# Worthwhile to Adjust Pressure on MaraX to 9.5 bar?



## Dallah (Jan 31, 2015)

So is it worth opening up the case and adjusting the OPV down to the commonly accepted standard pressure of 9.5 bar? Does it make much or any difference in the cup?


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## Doram (Oct 12, 2012)

I have done mine to 9 bar. Can't yet say if it has improved my shots (need to try with the some more beans), but I definitely can't see any negative effect. Took no time to do - just get the top panel off and twist the OPV (anti-clockwise) with a wrench, then check pressure with a blind basket. If you don't like it for whatever reason, two seconds and it's back to where it was. Really don't know why I waited so long to try it. As you are asking the question - you should probably do it now. 🙂


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## Dallah (Jan 31, 2015)

Might be a job for the weekend.


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## 27852 (Nov 8, 2020)

You can grind your way to 9bar too... there is no pressure without a puck.


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## Baffo (Jan 23, 2021)

@Dallah it's only one man's opinion, but John from Decent said in a video (kinda towards the end of this) that at around 10.5 bar, there are some adverse effects on the puck (ie the puck deforms weirdly and the water flow decreases instead of increasing as one would expect at higher pressure).

To be honest I understand K's point that "you can grind your way to 9 bar", but considering that such 9 bar is usually considered as more than enough, I don't see the point of risking going above this (let's say you wanted to achieve 9, in case you're grinding slightly too fine or maybe you tamped too hard or whatever, you unfortunately end up at 10.5..).

I've maxed my Bianca at slightly above 9. Can't say I've noticed differences in flavours cause I have non-functioning taste buds, but anecdotally I've not seen such a number of "bald spots" in my bottomless PF as I used to with medium light roasts when I had it at 10.5..


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## Luke Marley (Mar 12, 2021)

Ive been thinking the same, got my mara a week or so ago, have had some cracking shots of espresso though ( raves espresso blend to be exact ) @ 16 in 32 out in 36 s. However im extracting that at 10.5 bar. My grinds rather fine also ( so fine i have fines in the cup ). Im going to increase dose soon and coarsen my grind however. Any update on if adjusting the OPV to 9 bar made any noticable difference in your extraction?


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## Dallah (Jan 31, 2015)

Truthfully the reduction by 1 bar from 10.5 bar to 9.5 bar has not had a noticeably change in the cup. The issue maybe that I change beans almost every second day, so it is difficult to attribute which parameter is causing which effect.


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