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Back Checks

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2016-04-02 – This is a modification I no longer perform. Although the back checks do work as advertised, the improvement in playability is minimal and they require such precise adjustment that I’m afraid they’ll turn into a liability over time.

The action on a Rhodes piano is a dramatically simplified version of the same mechanism that converts a key press into a hammer strike on a traditional acoustic piano. Although Rhodes was able to remove all but a few essential pieces of the more complex action while still maintaining an acceptable feel, one part many wish they hadn’t omitted is the hammer’s back check. Without a back check, hammers tend to bounce after hitting a tine and returning to the key pedestal. When a hammer bounces, it causes two problems. Since the hammer is tied directly to the damper, a bounce pulls the damper away from the tine momentarily allowing the note to ring a bit longer than it’s supposed to. Additionally, while it’s bouncing, the hammer is not properly positioned for a subsequent key stroke and a great deal of efficiency is lost. This can make playing fast passages a hit-or-miss proposition.

Manufacturing your own simple back check system would not be too difficult but for those not interested in spending time reinventing them, Vintage Vibe offers their own solution for sale. The kit consists of a set of metal tabs, pre-cut self-adhesive felt strips and a set of the same type of screws that are used to mount the piano’s pickups. The idea is that the tabs are screwed to the tops of the keys so that the attached felt strips provide a landing pad for the hammers. In their instructional video, they indicate that the tabs are pre-bent to fit an early model piano with “hybrid” half-wood and half-plastic hammers but that for other models, the bend angles will need to be adjusted. For both of the late-model pianos in which I’ve installed these, I’ve had to significantly change the shape of the tabs so that they can reach the hammers.

To start off an installation job, single back checks are installed on the highest and lowest keys. These two are then used as references for a pencil line to mark the locations of the remaining pieces. Unfortunately, for the very first back check, I slightly missed the mark and it would not reach its hammer. Since moving the screw such a small amount was not an option, I used a file to enlarge the hole in the metal tab allowing me to scoot the tab forward enough to fix the problem.

After the reference line is drawn, the rest is a matter of bending, affixing felt and installing 71 more times. Although the back checks can be installed without removing the keys from the piano, I opted to perform the task in good light on my bench. In their video, Vintage Vibe shows the mounting screw being driven with no pilot hole while the narrator declares that the soft wood will accept the screw with no prior introduction. When installing these on my wooden-keyed Fifty Four, I found this not to be the case and quickly resorted to drilling pilot holes to avoid splitting any more wood. I drilled pilot holes in all of the plastic keys of this Seventy Three.

As they’re being attached to the keys, each back check must be fine tuned to provide the correct degree of support for the hammer. The allowable tolerance is almost impractically tight as the felt must prevent the hammer from bouncing while also allowing it to fall freely to its proper resting spot. Finding the perfect angle to accomplish this can be a bit frustrating but is do-able. This adjustment is much easier to perform individually as each back check is installed rather than after they’re all in and access is blocked by neighboring keys on both sides.

After installing the last back check, I was left with a handful of extra metal tabs and even fewer screws and felts. The extra tabs are important because the process of developing and practicing the perfect bend pattern incurs some casualties.

Cabinet Preparation

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At first glance, the case for this 1973 piano didn’t appear to be in very bad shape. Some of the latches had been replaced and a few extras were added. A couple of the hinge screws had been replaced with nuts and bolts. I expected this to add up to a few extra holes that would need to be drilled and plugged like with the last case. When the old Tolex was removed, the truth of the matter was revealed… and it wasn’t pretty.

The reason new latches were installed in non-standard locations was because the wood under the original latches was in no shape to support any hardware. On one side, the wood had come completely apart and was only being held in place by the Tolex. The wood under the hinge screws was still in place but was also split and would no longer hold wood screws. A couple of other corners were also missing significant amounts of wood and the front edge of the lower half had a perfectly shaped semicircle missing where a knot had come loose and disappeared.

