LinnStrument Darker Mod

[FranklyFlawless]

Credits

This thread showcases a LinnStrument DIY hardware modification, and is heavily inspired by the LinnStrument Dark Mod by Lars Daniel. Special thanks to Roger Linn for assisting me throughout this project from beginning to end.

Introduction

The LinnStrument (128)'s current silicone inner playing surface has a few features designed to assist LinnStrumentalists when learning and playing on it:

• The inner playing surface uses an indented grid to inform the player when near and passing a note’s outer boundary.
• The Braille-sized bumps across the inner playing surface indicate the “C” note within the 4ths Strings Layout when no other transpositions are applied.

However, these features also have certain drawbacks:

• The indented grid can produce inconsistent, jittery movement of finger slides across the surface, depending on the amount of fingers used, pressure being individually applied from them, direction(s) they are moving, and speed of travel. The grid’s intersections exacerbate this phenomenon.
• The Braille-sized bumps lose their meaning when using other layouts, so in these use cases they either need to be repurposed or ignored.

Having a flat silicone playing surface with the current matted polyurethane coating would be an ideal solution, but as Roger stated in the Speedbumpy Surface thread, from General Silicones it costs:

• Approximately $11,000 USD for a LinnStrument (200) mold with a minimum 240 piece order.
• Approximately $6,500 USD for a LinnStrument 128 mold with a minimum 180 piece order.

With assistance from Roger over the last few months, and learning from Lars’ own experimental hardware modifications, a more cost-efficient DIY alternate playing surface has been realized. After my own experimentations with various silicone playing surface revisions from Roger, as well as various materials from McMaster, CS Hyde, and Contrado from Sensel’s Material Whirl article, I have decided on bamboo fabric as the basis for the playing surface, alongside other hardware modifications to supersede Lars’ LinnStrument Dark Mod.

Requirements

• LinnStrument (128) with a steel top panel and silicone playing surface
• Screwdriver with a Phillips #1 (and optionally Phillips #2) driver bit
• Cutting board (wooden is preferred)
• Precision knife
• Bamboo fabric from Contrado (see below for measurements)
  • 18.4cm by 57cm for the LinnStrument (200)
  • 18.4cm by 40cm for the LinnStrument 128
• Set of 50 pan head screws from McMaster

Instructions

1. Outer Silicone Playing Surface
   1. Remove the countersunk top panel screws on the LinnStrument (128) using a screwdriver with a Phillips #1 driver bit, then place the silicone playing surface below the steel top panel on a cutting board.
      • If necessary, you can temporarily insert the top panel screws through the top panel and silicone playing surface to align the next task.
   2. Using the inner border of the top panel as a guide, use a precision knife along it and cut out the inner silicone playing surface below to the cutting board.
   3. Separate all of the components while carefully extracting the outer silicone playing surface for the next task.
2. Bamboo Fabric and Pan Head Screws
   1. Place the bamboo fabric on top of the touch sensors, then the outer silicone playing surface above it, and finally the steel top panel with the reverse side above that.
      • If necessary, you can temporarily remove the LinnStrument (128)'s wooden sides using a screwdriver with a Phillips #2 driver bit for the wooden side screws to make the next tasks easier.
   2. Align the bamboo fabric and the above layers along the edges of the LinnStrument (128), then, using the pan head screws, one at a time, slowly and carefully puncture through the bamboo fabric with them while keeping the fabric stretched. Use a screwdriver with a Phillips #1 driver bit to thread each pan head screw through each layer.
   3. Repeat this process until the entire bamboo fabric is tensioned across the entire surface, and no ripples occur from sliding your fingers in any direction using any amount of pressure across it.
   4. After this process, if there is excess fabric past the edges of the LinnStrument (128), you can cut them off using a precision knife. Then, if you removed the wooden sides, you can reattach them back to the LinnStrument (128).

Notes

Pros:

• The bamboo fabric has a very wide pressure range, and is a suitable substitute for the current silicone playing surface, with a similar coefficient of friction. Finger slides in any direction feel natural, and all row offsets are treated equally. Durability so far is excellent.
• The inner silicone playing surface can be overlayed above the bamboo fabric as a protective cover. Playing on either surface is possible by swapping between them if desired.
• The pan head screws distribute force more effectively than Lars’ recessed countersunk screws, and does not risk compromising the structural integrity of the steel top panel.

Cons:

• The bamboo fabric easily gets dirty. Wash and dry your hands with soap before usage to reduce maintenance. You can use the inner silicone playing surface cutout as an overlay/cover for the bamboo playing surface. When necessary, lift the LinnStrument vertically and lightly brush the bamboo playing surface to remove debris. Washing the bamboo fabric will cause shrinkage and make reapplying tension across it significantly more difficult.
• Slides on the X-axis are more difficult to precisely perform, but with practice, can be counteracted with the slightly raised spacers between each row which defines the upper and lower Y-axis boundary of each row’s notes.
• Due to their design, pan head screws stick up from the steel top panel, and are not flush like the countersunk screws. You can take advantage of them as general references to columns, similar to fret markings on a guitar.
• The LinnStrument (128)'s Touch Sensor Prescale value may need to be readjusted depending on how much force the touch sensors have against the upper layers.

