Author Topic: Homemade electric piano (Seeking help regarding pickup wiring!)  (Read 2358 times)

Offline gotkovsky

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Homemade electric piano (Seeking help regarding pickup wiring!)
« on: December 22, 2020, 05:46:33 AM »
Hello everyone,

I’m a new member on this forum and this is my first post. I’m french, so please excuse any english mistakes, I’ll try my best.

I’m a musician with a fine-arts sculpture/design background, and I’ve been working for about a month now on a homemade reed electric piano, mostly based on the Wurli 200A, as one can find quite a lot of informations online on this great instrument. Electric pianos are quite rare and pricey in France (a Wurly in good condition costs about 2500€), but this is not really what motivated the project. I just like going back and forth between music making and woodworking and thought it would be nice to build an instrument for my own use as a musician. I’ve got plenty of time, don't really feel like making music these days as I just released an album, so, why not?

I’m lucky enough to have a workshop with the essential machines and tools to work accurately with hard wood. I also have a fair stock of exotic wood (not sure what it is, probably padok) at my disposal, which could fit the task as it is very straight grain, almost doesn’t warp with humidity changes, and is quite tough. A good friend also lend me a 3D printer which is gonna be helpful for making very small parts.

I’m creating this thread for two purposes. The first one is documenting the process for me and others to see, second is being able to ask very specific questions on parts, materials, etc., as this forum seems to be full of great people with lots of experience.

My idea is to make a sort of Wurly/Rhodes hybrid, basically a passive Wurly with electromagnetic pick-ups. I’m currently making a first prototype of a one-octave piano, from C3 to B3, and if it is interesting enough I’ll be making a 64 notes version. I spent a good two weeks of reading every article I could find on the subject, and later came-up with a first 3D model.



The action is a copy of the 200A, based on the handmade drawings of the service manual, which might sound crazy but these drawings seems to actually have the right proportions, as I already built one action and it seems to work fairly well.



My plan is to start by building one complete action and fine-tune it until it feels perfect, and then hopefully build the rest. For now I made a first action, which is of course far from perfect. The jack spring (which makes the fly return to its home position) and the damper spring (which makes the dampers return and press on the reeds) are still missing, as I still have to try out different wire sizes/lengths/numbers of loops/shapes, and also ways of fixing them to the action parts.





In order to post stuff regularly and to do things step by step, for now my focus is gonna be on the action parts, so I won't talk as much in this first post about reeds, keyboard, pick-ups, sustain pedal, etc., but I'll obviously came to these later as I work on it more specifically. That said, I already prototyped a working electromagnetic pick-up with 3D printed plastic sleeves or holders, 3D-modeled the keyboard and the enclosure system, and also tried different reed shapes and materials (I might do different than Wurlitzer reeds, as their stamped shape is near to impossible to reproduce with common tools, at least without spending one year filing hardened spring steel).

So I hope this project might interest people here, and that some of you will be able to help answering very specific questions, as many will come! I also wanted to thank everyone on the forum who came with infos, as it's been a great place for me to understand all the parts functions of electric pianos.
« Last Edit: July 02, 2021, 04:29:48 AM by gotkovsky »

Offline bourniplus

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Re: Homemade electric piano
« Reply #1 on: December 22, 2020, 08:50:15 AM »
Super! Je vais suivre avec intérêt!

Offline gotkovsky

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Re: Homemade electric piano
« Reply #2 on: December 30, 2020, 02:01:59 PM »
So a first update on the project!

I spent two days trying to build a kind of asymetric tuning fork like the Fender Rhodes, basically reeds attached to a tone bar with the same pitch, to see if it could improve the sustain of the reeds, but I had very little success. So I decided to make a first pick-up (actually not exactly the first one if I count a few early tests), and see how the sustain was with the few reeds that I've made so far, without any tone bar.

The reed that we hear in this video is I think D2, going through a Roland JC-40 amp:

https://www.youtube.com/watch?v=G4XuNBs74OU

I'm actually fairly happy with the result, the sustain is quite good and the tone is nice. My phone's mic obviously doesn't really do it justice, and I should definitely try several ways of recording the output (DI and miked-up amp), but I'll do that when I'll have a full octave ready.

This working pick-up and reed combination, plus the sort-of functioning action gave me enough confidence to start building the first prototype of this piano, which is gonna be a single-octave keyboard from C2 to B2. So I built lots of small jigs to be able to cut the action pieces and drill holes into them accurately (and most importantly consistently). I printed templates of the actions pieces and a special table-saw sled with a series of stop-blocks to help cutting the right widths:




Here are the drill guides:



And the 12 actions parts roughly cut, they still have to be drilled and their intricate shapes cut with the bandsaw, which I'll do tomorrow.









« Last Edit: December 30, 2020, 02:04:07 PM by gotkovsky »

Offline epluznante

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Re: Homemade electric piano
« Reply #3 on: January 24, 2021, 09:19:27 PM »
Wow! incredible this thing sounds amazing!
Also: I love you
I was hoping to see something like this. your example gives me hope :)     ---I always dreamed of being able to do a similar project. Where I live it is practically impossible to get an electric piano. There is no offer and to buy internationally paying the shipping costs is IMPOSSIBLE.
I have studied the plans of rhodes, wurlitzer and hohner thinking of different combinations of action + pickups + reeds. I tried building a wooden action with a poor version of pickups (and even a guitar pu) and I tried different materials for the resonant parts but didn't like the result and was losing hope at this point

because I have not found examples on the internet of a good sounding diy EP... so ... finding your project really gave me hope!

