![\"\"](\"https:\/\/i0.wp.com\/www.pianola.ca\/wp-content\/uploads\/2018\/11\/2016-04-02-18.31.13.jpg?ssl=1\")
<\/a>As you can see in the photo, there is some other stuff going on in the box as well. The Theme valve is packed in here too, at least on this piano (there was a certain amount of design variation, even by the same maker, from year to year). The Theme valve is an extra expression valve which is triggered by rolls which are coded a certain way, known by the name \u201cThemodist\u201d, or other variations. In a Theme piano the stack and pump are divided in half (bass and treble), and when the valve is triggered on one or both sides of the pump, the corresponding side of the stack gets more suction and therefore plays louder. It does this by bypassing the \u201cregulated\u201d suction and connecting the stack to the full power of the pump. That\u2019s about it!<\/p>\n Well, that\u2019s the simplified explanation; HOW the valve operates is something a bit more complicated. Take a look at the following annotated image which is my interpretation (which I believe is probably correct) of how the valve works:<\/p>\n In evaluating the current condition of these boxes, the facings and pouches of the large valves seem* okay, probably due to the minimal exposure to atmosphere over the years. The small theme activation valve is a wildcard, I won\u2019t really know until it\u2019s up and running if the thing works. So, in this case I am making a calculated decision to push forward with the box \u201cas is\u201d, with the understanding that the Theme valve may not work as it should. I do reserve the option to return at a later time to rebuild it, all I would lose in that case would be a couple of gaskets.<\/p>\n Depending on who you ask, the Theme function is either a cheap gimmick or an expressive feature to make a roll more musical. It adds a little bit but is still a far cry from the level of expressiveness in a reproducing piano, which has a much more nuanced method of expression.<\/p>\n *to be tested!<\/p>\n<\/body>","protected":false},"excerpt":{"rendered":" There are a couple of peripherals remaining; this time I will discuss the valve boxes which contain an integrated stack \u201ccutout\u201d (or \u201ccutoff\u201d) and \u201cTheme\u201d activation design. The cutouts are actually a twin set of valve boxes (at least in my piano they are)\u00a0 which get mounted on the main trunk of the pump. As … Continue reading Peripherals III: Cutout + Theme expression valves<\/span>
\nThe Theme coding in a roll corresponds to special \u201csnakebite\u201d holes located near each end of a tracker bar in a piano with this system.<\/p>\n<\/a><\/a>
\nThe rub is that I would have to completely dismantle the valve box to rebuild that one small valve\u2026.which in addition to being rather tedious risks damaging the box itself.<\/p>\n