Author Topic: Pianet Specs for DIY Instrument  (Read 804 times)

Offline mitchamtuell

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Pianet Specs for DIY Instrument
« on: February 15, 2018, 10:01:24 AM »
Hey!

I'm a young engineer and musician and I'm always working on various DIY projects, largely music related. The most recent project to pique my interest is building an electromechanical piano. My running plan is to convert this MIDI keyboard I have into an instrument that functions like a Pianet, while preserving MIDI functionality. I'm choosing the Pianet design because I think building a hammer and damper mechanism like a Wurli or Rhodes will be very difficult, but I think I can make simple modifications to the existing keyboard to reasonably achieve the more simplistic Pianet design. Plus, I think Pianets sound cool. I've also got a few ideas for how to incorporate a sustain pedal...

I'm working through the different design elements in my plan and there are two things I don't have a plan for: reeds/tines and pickups

I have access to a water jet cutter, so making the reeds should be pretty straightforward, but I don't know their dimensions or material. Does anyone have information on the specs of the original Pianet reeds? What about Wurlitzer? Vintage Vibe has some great information about Wurli reeds, including a chart of their length and width and some thickness measurements. If I can't find info about Pianet reeds I may just make them to the Wurli size and still use the Pianet sticky hammer mechanism. I've heard Wurli tines are made of "Sandvik" spring steel. Can anyone confirm, or specify which alloy?

The other question is pickups. I've seen pictured of Pianets with what appear to be electromagnetic pickups with individual coils like a Rhodes, but I've also read that some models used electrostatic pickups. I'm not super keen on winding 61 pickups myself, so I'm interested in the electrostatic design if possible. I know it relies on variable capacitance between the reed and another plate, and has something to do with a 9V-400V step-up circuit, but I'm not sure I understand exactly what the layout is on the original or understand the technology well enough to design my own. Can anyone enlighten me?

Thanks in advance. I'd also like to be clear that I don't expect or intend my instrument to sound, look, or feel exactly like any particular vintage instrument. I'm building something new, but want to make my life easier by learning about existing functional designs.

VV Wurli Reed Info
https://www.vintagevibe.com/blogs/news/wurlitzer-electric-piano-reeds-case-study

VV Wurli Reed Chart
https://cdn.shopify.com/s/files/1/0666/2821/files/Wurlitzer_Reed_Cutting_Chart_by_Vintage_Vibe.pdf?10466772116713343912

Offline valentenet

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Re: Pianet Specs for DIY Instrument
« Reply #1 on: April 28, 2019, 06:03:16 PM »
Hello Mitch. I hope it´s not too late to try to help you.

I also have many DIY projects and I can try to exchange some of my experiences.

They are very superficial suggestions, more conceptual to you start your project. You should use these informations and after try some modifications and empirical tests for improovements.
The pianet it´s a nice option to start what you are looking for. I recommend in special the Pianet T to use as a reference. This pianet have a very simple design, mechanical parts and also the electronic circuit.

REEDS:
For you project I recommend you use Accordion Steel Reeds. They are vey easy to find and are very cheap. They are thinner than wurlitzer reeds that is better to get the sound using pads. To get the notes start testing differents sizes and putting some load with a soldering iron and tin, and removing the excess with a file, exactly as they do to wurlitzer reeds.

STICKY PADS:
You can make your pads using a soft silicon rubber, the same used to make silicon molds. Look for "DIY pianet sticky pads" on the web.

PICKUPS:
The pickups are very simple to do. You need to make a bobbin using plastic caps, a "iron" pin for the pole piece (the same as used for the metal structure in buldings constructions, something around 3 or 4 millimiter of diameter), a piece of magnet (neodymium disc) , some bond glue and copper wire (the same for guitars, something between AWG 36 to 39).
Make the bobbin set - glue the caps in to the iron pin.
Use a electric screwdriver or a drilling machine to roll the cooper wire in the bobbin. I believe that something around 1500-2000 turns may be ok. If you cannot count the rolls, you can try checking the final resistance using a multimeter device, somenthing around 100-200 ohms should be okay.
Fix the magnet piece behind the pickup. You can use a bond glue just to the magnet stay in place.
Use a aluminiun strip to fasten the pickup on place. You can use some stick tape. Tie it well. Bend the strip to find better harmonic positions, closing it to the reed and moving up and down, exactly as they do in Rhodes piano.

Note that the Pianets T has very low impedance pickups, doesn´t have magnets, and the circuit needs a transformer do correct the output impedance. Making pickups with magnets bring you to a more interesting results.

HARP:
You can use a steel bar to fix the reeds. Cannot be very light otherwise the reeds don´t get proper oscillation. Try to use something with the section around 1 x 1/2 inch. You can try differents metals, copper and brass are easier to work and make the screws. Aluminiun too but probally you will need a thicker bar.
To fix the reeds on the bar, make the holes on the bar and use a thread forming tool, preparing it to receive the bolts. As the reeds holes are too small, I recommend you use a thin bolt, some around 2.8 to 3mm, or a M3 screw and thread forming tool. Use a ALLEN SOCKET CAP or a HEX machine STEEL bolt, need to be a nice and hard steel.
You will need a spacer sleeve, as the Pianet also have. It´s important to settle and accomodate the reed and garantee that it will sound properly. I recommend use a screw nut, with a measure little bit bigger than the bolt, example a M4 nut. Use a nylon insert lock nut upsidedown, they have a special design shape that improove the clamping torque.

I attached some pictures to illustraste the ideas for you.

I hope it help you. God luck.


https://youtu.be/-TR8yQiWPyg

https://www.youtube.com/watch?v=FfC5bjZfjC0

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