is currently set up, I would first find the maximum dose it allows. Then I would set the grinder fine enough to choke it at that dose. Slowly ease off the grinder adjustment until you get the dwell time you want. It will probably be a fairly tight ristretto, but it will give you a starting point to adjust from there by taste. If it helps, I was normally getting a 5 second dwell, but I was also pulling shots that were between ristretto and normale in about 30 to 35 seconds.

I do agree with you though, I really think the performance and usability would have been improved with either a gicleur or line pressure preinfusion. But it is what it is, all you can do is adjust to what it allows or modify it to what you want if the owner will allow it. I always hated not knowing what a coffee could be capable of if I just had more room to adjust.

Jim

Was playing with 16g doses this afternoon but i didn't get anything i liked in the time i had. Could have easily gone finer with the grind but time didn't allow it.

Basically i only want an answer to one question at this stage. With 53mm baskets are the dwell times around the 2-3 second mark or are they on par with larger 58mm baskets (5-8seconds)? If 2-3 seconds is the norm then so be it. But if i can get it to dwell longer while maintaining a good brew ratio, how would i achieve this?

Seems like a lower dose might be the answer but logic would tell me a higher dose would yield a higher dwell time as long as channeling isnt an issue. The flow seems to suggest that there's no channeling at the moment but without a naked Pf i can't be 100% sure.

As Jim noted: dwell time has little to do with basket diameter. It depends on other factors, such as coffee, grind, dose, water dispersion, headroom, pump type, and preinfusion (or lack thereof). As I noted: I see similar short dwell times on my Spaz S1V1, likely due to the fast pressure rampup of the rotary pump and lack of preinfusion. But I'm quite happy with the results, and could care less about the dwell time.

In fact, I could make the argument that shorter dwell times produce more even extractions. A longer dwell time - say, 8 seconds - means that the upper layer of the puck extracts for 8 seconds longer than the bottom layer. This is almost one third of the extraction time, not an insignificant amount.

So... instead of worrying about dwell times, get some better coffee and enjoy your machine.