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Solved - "pocs" careful of ground noise from usb hub minilaunchpad novation
Hello,
It's quite weird, but it seems that as AUM receiving the midi message : Active sensing FE, it gives random little annoying "poc" sounds...
I have a midi interface that is sending this message all the time, connected to an iPad, then from this midi interface I connect a 2nd iPad, also connected to a midi interface, so they can both exchange midi datas.
This message is normal, nothing to worry about but...
If I quit AUM, no more pocs...
If I launch AUM, disconnect the midi interface (Edirol UM2X) the sound disappears...
This is very subtile sound, needs to hear loud, but the louder you need to push, louder it is in speakers...(obviously...But what I mean is I'll plug my iPads to a big sound system...)
All you need to do to reproduce this "bug" is having a midi interface that send this continuous midi message, then have any other midi interface that will receive the midi connection to it, then launch AUM...
Can someone confirm this issue to help "IOS music science " ? 
Comments
@j_liljedahl a young padawan needs your help...
Ok...Seems Soft drummer was causing the problem...Even deactivated...App needs to be completely switched off...
Well...Finally, seems really a little bug from AUM...
I've tested with just AUM opened, with nothing in it...
What iPad and iOS version are you using ?
Very weird. I looked at the waveform and have no idea where it's coming from. There's no code in AUM that would be able to produce sound from incoming MIDI by itself. Are you using internal audio interface (headphone jack output) or an external one? Does it happen with just one iPad and the MIDI interface?
@gonekrazy3000 Ipad pro 12' - IOS 9.3.4
@j_liljedahl in fact it's not a sound...It's a kind of artifact. I know that because I couldn't record it on the iPad !
I had to record it with an other iPad.
To be clear...
This iPad is connected to a Behringer QX1222USB (but yes, I also had this artifact while using the regular output from the iPad, without any sound card, just a simple audio cable.) then the outputs of this mixtable (witch is class compliant) goes to the audio 1 & 2 of my ICA4+.
I could record the sound using these inputs.
I've been able to contain a bit more the sound, but still here in random, by cutting a maximum in/out midi connections.
this might not make sense but..... have you tried increasing the number of samples ? just try putting it to 1024 or 2048 and see if the random sounds still happen. I'm honestly curious. i use an ica4+ myself and plug in both my Ipad3 and Air2 and haven't heard any artifacts so might be a pro specific bug. also. what is your ica4+ set to ?
96000 hz at 24bit ? or lower ?
I also deactivate MMC support, still have the artifact.
The Berhinger plays at 48 khz-16 bits, buffer to 256 into AUM, but whatever the size buffer is, same problem.
Without the Behringer (witch can be a sound card...reminder) it was set to 44100 hz, 16 bits.
The interaction with the ICA4+ is only audio, so normally nothings related to his config.
But to let you know the ICA4+ is 44100 hz, 16 bits, very "simple"...
To reproduce this artifact, you need 2 midi interfaces, or something that sends this "Active sensing FE" clock message. (a beatstep pro maybe ?) and a midi interface.
First midi interface sends from the out to the in of the second midi interface witch is connected to the iPad.
I also tested with Apollo (so thru bluetooth) and got also the problem...Not completely sure, but almost...
Using Midiflow I can bloc Sysex, and at the moment (for 2 minutes...), no more artifact...
Ok Sysex FE out (I can't filter just one I think, but as there was only this one...) no more pocs....
@j_liljedahl Well...It seems it's still there, even if it seemed killed at the beginning...I suspect an electrical problem based on one of the hub usb, or maybe a guitar effect that causing this...
As it has been really decreasing with killing all useless midi flows and clocks going to AUM and all around, I still believe that might affect AUM. Still believe that at 50%...
I'll test tomorrow and let you know...
just use iconnectivity iconfig and change it to 96000 at 24bit. i've actually tested with 2 external midi interfaces plugged in simultaneously. a novation remote zero sl and an M-audio midisport X1. no glitches whatsoever. Reason i have that many midi interfaces is i have multiple external synths being controlled by the ipad. the only only difference between us seems to be that i'm running in 24bit 96000 hz while you're running in 16bit. i used to get glitches in 16bit when i first got the interface. its mainly why i changed it to 24bit. although mine weren't as severe as the ones you are getting.
@gonekrazy3000 hmm ok, I'll test that also...I've organized my test protocol for this afternoon, feedback tonight hopefully...
@j_liljedahl @gonekrazy3000
Well...Good news, AUM is not involved in that problem...
I finally think these sounds are micro electric interruptions.
I'm almost sure that it comes from the mini launch pad, or my usb hub (which is a DLink 4 ports, with 5V, 2.5 A power supply) The 2.5 A are important, because I've tested with an other Dlink 7 ports which has a 3A , 5V power supply, and here I got a huge ground noise coming from the mini launch pad ! In full light mode, it's even worse...
If I unplug the mini launch pad, the sound seems not coming back...
I think I might need one of these USB isolator to prevent this issue
https://www.amazon.fr/Isolateur-HifimeDIY-ADUM4160-isolement-Isolator/dp/B00M1QQBJ0/ref=sr_1_2?ie=UTF8&qid=1471501616&sr=8-2&keywords=HifimeDIY
or
https://www.amazon.fr/Audioquest-USB-Filter-Reduzierung-parasitäre-Resonanzen/dp/B00YTA78FW/ref=sr_1_2?ie=UTF8&qid=1471501461&sr=8-2&keywords=audioquest
@gonekrazy3000 I didn't set my ICA4+ in 24bits, 96 khz.
)
First I think it's not related to that, and then I couldn't perform live as I wish with such heavy signal to process...It will take twice the ressources of the iPad for a micro crackle that happens sometimes, for no improvement in the sound quality. (I'm not a whale, and I don't trace nuclear Russian submarines...
OKAY !!! Got it for real
The hub usb Dlink DUB H4 was generating these electrics noises because of my ( very old usb 1 ) midi usb interface Edirol UM2x connected to it !!!!
As a sound card is connected to the hub + the mini launchpad, then connected to the iPad, it's "too much" for such an old hub.
I've temporary replaced it with my other hub Dlink 7, no more noises...
Note that I also needed to keep the 2.5 A power supply of the DUB H4, because the original 3A of the Dlink 7 ports, generates huge ground because of the mini launchpad !!! (that seems to handle max 2.5A....)
A bit tricky...
If you get a USB Y cable you could try running the hub off a battery. I suffered the same problem when using a powered hub to power my interface and running from a USB battery solved it completely.
Yes, the most glorious silence ever even with my cheapo Strat copy that seems like it can pick up radio transmissions from Siberia at times.
Here is a link that shows how to do it:
http://auriaapp.com/forum/viewtopic.php?f=21&t=11150
@richardyot ah good to know
Actually, I'm gonna get a nice MTT hub with a 2.5A...But that would have been useful with the mini Launchpad ground issue, and still could be useful in some cases ! Thanks for sharing !
SUPER FINAL EDIT : the mini launchpad / novation, was generating the ground noise. To avoid it, try to plug into your usb hub far away from other devices. That solved everything for me immediately....