Offline gotkovsky

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Re: Homemade electric piano
« Reply #4 on: January 25, 2021, 04:27:16 AM »
Thanks epluznante for the kind words, it's nice to see that someone else is trying to build an homemade ep too! What is the material that you used for your reeds? And could you post photos of the actions that you put together? Is it a reproduction of the Wurly action or did you came-up with something new? Making action parts is probably the most challenging part of the project, as it's really small and needs to be precisely made. I found that cutting the recesses accurately (in the whippen assembly for example) in which the flanges will fit is the most difficult task, as it was probably made with custom machinery by action parts manufacturer. For now I'm cutting those recesses with the table saw and clean them with chisels and files, but I'm not 100% satisfied with the results as some parts have too much side-to-side play when assembled with the flanges. I still need to try to cut these with a router and a custom jig made for this very purpose.

Ideally these recesses should look like this (I took this image from someone of this forum who 3D-modeled an entire Wurly, hope it's ok):



That could be done with a router and a special plunge bit, but I couldn't find anything like this anywhere, so personnally I'm just cutting them flat and it works ok.

For reeds I had the best results with XC100 spring steel which I bought in 5m roll, it's basically feeler gauge material, and it sounds good even if it's cut quite roughly. Don't hesitate to ask for anything if you need to, I'll be happy to help!

So back to the project, right now I've prepared 12 actions:


I'm actually not sure to use these as I'm not completely happy about how they turned out, I'm might redo some parts again with another method involving a router to cut the whip assembly recesses.

Then I worked on the balance and front rails:


The front rail is quite easy to make, the balance rail is more difficult as there's 3 bevel cuts in the same piece. But it's doable with a table saw, a featherboard and patience.

Then cutting 12 keys:


I'm also not quite sure about my method for making the keyboard, as it turned out to be not perfect at the end, but I'm pretty close. The traditional way of making a keyboard is to glue several boards with the grain running in the width, draw the layout of the keys and mortises on this glue-up, then clamping or nailing the whole keyboard to the keybed with the front and balance rails also attached to the keybed, drill all the holes in the keys and the rails at the same time, and then cutting all keys separately. This way the locations of the pivot pins in the rails are pretty much perfect. I chose to do it differently as I don't have a good way to cut the keys accurately from such a big piece. So I chose to cut each key one by one, and then glue them together (using non-permanent glue) with 1 mm shims between them (and 2 mm between the end of the sharps where they meet the naturals):



Then I positioned the assembled keys in the keybed on top of the rails, and I punched the holes positions into the rails using a 4 mm nail, which is what i'm using as the pins by the way.

Next I removed the keyboard and the rails from the keybed and drilled 3,5 mm holes in the rails, using the divets left in the rails by the previous operation:



And finally placed the keys on the rails, and added keytops to each one of them to lock them in their best positions:



I'm of course simplifying here, I'm not talking about how to cut mortises and gluing felt in the mortises, so if anyone needs informations on that, once again, don't hesitate.

So this method for making the keyboard turned out to be pretty ok but definitely not perfect. A few keys on the right part of the keyboard don't sit completely straight (there's a 1 to 2 mm difference in parallelism from the front rail to the end of the keys for the last 4 keys). But I think I know why: when positioning the assembled keys with shims on top of the rails, I also positioned two scrap pieces as spacers on both sides of the keybed, which also acted as wedges to lock the keyboard in place. These two spacers' width where cut according to my 3d plans at 23 mm, but in reality they didn't fit perfectly on the sides and I had to force them too hard to do so, which had the effect of compressing the keys between them, as wood (and paper shims) have a bit of elasticity in this grain direction. And that probably misplaced a few of the pins locations. I also have to be more careful when punching the pins holes in the rails through the keys, using a self-centering punch tool would be also better than a nail.

Offline epluznante

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Re: Homemade electric piano
« Reply #5 on: January 25, 2021, 08:52:56 PM »
Hey great update your system looks great!

And-- as for my attempts: I tried the action of the wurli which I copied from the service manual cutting it directly on mdf. The system was not perfect and the movement wasn't smooth but I prioritized the study of the sound generation...in which I did not find a satisfactory result. I also tried the action of the hohner pianet (with the sticky pads) as it is a lot simpler than the wurli's.
As for the sound I previously made my own guitar pickups with different variations (((currently I'm working on a handmade guitar))) so I tried to make a pickup aiming for 175- 190 ohms as recommended in a video from vintage vibe. And apart from that I also tried with a pickup with an impedance closer to that of a guitar. And for the reeds I tried different pieces of metal that I had around at that moment because I couldn't find any precise info on that. I even used a piece of plastic with a metal part on one end this was used on the hohner type of action bc it was easier to move with the sticky thing. THe metal parts that I used sounded good acoustically and was kinda easy to get in tune but the sound through the pickup was very weak and not very close to what one could expect. And the plastic version surprisingly produced a more clear sound but the dynamics were totally out of control and the sound neither was EP-like.

in short I never found a working combination of reeds + pickup + preamp.

