This is just an announcement to let you all know that the new Mk 3 breathpipes are now available for purchase for the Alpha. These are listed in the accessories section of the Alpha product page on the website, and should ship within a week or so of ordering (we make them up to order so it's not instant, but it's a swift process and we now have all the components in stock). They are now our new standard breath pipe, you can no longer buy the Mk2.
The Mk3 breathpipe is an improvement on the Mk2 that was shipped as standard with the Alpha (the Mk 1 is a different style again and only present on an earlier batch of instruments that were never sold to the public). They have a higher resistance to internal corrosion from saliva and exhibit improved dynamic response when playing.
For the interested and technically minded, the breath system uses a 'tube inside a tube' design. The pressure inside your mouth cavity is sampled at the tip of the mouthpiece via those little holes you see on each side. The bypass breath (which you need for a good 'feel' and ability to express) travels through the center hole of the mouthpiece. The tube that goes from the mouthpiece to the instrument is made of aluminium and has an inner tube made of Tygon that carries the bypass breath. The gap between the outer aluminium tube and the inner Tygon tube carries the static pressure that was sampled inside your mouth, and it is this static pressure that is used for expression. This seems like a weird way to do things, but if you don't do it that way then you are bedeviled by problems of turbulent air flow and the consequent noise (as a literal pinkish whooshing noise) that this introduces. In slower breath systems, with a low bandwidth, one just electronically filters this out, but the Eigenharp breath sensor is too fast for this, so we have to be a bit smarter.
We found that early versions of the Mk2 breath pipe experienced corrosion issues in the aluminium caused by the unexpected ingress of saliva into the gap between the Tygon and the tube. If this corrosion built up it could cause this gap to close up, making the BP less sensitive and finally to stop working. The corrosion itself did not represent a health hazard, but it was a problem in performance. Mk1 breath pipes did not suffer this problem as the tube was made of copper, but aluminium is a much, much more susceptible to corrosion, and it turns out that spit is nasty stuff. We fixed this by doing what drinks can manufacturers do, which is to coat the aluminium with a thin layer of a special epoxy. This starts out as a milky liquid. We degassed it in a vacuum chamber until it stopped outgassing, then used a syringe to pump it through the pipe. We then let the pipes drain for half an hour to get the coating thickness right and subsequently cured the coating in a temperature controlled industrial furnace for a set period of time. It's fiddly, but at the time it seemed to work well and both testing and field use it stood up well. The material was a well proven one, and the process well established through the manufacture of billions of drinks cans. We changed the material of the spigots to brass from aluminium (the weight budget for the top of the instrument could just stand this) and with that all seemed to be well.
After some time (several years) we noticed some problems. One or two people (and noticeably those playing a lot with the BP) began to experience corrosion issues. And those that played on earlier versions (Mk1 and early Mk2) also noted that in general the later pipes felt less sensitive, sometimes noticeably so. We deduced two things, firstly that due to the coating being on the inside of an extruded tube which we could not see to inspect there was a possibility of coating defects occurring that we simply couldn't find and secondly that the additional thickness of the coating, which was not originally allowed for in the design, was causing the air path for the static pressure to be less than optimal.
The solution to this, now implemented in the Mk3 pipes, was to use a new process to coat the inside of the pipes with a metal plated finish of nickel. This is quite difficult as the outside also has to be plated in a different process and the traditional electrical Nickel plating process cannot be used as the current won't get inside the pipe, but it was found to be possible. We made a couple of pipes - one went to a testing facility for destructive corrosion testing (they use a vapour of warm sulphuric acid in the industry standard test) and we lent one to Geert Bevin to play for some months. We sectioned both pipes after testing and they were in good shape with no signs of corrosion, so hopefully this will put this particular problem to bed. Because the thickness of the plating is much less than the thickness of the epoxy they also play better, with improved dynamic characteristics. They feel faster.
We have a limited number of gold pipes available (around the amount that responded when I canvassed for interest last year in fact), so if you want one of those it would probably be best to order it sooner rather than later.
Any questions, please feel free to ask me.
John
UK
