The tides module from mutable instrument2 uses a DAC85522 16bit low glitch DAC and voltage shifter, but the dac8552 is a msop package. I don't know how much of you are skilled with hand soldering smd parts but it's not to difficult.
FWIW, if "very high precision" is really important, better to look at Yarns (same TI family, but quad). The output buffer from Tides or Peaks isn't geared towards DC precision, Yarns's is.
thanks for the hint, I will check the schematics later. I think a 1V/Oct output will be realizable, but I can not ensure a precision range of 10Vpp at the moment. I have to do some math and try it.
Here are some reports and photos of the actual build state:
PUSH BUTTON and LED work fine
Pots haven't arrived till yet.
The inv buffer is biased by the CM voltage. It was discussed previously. LIN+ and RIN+ are connected together and biased. Each audio input should be connected to LIN- or RIN-. The corrected schematic /REV2 will be online later.
For now everything (pots are unchecked) works fine. But there is the GND problem.
trying to understand what is happening here...
You're plugging in a new source into a cv-in jack? From within the same eurorack system? If the cv-out source is not at zero and is of low impedance, inserting will connect that voltage source to ground first.
Or is the cv-source coming from something pc-connected?
If the cv source is an isolated device (separate ac adapter or its own battery power), I can't see why that 'd happen.
The euxoloti and axoloti is powered by an external +/-12V power source. The axoloti is powered by the +5V regulator from the euxoloti and vbus send is active. The axoloti core is also connected to the axoloti patcher.
When I connect any external source (CV, Gate, Audio in) from an other power source to the jacks of the euxoloti, the axoloti will be disconnected from the mac. But if a new source from an already connected GND is added, the axoloti stay connected. So it's seems like a GND issue.
The inv buffer is biased by the CM voltage
Well, I've looked at the schematic, so I've seen that. CM = 1.65V, no? So I calculate V_out = 1.65V*(3.3/22+1) = 1.8975V. So a typical signal will swing around 1.9V, from 1.15V to 2.65V; which is what I was wondering about. Nevermind
Hey 
I was wondering.. would it be hard to add cv out.. just thinkin loud 
really looking forward
UPDATE Euxoloti and beta tester
hi folks,
the pots arrived yesterday after 3 weeks of waiting. 
So it seems that the Euxoloti is running fine till now.
I have to make some modification.
check the short audio demo
Now I want to start a community beta test session.
Does anyone want to join the develop & debug process?
I have some PCBs left and I'm looking for people who are skilled in axoloti, soldering, electronics &/or programming. To own a modular synth system would be helpful too.
If you want to join the process, I will offer you both PCBs (Euxoloti Core & Control) for 8€ (prime cost) + shipping. Further PCBs will be offer for prime cost, too.
Cause of spam protection, you have to use the contact form to join the process.
Contact Form
I'm tempted to join the beta, but wonder what modifications you still have in mind. If they're major additions, I will hold off for a while.
a|x
hi alx,
this are the actual modifications:
- the audio input routing has to be reroute to its neighbor pin.
- some component values has been changed (updated BOM and mouser card)
- maybe LEDs will be connected to axoloti PWM out pin…
- Final Control pcb will be larger for the lowest jacks. (check above pictures)
I will send each one detailed descriptions.
Part cost for core pcb ca. 30€ (Axoloti and pcb not included)
Part cost for control pcb ca. 50€
Cool.
So the necessary changes could be made with some jumper wires, and the existing PCBs?
a|x
Same here. I'm kind of torn between doing this myself and being lazy, i.e. getting yours.
My main quibble:
What rate are the CVs sampled at? I understand the F4 ADCs don't have the best reputation, but will using a MCP3208 really improve things in any way? Note how they've entirely disappeared from the Mutable Instruments stuff.
For changing the audio input pins, you have only to solder bridge two pads and don't install any fe-/male socket at the euxoloti. The lm4040 diode has to be turned.
This are the biggest change of the the actual pcb rev 1.
@gloom_and_glare
I don't know the actual samplerate. I will check that later. The main reason for the mcp3208 was a hint from johannes at the old google group. I have looked for ideal protection and the mcp3208 has one build in and it will reduce the necessary axoloti input pin.
A feature-request: how about a Euxoloti expander, breaking out the two USB ports, SD card slot and 5pin DIN MIDI I/O?
Would be super useful, I think.
a|x
Or even just the two USBs. That way, you could program the module without having to take it out of the rack, and plug in a class-compliant MIDI keyboard, fader box etc. for extra controls.
a|x
@toneburst
check the green panel. That's my USB connection from Axoloti to my mac for live programming. It's a Neutrik USB adapter where the Axoloti is connected on the backside. Maybe a USB Jack and Axoloti MIDI part can be at a new front panel?
to get fully access to usb, sd card etc. you can mount the Axoloti by its jacks to a separat front panel. The necessary connections can be done by crimp contacts. Johannes mentioned that it's important to use Axoloti's power regulation (cut away part), because it has more power and protection for the use of the USB host jack.
here are two pictures of the main mod. The other changes are only other resistor value etc.…
diode D3:
audio in mod:
Looks easy!
The component that needs to be rotated.. isn't that a transistor, rather than a diode?
a|x
