Telex: Teletype expanders


I’m starting to consider building an audio euro rack case after only having my feet planted in the ciat lonbarde world for a long time and more recently the LZX video synth

I’m thinking teletype, ER301, ornament & crime to start and eventually getting ansible with an arc and further on yet the grid

that being said these expanders seems pretty crucial to a small setup like this

I would be looking for 1 of both the TXo and TXi


I appreciate your input!

I have a ciat lonbarde cocoquantus and plumbutter
as well as a stand alone meng qi voltage memory for all the extra inputs already

I am actually already planning on a planar for the video system as well so I’m sure it will end up getting used in both places

as I think I’ll end up with a control skiff that can be used for both audio and video applications

again I can’t thank you enough for your reply as someone who already has some of these modules it is very helpful


Good news: I’m almost done with another run of the modules.

I’ve used up all of my PCBs on hand and only have a small collection of panels from the first run remaining. I’ve finished my build and QA. All that is left is to build a few more europower cables and to update and print out a new version of the manual (which is going to be shorter this time and simply reference the code-generated documentation).

Once everything is accessorized and boxed up, I’ll be opening up a Shopify store to handle the business of selling them. I’ll give a 24-48 hour notice here and on Instagram with a hard date and time for the store to open. I’ve built about half as many modules as last run, but am hopeful that this will satisfy the current demand. (BTW: the store is already built; all I have to do is enter the final quantities.)

My optimistic goal is to have the store up before Thanksgiving here in the US. Based on where I’m at, there is a high likelihood that I’ll make that deadline.

Here are some recent Instagram photos from the build.

All passing modules get the orange dot under the bottom lip of the panel; TXo from this generation get the “1K” to designate their trigger resistor values.

Here are the Teensy for the TXo, lined up and ready to go into service.

Bags and bags of jumpers, screws, and plastic washers.


Can you try to make sure that the opening time for the store is not in the middle of the night in Japan ? :slight_smile:


Which one is more immediately usefull if you had to choose between the TXo or the TXi?


I’d like both but i would prefer the TXi


Having more inputs is probably useful to have the Teletype being at the center of a patch/composition without necessarily controlling everything directly (i.e. some other CV sources are used and processed by Teletype, which then controls a number of other things).


Yes, what oscillateur said basically
As it is the teletype has more outputs than inputs and being able to assume other roles like quantising, comparing, mangling external signals free’s up a lot of eurorack space. On the other hand the 4 cv outs and 8 triggers are not few…
Just my two - more than 20 characters- cents…:slight_smile:


I originally was in the same boat, and only got the TXi – one big thing that I missed about about the TXo is that it can be used as a digital oscillator, not just CV, and I’ve been kicking myself for only getting TXi after watching videos with TXo as the only sound source.


and additional metros too! :slight_smile:


Haha if I had room for 2 of each that would be incredible, but I’m still not sure how I’ll fit a TXo into my setup (6u). But I’m sure I’ll figure something out :smiley:


I picked up two of each on the grounds that they would be only available for a short while. Probably overkill but… bird in the hand…


I envision a rack with nothing but Teletype, TXo’s, LPGs, and a mixer.

Also wavetable firmware for the TXo :slight_smile:


Firmware Update Announcement

I posted a tiny, non-critical update to the TELEX firmware last night (v.017). It is only a small performance optimization for the TXi and adds no new features. Might only be worth bothering with if you have the units unracked or accessible for some reason. Up to you. :slight_smile:

I identified a couple of things that I wanted to address while I was doing the QA on the latest batch of TELEX. When experimenting with a new QA TT script for the TXi, I realized that the resting zero frequency would read differently based on the direction and distance that you approached it from. This was a byproduct of using a lowpass filter to smooth out the analog inputs.

After experimenting with a few techniques, I developed a different method that performed a windowed average and scaled the responsiveness based on the distance travelled (using a pretty curve). This made things very snappy and accurate. I then scrapped the code and replaced it with a well-regarded Arduino library that did exactly the same thing. If you are curious, here is a nice article with JavaScript examples showing it in action: (Wish I would have Googled first.)

Here are the detailed release notes:

TELEX Firmware Release v.017

Release Date: 15 November 2017
Release URL:

TELEXo (TXo) Changelog

  • No Changes to the Firmware; just a few lines of commented-out debug code were put into the primary INO file.