The case on this older piano was quite different than that of the 1981 I had previously worked on. An obvious difference is in the angled sides. On older models, the angle changes towards the front of the case so that the front edge is horizontal. The rear edge doesn’t get the same treatment and it mirrors the angle of the sides. At some point in a later year, this feature was removed from the case design and the same angle continues around the entire case. I was interested to see the obvious evidence of the saw blade that was used to cut the angled sides. Rather than concern themselves with making a squared cut, the builders just overran the saw then cleaned up the kerf with some filler.

Another difference was immediately apparent when the Tolex was first peeled back. Whereas the case for the 1981 Mk II was made entirely from 3/4″ plywood, the face of the top on this piano was made from something like Masonite. And although it should have been apparent by the splitting at the hinges and latches, I didn’t realize until I sanded down to bare wood that the sides of the case were solid pine. The only plywood in the entire case was the face of the lower half which needs to be sturdy enough to support the the piano perched atop its four legs.

Unfortunately, the plywood was not in great shape. The first clue to its condition was the gap where the the edge met the side board. The plywood seemed to be made up of only three quarter-inch thick plies and two of them had by this time parted ways. I was able to tap the wood, listening for the hollow thud to map out the extent of the delamination. I next drilled holes through the single loose ply, stopping short of the underlying layers to provide access to the cavity in between. I added a little rubber washer to a needle-less syringe so that I could force glue into the holes. After pumping in a generous amount of glue, I drilled the rest of the way through the wood and clamped the plies together with bolts and fender washers.

The gap in the front edge where the knot used to be was to be filled with Bondo but given the shape of the void and the smooth face of the underlying wood, I was concerned about the filler’s ability to stay put. To give the Bondo something to hold onto, I first drilled little pilot holes in the wood then installed finish nails that had been cut down below the surface of the case. I think the finished product will last for a while.

How to deal with the split wood under the hardware mounting points was a bit of a problem. Even if I could just glue the wood back together, I feel the design was flawed from the start since a great deal of stress is placed on the wood at a point where it’s quite weak. Replacing the sides with new plywood would have been a good option but I really prefer to keep as much of the original piano intact as possible. I decided to replace just the problem areas with patches made from plywood. The plywood would provide good anchors for the hardware screws but the rest would remain vintage wood.

First, a notch large enough to eliminate all of the split wood was cut out of the edge of the case. Then, a plywood patch about an 1/8″ larger in both dimensions was made. A groove was cut in three edges of the patch using the table saw and a tongue was created in the case by routing in an 1/8″ on both sides. After a little adjusting for fit, the whole thing was slathered in wood glue and clamped overnight. A little Bondo cleaned up my sloppy cabinetry and made for a seamless finish.

Just about every corner was coming loose but between more glue and some long clamps, they were all locked back together. Bondo put the finishing touches on the corners and this case is now ready for its Tolex.

Tines and Tone Bars

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“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.

Plating

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I spent too long debating how best to deal with the harp frame and tone bars. These internal steel parts were originally zinc plated and most have not held up well to the passage of time. Zinc protects the steel by being a ‘sacrificial metal’. Instead of preventing corrosion, the zinc simply corrodes preferentially to the underlying steel. When the zinc corrodes, a white powdery substance is left behind in its place. Although even this powdery oxidation still provides some protection, once the zinc has been converted, the steel is largely left to the mercy of the elements and soon begins to rust and pit.

My debate over these parts centered on whether or not I was going to outsource their restoration. There are a few sources for home electroplating kits and I gave very serious consideration to the product offered by Caswell Inc. which promised everything I’d need to go from bare metal to a professional-quality finish. This appealed to me for a couple of reasons. Ideally, I’d like to perform as much of the pianos’ restoration work as possible myself. Also, the plating kit would likely pay for itself after just a few pianos by saving the cost of using a third party for this service.

Ultimately, I was scared off from the home plating option by the apparent complexity and scope of the job. Even as a kit designed for amateur use, this is no simple operation. It involves multiple stages each requiring its own combination of potentially dangerous chemicals, tricky operating procedures and some degree of luck. The steep learning curve aside, a plating setup – especially one that could accommodate the large harp frames – would occupy a significant amount of real estate in my small shop.