And currently your post is making me interested again and giving me ideas to try and your info on your reeds is super useful thanks again!

Offline gotkovsky

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Re: Homemade electric piano
« Reply #6 on: February 14, 2021, 12:45:27 PM »
Hello!

Today is a lazy sunday for me so it's perfect to write a little update on the project. I've kept working on the prototype, got six actions and reeds working nicely, but as it's so much work to fit every action, I thought I'd stop there on the prototype and start to work on the real thing. And oviously keep the prototype close if I need to test anything.

I modified a bit the design of the casing and gave it a bit of a Wurlitzer 110 look. I'll be using some kind of wooden profiled rails to hold some sheet metal, which will be painted with automotive paint and clear coat, as I have some experience with that. I also designed the sustain mechanism which is a little different than the 200, not sure if it will work properly but I'll see as I go!




I started by working on the keyboard, which is almost done as I'm writing. I used a method that is a bit unconventional and might seem overly complicated, but that fits the tools and skills that I have (or don't have). The traditional method for making a keyboard is to draw the layout of the entire keyboard on a single glued-up plank, and then cut all the keys free with a bowsaw/bandsaw and chiseling or scrollsawing where the front of the accidentals meet the naturals. As I wrote previously, I don't have the skills to cut so many straight lines by hand accurately, and I don't have enough rooms on my bandsaw to cut in the middle of the keyboard. But I have a good table saw and sharp chisels, so I decided to cut each key one by one on it and then fine-tune them by hand. The keyboard rails are also done with the table saw, jointed with open tenons for the right and left crosspieces, and a wide dado for the middle one.



Then I printed a 1:1 plan of the whole keyboard.



And glued (with non-permanent glue) the back of each key on it, using paper 1mm shims between the few keys that were not sitting perfectly flat, probably because these warped a bit after they've been cut, as it's winter.



Then I nailed two rails to each key to keep them in position.



The balance mortises were already cut on each key. I then positioned the keyboard assembly on the rails, clamped them together, and transfered the balancing pins holes location by drilling about 2 mm from above the key with a handheld drill. Then I removed the clamps, put shims under the balance rail to level its bevel flat with the drill press table and drilled all the balance holes.





After that was made I cut 64 pins out of 4 mm coated nails, and chamfered both their ends by putting them in the drill press and using first a coarse file and then a finer one. These nails are pretty smooth to begin with, but definetely not as much as real chrome plated piano pins, so I'll hope it'll do the job. I can always polish them later if that's an issue.



Then nailing the 64 pins in the balance rail. I hammered about 10 pins by hand, checking with a square that they were straight according to the balance rail bevel, but that took forever, so I made a simple jig to help me guide the pins.



The pins were a bit too tight on the key balance holes, so I reamed and burnished every hole by putting a spare pin in a drill and wiggling it a little in the holes as it was turning. Then I flipped the keyboard and inserted the balance rail in it. Yes lining up 64 holes at once is a true woodworker's delight.



It took quite a lot of banging with a big mallet, but I managed to do it. I was afraid I might elongate the balance holes in the keys by hammering them so hard in the pins but that actually didn't happen. So far so good.



Then I pivoted the whole keyboard on its pressed position on the rails, add shims under the front of the keys to avoid chip-out and level the keyboard, drilled through each key at the center of their mortises (which are not cut yet) and also through 2 or 3 mm of the front rails. Have a look at my very sophisticated drill press table.



Then I removed the keyboard from the rails, removed the rails holding the keys together, and finally finished drilling all the front rails holes. So that's where I'm at right now.

If you read this and consider building a keyboard, I'd strongly suggest not to use this method and instead use the traditional one, as it's way simpler than mine and surely more accurate. If I had a bandsaw with more than 40 cm of elbow room, that would not have a been a question for me, but once again I'm limited by the tools and skills that I have, and my method also works, it's just more complicated and requires more fitting once the rails holes are drilled.
« Last Edit: February 14, 2021, 12:47:36 PM by gotkovsky »

Offline sean

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Re: Homemade electric piano
« Reply #7 on: February 15, 2021, 10:00:41 PM »


Fantastique!
Merveilleux!
Putain de cool!



I like it.

Sean

Offline drpepper

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Re: Homemade electric piano
« Reply #8 on: February 16, 2021, 05:10:13 PM »
I am looking forward to see how this works out. So far it looks amazing.
I have been working on my own rhodes/wurli inspired DIY piano design but it needs some work.
Rhodes Suitcase 75
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Offline gotkovsky

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Re: Homemade electric piano
« Reply #9 on: February 21, 2021, 08:33:23 AM »
Thanks Sean and drpepper for the kind words! Drpepper, could you share a bit of your design? I'm curious!

So I'm still working on the keyboard, and I started with the naturals.

I bushed all the fronts with 1mm strips of actual bushing felt, using small amounts of regular wood glue and homemade wooden cauls to clamp the bushings. The narrow parts of the cauls are actually 4,1 mm, so that should leave a very small amount of play with the front rails pins which are 4 mm. I had to fine-tune all the front key mortises with a mortising chisel and files, so that the cauls would fit perfectly (snuggly but not too tight). I also have different bushing felts rolls in increments of 0,1 mm in case I file a little too much and there's too much play.





