source file: mills2.txt Date: Fri, 10 Jan 1997 10:25:31 -0800 Subject: building an mbira From: prent@VNET.IBM.COM > Adam at Yale wrote: > > This is a question for all of you master-craftspersons out there. I > have decided to have a fancy mbira custom-built for my music, and > before I jump into it, I would like to know if anyone here has done > this and can offer any advice regarding design specifications. I > would like to have a double-level style like those found in Zimbabwe > (do we say Rhodesia?) but probably a second tier on either side. I > don't know why they usually are only double-tiered on the left. I am > also wondering if a fine-tuning mechanism could be devised, better > than just wiggling the tongues back and forth while hoping for the > best. > > Any advice? > > -Adam > abs22@pantheon.yale.edu I have built several microtonal mbira. I call them finger piano's instead of thumb piano's, since you play them with your fingers, much like a piano. I still use one that is tuned to 31 tones to the octave, arranged as in Erv Wilson's Bosanquet layout. Another has 12 tones in just to the 13 limit on C and F. Each is amplified. One uses a contact microphone and the others use magnetic transducers much like guitar pickups. The key to tuning them is to make sure that a pronounced overtone is tuned, as well as the fundamental. I found that adding a generous dollop (technical term) of rosin core solder to the ends of the low notes helps bring the overtone two octaves above the fundamental. Otherwise it is two octaves and a major third above, and very unpredictable. File off excess solder until the overtone is in tune with the fundamental, then shorten or lengthen the tongue until the fundamental is in tune with the note desired. I use .010 spring steel 3/16" wide for the tongues. This produces a very soft sound, which requires amplification to be properly heard. But it is very easy to work with and sounds nice. Multiple ranks can be made with proper design of the tongue support structure. As many ranks as you need, top view: --------------------------------- + + brass bars secured with screws --------------------------------- \ \ \ \ \ \ \ \ spring steel tongues under the first ---\-\----\-\----\-\-----\-\----- brass bar and over the next brass bar \ \ \ \ \ \ \ \ -----\-\----\-\----\-\-----\-\--- \ \ \ \\ \ \ \\ \ \ \ \ \ \ \ ---\-\-\ \\ \-\ \\ \-\ \-\ \-\ \- \ \ \+\\ \ \+\\ \ \+\ \ \ \+\ <--- solder on the tip -----\-\----\-\----\-\-----\-\--+ \ \ \ \ \ \ \ \ ---\- -\ \\ \-\ \\ \-\ \-\ \-\ \- \ \ \+\\ \ \+\\ \ \+\ \ \ \+\ -----\-\----\-\----\-\-----\-\--+ \ \ \ \ \ \ \ \ ---\- -\ \\ \-\ \\ \-\ \-\ \-\ \- \ \ \+\\ \ \+\\ \ \+\ \ \ \+\ -----\-\----\-\----\-\-----\-\--+ \ \ \ \ \ \ \ \ \+\ \+\ \+\ \+\ Side view: +/ <--- solder tip / / / <--- .010" 3/16" spring steel / / / / +------+ /+------+ ! ! / ! ! <--- 1/4" x 3/8" brass bar (approximate) +------+/ +------+ Secure to a steel or wooden base with screws. Slip the spring steel tongue under the brass bar, and insert or pull it out to tune, after tuning the overtone to the fundamental. Prent Rodgers Boise, ID Received: from ns.ezh.nl [137.174.112.59] by vbv40.ezh.nl with SMTP-OpenVMS via TCP/IP; Fri, 10 Jan 1997 19:38 +0100 Received: by ns.ezh.nl; (5.65v3.2/1.3/10May95) id AA19572; Fri, 10 Jan 1997 19:41:46 +0100 Received: from eartha.mills.edu by ns (smtpxd); id XA19580 Received: from by eartha.mills.edu via SMTP (940816.SGI.8.6.9/930416.SGI) for id KAA15135; Fri, 10 Jan 1997 10:41:44 -0800 Date: Fri, 10 Jan 1997 10:41:44 -0800 Message-Id: <25970110184152/0005695065PK2EM@MCIMAIL.COM> Errors-To: madole@mills.edu Reply-To: tuning@eartha.mills.edu Originator: tuning@eartha.mills.edu Sender: tuning@eartha.mills.edu