Among the plating businesses I looked at, it seemed standard to divide plating jobs into two general groups: drum and rack. Smaller parts (up to maybe twelve inches long) can be plated using a drum that rotates like a rock polisher. The parts tumble around inside until eventually all surfaces are consistently finished. Larger pieces must be hung from a rack and dipped individually in the plating bath. For my parts, I needed to find a plater that could provide both drum and rack services.

Prior to sending the parts away, they needed to be cleaned and polished. Zinc plating is extremely thin and does nothing to compensate for imperfections in the surface of the base metal. I tried using a blast cabinet to prepare the parts but even using a fine blasting medium, the result was a satin finish that was too far from the original look. Instead, the bulk of the cleaning was done with wire wheels, both on the bench grinder and chucked into a hand drill. After achieving an acceptable finish with a wheel, a final polishing was done with some 400 grit polishing papers.

In the old days, after applying zinc plating, parts would often go through a ‘chromate conversion‘ process that added a protective layer to the zinc. This is what gave the Rhodes parts their iridescent yellow coloring. Although you can still have zinc chromate plating done, it’s more recently been heavily regulated due to reasons discussed in the movie Erin Brokovich. Replacements for the chromate process have been developed but they offer little or none of the protection provided by the old, more toxic process. Although the plater I used offered the old stuff, I chose to go with his replacement option. The resulting color looks pretty good but, at least on the tone bars, could not stand up to even the slightest abrasion.

Parallel Wiring

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As mentioned in my last post, my latest Seventy Three is the first Seventy Three I’ve ever played, the others being unplayable since I’ve received them. It’s also the first time I’ve gotten to hear a Mark I in person and boy does it sound good. My trusty Fifty Four sounds downright sterile next to it. The Seventy Three is thick, chimey and a little temperamental in that you’ve got to apply more finesse to properly manage the available range of timbres.

I’m determined to figure out what gives the older piano its superior tone. The construction of the 1976 model is very similar to that of the Fifty Four. The keys are wooden, the hammers are all plastic, the harp frame is aluminum, the tone bars are of the same design and I’m fairly certain the tines are the same Torrington-made items. The most obvious difference is in the way the pickups are wired.

Probably because people were unhappy with the low signal strength of the traditional Rhodes pickup wiring scheme, the Fifty Fours were wired so that all of their 54 pickups are in series with each other. With 54 roughly 185 ohm pickups wired in series, the output at the jack measures somewhere in the neighborhood of 10K ohms – closer to the level of most other electric instruments that may be sharing the stage. One of the tradeoffs of increasing the signal in this way is a loss of some of the fidelity of each pickup. The high frequencies are lost and the sound becomes kind of muddy and homogenous.

I don’t mind turning the volume knob up on my amplifier to compensate for a weaker output. I’d rather be able to hear the full character of the pickups and to that end, I decided to rewire the Fifty Four to match the layout of the Seventy Threes. There may have been other wiring schemes used, but all three Seventy Threes I’ve got were wired the same way: groups of three pickups (one group of four because 73 isn’t evenly divisible by three) in parallel joined in series to each other. This results in an output of about 1.3K ohms.

Access to the pickup lugs is mostly obstructed by the tone bars suspended above them. To make the rewiring process easier, I first removed the tone bar rail from the harp frame. To convert the series wiring to parallel groups, jumpers were added between trios of neighboring pickups. This involved stripping a bunch of 22 gauge hookup wire, cutting it into short pieces and soldering each length to the lugs.

After adding the jumpers, the total output came to 1.25K ohms. Doing the math (185 / 3 * 18), it should have only been around 1K. A while ago I rewound six dead pickups with the incorrect gauge wire and they’re significantly hotter than the originals providing a boost to the total circuit’s reading.

Comparing a recording made before the modification to one made after, I’m pretty sure I hear a difference. It’s still nowhere near the sound of that Seventy Three though so this will bear further investigation.

One advantage of the rewiring is that the signal no longer overloads the input of the Tine Bomb preamp I installed. When it was cranking out 10K ohms, it was impossible to get a clean sound from the preamp. Now, it seems to be operating more within its comfort zone.

