Klavis - CalTrans

[bgribble]

If I then go through a neutrally calibrated I/O of CalTrans, it's off by a lot.

One thing that is tricky about the CalTrans is getting your “octave staging” right. Try switching your input voltage up an octave and your oscillator tuning down an octave or vice versa. Note that V/oct inputs are positive only and Klavis has said that accuracy is not great near 0v input.

Also are you sure that you have the channel under test neutrally calibrated?

[skxdlxx]

If I then go through a neutrally calibrated I/O of CalTrans, it's off by a lot.

One thing that is tricky about the CalTrans is getting your “octave staging” right.

Ah, haven’t thought about that, will give it a try. Definitely on a neutrally calibrated channel. From my understanding the neutral mode is just a 1:1 of what goes in is what comes out - perhaps I’m reading that wrong somewhere

[donutschool]

I'm revisiting my CalTrans and still struggling with 'neutral calibration'. If Im connected directly to an oscillator, my tracking is good. If I then go through a neutrally calibrated I/O of CalTrans, it's off by a lot. Perhaps its a beginners modular problem im having

(Assuming you're on 1.17 firmware and have the latest V1.5 manual...)

What happens if you do a V/Oct calibration (p9 of manual) - does the tracking work then? If so - and you calibrate it to an oscillator that already has good tracking - then the result won't be much different from neutral calibration anyway.

If it still doesn't track then the "Calibrating the inputs scaling" (sic) on p16, using a tuner +,VCO*, should put it right. If you trust the tracking on your VCO,that boils down to alternately playing 2 notes (say) 3 octaves apart, fine-tuning your VCO to match the first note then follow steps 9-10 from p17 to bring the second note into tune. Rinse and repeat, and maybe try reversing the two notes (tune the VCO to the second, adjust Caltrans to the first) if you have problems.

Also, if you're trying to check/set calibrations, I'd avoid using notes at the extreme ends of either the Caltrans' input range (0V - 7V) or your MIDI controller's CV output range, which sometimes get a bit non-linear.

* Don't try and use the voltmeter method unless you've got a "professional" one with something like 0.05% or better accuracy on the 5=10V range - the manual is a bit misleading here - "4.5 digit display and millivolt precision" is irrelevant if the meter only has ~0.5% accuracy (which is a quarter of a semitone on a 4V v/oct signal!) - which is pretty common on handheld meters, even from good brands (your money gets you a more honest figure on the specification sheet). If you didn't pay several hundred bucks for the meter, it probably won't cut the mustard, and even if you did you need to check the specs.

[SunPulse]

The tracking on my system has always had a mind of it’s own, even over one octave things would get wonky. After reading about the CalTrans I ordered one from Thomann & received it yesterday. So here’s a little rundown on how I got along with installing, updating the firmware & calibrating my system.

I have a smaller eurorack in 2 Intellijel 84HP cases. In one is a Pittsburgh Modular SV-1 & in the other case are 2 WMD/SSF Spectrum oscillators. So 4 oscillators in total, which works out nice with the CalTrans having 4 outputs.

I use a 5-octave Novation keyboard which sends MIDI to the SV-1, the SV-1 then sends CV to the Spectrums through an Intellijel buffered multiple. I’d already adjusted the tracking on all the oscillators as best I could with a Korg rack mount tuner, but there was definitely room for improvement.

I installed the CalTrans in the same rack as the SV-1. The first thing was to update the firmware to v1.17. I downloaded the file to my iPad and used a lightening to 1/8” jack adapter to send the firmware update to the CalTrans. I set the volume on the iPad to just above halfway and the upload was successful on the first try. Good start!

I then followed the calibration procedure on page 9 of the manual for each oscillator. When done each oscillator was outputting a sharpened E when playing a C on the keyboard so I adjusted the semitone for each channel on the CalTrans to a C & then adjusted the fine tuning on each oscillator to get them tuned to C correctly.

When playing up and down the keyboard the oscillators were in staying in tune with each other, but they would all go equally sharp as I played up the keyboard. On page 11 of the manual it says if this happens to try changing the octaves on the CalTrans to determine if the CV voltage to the oscillators needed calibration. Switching octaves on the CalTrans the oscillators stayed perfectly in tune, so I had a new problem I didn’t realize that the CV output on the SV-1wasn’t tracking properly.

I then followed the calibration procedure on page 16 “Calibrating the Inputs Scaling”, and the oscillators are now tracking the keyboard really well and are staying in tune with each other. Not perfectly, but they are analogue and that’s part of being analogue. The important thing is they don’t require any fine tuning adjustment over the 5 octave range of the keyboard.

Overall I’m really impressed with how this all turned out. I read the manual carefully and made sure to do exactly what it said to do, and everything went correctly on the first try. I didn’t have to redo anything. The oscillators now track really well across the 5 octave range of the keyboard, which is more than I expected. I would have been happy with tracking over a 3 octave range! I can now rely not having to retune the oscillators depending I what notes I am playing.

So the CalTrans is an excellent module which does deliver what it promises. You do have to follow exactly what the manual says, none of the “I don’t need to read that” mindset when calibrating your system. Very reasonable price & quick delivery from Thomann to Canada. I wish I had a CalTrans 2 years ago!