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MMD > Archives > June 1996 > 1996.06.06 > 01Prev  Next


Introduction and Kangaroo Leather Source
By Spencer Chase

My name is Spencer Chase and I am new to the Automatic Music Group and to the internet. I have received most of the last years digests from a friend and have some idea of the areas of discussion. I would like to present some of my interests in the hope that others share some of them.

So far my experience with automatic musical instruments is limited to Duo-Art reproducing pianos. I have been collecting and working on them for about five years. My goal is to eventually coax every nuance the artists and editors put into the rolls out again. My feeling is that many of the recordings are excellent although most of the pianos today do them little justice. I currently have three pianos that vary in their condition, and degree and quality of restoration. I hope to eventually restore them to "factory" or better condition. I am also very slowly building a Duo-Art vorsetser based on a late model fan regulator and an Ampico stack. I have received varying opinions as to whether there is any chance of this producing musical results since the two systems work on somewhat different principles.

Two of my pianos are Steinways with the infamous cross valves. After polling everyone I could find who was familiar with Duo-Arts I decided to rebuild the valves of my first Steinway using the original parts. Although my piano performs better in most respects than most that I have heard, I am not happy with the results. I searched hard and long for a leather that I felt would be the best from the available choices. I found some kangaroo that I thought had the right properties but it was too thin and I did not want to take chances laminating it to something else. I used a firm and smooth Italian handbag leather that I thought was firm enough to not take an impression from the seat. I tested it in mocked up valves and it seemed fine. In the piano it is another story. The leather never seated in and I get too much top seat leakage at low playing levels to reproduce proper dynamics of varying sized chords. It is my understanding that the roll editors expected about a .25 wci drop in stack vacuum per note played at or near zero level and whatever that translated into at other levels as determined by the properties of the leather and everything else in the highly interdependent non feedback type regulator (there has to be a better term for the Duo-Art control) system of the Duo-Art system. My valves drop an average of .4 to .6 with each valve on at a 4.8 wci zero setting (I can't set it any lower without losing toughly coded notes, which is a problem in a small room.) This causes an annoying wimpiness in some soft passages. It can be improved with a couple of glasses of wine, but I refuse to allow my piano to drive me to drink. I hope to get better results with the next Steinway. I would like to get opinions on types of leather to try and results that have been obtained with round retrofit valve plates. This brings me to my next topic.

KANGAROO LEATHER LOOKS GREAT AND IT IS AVAILABLE. There seems to be a lot of discussion about Kangaroo leather lately but everyone seems to be wondering where to get it. Schaff Piano Supply has it. I have samples and the stuff looks great. They also assured me (today) that they have a current stock and steady supply. They have a pouch leather that measures .008 to .010. It is smooth dense and supple. Is nothing like the fluffy porous sheep stuff that you could easily poke you finger through. It does not have pinholes. The color is lovely too, although only the moths would know. They also have a .045 thick leather suitable for valve faces. It is strong and supple and has the smoothest (without being squishy) nap I have ever seen on leather. At 60x binocular magnification it looks like a golf course, not like a shag rug as do most other leathers. The only problem is that Schaff does not sell to the public. THEY ARE STRICTLY A WHOLESALE SUPPLIER TO THE TRADE. They do not want to be bothered by hobbyists buying retail. They do not have a retail outlet of any kind. They only way to buy from them is through a piano technician or a retail piano store owner who is willing to place an order for you if you do not qualify yourself. They also have excellent fabric covered pole hose and some very fine pneumatic cloth in a few weights. These three hard to find items may make it worthwhile to befriend a local piano technician. The LEATHER SUPPLY HOUSE 219 234-8990 also purports to have KANGAROO pouch and valve leather. They sent me a card saying so, but I have not seen samples. They will sell to anybody.

My next major area of interest is the preservation and duplication of original piano rolls. I would like to build a scanner and punch eventually but this may have to wait for my next lifetime. I have read with interest the postings regarding these topics and would like to see the discussion continue and would also like to see a collaborative effort to develop a system that can be widely used to preserve this heritage. I'm sure the efforts of the members of this group could produce an inexpensive and accurate recording system that could be used to this end. I remember reading about ideas for using readily available hardware for optical scanning. It seemed that line scanners were too narrow and that ccd frame devices were too slow to use for a single scan line unless the vertical element was suppressed which seemed like a difficult reverse engineering job. Also frame grabbing and advancing sounds like a mechanical nightmare. A thought occurred to me that I discussed with my father, who is an electronic instrumentation engineer. We worked through the numbers and it looks like real time scanning should be no problem with cheaply available ordinary stuff. The idea is to suppress the vertical element optically. Illuminating the roll with monochrome light and masking a narrow window (eg. narrow enough to detect chain bridges) would allow a cheap cylindrical lens to spread the scan line over the whole ccd frame. This would turn a row of dots into a series of vertical bars. Therefore any scan line from the ccd would be the same and the scan rate would be the line rate instead of the frame rate. This speed would allow about 4x scanning (though I doubt the paper could take it) or lots of redundant information for checking errors or bad pixels. I tried a crude experiment and even a piece of Pyrex rod seems to do the basic optical part. If there were optical distortions I guess these could be adjusted in software, but I don't think it would be necessary. Has anyone tried this or thought of it ?

If there is anyone still awake at this point, I promise to be more concise the next time. I have been trying to get onto this discussion group for some time and I couldn't control myself. I'm sure there are other things I forgot to mention or ask.


(Message sent Thu 6 Jun 1996, 08:11:47 GMT, from time zone GMT-0700.)

Key Words in Subject:  Introduction, Kangaroo, Leather, Source

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