TELEXi (TXi) Changelog

  • Increased read resolution to 16 bits and then shift to 13 bits (the max useable on the Teensy) on read. Probably didn’t do anything meaningful - but I found a blog post where Paul Stoffregen recommended doing this over just setting the read resolution to 13 bits (which is what I was doing before). So, I made the change cuz that guy knows his Teensy! :wink:
  • Removed the lowpass filter based input smoothing.
  • Removed the collection of a windowed read buffer.
  • Implemented the ResponsiveAnalogRead library with sleep disabled.

Things are still progressing well with the build. I’m going to reflash the firmware with these latest builds and then box them up. I also have a bunch of “iiBackback” busboards (my dumb name - sorry) to build. I’m almost done with the SMD portion and then I’ll be soldering on all of the @#$&!**@#&* headers. :wink:

I have a feeling we’re looking at a Cyber Monday store opening. Feels right…but, we’ll see. :wink:

(Teletype) IN cv read latency?

TELEX Build and Sale Update

Hi all! We’re right at the end of the second TELEX build and preparing to put the units up for sale at a new, dedicated Shopify site. Due to the fact that I have some business travel in the middle of the week, I’ve decided to push the opening of the store to Friday. This will give me some time to finish my preparation and fully test the Shopify process (I’m new to their platform). This also will ensure that I’ll be able to get things in the post right away.

I worked to pick a time where folks in a few different time zones can log in without too much trouble. Hopefully this makes most people happy. :slight_smile:

TELEX Store Opening: Friday December 1st at 2 PM PST [ 5 PM EST / 7 AM TST (Tokyo) / 10 PM GMT (London) ]


Additional Details

  • I’ve built a bunch of powered busboards that attach to the Teletype. You will need these if you want to connect more than three devices via ii/i2c. You can also order these from the Monome store if you prefer (or plan to do it later).

  • Yield was exceptional across the while run (initial and this pass), so we have a decent amount of units that will be going up for sale next week. There are a few more TXi than TXo, btw.

  • TELEX units boxed are in three groupings: Single units (TXo or TXi) and a TELEX Bundle which includes a TXo and TXi in one box. The TELEX Bundles will not be broken up as they are already packaged and ready for shipping.

  • Each unit ships with a pair of screws, a pair of washers, a europower cable, an i2c interconnect, a quick-start manual, and the TELEX section of the autogenerated command reference. Full documentation is available on the Monome site in the latest Teletype Manual (in HTML and PDF).

  • I’ve held back a small handful of TXo (6) and TXi (3) as a contingency. Once the sale is over and everyone is up and running, I’ll probably make them available on the Shopify site as well. They are functionally identical but cosmetically slightly different in that they have OSH Park purple PCBs for their back boards as opposed to white ones. (Our board shipment was slightly uneven and I also used up a few of each backboard for header assembly stencils.) You won’t be able to tell when they are in the rack. :slight_smile:


Great news. For budgeting purposes, what are the prices going to be?


@speakerdamage - I’m still trying to figure out the shipping insurance details (which may have to be added into the price). Base price for the units will be the same as the last run:

  • TXo: $175
  • TXi: $140
  • TELEX Bundle (1xTXo and 1xTXi): $315
  • Powered Bus Board: $20

Again - you need the powered bus board if you are planning on connecting more than three devices to your Teletype.


I am not @bpcmusic, but I have one of the powered bus boards from the initial run of TX units. I just looked at the Monome site, and it looks to be the same thing.


@bpcmusic are you going to restrict the number of units one can purchase?


Good question. Think I should? I go back and forth.


The reason why I went ahead and built all of these things was so that all of you could have one. I like the idea of more people getting in on the action. A pair consisting of one of each adds a tremendous amount of capability to the already super-capable Teletype. The more people that have this - the better, in my book. :slight_smile:


Each person’s need is different - based on the how they want to create their music. I had a blast working with a big setup of expanders and the Teletype. It allowed me to do things that were specific to some ideas that I’d had. Not for everybody - but who am I to say what anyone’s needs are? Limitations on the ordering seem needlessly arbitrary … and we certainly wouldn’t be able to block past purchasers who already have a pair.

I looked into the rules options on Shopify; with a plugin, I think I could set it up so that you could either get 1 of each module (TXo and TXi) or a TELEX bundle. Either order could add a busboard. This would be done with the combination of a total dollar limit plus limits on each item to only one of each type.

Seems doable; I’d be willing to try to figure it out if you all want me to. We have a few days for me to get this set up. Let me know your thoughts. :slight_smile: