Voltage Trimming

I just lockup the specs your voltmeter is only accurate to 0.5% - it’s also reasonably likely that it’s calibration is off.

Maybe this instead:

https://www.tester.co.uk/uni-t-ut71e-intelligent-digital-multimeter

I wouldn’t try using that cheap multimeter for this if you want that level of accuracy!

You can spend a lot more cash than this getting stuff that’s more accurate!

Thinking left field a bit, would you not be better off with a tuner? Even an iPhone app might provide a more accurate reading than your multimeter - that sounds ridiculous but they are pretty good, this one has accuracy ±0.01 semitone (±1 cent)

e.g. ‎Cleartune on the App Store

Or you could get really serious about your tuning hehe :wink:

http://uk.farnell.com/keysight-technologies/b2987a/electrometer-bench-6-1-2-digit/dp/2491337DM

its not really tuning though, it’s about voltages. but yeah maybe it is too blunt an instrument. :frowning:
It was recommended on muffs for calibrating the rubicon by the guy who designed it, maybe i just got a duff one.

Or maybe your standards are just higher? :slight_smile:

I have a similar cheap multimeter and they are fine for checking things like resistor values or that there is about -12v on the -12v rail etc… but impossible to say, match resistors with them! They’re just not very good!

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if it was about by exactly .6% that would be just outside the tolerance of the device but almost pretty much account for the error, I’m seeing.

On the plus side assuming that the multimeter is at fault then i now have a new more reliable voltage source and meter in the er101 for recalibrating my osc and other voltage sources.

oh well :slight_smile:

Yeah that’s a seriously cool feature I was previously unaware of, way better than the multimeter!

I might actually tune something :joy:

Ok used the 102’s voltage measuring to get as near as perfect voltages from My Analog Keys (using its internal trimmers). So C0 = 0v, C1 = 1v etc…

Then used these to re-calibrate all my oscillators and everything sounds great with 101 except for the very first voltage of 0v, which has a small positive bias of 0.010v (according to the 102).

Is it possible to tweak this down any further (closer to 0) at all, could it be OS tweak somehow?

From my 101 feeding back to the 102 to measure voltages they go like this:
101Out ----- 102Reading
0.000----------0.010
1.000----------1.001
2.000----------2.002
3.000----------3.002
4.000----------4.002
5.000----------3.001
and so on.

Its just the first one (or 0v) that seems to have that little bias. Its nothing major, so no worries if not but just wondered if there was a way to tweak it?

I’m getting really lovely tracking from my osc now apart from that very first note/index.

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I wouldn’t really consider it a cheat. In fact it’s part of the reason I’m getting a 301! :wink:

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Good call! :slight_smile:

So I just tried this method to tune an OSC303 I’ve just built for someone and I couldn’t get it to stabilise, it was like the voltage reading was following the saw wave i.e. it was flickering about all over the place.

Am I misunderstanding something? Feel a bit dumb all of a sudden!

Well, not that dumb, I tuned the OSC303 up anyway using an iPhone app called Tunable - it’s very good - sounds as perfectly in tune as this gnarly oscillator is going to anyway, there is some drift which is to be expected but it hits the green across three octaves, so more than good enough and expected behaviour.

https://itunes.apple.com/us/app/tunable-tuner-metronome-and-recorder/id608540795?mt=8

From your description, it sounds like you are expecting the ER-102 to be a tuner?! :dizzy_face:

It can act as a voltmeter but not a tuner.

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Haha - thanks yep slight misunderstanding there - I was being dumb :smiley:

I realised my mistake after I posted, but thought I’d wait for an answer anyway…

Onward and upward!! :smile_cat:

Is there any possibility of an update to make it to work as a tuner? Although having said that, it would probable make more sense to put this in the ER-301?

I’m having this same issue, and while not a huge deal, it is a little annoying. :slight_smile:

Is there a fix/workaround?

Unfortunately, there is no fix for this. The ER-101 cannot output exactly 0V. Due to the limitations of the DAC it will float slightly above. All other values should be good though. In practice it shouldn’t really be a problem if you use 1V (or higher) as the root.

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Thanks for the quick response! Do you mean tuning/calibrating my oscillators so that 1V is my root pitch and then using (in the 12ET voltage table for example) only index 12+ (or shifting the stored voltages up 1V)? If I’m understanding correctly, I’ll try that when I get a chance.

P.S. On a totally unrelated note, I’m off to Japan for the first time in a few hours! I’ll be in Tokyo for the next week if you’re anywhere near there and want to let me buy you a beer in return for the awesome modules, or if you have any interesting recommendations.