1976 Seventy Three Mk I

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The third Seventy Three I’ve owned has turned out to be the first one I’ve ever played. The eBay listings of all three pianos have been sort of “sight unseen”, or “sound unheard” as it were. None of the sellers have known the histories and all were unable to say whether the pianos were playable. So it was a pleasant surprise to find that the most recent purchase was of a fully-functional Mark 1. While there’s still plenty of room for improvement, I’m at least now able to play a tune through without having to avoid dead notes or hear the popping of tines colliding with their pickups.

Like the last one, this piano includes all components except the leg brace knob and the vinyl leg bag.  Damage to the case is minimal including a few minor tears in the Tolex and a mangled corner brace. Some of the case hardware has made it through the years with its plating intact while other pieces show some amount of rust. On the inside, the name plate has been scratched up but the harp cover is remarkably unscathed. All tines and tone bars are present and accounted for. A few tines have got a minimal amount of rust growing on them and the bars and harp frame will need their zinc plating refreshed.

The interior bears several pieces of evidence that this Rhodes has been serviced at some point in its life. In addition to several sets of initials scrawled on the keys, someone wrote out a key reference on the underside of the harp. Maybe someday I’ll realize the benefit of adding those marks to the harp but for now, it seems like defacement. The plywood appears to be unfinished underneath so I’m hopeful I can sand down through the marks but they were clearly made with a wet ink that may have penetrated too far.

Up to 1978 Rhodes manufactured pianos with their original, unimproved action. Until they started contouring the key pedestals, playing a Rhodes was like wading through deep snow. Fortunately there’s a relatively simple remedy in the form of what is commonly called the Miracle Mod. This involves adding a small bump to the pedestal thereby dramatically changing its interaction with the hammer. The effect is a quicker, more responsive action with a feel that is closer to that of a regular acoustic piano.

Other than being sluggish, the action on this piano is in decent shape. It includes a full set of what are likely replacement hammer tips. Some obstruction has found its way under the lowest G flat key and holds it a bit higher than all the rest. The contact between key pedestals and the undersides of hammers is buffered by strips of felt. On most pianos, the felt was applied to the key pedestal but for some period of time, the hammer got this treatment instead. This 1976 model fell into that category. I’m not sure, but I think the felt may need to be switched to the pedestals to facilitate the Miracle Mod improvement.

Pickup check YouTube video.

Stretch Tuning

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I’m waiting for parts before I can proceed with the Seventy Three so I thought I’d use the time to try retuning my Fifty Four. According to the Service Manual, Rhodes pianos are tuned to equal temperament at the factory – each note is tuned to its theoretically correct frequency. I’m not certain why that is as I don’t think there’s much question that stretch tuning is more appropriate. I’ve never fully understood the theory behind stretch tuning so I’ll leave it to Wikipedia to provide the back story.

I’ve heard more than once that Rhodes pianos are notorious for going out of tune. Even though mine spent more than a few years being moved around on a regular basis, I guess it’s led a relatively sheltered life. In all the years I’ve owned it, I don’t think I’ve ever adjusted the tuning and according to my tuner, the tines haven’t moved very far off their targets.

Generally, the pitch of a particular note is determined by the size of the tone bar and length of the tine. By themselves though, the tone bar and tine are engineered to produce a pitch somewhere only in the neighborhood of the desired value, give or take a half step. To get the rest of the way, little springs are wrapped around the tines. The pitch can be fine-tuned by sliding the springs along the length of the tine. Making this adjustment can be tricky business though and I went through a few different ideas trying to find the easiest approach.

Perhaps the most interesting attempt involved a Dremel engraver. I chucked a modified screwdriver into the tool thinking maybe the reciprocating vibrations it produced might help move the springs in a controlled manner. It actually worked to a degree but was a pain to use and not really worth the effort.

Vintage Vibe sells a standard tack puller as a tuning tool. The angle on the end allows you to reach around the tone bar and the notch cut in the end helps to catch the spring. I found it hard to control the adjustments I was making, particularly on the higher notes where smaller and smaller movements are required to make the same pitch adjustments. For a while, I tried using a small hammer to tap the tool’s handle as it pushed against the spring but it was still too difficult to give it just the right nudge.

