High pitched background noise, around 2340Hz (anyma phi)
AndyHornBlower last edited by AndyHornBlower
I've been meaning to mention that my anyma phi has a high pitched background noise, most of the time, wavering slightly, around 2340kHz (maybe 2343Hz) - that frequency is according to ClearTune on my iPad 3, connected with an iRig, and it identifies it as roughly D7. It sounds above the top C that I can play with an "empty" patch, but within the range that I can bend that note up to.
It's present on the headphones socket and the left audio out - I assume that's what I should use for mono. I expect it's the same on the right audio out, but I haven't checked. It's largely independent of the volume knob - I hear it as clearly with the anyma phi's volume knob turned all the way down.
It does it whether I'm using DIN MIDI or USB MIDI via the USB Host socket. It does it with headphones plugged in directly, or when taking the output of either the headphones socket or left line out to something else.
I've been working around it by using a FiiO E06 headphones amp from the output (either from the headphones socket or left line out), by turning the gain on that low enough so I can't clearly hear the noise, and turning the volume full up on the anyma phi, to get a better signal to noise ratio.
If I switch to the original factory patch 7 (a piezo patch that has audio in turned full up), I hear the same sort of sound, but louder.
At one point, I was able to get the sound to get louder and softer by turning the LED brightness up and down - I did it a few times in a row and it seemed consistent. I can't get it to do that reliably though. Once when I did that, it suddenly stopped, or got much quieter so I couldn't really hear it any more (still via the headphones amp, with less than unity gain, so it might just have got quiter). I've heard it suddenly get louder when changing patches too - to ones without audio In turned up, and no envelope follower.
Is there a way to turn the LEDs off all together, so I can hear the difference? Since they can be faded, and the colour mix can be adjusted, I'm guessing they're driven by PWM. Is the frequency I hear the PWM frequency, by any chance, or maybe an octave either side of it?
It would be good to be able to turn the display off too, to check if that's being picked up.
On a maybe not directly related problem, I've also been hearing a metallic ping or pling, not unlike the sound that the built in piezo might make if something small and hard fell on it. It's intermittent - it can go quite a while without making the sound, then do it a few times within a couple of minutes. I was hoping that was a bug, maybe from CPU overload, but it does it even on an "empty" patch.
Are these known problems? I thought I'd read about noise on the outputs, but I can't remember who said it.
AndyHornBlower last edited by AndyHornBlower
Perhaps this will help me get a reply. Here's a scope and frequency analysis of the high pitched noise. You can see the fundamental is around 2.3kHz, as detected by ClearTune.
I've also attached a short recording of the noise, made through a cheap generic USB sound "card" (key fob style audio interface), simply setting the level for that input via Sounds, in Windows - no other hardware. No MIDI or USB device is connected to the anyma phi, just power and a connection from stereo audio out to the audio interface.
This is exactly the sound I hear when I connect headphones directly, or via my FiiO E06 headphones amp. I can make the level less, compared to the synth sound, as described, but I can't get rid of it all together.
It doesn't always start making that sound from cold. It kicks in, usually after selecting a patch with the encoder, then it stays on until I power it off again - changing patches again, makes no difference.
Since it's always the exact same tone (frequency and overtone series), it seems to me there must be a physical reason for it, or maybe even a firmware bug, and the exact frequency ought to be a clue as to why.
On this occasion, altering the LED brightness in settings didn't affect it.
Turning the Volume knob to zero didn't affect it either.
Only the original power supply and cable (no extension added) was used for this analysis and recording. I've also verified that it sounds the same with an Apple USB power supply, used for charging my iPad 3.
On a perhaps not straightforwardly related issue, I've additionally been hearing a metallic ping or pling, similar to the sound that the worked in piezo may make if something little and hard fell on it. It's discontinuous - it can go a really long time without making the sound, then, at that point, do it a couple of times inside two or three minutes. I was trusting that was a bug, possibly from CPU over-burden, yet it does it even on an "vacant" fix.
Support_AODYO last edited by
@andyhornblower That is interesting. The noise is always the same? Could you possibly try with a different cable and with a different power source, maybe an external battery to avoid ground loops?
AndyHornBlower last edited by
@support_aodyo Yes, the sound is always the same, though the amplitude of it sometimes changes suddenly.
I've now tried it with an adjustable power supply, powered by a battery pack, and a different cable. That's the quietest power supply I own. There is no difference. I've also checked that the same noise/sound appears on all three audio output sockets, even with Volume all the way down.
I notice the sound is also picked up at Audio In, even if I plug in a cable to short it to ground - e.g. if I take an "(EMPTY)" patch and set the Main Audio In as In-R, with a short mono patch lead plugged into the Audio In socket, shorting the right input channel to ground. If I then turn up the Main Audio In level, I can make the sound louder using the Volume knob.
Is there a DC-DC converter inside the anyma phi, with a conversion frequency of 2340Hz, or similar? If so, my guess is that it's being picked up by whatever circuitry drives the outputs, and also being picked up at Audio In, so it can be amplified further.