So Im relatively new to espresso however I have been playing for about 6 months. I have a saeco sirena with a baratza virtuoso grinder. I took out the pressurized puck thing so no artificial crema. After a lot of trial and error I am getting pretty nice pulls with a fair amount of crema. I have my timing about right 24 seconds (plus or minus a few). Always using the same amount of freshly roasted beans from a local roaster (less than a week old). I always try to use the same amount of tamping force. I preheat all my equipment to try and maintain higher temps. I tried the Styrofoam cup trick and I have my temps between 190 and 200 in the cup. I tried adjusting my grind and tamping pressure, independently, to see if it could be an extraction problem. It just doesnt seem to help; sometimes I overshoot and will get a bitter and sour shot.

What really beats me is the shot looks great! I use a naked pf and there is very littler spraying with a nice center stream. I have tiger stripes and I am as certain as I can be my beans are fresh. Sometimes it takes the stream a few seconds to mass together but it doesn't seem sporadic and my shots are not watery. My pucks also come out of the pf as a mass, there may be a small amount of water on the surface but i wouldn't call it soupy

I am open to any ideas. I have read around looking for guidance with users suggesting brew temp and extraction and old beans as possible suspects. I'm just out of ideas.

let it heat for at least a half hour before you use the machine. 24 seconds is relatively fast although some coffees do work good at that speed. Your coffee may work better with slower extractions. Plus or minus a few seconds, how many is a few. To me that is 3 or more, so one shot is 21 seconds, the next 28 seconds. That is way to much variation. They should be withing on second either way if you want any kind of consistency. I assume you are not using a scale so your dose probably varies a gram or two either way which accounts for the swing in extraction or you have channeling issues.

Sour and bitter sounds like channeling combined with a fast extraction which is reinforced by your timing swings and the statement 'very littler spraying'. There should be no spraying/spritzing at all. You should also have an even flow from the basket, not starts here and there then eventually evens out. That is a sign of bad distribution in the basket. So it sounds like you have several issues. Get a scale so your dose is +/- 0.2 grams or less every time, and you may want to use the WDT distribution method to settle out the spritzing and uneven extraction. Then you can work on adjusting the extraction time and dose. 200f in a Styrofoam cup is about right if not a little on the hot side but again, temperature, just like dose and extraction rate/volume varies by coffee.

Try to grind finer but the virtuoso can be on the edge of usable for consistent and good espresso.

The other thing to consider is that "fresh roasted" does not always equate to "well roasted". I never liked the results from many places like Whole Foods who sell fresh roasted espresso blends.

Part of the joy of espresso is trying new blends and roasters. Try some of the blends listed in the Favorite Espresso blends thread...that may completely solve your problem. They all mail order and have good turn around times. Some are available on Roaste which has free shipping.

Favorite Espresso Blends 2010

Wow Thanks so much for your responses I will certainly try them and report back....it may be a while with all the issues you pointed out