There is an alternative to using the keys to sound the notes while adjusting the tuning. The harp assembly is mounted on two arms that, after a few screws are removed, allow it to swing up clear of the hammers and dampers. Even though the hammers can’t reach, the tines remain positioned in front of their pickups and the harp can remain plugged into the amplifier. From here, the tines can be plucked and the springs can be moved by hand. I quickly found that very small adjustments could be made by twisting the springs around the tines while applying just a little pressure in the proper direction. This suddenly made it much easier to get even the treble end locked onto the exact pitches.

Traditionalists tune pianos by ear. They strike a tuning fork and match a note, then finish the keyboard by listening for the ‘beats’ made when two nearly identical wavelengths collide. This involves skills I don’t currently possess and for this job, I availed myself of the Peterson StroboFlip tuner. A strobe tuner is a significant upgrade from regular quartz tuners. Compared to the erratic wanderings of the quartz devices, the stability of the strobe’s display makes it a pleasure to work with. The Peterson also allows a much finer control and wider range of pitch offsets making it easier to use for stretch tuning. I recorded a video of the Peterson at work showing how accurate it allows you to be.

To find the proper offset values to use, I referred to the chart provided by the Rhodes Service Manual. A4 (the A above Middle C) is used as a starting reference and is tuned to the standard 440 Hz. As progress is made away from A4, notes are tuned increasingly further away from their mathematically-correct frequencies. Higher notes are adjusted sharp and lower notes are flattened.

The result of this tuning process should be an instrument that sounds more in tune than one set to an equal temperament tuning. I don’t hear it. I played another take of Recorda-Me after retuning. Comparing this to the same tune recorded before, I can’t tell the difference. On a Seventy Three’s wider scale, the “stretching” would be even more pronounced so maybe I’ll have a greater appreciation when I get one of those tuned up.

Pickups

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With their delicate, hair-thin copper wire, Rhodes pickups are particularly vulnerable to the dampness that only caused cosmetic damage to the rest of the piano’s components. After a pickup was wound at the factory, it was generally wrapped in plastic tape to protect the wire. Earlier pianos that I’ve seen were wrapped with clear tape while in later years, opaque white tape was used. The consensus seems to be that the pickups wrapped in white tape are more prone to broken internal connections rendering them completely dead. My guess is, it has nothing to do with the tape itself but probably the grade or type of wire used to wrap them. Even for a white-tape unit, this piano had more than its share of deads.

As pickups were removed, they were each tested. The good ones measured consistently in the low 190s which is right about where they should be. Others didn’t report any continuity at all and by the time I had removed the first twenty pickups, I knew by the size of the reject pile, I was going to have my work cut out for me. By the end, I had 46 working pickups and 27 out of commission.

I’ve wound Rhodes pickups before. My Fifty Four also features white-tape pickups and so far, six have expired on me. When I did those, I judged the amount of wire to use by measuring an original pickup’s diameter and comparing the new one. I have no idea how close I came to the correct number of wraps because it turns out that the 42 AWG wire I used was much thinner than the original and I ended up with a pickup that read over five times hotter than it should have. This time I was able to get some proper 38 gauge wire but I still wanted a better way to calculate the wrap count.

While looking for counting mechanisms on-line I saw some mention of using a computer mouse. The center scroll wheel on most mice uses an optical sensor to determine when the wheel has been moved. This can easily be re-purposed to count revolutions of a pickup winding spindle.

To replace the mouse wheel’s little pinwheel that serves to alert the optical sensor to movement, I went with a CD-ROM. I cut a small notch in the edge and mounted the disc to a hanger bolt with some washers and nuts. Next, a mounting block was made to hold the pickup as close to the center of the rotational axis as possible. The mounting block was screwed onto the wood-threaded end of the hanger bolt and the machine-threaded end was chucked into a hand drill which was clamped into a vise. The mouse sensor was just stuck to a two-by-four and the height of the drill was adjusted until the CD-ROM passed between its eyes. Now, for every rotation of the pickup, the sensor would see one brief glimpse of its sending unit and send a single movement signal to a computer.

