Scott Rao mentions in his book, The Professional Barista's Handbook, that cone-shaped singles extract more evenly than your average double basket.

I got my hands on a Synesso single basket (which is cone-shaped) but couldn't get a shot without (major!) channeling yet. I use fresh beans, tried doses from 7 to 10g, my distribution is almost perfect and headspace is the same as my doubles.

I'm still experimenting...any tips?

Try about one or two clicks finer and adjust the dose down until the shots are good.

Are we talking ~5g, Ian?

With a given coffee, at your double grind setting, move one or two clicks finer.
Run a couple of sacrificial shots to clear the grinder of old grind and check the flow. Dose to the same approximate height as your double shot.
For me, this results in a very ristretto shot. I lower the dose to get a normal flow. From then on, adjust grind and dose to taste. Trying to pull optimum singles at a double grind or the reverse is an exercise in frustration.

There is some good information here :
How to consistently dose coffee for a traditional espresso - Page 3

Usually, a single shot basket takes a finer grind. I do know of occasions where a single and double basket could be matched so the grind would not have to be changed which is important in a commercial setting. I find singles to be particularly touchy when it comes to dose. One gram to much or little and you get a meltdown. I will often use the nickel test to zero in on a starting dose

Well, guys, I thought in a different direction. I suspected that my smallish puck (anything below 10g) wasn't prepared to be strong enough to withstand the initial water flow coming its way (before full pressure starts) and would be digged (as in disturbed or moved around) creating a totally different puck than the one I prepared and therefore would channel like no tomorrow. So, I tried to up my dose to a little less than 13g making a pretty firm puck; and the result was a ristretto with no apparent channeling!
It seems my intuition was in the right direction. So now if I wanted smaller doses, it appears I must use a smaller, very conical, tamper to create a puck that can handle the wetting water force.

I hope what I'm trying to say here is clear*. Makes sense?



* weak English disclaimer here!

I've used a Synesso single with both my current and previous machines. Having just weighed the beans for the first time I seem to be using 13grams with it (I use a heaped single scoop and it seems to be consistent). I came upon this dosage purely by experimenting with what gave ME the best results.

In the book, I believe he is referring to a cone shape single extracting a 'more even soluable yield' from the different coffee layers within the basket, rather than what we often call an 'even extraction' in terms of a visual lack of channeling etc.

Cheers, Chris

As with most things, it really depends on your kit. They all behave a little different. Different basket shapes, grinders, dispersion screen to puck clearance, etc... You just have to experiment around to find what works best for your setup. Just keep it incremental, change one thing at a time. If you start at 9 grams and get bad results, go to 10, 12, 13 etc until you get a good shot but don't change the dose, grind and temperature all at the same time. You won't know what effect each change had.

I don't know how the Italians do their singles with pump machines, but I only just started getting decent singles for the first time using my PV Lusso. I suspect that has more to do with the spring lever's lower shot pressure (~ 6 bar) than the basket shape -- though it's also true that the PV's basket is relatively narrow, so the puck has slightly taller proportions compared to a 58 mm basket. Whatever it is, channeling has ceased to be an issue for me, on the 1-pull shots at least.

Happy Brewing,
Wayne