Tines and Tone Bars

“Asymmetrical tuning fork” is how Harold Rhodes described the assembly that provides the vibrations detected by the pickups in a Rhodes. One leg of the tuning fork is the tone bar and the other is the “tone generator”. The tone generator consists of the tine itself and the metal block into which the tine is permanently mounted. The tone generator is connected to the tone bar by a screw to form the complete fork.

Once all of the tone bars had been removed from the rail, they were separated from their respective tines. This was most easily accomplished by mounting the tine block in a vise before attempting to loosen the hex head screw. The connection between the tine block and the tone bar is critical to the proper resonance of the entire assembly and these screws are typically torqued quite tightly.

One of the tone bars on this piano was a real curiosity. In all but the highest registers, the tone bars have a 90 degree twist so that they can vibrate without risking interfering with their neighbors. On one bar, this twist was in a different location than on all of the others. Additionally, its stamped number duplicated that of its lower neighbor – I had two #22 bars and no #23. My first guess was that at some point, #23 had been lost or damaged and the repair person only had access to another #22 and, in an attempt to make the #22 vibrate at a slightly higher frequency, it was straightened then re-bent at a different location. That theory was challenged by the fact that there was no evidence of a previous bend. Every bend that was made left tool marks behind and there were none where a previous bend would have been. Also, the metal would have shown signs of stress from being twisted, untwisted and re-twisted. I’m left to conclude that the bar was incorrectly twisted at the factory, found to be suitable for a different pitch and put to use in that capacity.

The tone bars for this piano were sent to the plater as-is, without any preliminary cleaning. The tone generator blocks were almost completely covered in oxidation which came off easily using the wire wheel. The tines themselves are not plated and many showed evidence of corrosion even after being cleaned. There are no numbers stamped on the tone generators so to make it easier to reassemble everything later, they were each labeled before being put in a box for storage.

Each tone bar and tine is mounted to the plywood tone bar rail by two long screws. Each screw also passes through a spring which suspends the bar just under a half inch from the rail. Rubber grommets regulate the screws’ clamping power leaving the bars the freedom to vibrate and even wiggle around a little. As I noted in an earlier post, at some point someone modified the highest ten tone bars by removing all springs and replacing them with single rubber blocks installed under only the rear screws. I believe this is to promote a more tonally dynamic response by allowing the very rigid small bars to move around more than they otherwise would. Although the blocks appear to be designed specifically for this purpose, I’ve never read or seen any indication that this was a factory-authorized modification. When I reassembled, I replaced the blocks with standard spring supports.

  •  Update 12/1/11

A couple of the experts at the Electric Piano Forum informed me that the rubber “stand-offs” were actually factory parts.

Different grades of springs were used across the scale of the Rhodes pianos. The lower registers received the stiffest springs in order to manage the increased mass of the larger tone bars. In the middle, a softer spring was used. For the upper third of the piano, the rear spring remains the same as the middle but the front spring is even softer. I’m not certain this pattern holds for every Rhodes, but it has for the three I’ve had apart so far.

There are also three (sometimes four) sizes of tuning springs that follow a similar pattern up the scale. To help keep all of these similar springs organized, they were typically color-coded by the application of some sort of very utilitarian paint or dye. I don’t like the sloppy appearance of the dye and even though it represents a divergence from my otherwise fairly rigid ethos of maintaining the original appearance, I scrubbed all of the color off along with the crud before reinstalling the springs. To clean the tiny tuning springs, I first threaded them onto a length of some fence wire then just pulled the wire back and forth across the wheel. Without the color-coding, it can be difficult to differentiate between some of the tone bar springs but they could always be accurately distinguished by squeezing them together to compare their relative strength.

It was very satisfying to finally be able to reassemble the harp. The piano suddenly went from a pile of parts to a fully-functional Rhodes. Not much progress has been made since as I’ve been having too much fun playing it.

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