So I'm struggling a bit at the moment with my shots in my new Slayer to get the sweetness and strength balance I had with my lever (Londinium LR)
Having felt I had nailed the LR I wanted more flexibility to adjust temp and flow profiles to try to get the very best out of coffee. It is a hobby as much as a chase for the flavour)

My grinder (Ceado E37Z) has a very EK like output, just getting that out there as it may have an impact.

So having dialled in, I thought, some coffees (That I knew) and played around with grind, pre brew length and post brew a lot to try and get what I'm after I'm still struggling with an underlying bitterness/super strong after taste that just stays with me.
Almost like an underlying bitterness.
It seems to come through even though the shots are often balanced tho with varying degrees of flavour focus depending on what I have done.

It became clear very long pre brew with the coffees I'm using was just over extracting, confirmed by some posts I read in here.
The best and closest shots have been back to a more standard 7-10s pre brew then main brew at full pressure whether I have full saturation or not. This is a very different approach to with my lever with PI control.

I am now much more coarse and shorter than when I began brewing a few days ago.

Having been advised to stick with 19g dose and the Slayer basket (my normal basket is a Pullman 17-19) for consistency I have been using 19g dose to 38g yield. I'm using 2g/s 60g/30s pre brew flow rate.
Even with a 9s pre brew and 23s main, as short as I have gone so far, and a nice sweet fruity shot in the mouth I still get this aftertaste of bitter and not the lingering good flavours.
Brewing at 93C
I tried dropping to 90C no other variable change with the same result.

Longer prebrew makes it worse for sure.

Water is through BestMax premium, the water in its own tastes fine, runs clear etc.

My next step was to brew with even shorter pre, 2-3s then main and still target 38g in 28-32s. But it's not why I bought the Slayer!

I would say the bean is a med roast, not more.
Pulped natural, Nicaraguan, yellow Pacamara, La Huella which previously had wonderful grapefruit and orange flavours. Beans are coming up 4 weeks old, having used from 2 weeks post degas. I can get these flavours, and soften, make them more forward with the prebrew length but always with the undertone and aftertaste so far.

I'd rather use 17g, 19g is more than I previously used but the headroom seemed to cause some very fast main brew extractions initially with the Slayer as I was getting a bit used to it.

Having theoretically eliminated temp and still thinking it's a form of over extraction, my thoughts are to brew shorter and increase my ratio (worried about even more bitter though but I gather this is the EKspresso approach)
Revert to a control main brew only in 28-32 sto see if it's still present then drop temp at that.
Change my water cartridge.
Try a different grinder with different output as a control.
Seek therapy.

So having felt really on my game and super consistent with my Hybrid Lever and loving the output, albeit with the simple variable of grind and PI pressure/inferred temp) in seeking to take it the the next level, getting my dream machine, I find myself very humbled, feel like I know nothing and not sure what to try; so back to school.

Any constructive help or advice, especially from
Slayer veterans, gratefully received.

Thanks

What tamper are you using...I recently had enlightening experience on a very simliar situation, I changed the grinder and everything was bitter, it's was after much trial and error when I realise my self leveling tamper was not ranking deep enough

What happens if you simply decrease your yield?

If you are over-extracting, perhaps a simple experiment would be to extract less beverage into the cup. I find that my Slayer-style shots are best when pulled in the ristretto range. Extending pre-brew longer than 15s is seldom a move on the right direction for me, and 10s seems to be a good starting place.

As shorter shots tend to be brighter and acid-forward, I pull them at a higher temperature to bring out the sweetness. I find that these hot, tight and short (volume) shots leave the bitterness behind and highlight the vibrant flavors that these coffees have to offer.

Cheers!

- Jake

Thank Jake, I'll give it a go

Rytopa, Pullman Bigstep, which was matched to basket.

My grinder is very unimodal and has this very fast extraction, I gather like an EK, in the last part of a brew. It seems to allow very easy extraction.

Coming from the lever world, it may be that your underlying assumption is that long preinfusion is best for all coffees. I don't think that's necessarily true.

Given that this is a medium roast, I would start by dialing in the best shot you can without using prebrew. Just let the Slayer do a normal pump ramp. If the shot is still bitter, try updosing and/or pulling shorter. If I can dial in a great-tasting shot that way, I don't see any reason to use long-slow preinfusion.

Now, some contend that long-slow preinfusion can enhance medium roasts. That may be true, but it's very likely that you'll have to pull Ristretto to avoid bitterness. You'll probably have to grind finer as well, to avoid having the shot run too fast and end up really sour. This is because long-slow preinfusion will make the puck more permeable. Of course, grinding finer will likely extract more, so you'll be walking a pretty fine line when using long-slow preinfusion with a medium or darker roast. Personally, I haven't found that kind of shot superior to a well dialed in medium roast pulled with "standard" espresso parameters.

IMHO, Slayer-style shots are mostly useful for dealing with light, very light and ultra light roasts -- beans that are hard to fully extract. The trick is to grind extremely fine and increase contact time by reducing the preinfusion flow rate. The preinfusion also makes the puck more permeable so the extremely fine grind won't choke the machine. If you use that technique with a medium or dark roast, you're likely to over-extract and get bitter flavors.

I very much appreciate the feedback here, some of which is what I suspected, but really needed to hear from someone else!

Strangely having bought the Slayer I almost felt it mandatory to pull those kind of shots with long preinfusion and yes very used to that with my levers (I have had std machines too)

So I've been kind of avoiding a straight pull out of some kind of weird deference or code with myself. I think it's clear I need to get over myself and start at the basic pull.

My first shots at almost Turkish grind (to make it work on the long prebrew targets I 'thought' I was 'obliged' to pull) and 40s pre 25s main were amazingly deep and complex flavoured, stewed fruit, very full bodied and soft all sorts going on but absolutely with that bitter background that made it sort of nice and interesting in the mouth for 20s but unpleasant for the next two hours!

Ok. This morning. Having flushed the water through with 5 gal and flushed the boilers through just in case, I will start with a std shot!

Oh the relief! After flushing the machine too normality is restored.

This coupled with a more standard approach of 7-10s pre brew has solved the challenges.

Managed to dial in two coffees today, enjoy them with no bitter after taste just lovely balanced shots with options to explore highlighting the elements I liked.
The only aftertaste being a lingering one of the good bits

Thanks for help. I can now get on with learning and improving my Slayer action!

Hey Phil,

Good to see you here too. I urge you to compare what you have done to allowing a few drops in the cup and then going to full brew. Then maybe try up to 4 grams in the cup and inbetween and then compare those to stopping pre-brew before any coffee drips into the cup.

I see you didn't like this up above, but I would encourage to continue with changing the dose and grind on these experiments.

Michael

Thanks Michael nice to see you too, I'll feel a bit more comfortable doing that now. It was very un-nerving and unfortunate that such brewing coincided with this water contamination.

I'll try that. is suspect that the nature of my grind output will still make that challenging, it is a different output to most grinders, even with the std shot the speed it accelerates towards the end means it can be a challenge to catch it within a gram or two of target weight. There are very few fines in it so once extracted the water gets gets little resistance it seems.

However, I'll give it a go.