Then I worked on the key buttons. The Wurly 200 doesn't have key buttons, but I decided to use these as it makes things easier. I first routed 1mm grooves on both sides of several cross-grain rails. These grooves are cut so that the felt sits flush with the top and bottom surfaces of the buttons.



Rounding-off the fronts and backs of the button rails, using the belt sander.



Marking-up the positions of three 5,5mm holes for drilling the mortises on the drill press.



Drilling the mortise. Using a drill to cut the mortises is not the best, I thought about making a homemade tool for this, consisting of two chisels glued back to back to ensure the parallelism of the mortise, but ended up continuing with the drill press as I got quite good at it. Drilling the mortises instead of cutting them leads to more fitting afterwards, but I'm fine with that.



And then cutting the key button on the table saw using a crosscut sled and a stop-block.



Then I bushed all the key buttons, using the same procedure that I used for bushing the key front mortises.



I was a little nervous about gluing the key buttons without knowing if the naturals where running perfectly perpendicular to the front/balance rails and level with the keybed, so I made two reference rails with pencil marks on both the front and back of the keys.

 

These rails are nailed directly into the keybed.





Gluing the key buttons. I used wood glue and a few drops of CA glue to hold the buttons in place while the wood glue dries. I had to press on the buttons with my fingers for about 5 seconds, which is enough for the CA glue to bond, then remove the key from the rails and clamp the key button to the key with a spring clamp.



Then trimming-off the key buttons flush with the keys using a hand-plane.





So I almost finished to glue all the key buttons to the naturals, and reamed a little bit of the keys balance holes to limit friction. I'm a bit worried because this morning I noticed that I had quite some play in the keys in their up-position (not pressed), and I can't find info about what is an acceptable amount of play in the key bushings and key buttons. I guess as long as the key are not rubbing against others, it's sort of ok, but it'd be best to know what is the standard amount of acceptable play, so if anybody can shime in that would be great!

Right now I have between 0,6 and 0,7 mm of play in the naturals (which is a tiny less than 1/32 inch for american friends), measured at the back and front of the keys, in their not-pressed position. Does that seems too much? I have to say that I still didn't polished the pins, which I should have done before bushing everything, damn me%u2026 and I also don't have an acoustic piano around to compare.

So, should I rebush the keys front mortises and key buttons using 1,1 or 1,2 mm felt instead of the 1 mm I used, or is 0,7 mm of side-to-side play in the keys acceptable? Theoretically 0,7mm is too much, as I only have 1mm of clearance between each key. Here's a link to a video showing that: https://youtu.be/mEnoQPDt0o0

I also have to mention that it's winter, so the wood of the keys might shrink a bit when summer will come, and therefore tighten the mortises a bit. Should I take that into consideration? I also guess there's a bit more friction in a brand new keyboard than one that has been played for years. I'm pretty ignorant on this subject, so if any of you experienced piano tuners could enlighten me, I'd be very grateful!

Wish you all a great sunday!

Offline Cookymonster

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Re: Homemade electric piano
« Reply #10 on: March 11, 2021, 06:51:22 AM »
Eager to see your progression...Respect....
I will turn all my mountains into rhodes.

Offline gotkovsky

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Re: Homemade electric piano
« Reply #11 on: April 20, 2021, 04:44:00 AM »
Hello,

I've been caught on other projects on the last few weeks, so I didn't post my progress here lately, but I didn't stop to work on the piano. I'm currently working on the external case as I realised it made more sense to do that before the internal rails, actions and pick-ups, as I'd be sure to have a nice and precise base.

So moving on from my last post, I first made the black keys, which are shaped like organ accidentals. They were quite tricky to make as all the cuts are slightly angled, but it turned out ok. Then I've put a bit of grain filler on the tops, spraypainted three coats of primer, and finally sanded them to 500 grit.



Then painting them black with a cheap spraycan I had laying around:



I didn't clear coat them as I liked the satin finish of the black paint, I just buffed them by hand using turtle wax.

Finished black keys:



Then I spent at least a week fitting the white keys, as the margins between them were far from perfect. It basically consisted of sanding the sides or sometimes adding thin layers of the same wood. It took absolutely forever but it was worth it.

Gluing some cheap white PVC as keytops, using contact cement:



Then trimming the PVC flush with the wood. I used a combination of tools for that, mostly a router table with a flushtrim bit for the sides, then table saw and chisels for the corners.



Gluing small pieces of PVC to the fronts of the keys, trimming the overhang of the keytops, rounding off the corners and chamfering all sides using small files and fine sandpaper:



Here's the finished keyboard. I had to remake a few bushings that were too loose, and I still have to ease some of them, but that will come later.



Then I started working on the external case. I first made the frame that would hold the pieces of steel sheet, and then finished the sides:



Yesterday I cut the pieces of sheet steel with a jigsaw and careful measurements, and coated them with silver paint and automotive clear coat. I'm currently sanding and polishing the clear coat on all the pieces. There's only the top panel on this picture, but there are actually three!



So that's it for today, next step will be to glue the steel panels to the rails, and then start to work on the internal pieces!

Offline Alan Lenhoff

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Re: Homemade electric piano
« Reply #12 on: April 20, 2021, 08:02:04 AM »
What beautiful craftsmanship! Can't wait to hear it!

