April 19, 2020: PipeMare update

Well, the PipeMare project is beginning to take shape. The secondary controller and PSU passed unit testing with flying colours. It’s a relatively simple circuitry with an Arduino Nano, a couple of relays and current sensors and some simple LED feedback, so no surprises there.

The PipeMare controller drawer
Primary controller

The primary instrument controller is quite a bit more complex, but after a few problems, the Teensy 3.5 firmware started working. However, there are still a few problems.

The 8-channel combined optocoupler and MOSFET driver, used for both the instrument LED illumination and controlling the quad half-H bridge for the two swell motors, needs to have its 74HCxx logic ICs replaced with 74HCTxx to ensure lower low-level voltages. No biggie.


A much more serious problem is the initial tests of the two pipe stops (the piccolo and the flute). There’s always been the risc that the flutes (designed for 2″ w.c.) would overblow, when the organ pressure level is closer to 3″ w.c. needed for the harmonic piccolos. However, the problem seems to be the exact opposite. The flutes play quite nicely, but many of the piccolo pipes don’t quite reach the overblow state. Now, some more specific testing needs to be done, and it may very well be easily solved during the voicing of the pipes. If not, we’ll have to adjust the valve holes in the windchest, thus facing some serious hardware modifications in a windchest which is very hard to work with.

The piccolo windchest cabled

Also, it seems that we are finally facing the consequences of not building any kind of compression chambers into the piccolo windchest, like we did in the flute windchest. This may change, when we modify the valve holes, but so far it looks like we are going to live with some quite harsh tone attacks in the piccolo pipes.


Besides those troubles, we still haven’t made any real tests of the accordion, except for the very early hardware tests. And we also need to build the cabinet swell panels.

But, the show must go on…

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