To use the output of the mouse sensor, I wrote a small Visual Basic program. In addition to showing the number of rotations, a target can be specified and it will also show a count-down and a progress percentage (hmm.. maybe I’ll add a progress bar). An audible alarm would be very helpful so that I don’t have to take my eye off the pickup. I started to add a beep that increased in frequency as the target approached but ran into a little issue and set that aside.

The counter works amazingly well. I first tested it a few times by making around fifty to seventy wraps with string then manually auditing the count. When I started wrapping pickups, it took a few tries to arrive at a good number but it seems like 3,100 puts me in the best range. The first was a little low, the next a little high and the third was just right.

Before winding each pickup, the previous wraps were removed with a box knife. This actually turned out to be the most tedious part of the job. It was difficult to avoid damaging the plastic bobbin with the knife.

I don’t do much de-soldering and don’t have the proper tools for it. Besides that, I like to keep the number of times I heat up the lugs to a minimum as the plastic they’re mounted in tends to soften easily. So, instead of melting off the old solder, I used a small nipper to trim the lugs. This was important as any little snags can easily catch the wire as it’s being wrapped.

Even though pickup wire appears to be uninsulated, it actually is covered in any one of several types of coatings though I think generally either polyurethane or enamel is used. I believe I’ve heard that Rhodes pickups were wrapped with enamel-coated wire but I think my wire is poly. Either way, the insulation was first scraped off the end of the wire before it was wrapped around the lug to ensure good conductivity. The beginning of the wire is wrapped around the first lug – the one closest to the pickup’s mounting tab. Wrapping it clockwise around the lug helps the wire find the groove in the bobbin allowing it to reach the hub without obstructing the subsequent wraps. To wrap the wire around the bobbin in the correct direction, the drill was run in reverse.

I wanted to be able to control the speed of the winder and using the drill’s trigger for this control was not a practical option. Since I also wanted to be able to start and stop it remotely, a dimmer switch was in order. I basically wired a dimmer switch into a short length of extension cord. This provided a pretty good range of speed control.

Note: this is not the proper method for controlling the speed of an electric motor. A common dimmer switch will eventually cause the drill motor to self-destruct.

I found that to get the correct number of wraps onto the bobbin, I had to make them pretty tight by pinching the wire between my fingers as it ran off the spool. The spool was mounted a few feet away, oriented so that the wire fell off the end rather than unreeling by spinning the spool. With this heavier wire it probably would have worked either way but lighter gauges may not be strong enough to handle the load of trying to turn the spool.

Using this setup, I’m able to wind a pickup from start to finish in about ten minutes. Again, the most time-consuming part is probably removing the old wire. Otherwise, it’s a pretty easy and fun job.

There are a couple of videos on YouTube. One of the counter being tested and another clip of an actual winding job.

The counter program can be downloaded here. It’s just an executable and doesn’t use any special libraries so it shouldn’t need an installer. Just download and run.

The source code for this program (much of which was copped from somewhere on the web) can be downloaded here. It’s written in Visual Basic 6.

Hammers and Dampers

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I don’t think this piano was ever played much. The hammers showed only a little wear and all of the felt seemed to be in decent condition. I suppose it could have been serviced prior to being stored in whatever damp basement was its home for years but I think a disinterested owner is more likely. I’m going to stick with the existing felt everywhere except the bottom of the name rail but I replaced the hammer tips to give the piano the greatest chance of sounding and looking brand new when finished.

With the action completely disassembled from the piano, it was the most convenient time to work on the hammers. The first step was to remove the old tips. This was done by peeling the tips sideways until they broke free of the hammer end. The neoprene hammer tips on a Rhodes are grouped into five sets, each set is formulated to a different hardness. The softest material is used on the bass notes with the tips getting progressively harder as you move up the scale. The last and hardest set of tips have a wooden core to make them particularly hard. While the softer tips tended to leave remnants of rubber as they were pried off, by the time I reached the highest notes, the hard rubber was snapping off quite cleanly.

