Technical Tips

Technical Tips

When did you last ‘play’ a test-roll on your pianola? Some of us use the test-roll on a regular basis, perhaps to check that the speed of the air-motor is correct, or to ensure that each note of the action is playing and repeating correctly. To those who never use one, fearing perhaps that it would reveal a costly repair bill, take courage!

Obtain one, perhaps by borrowing from a fellow enthusiast if you can’t find one for sale, and start by trying the section that tests each note in turn, starting at the lowest. Now, a word of explanation about the lowest note: the test-roll and your pianola may not agree on this point, so we need to settle the matter. On many modern re-cut rolls, e.g. QRS, the lowest note on the roll may be “Number 5”, which is the first C# on your piano – the fifth note from the left. This is mainly because a lot of pianolas from the heyday of their production (mid 1920’s) didn’t use the bottom four and top four notes of the piano – the Duo-Art reproducing action had appropriated these eight note-positions on their rolls and used them for dynamic coding. So, if you own an Aeolian Company Ltd instrument made from the mid 20’s onwards, these notes will not play other than by hand. If you have an original test-roll, it will probably start at note 1 of the keyboard, and the older your instrument is, then the greater the chances are that it will play from note 1 on that roll.

The test-roll will incorporate a method of checking that your rolls play at the speed indicated on them, usually this is marked on the note-testing section of the roll. There will a starting point marked, and if the roll is played at Tempo 70 then the finishing point will be reached in one minute, the distance covered between these two points being seven feet of paper. Occasionally, test-rolls are found which indicate a Tempo of 80, in which case the distance between start and finish is eight feet per minute. If the finishing point of the Tempo test is found to arrive either very early or very late during this test, then the regulator that governs the Roll Motor needs adjustment. On an Aeolian Company instrument (Aeolian, Steck, Weber, some Steinways, and a few others), the motor regulator on an upright is found under the keybed on the right-hand side. To increase the speed of the motor, tighten the coil spring that is fitted vertically to one end of the regulator – to decrease it, slacken that spring (see Photo A). It will usually take several checks of the Tempo, and adjustments of the spring, to get the right results.

Once you are satisfied that the Tempo is as accurate as you can get it to be, then you can check the performance of each note using the test-roll. The performance and repetition depends on several things:

Condition of the piano action. If the piano action is in need of regulation and overhaul, the pianola action cannot be expected to repeat notes quickly, and in some cases notes may not play at all. Also the pianola action must be adjusted so that it interacts with the piano action correctly.

Tracker-bar and tubing. If the Tracker-bar has not been pumped out for some time, then dust and paper fibres build up in the system. Initially, this gathers at the bleed-hole inside the Stack (the upper part of the action, just in front of the piano action), whose function is to allow the valve for that particular note to reset itself quickly in time to play the note again after a short rest. If a note on the

test-roll plays once but doesn’t repeat as the roll requires it to, then very often the problem can be cured by using a tracker-bar pump to clear the tube and bleed. Tracker-bar pumps can be unfriendly to use, and many people put them to one side and quickly forget them. A vacuum cleaner with a crevice tool attached is the alternative, and this is undoubtedly easier if your hands are not as strong as they once were.

Condition of tubes from Tracker-bar to Stack. If the small tubes leading from the Tracker-bar to the stack valves are original, then a silent or sluggish note can sometimes result from old tubes sagging, closing up slightly, or kinking. Usually, the only cure for this problem is to re-tube the stack, although replacement of one or two offending tubes is possible, provided that they are accessible and neighbouring ones are not disturbed in the process.

Stack valves, pouches and pneumatics. A sluggish or poorly-repeating note can be caused by a problem with its valve, but this is uncommon and the trouble can usually be found in the signal tube (see above), or the pouch (see below). One notable exception to this is if the note plays weakly, and a hissing sound can be heard when its hole in the roll is open and the note operated – the hissing stops when the hole is closed again. This is either due to a piece of dirt or foreign matter caught on the outer (or atmosphere) face of the valve, or more unusually by the valve not being moved sufficiently by its pouch. The first of these can sometimes be rectified, certainly in the case of Aeolian Co Ltd actions, by removing the cover from the front of the stack and identifying the offending valve. There is a hole behind the strip of cloth in front of the valve which can be revealed by cutting a hole in the cloth (see No.1 on photo B), you can then see the side of the valve itself. Armed with a bright light and a long needle or similar, gently turn the valve round with the needle whilst looking at the gap at the top. The piece of dirt or glue will eventually come into view, and can be gently dislodged with the needle. Use a vacuum cleaner to ensure that the valve hole is clear, then cover the hole again using a piece of thin rubber-cloth glued into place, or strong adhesive tape if necessary. If a note tries to play even if there is blank paper over the tracker-bar, and if you are satisfied that the rubber tube is intact, it is likely that a small piece of dirt or glue may be caught under the lower face of the valve – proceed as above. The second likely cause – insufficient valve movement – is rather more difficult to rectify unless you are feeling adventurous. Expose the pouch by carefully cutting the cloth just below the valve hole mentioned above (see No.2 on photo B), the button on the valve stem may be too far from the pouch – though that in itself is unlikely to cause the trouble – and turning the button anti-clockwise with a needle whilst pressing gently on the top of the valve with a small screwdriver to stop the valve from turning will bring the button closer to the pouch (it must not touch it), which may be enough to make the valve work properly. If the note is reluctant to play, but will do so if you treadle with more effort, and all other possibilities have been ruled out, the pouch may be porous. This often applies to more than one note. Treatment involves dismantling the stack to seal them all, but if one note is at fault you can sometimes put off doing so by exposing the bleed which is found behind the seal cloth previously mentioned, just above the bottom edge of it (see No.3 on photo B). The bleed is a tiny hole which admits vacuum under the pouch and into the tracker-bar tube to allow the valve to return quickly after playing. If the pouch is porous, it is effectively acting as another bleed, and more atmosphere is required to overcome this and inflate the pouch to operate the valve. Try putting a small piece of adhesive tape over the bleed hole, thus making the porous pouch the only provider of vacuum to the pouch well and the tracker-bar tube. When the stack is eventually rebuilt and the pouches re-sealed, the tape can easily be removed.

The last factor which can affect the performance of certain notes is the condition of the thin rubberised cloth that covers each of the small pneumatics. These are not visible until the stack is removed from the piano, and sometimes physical examination doesn’t disclose their true condition. If the cloth is rather stiff and not pliable, it is unlikely to be very air-tight and will also prevent the pneumatic from opening and closing as quickly as necessary. Re-covering with new cloth is really the only solution.

Also, check that the roll is tracking properly. If the tracking uses holes on the tracker-bar at the edges of the paper, pumping them out often improves tracking sensitivity. If the tracking uses small triggers or “ears” either side of the roll, make sure that they have their tiny leather pads intact. These are on the moving ear, and seal the small tubes that lead to the tracking valves until the roll moves to one side and opens one of the tubes, thus operating the tracking bellows and aligning the roll again.

Michael Boyd