Box wrote:Frequencies are frequencies, it doesn't matter if they're produced naturally or synthetically.
My point was that it does matter when we are talking about minute differences in pitch and/or phase vs.
the possibility/expectation of perfectly locked waves. The latter are the province of digitally controlled synths only, for constant synchronisation between two oscillators/notes isn’t something that can be guaranteed in analogue ones or non-synthetic instruments such as acoustic guitars, oboes, etc.
The minor difference in pitch in the AN1x is due to its VCOs not being exactly the same frequency, whereas one might expect identical frequencies fairly logically, and they’re certainly possible from its digital nature – unlike in non-digitally controlled instruments, hence my assertion that they are hardly relevant here. Whew! That was a mouthful. Do you see what I meant now?
I went back and checked the JX-8P and AN1x and they do the phasing thing, not amplifying the signal as the Triton did. So it'd seem all my years of using analogue synthesizers have gotten me used to the oscillators being out of tune with each other. But it's so minute, a fraction of a cent difference for the phasing to be so slow.
Great, so I was right after all?
 Thanks for confirming, of course!
Miks wrote:Wouldn't it be possible to have both osc's waves on a scope whilst performing those test procedures? Imho this should visualize if there's any detuning between the oscillators?
Or just use a tuner that gives out the frequency in hertz for a definitive reading. I have one but people are sleeping and since it uses a microphone it'll have to wait.
It would be nice to see concrete measurements like this, so thanks in advance to anyone who performs them. This has further encouraged me to get a proper analyser in my signal-chain, at least on the PC… which could help greatly with understanding FM synthesis, too, since FM Theory and Applications
is nice for a theoretical description but leaves most of the practical results to the imagination.
SysExJohn wrote:Couldn't we record the output of osc 1 against osc 2 at say A below middle C and measure the exact frequency of each? I suspect we would find a fractional pitch difference. Maybe I'll try that, but I'm not sure whether Audacity can measure fractional pitch differences, although maybe just comparing one waveform against the other will show it.
It would certainly show the difference with sufficient probing, but I don’t know whether the effect could be summarised well (e.g.
visible while maintaining discernability of the individual cycles). Anyway, something that could make this easy to check would be setting up two Scenes, one with VCO1 only and one with VCO2, setting Separate to full (Yamaha, y no spread of oscillators within a single Scene?), and recording a stereo wave into a PC for checking of the two channels relative to one another. Again, maybe it’s not worth it, though, if it wouldn’t be very informative visually. I can try this again later but would need to transport the screenshot or whatever from my PC to an online one… I did the same thing before with a mono signal and confirmed the existence of the slight phasing between VCO1 and VCO2.
In anticipation of someone asking why this small difference in VCO2 matters, I’d better state that I’m not claiming it’s an instrument-breaker, abnormal compared to other instruments (especially genuine analogue synthesisers), or anything. The point of all this has been to determine whether it was a general and unavoidable feature of the AN1x, which we now seem to have confirmed, and later to obtain some more concrete data on its nature: we know it’s VCO2, but it’d be nice to get some shots from an oscilloscope, an idea of the difference in tuning, and so on.
These sorts of things are good to have available online for reference. I’d like eventually to put together a table of how parameters such as VCF cutoff map to certain values of Hz and other ‘real life’ figures, and info on the native detuning of VCO2 will be a nice addition to that sort of reference. I know there’s a list of frequencies for the LFO on the list on Yahoo; however, I’ve not come across any other translations of the AN1x’s native ranges to their equivalent measures. That is, of course, barring those for the effects provided in the official Data List, which seem somewhat strange in their inclusion when the more relevant main parameters are not described!
Working on such a reference could be a nice prelude to starting something similar for the 99/77… but I won’t even consider that
for a while.