Telex: Teletype expanders


To perform the update, you need to remove the old Teensy from the back of the TXo and replace it by a “structure” (see photo) consisting of a Teensy 3.6 and a small PCB with just two or three SMD components soldered on it. If you DIY you also need to flash the Teensy firmware of course :slight_smile:

I think you can buy the teensy 3.6 and its “power board” from BPCMusic (soon) - already soldered and ready to be mounted on your TXO - or you can get the PCB from OShPark and the Teensy from anywhere you want and DIY.

I don’t know if some capacitors need to be changed on the main boards (C2 C3 C4, maybe ? 180p instead of 110 according to the BOM. I don’t know if it’s important, I built the 3.6 versions directly with 180p)


In case it helps, I’ve found a reference at Mouser but it’s quite expensive, the brand is called Samtec, they make machined pin headers male/male and female/male 07


Hi there - I’m late coming to the TELEX range, so not fully clear on all the options. I would really like to add a TELEXi to my TT, and keep my connection to Ansible. Looking at the gear that means I’d need a TXb right? many thanks :grinning:


Not necessarily. My Teletype supports three connections (Ansible, Just Friends and a Slashes board for W//) across my small case with just a ribbon cable with multiple headers. TXb could be useful for other things as well, ofc


ok yes many thanks for that!¬ :yum:


I also have a very newbie question to ask, is it possible to use a Txi as well as an ansible in the same scene? I essentially want to use my ansible as 4 additional outputs while using the parameter knobs on the Txi to control aspects of those outputs.


Yes, this is possible. Teletype can communicate with several modules at once over I2C; the commands that aren’t relevant to a given module will just be ignored


Thanks to all for answering the questions before I could get to them. Appreciated.

As for the parts on the back board that are different for the TXo+ - they really don’t matter much at all. I’m doing all new TXo with these values (raising the lame single-pole filter cutoff to match with the TXo+ sampling rate). As described in previous posts, you will need additional filtration regardless if you want to get a pure-ish sine out of the oscillator mode. Once you go into other waveforms, the aliasing is pretty much baked into the sound (though I do use PolyBlep to reduce it on the saw and square waves).

There will be some TXo+ upgrade kits - though I’m not sure how many yet. Need to do my final counts. I should have some populated TXHelper boards left that aren’t paired with a Teensy 3.6. Not sure how many or what I’m going to do with them as I’m about as sick of soldering Teensy headers as anyone could be at this moment and just can’t go there yet. :wink:

Just for clarity, I should point out that the TXo and TXo+ have exactly the same functionality. You only should want/need/desire/covet/lust-for/dream-about an upgrade if you are frequently using your TXo as an oscillator. A TXo+ allows for a) a slightly higher sampling rate, b) less aliasing on the basic primitive waveforms (sine, triangle, saw, and square), c) less aliasing when combining features with oscillation (like pitch slew or envelopes), and d) a gaggle of additional waveforms for the oscillators. The unit will still need additional external filtration in order to be the best oscillator that it can be (4-pole instead of 1-pole).


Is there any chance you will also have iiBackpacks as well as i2c cables available with your upcoming restock of modules? If not i’ll have to start figuring out a DiY solution in preparation for the release.


Depends on how many i2c cables are left after boxing the final units. I’ll put those up for sale.

Not doing the backpack again - though I may have a few reserve stock laying around that I’ll drop in. I’ve built the TXb for that purpose. It is a small 2HP module that provides a powered bus header on the back and two stereo jacks on the front for bridging rows or connecting to the 16n via its i2c jack.

Details are here:

Looking at that makes me realize that I need to do new product shots; the metal panels look pretty fantastic.


@Minimum if you have no need of the external I2C connections then the TXb could live inside your case. Little less elegant than a backpack but same exact function. You’d want to stick it down somehow to avoid it flopping around and shorting something.


yeah I was never planning on using the external connections at least as of right now so I would honestly prefer the backpack if possible to make it a little bit more elegant. @bpcmusic if its possible I would gladly take a remaining backpack if you have one as I am planning on ordering a couple modules from you when they are available.


Oooh … I missed that the Txb also had the powered headers on the back. Nice.


@Minimum - I’ll look to put the few i have left in the store when it opens up. :slight_smile:

@apeirophobe - yup; it is a busboard replacement if you power it. You can also leave it unpowered and just use it as a passive bridge. This will be handy with all of the stuff @scanner_darkly has been doing in terms of the trilogy module extension capabilities. It is also good if you use two TXb to bridge rows - only one should be powered (and the stereo cable should be as short as humanly possible).

@desolationjones - absolutely. Although, I would be very careful of things shorting to a case or other modules. Too much accidental voltage down an i2c line can fry processors. That’s why I was never a fan of the bus strip (especially since I have a metal case). A little electrical tape or other isolating mechanism would go a long way if an installation scenario forced someone to put a busboard unmounted in a case. :slight_smile:


I’d like certainty before I go exploring…If I already have the Monome TT-Busboard but I “think” I need the TXB to power the 16N, how does the i2c connection of the TXb talk with let’s say my ER-301 if I’m already connected via i2c to my Teletype/Ansible/TXo/JF setup?


Poll the 16N from the Teletype and pass those polled values to the 301?



L 1 16: SC.CV I FB I

You can also bypass the TT and use the master mode firmware for the 16n, though it doesn’t play as nicely in a “dual leader” configuration - the master mode 16n on the same bus as the TT (in my tests a while back the TT sometimes would sometimes freeze, but @scanner_darkly may have made some changes that abated that in later firmware updates).


I’m tweaking out can I just give you all my money now
The suspense is killing me


to clarify, the i2c change i tried haven’t been applied to teletype yet, just polyearthsea. it’s hard to say at this point if it actually fixes the issue (it’s a super simple change to basically avoid freezing if something goes wrong with i2c), so i wouldn’t consider it a proper fix for a multi leader set up, such as having teletype and faderbank in leader mode both sharing the same i2c bus.

having said that, in my tests i was able to use polyearthsea (with the change) and teletype (without the change) both controlling just friends / telexo at the same time seemingly without issues. didn’t have a chance to try it with 16n yet.

i’d just try it and see if it works - i don’t think there is any danger to the hardware (but i’m not a hardware expert so don’t take my word for it!).


Another option if you like…

I’ve made a mini-me version of the i2c backpack - meant to be used with “flying” cables, placed or floating inside of your rack. TT-BusBoard-Jr. :slight_smile:

The first one is en route to @scanner_darkly for testing, but there’s not really much that could go wrong here. I still need to sort out a case or back-cover for it to avoid potential case shorts.

If you (or anyone) is interested in one of these, please PM me and we can figure out details.