Alan
Co-author, "Classic Keys: Keyboard Sounds That Launched Rock Music"

Learn about the book: http://www.classickeysbook.com/
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1965 UK Vox Continental;1967 Gibson G101 organ; 1954 Hammond B2; Leslie 21H; Leslie 31H; 1974 Rhodes Mark I Stage 73; 1972 Rhodes Sparkletop Piano Bass; 1978 Hohner Clavinet D6; 1968 Hohner Pianet N II; 1966 Wurlitzer 140B; 1980 Moog Minimoog Model D; 1983 Roland JX-3P; 1977 Fender Twin Reverb; 1983 Roland JX-3P synth; Vox AC30CC2X amp.
(See the collection: https://vintagerockkeyboards.com/ )

Offline gotkovsky

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Re: Homemade electric piano
« Reply #13 on: May 18, 2021, 07:21:15 AM »
Thank you Alan, I can't wait to hear it too  :)

Here's a little update on the project. I made the feet, which are classic 70's style tapered compound-angled cut feet:



They are attached to four square steel plates, and these are attached to the bottom of the keybed in specific recesses, with 4 bolts per foot. As the piano wobbles a bit, I might add some metal cross-braces between the legs, but that will be for later.

Other than that I started to work on the most important pieces of the puzzle: the actual tone generators, aka the reeds. So far I've made about 40 of them:



I'm using some XC100 carbon steel in two thicknesses, 0,5mm for the bass section (reed 1 to 20), and 0,8mm for the rest of the reeds. I started by using the actual lengths and widths of the 200A's reeds, but by experimenting different shapes, I finally moved on to my own empirical system, and it seems to work for now. I'm cutting the reeds using an angle grinder with a cutting disc, and then use various files to get closer to the final shape. And then a soldering iron and small files for the lead at the tip of the reeds, as you know. I'd say it takes between 15 and 30 minutes to cut and tune a reed, which isn't too bad!



I also ordered some 1mm thick samples to try on the treble reeds. I'm mainly curious to hear if that could improve the sustain (as I'll have to make these longer than if they were cut from some 0,8mm thick material).

Anyway, so far they sound great in the prototype pickup that I'm using for tuning them, and the sustain is pretty good (that said it seems that this is highly influenced by the placement of the pickup).

Now I'm waiting for the 1mm steel to arrive, so in the meantime I started to work on a better version of my pickup prototype:



The 3D printer is running as I'm writing, so let's hope this version will work and will be less flimsy than the first prototype!

Offline drpepper

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Re: Homemade electric piano
« Reply #14 on: May 19, 2021, 03:05:06 AM »
It's really starting to take shape, looks amazing!

Is your plan to mount the pickups the same as a Render Rhodes?

Looking forward to hearing what this sounds like.
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Offline gotkovsky

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Re: Homemade electric piano
« Reply #15 on: May 19, 2021, 04:18:20 AM »
Thanks!

Yes, the pickups will be mounted like on a Rhodes, and probably wired the same way too. The green piece on my last posted image is actually the mounting bracket, I'm just gonna use two screws threaded into a wooden pickup bed.

Offline epluznante

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Re: Homemade electric piano
« Reply #16 on: May 20, 2021, 03:25:49 PM »
its great to see this progress ! the project is looking great  8)

Offline gotkovsky

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Re: Homemade electric piano
« Reply #17 on: June 07, 2021, 05:11:07 AM »
Reeds are done!



I tuned them on the reedbar installed in the piano using just a cheap chromatic tuner. I'll probably fine-tune them later with all the pickups mounted and connected to a better tuning app. Btw if anyone knows of a good and not too expensive app, please let me know!





I also took the time to build a quick and dirty pickup winding machine, using a small motor from an old scrollsaw which has a variable speed circuit. I also attached a cheap tachometer to it. I'm aiming for about 3400 turns which gives a resistance of 200 ohm for a single pickup. As I'm using 20 mm long cylinders magnets (south facing the reeds) and my pickups are about 40 mm long, I'm putting a piece of round steel at the end of the pickups to extend the magnet. Right now the rod is what is closest to the reed but I might invert that because there's not so much volume. 





I'm facing a quite serious problem with the reedbar/harp, just like Wurlitzer did in their first models. Basically I have about 2 to 4 reeds in the high part of the bass section that don't ring at all, as they seem to be in conflict with the resonant frequency of the reed bar, or the resonant frequency of the whole piano.

I tried various ways to mount the reed bar in the piano but nothing worked out so far. The best I've been able to do has been to shift the problem to the next or previous reeds, by clamping weights at various parts of the bar. The last two octaves of reeds are also not so great in terms of sustain.

I've been reading about the Wurly 120 reedbar sustain blocks, also read the 200A reedbar patent, but I'm still stuck at the moment. This resonant frequencies/standing waves stuff is absolutely esoteric… I guess the goal would be to mecanically decouple the reedbar from the piano, but apart from rubber washers, which I've already tried, I have no idea how to do that.

So if anyone can chime in, please don't hesitate to give ideas!

Offline drpepper

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Re: Homemade electric piano
« Reply #18 on: June 07, 2021, 04:32:58 PM »
Amazing work again.

I would hold off the final tuning until the pickups are there. As the magnetic field may change the acceleration the reeds will be subjected to - which will change the frequency.

