Is anyone aware of whether the UA Apollo interface works with Audulus? The Apollo is able to output CV signals through audio outputs and works well with other applications that send CV out of the computer without_ needing the ES-8 module.
I’m interested in designing sequencers and such to send signals to some excellent granular manipulation modules of which I am overly fond–the Morphagene and Qubit Nebulae.
Thanks for being such a positive, supportive, and quantitatively literate community! I am inspired instead of intimidated!
Patrick
Not sure of the math on this, but basically you get the output level from the dBus
The best way to verify though would be to get a multitester - great tool to have if you have a modular synth since it can help debug stuff like this! It’s a very easy tool to use, you’d just send a 1 value out of Audulus to the output and then measure from the tip of a cable plugged into it to the sleeve.
Long story short, it doesn’t appear to be tuned to a particular whole number voltage swing, so you’d probably have to do some “tuning” of the output anyway to make sure the -1 to 1 matches -10 to +10, but it seems at least like it covers that whole range, which is great.
15 dBu is equivalent to 4.3559 volts rms, this results in a peak voltage of approximately 6.2 volts assuming a sine wave output or a swing of around 12 volts. It would be best to measure the voltage with a multimeter if you have one available since the actual output voltage may be somewhat different. One thing I noted from the specs is that although the outputs of the 476 are DC coupled, the inputs are AC coupled so you won’t be able to input CV to the interface
Thanks for the facts! I saw 12 volts there but misread it as -12 to 12. It’s still a nice range for lots of things in modular, though you may need a voltage adder to get it into the range you want.
Your readings are a bit puzzling. If you’re sending a static 1 to the DAC channel the AC voltage reading should be zero. If you’re sending a 1 peak to peak sine wave then the voltage reading should be 0.707 (RMS) times the DC voltage. You need to determine the DC output voltage output for an input of 1, 0, -1. A signal of 1 in Audulus should result in the maximum positive voltage that the interface will produce and similarly -1 will produce the maximum negative voltage. A value of 0 will give you the DC offset that the interface is producing. Once you know the maximum DC positive and negative voltages the interface will produce, you should be able to calculate a conversion factor.
hmm, please forgive I’m a little inexperienced with this stuff
I’m sending an ‘expr’ object (with values -1, 0, 1, .5, etc) directly to DAC 3 (Volt output 4), measuring across TS sleeve (neg) and tip (pos). Multimeter is set to 20V dc range
This is the correct approach. Your rack expects 1 volt per octave. You now now that your interface acan provide about -3 to 3 volts DC. The output appears fairly linear so you should be in good shape. Your maximum swing is about 6 volts but that translates to 6 octaves which should be pretty good. You will probably need to tune your oscillators up an octave or so if you want to use the full range.
Given that Audulus expects 1 per octave and your interface gives you about 3 octaves from 0 to 1 you will need to divide the Audulus output by 3 or so to get reasonable pitch tracking.
