Hi Ken,

As evidenced by the one valve block with four poppet valves, the system appears to be a Recordo type expression system. Each valve controls a level of vacuum which in turn controls the volume of the music. The 'boxes', to which the tubes from the valve box are connected, are regulating bellows. They work by restricting the flow of air and thereby reduce the vacuum level.

The system in your piano is unlike any I have seen, and I don't have any references that will be of value. What may be of value is the book 'Player Piano Servicing & Rebuilding'. It has a section about the basic principles of the Recordo, which would be helpful in understanding how it functions.

Somewhat surprisingly, there is one piece in the system that was obviously made by Aeolian. The 'pointer' that's connected to the Tempo Indicator is found in all the player pianos with an Aeolian stack. Aeolian made a variety of expression and reproducing player systems, although I've never seen one quite like yours. Another 'earmark' that says Aeolian are the two rectangular holes on the trackerbar. They are called "Theme" holes. When using a music roll with Theme perforations, the volume of the music will change automatically in the Treble and Bass respectively.

I also noticed in HPIM0588 that there are manual controls for volume (or intensity). I'd like to see a good picture of the Controls in front of the keys.

What's curious is that Recordo didn't use Theme perforations. So this is a bit of a mystery. Fortunately, it looks like all of the tubing is connected. What I would do is draw a detailed diagram of where every tube in the unit starts and ends. Then, by disconnecting and connecting the tubes one at a time while the unit is in operation, you will be able to tell what function each tube controls. It's a painstaking but very worthwhile process. Perhaps of greatest importance is knowing which tubes connect to which holes in the trackerbar. There is a great reference that lists all known trackerbar scales, and once I know what each hole in the trackerbar controls, I can cross-reference that information to the scale design and determine exactly which system is in the unit.

Hope this helps. I would very much like to get as much information about this system as possible. I have already started a new file and plan to create a new webpage about the system to archive the data.

Musically,