For the natural frequency of the rail absorbing the energy of some of the reeds. My guess would look at stiffening it. Do you have space to add a plate at the rear of this? so you can make it an L-section?
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Wurlitzer 200a
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Offline gotkovsky

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Re: Homemade electric piano
« Reply #19 on: June 08, 2021, 03:16:26 AM »
You're so right about the reeds tuning, I'll definitely do that. Thanks for the suggestions!

About the reed bar, unfortunately I have no space to transform it into a L-shaped section, and don't have an anchor point at the middle of the piano, which was a rookie choice I made to simplify the keyboard design. I kinda regret it now, I guess it's an ok solution for up to about 50 keys piano, but for a 64 keys like the Wurly, all my rails are probably gonna bow down like an unsuspended bridge at some point… so yeah, early mistakes…  :)

I've been experimenting with the reed bar outside the piano and had the best results with it sort of floating on foam at both ends, or one end on a piece of foam and the other on a hard surface. I guess the foam simply dampens the vibration, it's not perfect but it's better than before. I also found this few words from the Wurlitzer 120 service manual:

"The reed bar must float freely on the two rubber washers located at each end of the bar. Be sure the two large bar mounting screws on each end are not screwed down tight against the rubber washers. There should be at least 1/64" space between the head of the screws and the rubber washers".

So it seems I'm going into the right direction.  I'm trying to avoid to remake the whole reedbar (tapping 64 holes took two days) and use the existing mounting holes, so I'll try to put rubber washers in various spots to see how it reacts.

Offline gotkovsky

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Re: Homemade electric piano
« Reply #20 on: June 27, 2021, 06:04:24 AM »
Hi everyone,

I almost solved the harp resonant frequency problem by mounting it on three rubber washers on both sides, so that it kind of floats freely. The sustain of the treble reeds is still so-so, but I think I'll have to go with that if I don't want to redesign the whole reedbar.



I used punchings from 3 mm thick sole rubber that I had. Works fairly well.

I also got a new cheap 3D printer and already made a few pickup bobbins with few design improvements. It takes about an hour to print one bobbin, so pretty long but I can do others things while the printer is running.



I started working on the action parts, starting with the most difficult piece which is the whip assembly. I made router jigs for cutting the birdseyes of each part. Making this jigs takes a while but it's definitely worth it as there's quite a lot of parts to make, and I found this method to be the most accurate and consistent. I'm using a dovetail bit in a plunge action, which is not what these bits are for but I couldn't find any router or drill bit with the right shape. Ideally I should have made a special bit for this purpose but I don't have many metal skills and tools.





I'm trying to use the table saw with stop blocks as much as possible for cutting the final shape, especially the reference surfaces. For the rest of it I just use a bandsaw with a fence.

I also made the damper jacks/flanges and glued the bushings.



So it's going quite well, and I finally feel that I'm closer to the end than the beginning! The depth adjustement of my table just broke so while waiting for the new part from the manufacturer, I'll be working on the pickups and everything else that doesn't require a table saw.

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Re: Homemade electric piano
« Reply #21 on: June 28, 2021, 03:34:39 PM »
This is looking closer and closer to being an playable instrument.
Cant wait to see how this turns out.

You ready to move to mass production yet?
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Offline gotkovsky

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Re: Homemade electric piano
« Reply #22 on: July 01, 2021, 01:52:34 PM »
Thanks man, looking forward to see yours too, it's nice to see how we took quite different approaches.

And yeah I'm definitely ready to mass produce this, final cost should be just around 25000$  8)

More seriously I'm thinking about working on another prototype in the future, it could be an interesting challenge to design and craft such a piano with a not too high end-price in mind. Maybe a 44 keys like the Wurly 106P, I'll see!

Offline gotkovsky

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Re: Homemade electric piano
« Reply #23 on: July 02, 2021, 04:28:12 AM »
Hi all,

I'm almost done making the 64 pickups, and because wiring is really not my forte, I would greatly appreciate input from Rhodes experts. Based on the Rhodes system, this is what I came up with:



Does this seems correct? Are my pickups gonna be in phase and hum-cancelling with this configuration? Please note that at this point I'm not planning to add any bass roll-off/enhancement control, and that the magnet polarity can be easily reversed if needed.

I hope someone will be able to help me, thanks in advance!

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Re: Homemade electric piano (Seeking help regarding pickup wiring!)
« Reply #24 on: July 10, 2021, 04:26:19 AM »
Hi Gotkovsky,

I'm not a Rhodes expert but your wiring looks to be the same approach I plan to take with my piano.
This is the same as Fender Rhodes wiring, though for a different number of pickups.

I know the stage piano used a 10k pot, but I would be interested to try a larger pot.
Guitar volume controls sometime use 500k pots.
There might be some potential to get a hotter signal with a larger pot.
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Offline gotkovsky

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Re: Homemade electric piano (Seeking help regarding pickup wiring!)
« Reply #25 on: July 11, 2021, 07:13:43 AM »
Hello drpepper,

Thanks for the reply, which came out just before I was about to do the full wiring, that was perfect!
Everything seems to be working fine, I didn't wire the volume pot yet, but I'll experiment with different values.

Offline sean

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Re: Homemade electric piano (Seeking help regarding pickup wiring!)
« Reply #26 on: July 14, 2021, 12:21:28 AM »

M. Gotkovsky,

Is Ida your aunt, grandmother, or not related?

