[sdiy] [OT?] Audient iD22 audio interface phantom power issues

Jimmy Moore jamoore84 at gmail.com
Thu Apr 29 21:30:42 CEST 2021


Makes sense, I will check that out this evening.  Thanks!

On Thu, Apr 29, 2021 at 1:19 PM Mike Bryant <mbryant at futurehorizons.com>
wrote:

> Hmm this guy seems a bit biased.  Nothing wrong with Jamecon caps or XMOS
> USB.  More expensive solutions aren’t going to sound any better.
>
>
>
> I’d put a multimeter on the power rail feeding R7 with a load attached and
> see what it does.  Possible the supply is flaky and turning on slowly.
> Conversely it could have been engineered to come on slowly.  Note that 44V
> is inside the phantom power spec so if it gets there eventually it’s not
> actually non-compliant.
>
>
>
> *From:* Jimmy Moore [mailto:jamoore84 at gmail.com]
> *Sent:* 29 April 2021 20:06
> *To:* Mike Bryant
> *Cc:* synth-diy at synth-diy.org
> *Subject:* Re: [sdiy] [OT?] Audient iD22 audio interface phantom power
> issues
>
>
>
> Hi Mike,
>
>
>
> I've tried the other device (A Cloudlifter CL-1) on a separate mixer and
> it works as expected.   I should have spent more time looking at that
> schematic -- the 24V on the phantom power switch doesn't make sense to me,
> either.
>
>
>
> I'm just piggybacking on what others have compiled.  A lot of the
> sleuthing goes to Khron:
>
>
>
> https://khronscave.blogspot.com/2021/02/66-audient-id22-teardown.html?m=1
>
>
>
> Plus a great deal of general griping on gearspace
>
>
>
>
> https://gearspace.com/board/music-computers/1050068-audient-id22-issues.html
>
>
>
> On Thu, Apr 29, 2021 at 12:57 PM Mike Bryant <mbryant at futurehorizons.com>
> wrote:
>
>
>
> Definitely not based on the Douglas Self preamp – his has balanced
> feedback whereas this has unbalanced feedback and is a bit of a mish-mash
> of other designs.
>
>
>
> Have you checked whatever you are plugging in using the phantom power on
> another device ?   Sounds like it may have a large input capacitor and is
> taking far more current than the 6k8 resistors can supply.   The phantom
> power arrangement shown is the one used on all but the highest end
> devices.  That said R7 is only connected to 24V on your schematic.  This
> must be wrong if it gets to 44V eventually, but one wonders if there is
> more circuitry than shown.
>
>
>
>
>
>
>
> *From:* Synth-diy [mailto:synth-diy-bounces at synth-diy.org] *On Behalf Of *Jimmy
> Moore via Synth-diy
> *Sent:* 29 April 2021 18:35
> *To:* synth-diy mailing list
> *Subject:* [sdiy] [OT?] Audient iD22 audio interface phantom power issues
>
>
>
> (Less to do with synths, but still in the broader signal chain, so
> apologies for being somewhat OT)
>
>
>
> I have an Audient iD22 interface that's been great for the 6 years I've
> owned it. However, using phantom power (for the first time) only output
> 38VDC, which eventually climbed up to 44-45VDC, and seems to sit there.
> I've had trouble using it to power a cloudlifter.
>
>
>
> I don't have schematics for the Audient iD22, but its preamp circuit is
> apparently inspired from Douglas Self's Soundcraft preamp
> <https://patentimages.storage.googleapis.com/52/76/46/8792fb86ea4215/GB2242089A.pdf>.
> Someone else reverse-engineered a schematic
> <https://1.bp.blogspot.com/-1twYw6xYHS0/YBh0OBol7sI/AAAAAAAAELs/VR6cPIPxRtAQULgTOpiTylR9FPWWshplgCLcBGAsYHQ/s1751/PreampSchematic.png> indicating
> the P48 source and specific componentry -- it touches a few 47uF Jamicon
> caps which might play a role.
>
>
>
> Would anyone know why a phantom power circuit (or this circuit?) would
> produce such low and variable output?
>
>
>
> Audient's power controller -- an LT3439
> <https://www.analog.com/media/en/technical-documentation/data-sheets/3439fs.pdf>
> -- is responsible for generating the various power rails in the device,
> which is not without some questionable design choices from an undersized
> heatsink and potentially not being properly soldered to the ground plane
> <https://1.bp.blogspot.com/-bNr19B8hntQ/YBmtQyRfP5I/AAAAAAAAEMI/QdWLMuHWTdUoV9MWjmX_zIxosI2PVEhowCLcBGAsYHQ/s2048/IMG_1292.jpg>
> to help with heat dissipation (source and more info here
> <https://khronscave.blogspot.com/2021/02/67-audient-id22-part-2-repair.html?m=1>
> )
>
>
>
> I've written up my own explorations into this
> <https://utahjimmy.github.io/projects/8_project-audient/>, but the TL;DR
> is: things get really hot on the inside, and perhaps this is all due to
> component wear and tear.
>
>
>
> I'm only a hobbyist, and not sure if something like this is fixable.
> Regardless, I am very curious to hear people's thoughts on what might cause
> my output to be low, but slowly increase over time. Does this sound like a
> capacitor problem?  A power controller problem?  Both?
>
>
>
> Thanks for your time!
>
>
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