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Connecting IEM w. built-in DSP USB-C cable to a device w. standard 3.5mm audio jack

DanielB_Canada

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Scenario: you have a set of IEMs with a built-in DSP in the USB-C cable (male) and would like to use them with a device that has a traditional 3.5mm stereo audio jack.

ex: I have a mini Bluetooth receiver w 3.5mm audio jack that can receive audio from a media player, tv, or phone. It's great to use when I don't want to be tethered to a phone due to a high risk of damaging it, such as when exercising or laying in bed/sleeping

Ideal solution: use an inexpensive 3.5mm male -to- USB-C female adapter

Issue: it doesn't work. It's designed for 'analog' headphones only, ie "headphones without DAC decoding chip" (built-in DSP?)

I found this out the hard way, having got no audio out of the two adapters (~US$1.50ea, shipped) I bought direct from China, from different sellers. (See image below, top-right quadrant). Many of the ads now even explain "there are 2 types of headphones" and that the product being sold is "for analog headsets, not digital". Yet there are no digital versions of a similarly designed adapter that I can find. Or any, in fact.

My potential solution: I found an inexpensive 3.5mm -to- USB-C male adapter cable, with built-in digital chip*. They make a few different versions including chip or no chip, and 3-pole or 4-pole, for use with headset with built-in mic. So, I'd get a 4-pole chip version, plug that into my device's 3.5mm jack, and at the male USB-C end of the cable, I'd attached a female-to-female USB-C adapter. Into the other side of that, I'd plug my USB-C IEMs. Total cost, shipped: ~$5.75

* ad text explains: "Note: The difference between Simulated version and Digital version

Digital version comes with DAC, which is decoding. If the decoding chip of the phone is not good, you can use the built-in DAC of the earphone to decode and obtain better sound quality.

If the phone has a digital interface, you must purchase a digital version(with Chip), such as for Samsung phone.
"

So it'd be like following the red arrows in the attached image.
IMG_20231212_040551.jpg


Does that sound like a workable solution? If not, what am I missing?

My other option is to just get a spare (non-DSP) headphone cable, 2-pin .78mm to 3.5mm stereo jack - and swap them out of my IEMs whenever I want to use them without my phone, with older 3.5mm-jacked technology. But that actually works out more expensive :)
 
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staticV3

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I'm fairly sure that it will not work.

In order to plug your Type-C headphones into a 3.5mm analog output, you would need a dongle with all of these built-in:
-a 3.5mm analog input
-an ADC to digitize that
-an operating system that can act as USB host
-a USB chipset to output audio to external USB DACs.

I do not think such a dongle exists at the moment. They all are USB slave devices.
 
OP
D

DanielB_Canada

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I'd just get a new cable on AliExpress and a $9 Apple USB 3.5mm adapter. All in $20 to get both working and make your IEMs sound good.
Having now had time to look up that adapter, I see that it has a C(m)-to-3.5mm(f) configuration — which doesn't fit my scenario unless you meant to get a new headphone cable with a 3.5mm male plug to use with 3.5mm(f) devices and to also get the Apple adapter so the 3.5mm(m) cable could be used on USB-C-ported devices such as phones. Is that what you meant? If so, unfortunately, that would be less than ideal as means the IEM's DSP-based features can never be used.

At least with my 'swap-cables-based-on-usage' workaround the benefits of the original DSP cable can still be realized some of the time, and other than the purchase of a new cable, no other things are needed. A downside to this being that repeated removal & reinsertion of the cable at the IEM-end may compromise the connection on the IEMs themselves.

An alternative workaround I also considered was to replace my Bluetooth audio receiver (w 3.5mm(f) output) with a new one that has USB-C(f) audio-out. But, for some reason, there's nothing available that I can find. Sure, some do sport USB-C ports, but on all the ones I found, it was for charging purpose only.

For using the USB-C IEMs when listening on a PC that does not have a USB-C port, I understand a simple and cheap USB-A(m)-to-C(f) dongle would do the trick.
 
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