The pickup rail wiring in your drawing is almost perfect.  The rail will be hum-cancelling, because every group-of-three is paired with an adjacent group-of-three with hot-to-ground* reversed.  EXCEPT for those bottom four pickups!

* Think of the hot-to-ground direction as left-to-right (as in your drawing, and as in a Rhodes) for the whole series of pickups.  The topmost/rightmost group-of-three pickups has the tips toward ground, next group has tips toward hot; next group has tips toward hot, but next group left of that has tips toward ground, etc.  In your 64-note drawing, there are ten groups-of-three with tips toward ground, and ten groups-of-three with tips toward hot.  If an incident electro-magnetic wave induces a current from tip-to-tail (front-to-back) in each and every pickup, the currents will cancel where tips-of-three meet tails-of-three.  Except for that group-of-four pickups at the very left.

The obvious solution is to split that group-of-four into a pair of groups-of-two.  Then the whole 64-pickup rail will be hum-cancelling, humbucking, less noisy.  The group-of-two should be a tiny bit louder than a group-of-three, but you will compensate by moving the pickup a hemi-demi-semi-centimeter further back.
_____

Your volume pot is shown on the right side of the keyboard.  I would rather lift my left hand off the keys to fiddle with the volume, rather than interrupt my right hand from the melody to adjust the volume.  This might have simply been a matter of convenience in the drawing, so it might not actually be your plan.

*** [edit] ... Wait a second, I just tried it, and noticed that I most often do use my right hand to reach across to the left to tweak the volume knob!  So maybe putting the controls on the far right of the piano might be nice!  ***
_____

In your drawing, the long wire that goes from the leftmost pickup to all the way to the right is the hot wire.  This long wire may act as a little antenna, bringing some induced noise into the hot terminal of the volume pot.  The Rhodes also has the hot wire coming out of the left end of the harp, but the volume pot is on that laft side.  On a Rhodes, the long squiggly black wire that runs across the back of the harp is the ground wire.  Any induced noise in this wire will touch ground (and hopefully disappear in the power supply ground in whatever amplifier stage comes next).  The squiggliness of this ground wire also makes it a tiny bit less susceptible to EMI noise.  [I am surprised that Google Translate doesn't hiccup/hoquet on the word "squiggliness" and translates it as "ondulation."]

*** If you do wind up putting the controls on the right side of the piano, you should connect the rightmost pickup wire to hot, and the leftmost wire to ground.  This way, the long wire is still a ground wire.  ***
_____

I will bet you deux balles that you will prefer the 10K potentiometor to any other value for the volume pot.  Of course, make certain that you get an audio-taper (or logarithmic taper) pot, and NOT a linear pot.  (But I think you already know that, because your drawing shows it as "A10K.")  Make sure that you do your testing with the preamp or amp that you will most often use with your new piano.

Anyway, I tested a variety of potentiometer values and built a jig to make it easy to instantaneously switch from value to value.
See my comments at https://ep-forum.com/smf/index.php?topic=9793.msg54382#msg54382

All values of volume pot will allow you to get max volume and zero volume, but what made the difference for me is that the A10K pot felt more natural when trying to make volume adjustments while playing.  Smooth turn of the knob provided a smooth change in audible volume.  With the A50K pot, the volume drops off sharply from the maximum, so it is very hard to find the "just a little bit quieter" setting.  The A50K volume pot doesn't seem useful across the full range of fully ccw to fully cw.  The A250K and A1M pots were worse.

Also listen closely for differences in the tonality of various ranges on the keyboard with the higher-value volume pots.  Upper octaves might sound very different from what you prefer.

Anyway those are my thoughts.  I hope they are helpful, and can't wait to see and year your finished piano.

Sean

P.S. - I have used "hot" to refer to the audio signal-carrying wire, as distinguished from the ground wires.   I don't know if "hot" is universally used in this sense.  Does "fir chaud" make sense in French?
« Last Edit: July 14, 2021, 08:11:59 AM by sean »

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Re: Homemade electric piano (Seeking help regarding pickup wiring!)
« Reply #27 on: July 14, 2021, 02:53:00 PM »
Hi Shaun, thank you so much for taking the time to write such a detailed post!

Quote
Is Ida your aunt, grandmother, or not related?

Yes, she's my great aunt, do you know her music? This is actually the first time ever that someone mentions her to me  :)

Quote
Think of the hot-to-ground direction as left-to-right (as in your drawing, and as in a Rhodes) for the whole series of pickups.  The topmost/rightmost group-of-three pickups has the tips toward ground, next group has tips toward hot; next group has tips toward hot, but next group left of that has tips toward ground, etc.  In your 64-note drawing, there are ten groups-of-three with tips toward ground, and ten groups-of-three with tips toward hot.  If an incident electro-magnetic wave induces a current from tip-to-tail (front-to-back) in each and every pickup, the currents will cancel where tips-of-three meet tails-of-three.  Except for that group-of-four pickups at the very left.

The obvious solution is to split that group-of-four into a pair of groups-of-two.  Then the whole 64-pickup rail will be hum-cancelling, humbucking, less noisy.  The group-of-two should be a tiny bit louder than a group-of-three, but you will compensate by moving the pickup a hemi-demi-semi-centimeter further back.

That makes perfect sense, I'll defintely try this!

