Yup!! My beloved GS-1 is for sale. Come on, you geeks...where are you? This machine is gorgeous! Will someone please break from the herd before I change my mind!

Here is a rundown:

This is a rarely seen 1989 GS-1 Single Group Solenoid unit and is in fine condition with no need whatsoever for restoration. It has been modified with several improvements to accomplish stable precision thermal control of brewing water during shot delivery. The modifications were done in such a way as to make them easily reversible to return the unit to its fully original state, should that be desired by a collector. There is no rust, corrosion, or crud anywhere and all functions perform perfectly. The group chrome has no dents or scars, the stainless steel panels and the handsome black wrinkle-paint side panels and frame are in great, near perfect condition. Aside from additions required to implement the control electronics, the wiring is the original cloth-insulated and is all in perfect condition. It has a whimsical cup heater which delivers a puff of steam to the cup storage tray on command, as though it's not warm enough up there already!

A pre-heat tank has been added which feeds the original brew tank environment. This third tank is controlled by a mechanical thermostat located in a thermowell and it supplies water elevated to ~204 F to the brew tank. The third tank modification was fabricated and installed by La Marzocco when located in the Ballard district in Seattle in around 2001.

An Omega Micromega CN77000 series auto-tuning temperature controller uses a PID algorithm to exact thermal control over the original brew tank. The Micromega drives an Omega Solid State Relay which modulates power to the brew heating element. The machine has an exceptionally tidy and solid electronics integration with an elegant custom made fan-ventilated stainless steel module holding the splashproofed Omega controller. The extra tank is slung back under the steam tank. The Micromega module hangs back under the left frame rail, easily visible but out of harm's way both thermally and operationally. The pre-heat tank also has a J thermocouple installed for tuning that tank's temperature using a Fluke or other external instrument. That thermocouple could inform a second PID loop if a two-channel controller were installed in place of the single channel Omega.

This is a rare and beautiful La Marzocco machine that played a significant role in researching the importance of temperature stability during shot extraction.

If I were keeping this machine I think I would add another modification that would place an on-delay timer before the pump so that when the brew switch was closed there would be a period during which the solenoid flowed water under only mains pressure to gently wet the coffee load. Then, some few seconds later, the timer would turn on the pump to deliver full extraction pressure. This would bring the machine into the realm of current state of the art in terms of pre-infusion versatility. Also, pressure profiling could be accomplished with a bit of thought and some pump hardware. This would advance the unit another step and place it abreast of certain other machines used in experiments at the frontier of espresso extraction research in the labs of Synesso, La Marzocco, Slayer, and a small number of independent workers around the world. The machine is poised to be a very solid experimental testbed, if so desired.

Comparitively few of the GS-1 Single Group machines were produced by La Marzocco. I should mention that I also have available a Paddle Group neck w/o the brass valve components - just the chrome plated neck. With effort, one could find the necessary valve components and convert this machine into a manual Paddle Group unit. It's potentially a convertible!!

LOTS OF PHOTOS HERE: http://flickr.com/gp/29800684@N07/4h9S3z

This is a trouble-free machine for the hardware aficionato who would appreciate a rare and handsome example from the golden years of La Marzocco innovation and accomplishment, but who would also appreciate state of the art control of water and the very real potential for doing interesting experiments in espresso extraction technology.

$4500 I invite discussion.