Even though the treble tips were breaking off cleanly, they still left an uneven surface of residual glue behind so every hammer was carefully cleaned using a small sanding drum on a Dremel tool. I first wore the coarse sanding drum down on some cast iron to take some of the bite out of it but it still required a steady hand to keep from cutting and burning the plastic hammer surface. As each hammer was cleaned, I snapped it back into the hammer comb already mounted to the action rail.

Since I was waiting on delivery of the new tips, I proceeded with the dampers first. The damper strips had some of the most tenacious corrosion I had yet found. I ended up resorting to the same Dremel sanding drum to remove most of the staining. The thin metal damper arms act as their own springs and as such are subject to metal fatigue over time and I’m worried that my aggressive cleaning tactics may have prematurely aged them. They’re relatively easy to replace so I’ll wait until the piano’s playable before deciding if they’ve still got enough spring in their step.

The dampers are connected individually to the hammers by way of a bridle strap so that as a hammer rises to strike the tine, its damper is simultaneously pulled out of the way. Old bridle straps can stretch out making it difficult to maintain the proper relationships between hammer, damper and tine. At first I wasn’t sure how to determine the condition of my bridle straps until I learned that the hammer comes equipped with a built-in length gauge. A small protrusion that I had previously thought was a remnant of the mold used to form the hammer turned out to be a hook placed there to aid the installation of the bridle straps. The distance from the hook to the strap’s anchor point marks the appropriate length for a correctly trimmed bridle. Since all of my existing bridle straps fit perfectly to that hook, I determined that they did not need to be replaced.

With the dampers all installed, I could finally reinstall the damper rail. Through the years, damper rail hinges have been designed in different ways. On this model, one of the rail’s hinge pins protrudes further out the side than the other. The excess length is occupied by a spare tone bar spring so that the opposite pin can be inserted while the spring is being compressed. The whole arrangement is locked into place by what appears to be an extra wide tone bar clip.

When I first installed the damper rail, I was concerned that it was only making partial contact with the lowest note’s damper spring. Since there was plenty of rail at the treble end, I decided to try to shift it a bit by the addition of a washer. The small shift was enough that it prevented the locking clip from being inserted so, rather than make any more modifications, I put it back the way it was.

By this time, the new hammer tips had arrived. These are installed by just gluing them in place with a small amount of medium viscosity super glue. When I replaced the tips on my Fifty Four, a couple of the high ones fell off after a little bit of playing. The hard rubber on the wood-core tips is very smooth and slippery so this time I first scuffed them with a small file before gluing them down.

With the action rail ready to go, I was able to reinstall everything and the project started to once again look like a real piano.

Tine Bomb Preamp

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I’ve always been pretty happy with the tone of my Fifty Four. With the right voicing and through the right amp, it produced a sound that could hold its own amid other electrified instruments. That said, I’ve considered it to be lacking the range of harmonic content that could be heard from a full Suitcase model. Only on the very hardest of strikes are you ever rewarded with a hint of the crunch that gives other models so much character. Vintage Vibe’s new Tine Bomb Preamp is designed to help make up for the shortcomings of the Stage’s passive electronics by fattening up the sound both in breadth and strength.

The Tine Bomb arrives with everything needed to retrofit a standard Stage Seventy Three with no soldering and nothing more than a screwdriver and a drill with a 1/8″ bit for tools. The supplied RCA patch cable, tone and volume pots and 1/4″ jack are drop-in replacements for the existing electronics. The new volume pot is also the power switch for the preamp. Unfortunately the new components are not matches for a Fifty Four which features fader-style tone and volume controls.

The preamp is powered by a 24 volt DC wall-wart transformer. A barrel-style power jack comes mounted in a replacement cheek block. I debated for a while whether to use the supplied cheek block or remount the jack in the original block. At my day job, I’m frequently reminded of the value of original components once an instrument moves from being old to being collectible and I believe Rhodes pianos are already beginning to make that transition. The new cheek block was exactly the same dimensions as those from both the Fifty Four and my 80’s Seventy Three although the plastic-keyed Seventy Three fastens its cheek blocks with a tab rather than a screw in front. The replacement block was not as dimensionally consistent though and the sides cupped inward a little bit. Once installed, this probably wouldn’t be noticeable. Although not for that reason, in the end I decided to re-use my original block.