Quote
Your volume pot is shown on the right side of the keyboard.  I would rather lift my left hand off the keys to fiddle with the volume, rather than interrupt my right hand from the melody to adjust the volume.  This might have simply been a matter of convenience in the drawing, so it might not actually be your plan.

My drawing was actually backwards, sorry about that! In my piano the reeds are behind the pickups when you're sitting in front of the piano. I have to admit my plan was to put the volume control on the right side, which is different from most eps, but as a right-handed synthesizer guy, I think I'll find more convenient to have it like like this, as I'm so used to use my right hand to turn knobs.

So based on your suggestions, my diagram now looks like this (I corrected the orientation):



Is that a correct interpretation of what you suggested?

Quote
I will bet you deux balles that you will prefer the 10K potentiometor to any other value for the volume pot.  Of course, make certain that you get an audio-taper (or logarithmic taper) pot, and NOT a linear pot.  (But I think you already know that, because your drawing shows it as "A10K.")  Make sure that you do your testing with the preamp or amp that you will most often use with your new piano.

Yes I'm aware of the difference between log and lin, but thanks for the reminder! And good suggestion about the amp/preamp choice. In a recording context, I think I'll mostly track this piano using the DI input I have in one of my preamps, maybe with a few effects pedals before that. So I'll make sure to do the testing with this configuration.

Quote
Also listen closely for differences in the tonality of various ranges on the keyboard with the higher-value volume pots.  Upper octaves might sound very different from what you prefer.

To be honest, the highest octave has close to zero sustain at the moment, probably because my quite crude harp design is not stiff enough and not perfectly mechanically isolated from the rest of the piano. It's quite hard to tell how it's really gonna sound like at the end, as right now the only way to test the reeds is by hitting them by hand, which is not very reliable compared to the consistent hit of a hammer from the actions. Anyway, your suggestion is again very helpful and I'll pay close attention to that when the time is right!

Quote
On a Rhodes, the long squiggly black wire that runs across the back of the harp is the ground wire.  Any induced noise in this wire will touch ground (and hopefully disappear in the power supply ground in whatever amplifier stage comes next).  The squiggliness of this ground wire also makes it a tiny bit less susceptible to EMI noise.  [I am surprised that Google Translate doesn't hiccup/hoquet on the word "squiggliness" and translates it as "ondulation."]

I think an understandable translation in french would be "en tire-bouchon" or "en queue de cochon", which means somethink like "in the shape of a corkscrew", or "in the shape of a pigtail". 8)

So based on my updated drawing, do you think I should "squiggle" the blue ground wire coming from the bass section on the left to the volume pot, to reduce potential EMI noise?

Quote
Anyway those are my thoughts.  I hope they are helpful, and can't wait to see and year your finished piano.

Thanks, your thoughts are super helpful! I don't think I've mentioned that I'm actually a beginner piano player, and that this project is a bit of a fantasy, basically trying to learn on an instrument that I built. That said, I do have a plan to invite a few friends to play with it and film it, just to show how the piano sounds when played properly  :)

Quote
P.S. - I have used "hot" to refer to the audio signal-carrying wire, as distinguished from the ground wires.   I don't know if "hot" is universally used in this sense.  Does "fir chaud" make sense in French?

Haha, I'm actually not sure, as I have very little notions of electronics in english, and even less in french. But I understand what you meant by "hot", I guess we would say "le signal" (the signal) for "hot" and "la terre" for ground.

Thanks again Shaun, I'll hope I didn't make mistakes on my new diagram and that you will have the time to check and confirm that it seems correct  :)

Kevin

Offline sean

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Re: Homemade electric piano (Seeking help regarding pickup wiring!)
« Reply #28 on: July 15, 2021, 11:59:19 PM »

Kevin,

I did not know Ida until a few days ago when the magic of a youtube search found her.  But it is cool that you are related.  I will pat myself on the back for the lucky guess.


A closer look at your second drawing has revealed a few concerns:




Here is a quick drawing showing how you should correct your drawing.




Sean


Offline gotkovsky

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Re: Homemade electric piano (Seeking help regarding pickup wiring!)
« Reply #29 on: September 01, 2021, 04:32:28 AM »
Hello all,

Sean, thank you very much again! I wired the pickups according to your diagram and everything seems to work fine. Reposting your diagram as for some reason the image link seems to be dead:



So I finished all the whip assemblies, which took ages:



All actions pieces are made except the dampers which I still have to finish, here's a few pictures of the current state of the piano. On the first picture, which shows the whippens actually regulated, we can see that nothing is really aligned, a definitive proof that this is a homemade piano.







I'm currently voicing the whole thing (basically adjusting the horizontal and vertical distances between pickups and reeds), which is far from easy, as I have to find a good compromise between consistent volume from bass to treble, without being too close so the bass reeds tuning are not too affected by the magnetic pull of the pickups.

I voiced and tuned the two middle octaves so I could hear how it sounds, and it's pretty close to a Wurly 120, but definetely muddier. EQ is not really enough so it might be that my pickups are too high, picking up mostly fundamentals and not enough overtones.

So I still have to experiment to find the sweet spot! When this is done I'll finish tuning all the reeds, then make and install the dampers, and then make the sustain pedal and sustain mechanism. Still quite a lot of work, but I can see the light at the end of the tunnel.  :)