This is an upgrade for the Valve Index speakers using a larger square BMR driver from Tectonic the TEBM36S05. This results in overall better sound quality at the cost of greater weight and size. The integrated dac in the Index is capable of driving these speakers, although not quite to their full potential. I made these for a twitch streamer friend RAGESAQ. They have held up pretty well so far through 2+ weeks of daily 3-4 hour streams, so they seem reasonably durable.

This project stemmed from another project I am working on. Off-the-ear headphones using these BMR drivers inspired by the Index headset. Here is the link to that project: https://www.thingiverse.com/thing:6402165

RAGESAQ is also working with sctanf on an index strap adapter for the Big Screen Beyond along with an audio solution using these speakers and the E1DA dac. I will update this with more links to that project as they are published.

Here is a link to an adapter that sctanf made to adapt the index strap to the beyond:
https://github.com/sctanf/Bigscreen-Beyond-Valve-Index-Strap-Adapter/blob/main/Beyond%20Index%20Strap%20Adapter%20-%20v8%2C%20Right%2C%20No%20Hex%20Nut%2C%20Reverse%20Cable.stl

Note that these speakers will require running a custom EQ using Equalizer APO on your PC to get decent sound. I have included the eq file that RAGESAQ created with a calibrated mic for the Index. It will work in Equalizer APO or Peace UI for Equalizer APO.

For this upgrade I bought a pair of used replacement index speakers from Tundra Labs for $25 each, ripped them apart, and swapped out the speakers on the original index mounts making them a drop in replacement for the index speakers. This is a good way to do it if you would like to be able to go back to the original speakers at any time or if you are afraid of breaking them.

• left speaker: https://tundra-labs.com/products/valve-index?variant=41566176608465
• right speaker: https://tundra-labs.com/products/valve-index?variant=41566176706769

Parts you will need:

• 2 Tectonic TEBM36S05 BMR speakers drivers, I got mine from parts express for $10 each at the time. Here is a link: https://www.parts-express.com/Tectonic-TEBM36S05-4-1-1-2-Square-BMR-Full-Range-Speaker-4-Ohm-297-2166?quantity=3000
• 4 Small M2 bolts with nuts around 8-12mm long, this is what I used: https://www.amazon.com/gp/product/B0C3VQ5N5W/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
• Small stranded wire, 20-26 gauge or so I would guess.
• Small shrink wrap that will fit the wires.
• 2 index speakers

Tools that you will need:

• Soldering iron, flux, solder
• Good pry tool, I used the ifixit jimmy
• Allen key for the M2 bolts, the bolts that I linked came with one.
• Super glue

Assembly Instructions:

• Print and clean up the front and back speaker housing, invert in Cura for the right side.
• Solder a couple of low gauge wires onto each of the new drivers, make sure that they are plenty long and small enough to go through the hole in the center of the mount stem.
• Assemble the new speakers, I used 4 M2 x 8mm bolts to attach the speaker together. It may be necessary to press the nuts into the plastic using a hot soldering iron, they are a tight fit.
• Pry open the index speaker mounts, they do not come apart easy, they are glued, but a lot of force with a good pry tool will get them apart with very little damage. I also used a heat gun, but I am not sure that it helped much and it discolored the plastic a bit.
• Cut the original wires about half way, pull the clip and remove the original speakers.
  Insert the new speakers, you may need to whittle on the mount with an exacto knife as needed to get it to seat in place correctly. There is a bit of plastic on the index mount that locks the speakers from rotating, this needs to slot into the housing in the correct place. refer to the original speakers to see how this should work. Once the speaker housing fits into the mount correctly reinsert the metal clips to lock in place, there should be a small groove in the stem on the printed housing that the metal clip can slide into.
• Trim new speaker wires, leave enough slack for the height adjustment to work, but not too much or it will be hard to fit the wires in the tiny casing. Make sure to put some shrink wrap on the wires before soldering.
• Solder the wires together, press wires in place beside the slider mechanism and glue with a very small amount of super glue, do not use too much or you will ruin the slider.
• Make sure that the slider still works correctly. Put small drops of super glue around the edge of the speaker mount and press the top cover back in place and wrap with tape until the glue dries. The super glue may discolor the plastic a bit, I just touch it up with a bit of flat black paint.

On a side note I also tried the slightly larger and supposedly improved version of the TEBM36S05, the Tectonic TEBM36S12 and it is actually slightly worse for this use case, they are larger, heavier, and have a bit worse bass response. I also tried a couple of smaller round BMR drivers the TEBM35C02 and the TEBM35C10, but they are worse then the original index speakers.

I also included the blend file if anyone wants to make modifications

If you would like to get updates on my projects consider following my DevRandVar account on X. I just made it for random projects like this: https://twitter.com/devrandvar