Improvement Concepts:

• Extended bamboo fabric (2 inches more in length) tensioned under the wooden sides, to increase vertical stretching.
• Washers from McMaster in conjunction with the pan head screws to distribute more force above the top panel and keep the bamboo surface under tension more easily. This may also increase the Touch Sensor Prescale sensitivity range compared to the current hardware modifications.

[greaterthanzero]

@FranklyFlawless

Having a flat silicone playing surface with the current matted polyurethane coating would be an ideal solution, but as Roger stated in the Speedbumpy Surface thread, from General Silicones it costs:

• Approximately $11,000 USD for a LinnStrument (200) mold with a minimum 240 piece order.
• Approximately $6,500 USD for a LinnStrument 128 mold with a minimum 180 piece order.

Am I reading correctly that pre-selling 240+ units for the 200, they’d only have to cost $46 to break even?

(and $36 each for the 180 units he’d have to sell for the 128?)

I don’t know how many Linnstruments are out in the wild, but those numbers don’t sound unattainable.

Like, if he charged $110 for the 200 and $65 for the 128, he’d only have to pre-sell 100 of each, with 140 200s and 80 128s left in stock for more orders.

I think.

Math was never my strong suit.

EDIT:
Those numbers don’t include any room for profit. Add some arbitrary amount for each, to be worth their time.

[FranklyFlawless]

The price quotes from General Silicones includes a new mold for either LinnStrument models. Once you have a mold, you can reuse it for further batches of silicone playing surfaces for that specific model.

Chris over on our local Speedbump thread wants to start a campaign for crowdfunding their playing surface, but $17,500 USD is a tall order for both molds and batches. Unlike my mod, theirs is far more popular. I wish them good luck on their ambitious campaign.

"Speedbump" surface for LinnStrument to improve tactility and play by feel

I’m an enormous fan of the LinnStrument. One drawback of it is that the ability to play by feel is limited. You can feel for the gaps between the pads, but that’s usually not where you want your finger to be during play. When you jump your finger back to the correct position, you loose the tactile feedback. I think that adding a speedbump shape to the rows could allow you to feel the rows without interfering with pitch slides. So I 3D printed a mold and made my own sheet with speedbump rows. …

The silicone playing surfaces are durable and do not require frequent replacement. Only the earliest batches have leaking silicone oil or short-lasting non-stick coatings.

There are over 4,000 combined LinnStruments sold, but you can ask Roger for further details.

[thetechnobear]

Cool project … looks good too

[FranklyFlawless]

It is a small but significant step towards reaching my greatest potential on the LinnStrument. I no longer struggle with the interface working against me.

[jpsheffer]

I have a question about the darker mod. Are you able to get a more even pressure response between notes than the default overlay? I ask because one of the main things I don’t like about the LinnStrument is the drop in pressure sensitivity between notes, which makes for a very uneven pressure response while slowly sliding, or trying to hold a microtonal pitch. I was under the impression that this is mostly caused by the gaps between the notes.

[FranklyFlawless]

From a tactile, auditory, and visual perspective, I am highly convinced so, although I have not bothered to record any MIDI to truly do an A/B comparison, nor do I have any interest in going back to the gridded silicone playing surface just to verify or debunk my claims any further.

This mod was designed to supercede Lars’ modifications that focused on a flat, smooth playing surface. Other than the Dark Mod referenced above, I also wanted an effective solution against the various issues encountered in the Plastic Strip Mod thread too. Unlike me, Lars does record and test their findings with actual values. A major advantage with my Darker Mod is uninterrupted slides in any direction, so vertical and diagonal polyphonic slides have been very close to the forefront of development with my musical style.

Holding a microtonal pitch is a different issue entirely, and due to hardware limitations is difficult to achieve. Based on what Roger said during the August 2023 monthly Zoom meeting, the X-axis values between columns are interpolated via firmware to approximate it.

[jpsheffer]

Thanks for the detailed response, that makes sense.

[FranklyFlawless]

Note that my touch sensor prescale value is higher because of the tensioned bamboo fabric, because I have to keep the steel top panel screwed in more tightly than usual. This results in less dynamic range in practice, but if you apply a lesser amount of tension, the dynamic range can be increased again by reducing the touch sensor prescale value, but ripples and waves may be more easily produced across the looser bamboo fabric playing surface as a result.

The Improvement Concepts listed at the end of the initial post highlight some areas where these tradeoffs can be further mitigated, but I have been largely focusing on developing my proficiency on the LinnStrument using my Darker Mod, not spending more funds just to experiment on it once again. I may revisit it a later time once I am more satisfied with my musical progress.