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Pops, crackles, noise bursts, disintegration when using two iOS devices

Hi

Is anyone else having trouble getting a clean audio stream when playing instruments on an iPad through iCA4+?

I'm using two iPads - one runs softsynths/samplers, the other is a loopstation using Loopy HD.

You can read more about my system here:

http://iconnectivity.com/vanilla-forum/discussion/169/chaining-midi4-with-audio4#latest

I've opened a support ticket regarding multiple associated problems but not had a result from iConnectivity yet.

In the meantime, I've managed to derive a very simple audio routing, MIDI routing and MIDI Clock routing which works sufficiently for now.

However, no matter which settings I tweak (buffers, audio clock), I'm unable to eliminate constant crackles, pops, noise bursts and sometimes total disintegration of the audio when playing synths/samplers. Same occurs if I open a music player on the "player iPad" and route it to the loopstation iPad.

I've spent many hours and days very patiently trying every possible setting related to buffers and/or sync, but havent found a setting which fixes this problem.

Rightly or wrongly, I've reached the conclusion that something is broken when using iCA4+ with more than one iOS host computer device.

The problems persist even if I output the player iPad's analogue audio from iCA4+ outputs and loopback into the iCA4+ inputs to route the audio to the loopstation iPad. (IOW, bypassing the direct internal USB audio channel between the two iPads, but both iPads are still connected to the two device ports)

I've swapped the iPads between device sockets - no difference.

I've swapped the roles of the two iPads (player vs loopstation) - no difference.

I've swapped iPad cables - no difference.

None of these problems occur if I disconnect the 'player iPad' and listen to it in isolation.

Similarly, the problems cease completely if I use a different docking device and send the audio to iCA4+ via the analogue inputs.

For example, as Josh may recall from his previous tenure at Alesis, I have an Alesis iODock here which I no longer use because it doesnt charge the iPad.

I've tested replacing the iCA4+ with the iODock (docking the player iPad), patched into the iCA4+ via the analogue inputs and all of the iCA4+ problems vanished immediately. Suddenly the audio was perfect.

I've also tested with the two iPads connected to the MIDI4+ instead of the AUDIO4+.

Using USB audio in the MIDI4+ works fine (as it always has ever since i bought the MIDI4+) except the only method available to bring the audio back into the physical world is via an iPad jack socket.

I bought the AUDIO4+ to solve the lack of analogue I/O on the MIDI4+ .
So far, it feels like a step backwards rather than forwards. :(

It seems to me that this could be a digital audio clocking issue which only occurs when two iPads are connected to the iCA4+. Two iOS digital audio devices connected via USB to a third digital audio device, where (as far as I know) only one of the devices can be the audio clock master. That's assuming the iCA4+ and/or the iOS operating systems don't use forced ASRC to re-clock the audio. I dont know enough about iOS or USB audio clocking to know the answer, but "digital audio master clock problems" would explain why the problem persists no matter which buffer settings I choose. That said, with both iPads connected to iCA4+, changing the master clock via iConfig makes no difference, no matter which device I select to be the audio clock master.

Apologies for the long post. It's not meant to be a rant, so I hope it doesnt sound like a rant. I'm hoping someone else has either managed to get good results from the AUDIO4+ using a dual iPad setup, or suffered the similar problems. Any info is good info!

Thanks

Diggo





Comments

  • Hi again,

    In the previous post above, I said this:

    "I've opened a support ticket regarding multiple associated problems but not had a result from iConnectivity yet.

    In the meantime, I've managed to derive a very simple audio routing, MIDI routing and MIDI Clock routing which works sufficiently for now."

    To clarify, by "very simple", I mean I'm bypassing the analogue mixer because opening the iConfig analogue mixer in Windows 8.1x86 almost invariably invokes a "communication error" popup after a few mins and iConfig crashes. I'm reasonably confident this relates to GUI issues with the fader meters (or perhaps "meter hanging" is just the first symptom an error has occurred), so I've bypassed needing to adjust mixer faders in lieu of adjusting the analog I/O faders via the touch panel.

    So the simple routing I referred to directly patches the player iPad to Analog Out 3+4, loops back via audio cables to Analog In 3+4, which patches to the loopstation iPad. The loopstation iPad patches to Analog Out 1+2, which is routed to my external mixer. Using this simple "workaround" routing, I still cannot derive a clean audiostream due to clicks, pops, crackles as described above.

    To derive a clean audio stream via the above routing, I have to disconnect the player iPad from AUDIO4+, connect it to another dock device, then route analog out from that device to Analogue In 3+4 on AUDIO4+ (which is patched to the loopstation iPad in AUDIO4+). This derives a clean audio stream. I've tested this with Alesis IODock and a Tascam iU2 dock. In both cases I can work without problems until the player iPad battery expires (iODock and iU2 dont charge the iPad)

  • edited May 2015
    Hey @diggo - can you post the ticket number so I can look into your Inquiry and escalate with my team? If you're having iConfig connection problems or crashes, it's best to have all you details documented in a support ticket.

    If needed, feel free to use jsandeen(at)iConnectivity.com

    Hope to resolve this for you as soon as possible.
    -JS
  • Hi Josh
    Ticket number 840517, lodged 12 May.
    Thanks!
  • Thanks. I have escalated the ticket for you.

    We appreciate your patience as well as all your feedback and participation on the forum.
This discussion has been closed.