Disclaimer: I'm a newbie, just started brewing my own espressos at home. But I did watch a ton of videos, read a lot of pages on espresso and am trying to follow the advice that I found. The issue is that the recommendations are contradictory.

I have a Solis Barista Perfetta Plus machine, which has a built in manometer. As far as I understand, the ideal pressure for an espresso is 9 bar, and it should take 25 to 30 seconds to brew. But I won't be able to reach both: I can either get close to the ideal time (e.g. 29 sec at 13 bar) or I can choose a coarser grind and get to a pressure of 10 bar in 17 s. I haven't tried an even coarser grind to reduce the pressure further as the brewing time is already very short (and yes, I measure it from the press of the button).

So the question is: should I watch the pressure or the time? The 29 s shot tasted better for me but the pressure at this setting is about 50% higher than normal so this can't be right. And being a newbie, I wouldn't necessarily trust my own opinion about the taste at this point

I settled at a dose of 10 g for a single shot. I'm not actually sure if this is the correct amount (couldn't find anything on the internet), but it seems to fit the measuring spoon that came with the machine.

Better espresso machines would have a pressure reducing element between the pump and the basket reducing the pressure to 9bar or so which would make you're life much easier. without that, if you ran the machine off something like a router speed control so you could lower the power for the time you're pulling the shot, you might do better. I know little or nothing about that machine, but either that element is mis-adjusted or it doesn't have one and I'm guessing it doesn't have one.

If you're stuck with what you have, go for best taste.

Ira

Welcome to HB Tom,
The reason that you find that the brew time and pressure are connected is that your machine does not have a Over Pressure Valve (OPV). Instead the flow (and thereby time for a fixed amount) and pressure follow a specific curve - called the pump curve. And by varying the coarseness of the grind you change the resistance from the puck and move along this curve.
I assume that you stop the extraction when the weight of your espresso is twice that of the coffee grounds. So if you want a longer extraction time you can increase the dose as much as possible using the double basket (test with a coin on top of the coffee bed, lock in the portafilter and check that there is no indentation on the bed from the coin) and coarsen the grind even further to keep the pressure (and flow) the same. This should give a longer extraction time since you are now aiming for a larger volume. I do not know how large the baskets are on your machine, but since it has a 54 mm portafilter I would think that the double basket could fit something like 16 grams.
Finally I would not put too much importance on what the pressure gauge reads and instead go by taste.

Following on with those thoughts, you probably will never get a good "single" shot from the machine. Less coffee in the basket at a given grind generally means less resistance. Without an OPV to control pressure, you have to give up the freedom to set one of your variables, such as grind and dose, to compensate for that.

Thank you for the responses, especially for the advice to try the double espresso. That put me in the good range immediately, 9 bar and 31 sec at first attempt. I can find the good spot from here.

BIG RANT ON!!
I wish folks would call the parameters suggestions rather than rules! I use a spring lever machine so cannot change the pressure/time other than by manipulating grind or volume in the basket. Some of the best shots I have tasted fell outside the Norm by a considerable margin. I have learned that my best enjoyment in this hobby is to shoot for what tastes best to me and this generally seems to taste good to my friends and not be overly concerned about the rules. I often think the rules are for commercial shops where they cannot spend an extra 20 seconds if the shot runs slow but tastes really good. They are there to make a profit but supply a sometimes reasonable tasting shot. Look at the Charbucks and numerous other chains modus operandi and tell me I am wrong. They make crap coffee and have it ready quickly but convince the masses that this is how good espresso should taste. If what you are making tastes decent to you, just change one parameter. If it tastes better continue, if not go back to previous setting and change something else until you are making the best shot you can for your palate.
Rant off.