Dear Friends, I'm coming from automatic espresso machine and I wanted to upgrade to a semi professional machine with the main goal of preparing an excellent espresso.

So I've decided to do the big jump and just bought a Bezzera Magica and an Eureka Atom 65 grinder (2nd hand). I've spent the last 15 days trying to produce a decent cup but I just produce undrinkable shots that are mostly OK in cappuccinos but, if I taste the coffe itself, the taste is bitter or sour and I can't find the sweet spot.

One of my dial-in log:
- I start with a coarse grinding (5 on my grinding settings). 16 grams. Very quick shot with channeling (I have a bottomless portafilter).
- I grind finer (4, then 3). Still quick. Channeling. Soar.
- I grind finer (2) and I have an extraction time of 15 seconds. The espresso cream and colour seems too dark like in over extracted shots. Minor channeling. Bitter.
- I go finer (1.5). Machine almost choke.
- I go coarser (1.. 25 seconds 2:1. No channeling. Bitter taste
- Same grinding settings (1., less dosage (15 gr). No channeling. Bitter taste
- Same grinding settings (1.6), less dosage (14 gr). No channeling. Bitter taste

So I go from channeling to over extraction. In ANY case the taste of espresso is awful.

Facts:
- Beans: I've used 100% arabica beans, from Illy store, local roaster, green beans roasted by me. All beans from local roaster are fresh (Guatemala, Ethiopia, Tanzania).
- Distribution: I'm trying to distribute already from grinding, then I'm using both WDS and a distribution tool to have a even distribution, then I use a tamper with mild force
- Grinding: I've started from a coarser grinding going to finest settings with small steps. When I've reached a decent shot with 1:2 ratio in a 20/25 seconds, I've used the dosage to fine adjust
- Dosage: The default basket is a 16 grams on Bezzera: I've experimented from 14 to 20 grams. The high I was dosing the more bitter the taste was
- Water: I've mostly used a purified water (with a mineraliser section of purifier that integrate some minerals to the water). It has 15 French degrees hardness and 60 ppm. I've also tried bottled mineral water to double check the water was not the problem.

I feel very frustrated because I've spent a lot of money both in equipment and beans to reach the "basic" goal to make a decent espresso but I've been not able to make anything drinkable.

Also, my Bezzera Magica has an OPV set to 12,5 bar. While someone has changed this value (and some returned then back to the original pressure), I saw a lot of good shots at 12 bar.

My latest hypothesis is that the Bezzera default pressure is too height and I have to almost choke my machine to reach the right ratio in the right time so I go from under-extraction with channeling to a super fine grinded and over dosed puck to slow down the flow resulting in a bitter, and some times burnt, flavor.

My questions is: is anything that I'm missing? Have you had a similar experience and you went out of the tunnel? Do you own a Bezzera and have you passed thru a similar situation?

Need help.

First step, in my opinion, would be to drop the pressure so you've got no more than 9 bar into a blind basket (some suggest 10 bars). That should help channeling problems, as well as moving into the range of extraction pressure that many prefer (I ran my vibe-pump HX at 8-9 bar blind, and often extract in the 6-8 bar range on my DE1).

PID control of an HX steam boiler doesn't do anything meaningful for brew-temperature control. You still need to manage the temperature with a flushing regimen, preferably with an EricS group-head thermometer or similar. Excessive brew temperatures can not only lead to bitterness, but can also change extraction rates to the point of changing time for a given grind and dose.

Personally, I would remove the coffee from the possible causes by purchasing some good-quality "espresso" blend/roast beans from a respected roastery. Not that there is anything wrong with your beans or roast, but moving to a "forgiving" coffee intended for espresso might make things less frustrating and quicker to get to an at least satisfactory cup.

Thank you Jeff: I've opened the Bezzera and changed the brew pressure with OPV. I've set it to 9.5 bar. In fact I've read that the vibrations pump needs to be set at an higher brew pressure like 10 bar to reach 9 bars on the group head.

The results are much better, channeling has disappeared or, in some cases, mitigated a lot. Dial in it's much simpler.

I've two questions for the community:

1. I've experienced a "darker" taste of the shots. No more bitter/sour taste but, even with a 16grams/32 grams of coffee in 22 seconds, the coffe color seems dark as when you over extract. I've ordered a brew head thermometer and I'll check if temperature is playing a role in the taste

2. The pressure that I have in the "pompa" manometer (9.5 bar) is the same that I have in the group head manometer. Is it not supposed to be lower on the group head? Do you suggest to further lower to 9 bar (or raise it to 10 as many suggests on vibration pump?)

Thank you for helping me solving this problem. I'm less frustrated and confident that I'm going in the right direction.

Glad things are a lot less frustrating!

Reaching "9 bar" isn't anything magical. As I mentioned, I was extracting at slightly lower pressures on my E61 HX and found the shots better for my taste. Going over 9 bar or so enters an interesting "world" where higher pressures result in lower flow, "backwards" from what you'd normally expect. Many people find that 9-12 bar on the shot doesn't taste as good as lower pressures.

With no flow, you'd expect the pressure within your machine to be the same everywhere. As soon as there is flow through a restriction, there will be a pressure drop. Since there are a lot of restrictions in an E61 group, that is probably why people suggest one bar higher blind-basket pressure than the target extraction pressure.

Extraction pressure is personal preference, and may vary by machine and coffee. My preference, for the coffees, HX machine, and baskets I was using, was slightly lower than others sometimes suggest. Now that I have a machine with both shot-to-shot pressure control, as well as within-shot control, I almost never use a profile that hits 9 bar and stays there (as it would on a conventional, pump-driven machine), but rather ones that decay into the 6-8 bar range during extraction.

I'm not sure what you mean by "darker" and "over extraction". I usually consider darker flow "better" and the flow lightening a sign that the extraction is coming to an end.

Thank you for your insights Jeff. They were enlightening