Since I was going to have to do some rewiring anyway, I decided to add a few more options to the setup at the same time. The main feature I was interested in was the ability to bypass the preamp but I also wanted to be able to select through which tone control the sound would pass. The Tine Bomb is pre-wired using a choke rather than a capacitor for the tone circuit. I’m not familiar with the effect produced by a choke and I was concerned it may not work as intended when bypassing the preamp. To put all of this together required the assistance of two double-pole, double-throw mini toggle switches (actually, the tone selector only needed to be single-pole) and a little shielded four-conductor wire. The project also gave me my first chance to try out my new soldering rig.

I first drew up some fairly crude wiring diagrams to both figure out the workings of the old controls and also plan the integration of the preamp. The switches and power jack were wired and installed first. The power leads connecting the cheek block jack with the preamp include a connector plug allowing the two to be easily separated. This allows the nameboard to be removed from the block without having to cut any wires. Unfortunately, I didn’t consider this convenience when drawing up my plans and will have to come back later and upgrade the installation.

Update: I feel I should note that the wiring diagram in the picture linked in the post is not complete or correct. I didn’t expect it to actually be legible in the photo. It doesn’t include the tone control switch and it’s missing a ground connection on the volume control.

I also didn’t plan for the block of wood used to mount the cheek block to the key frame. The wood obstructs most of the space inside the hollow cheek block and makes wire routing tricky. Luckily just enough room remained to accommodate the electronics and with a little finagling, I was able to keep the wires from being crushed on their way out the back.

The preamp itself mounts to the nameboard by a single screw through its heat sink into an 1/8″ hole in the base of the rail. If the hole in the rail is drilled at the proper location, the edge of the preamp’s circuit board butts against the rail keeping things from pivoting on the single screw. I didn’t really pay attention to the instructions when I chose a location for the hole in the rail. Although I positioned it as close to the output jack as I could, it still only barely avoids being hit by the harp frame. Had I read the instructions, I may have realized I was supposed to orient the preamp vertically rather than horizontally. It seems fine as it is but I may change it when I add disconnects to the new wiring.

Though my karma account probably took a huge hit for it, I was happy to find everything working properly when I finally plugged it in. The new sound was definitely fuller but it was mostly LOUD. My little Kustom KLA-10 practice amp was not able to handle the signal cleanly unless it was reigned in significantly at the piano’s controls. My Fender Stage 160 seemed much more tolerant of the hot signal and produced a clean but ear-bleedingly loud sound even at the lowest volume settings.

The difference between using the capacitor and the choke for tone control is significant. The choke is supplied as a “bass cut” to help bring the sound out of the mud if necessary. I found it useful as a way to tame the signal without having to drop the volume so much.

I’m not a tone connoisseur and don’t have much to say about the new harmonic content provided by the preamp. Even if I had a more discerning ear, a fair assessment would not be possible running through a Kustom KLA-10.  Although it still does not sound like an all-wood early seventies Suitcase model, I am able to get a noticeable amount of expression from the keys that was either difficult or impossible with the passive electronics.

I recorded a short video to demonstrate the preamp’s effect. The sound was recorded using the camera’s built-in microphone so the video does less to demonstrate the tonal qualities as it does the differences in output levels. The video focuses on the controls of the piano. On the cheek block, the first switch controls both the DC power and also whether to send the signal through the preamp (Up) or around it (Down). The middle switch selects between the original capacitor (Down) and the choke (Up) for tone control.

  • Update 9/5/11

I added a couple of .wav files to try to demonstrate the tonal effects of the preamp. I attempted to play the same piece of Recorda-Me, once with no preamp and again with the Tine Bomb turned on.

  • Update 10/1/11

In a discussion on the Electric Piano Forum, Chris Carroll of Vintage Vibe advises that when ordering a Tine Bomb, you can specify that it will be installed in a Fifty Four and they will make the necessary adjustments so that it can handle the increased signal strength.