Solved! How to Transform a TRS Hp Output into a Microphone input ?

[Luckybob]

Hi!
🤞Goal : Transforming the Direct Monitoring Output of the Focusrite into a Mic input (so that I don't need any numerical compatibility between devices, such as USB, drivers, etc), allowing to use any mix plugged into the interface, including 48V/Phantom power ones, on any device, 100% analogically.
Of course, I came to that idea, since I couldn't make the USB interface work on the smartphone, for every mic usage, notably rec & calls. Couldn't use apps through Windows PC either; the "My phone" Windows App was supposed to allow that, but it never worked for me & seems so unreliable anyway (Force close all the time, ppl saying it cancels calls randomly...); Samsung Dex is also an app very close from achieving it (it probably could in the future?), but the feature is just not available, only audio Phone→PC is supported... & I don't want wireless apps like Airdroid, wire = no data spying, best quality + reliability, - battery drains, & no Wi-Fi required in order to work (I actually have no Wi-Fi 😅)...

👉 Material :
♦ Focusrite Scarlett USB Interface, with XLR 48V mic
♦ Android phone (Galaxy S10e), with 3.5 hp jack ; High Res Audio Recorder & Call apps
♦ TRS & TRRS 3.5 male² cables ; TRS cable cut on 1 hand for experiments
♦ This TRRS screwable adapter: https://www.amazon.fr/gp/product/B08CVM2T31
♦ this Male TRS ↔ Female TRRS adapter for mics: https://www.ebay.com/itm/3-5mm-3-Po...icrophone-Jack-converter-Adapter/224045325396 (converts TRRS mics like SmartLav+ into TRS mics, making them compatible with smartphones → cameras) ; equivalent to the Rode adpter : https://www.ebay.fr/itm/Replacement...e-TRRS-to-3-5mm-TRS-Male-Adapter/224088834243
♦ This TRRS Mic/Hp splitter: https://www.ebay.com/itm/Ugreen-Hea...Cable-3-5mm-Male-to-2-Female-PS4/152594143413
♦ OMTP/CTIA converter: https://www.ebay.com/itm/3-5mm-Jack...tal-Male-to-Female-Audio-Adapter/324299553568

👇Experiments : [Spoiler: All FAILED 😭]
I mean, hold on... no, hang on!
→ Plugging the splitter to the phone, & the USB interface to the PC for power & tests, will be all along the tests; keep in mind the splitter makes the mic signal equivalent to a TRRS mic, when it comes to which pole transfers the signal (Sleeve).
→ As a contextual validation: Smartlav+ Rode mic → [Male TRS ↔ Female TRRS adapter for mics] → Splitter on mic side→ Smartphone : 🍾WORKS✅ 🍾(redundancy of TRRS→TRS→TRRS)

• Interface output → OMTP/CTIA converter → TRS Male² cable → Splitter on mic side → Smartphone : Fail
• Interface output → TRS Male² cable → OMTP/CTIA converter → Splitter on mic side : Fail
• Interface output → TRS Male² cable → [Male TRS ↔ Female TRRS adapter for mics] → Splitter on mic side : Fail
• Interface output → [Male TRS ↔ Female TRRS adapter for mics] (reversed)→ TRS Male² cable → Splitter on mic side : Fail
• Interface output → OMTP/CTIA converter → TRS Male² cable → [Male TRS ↔ Female TRRS adapter] → Splitter on mic side : Fail
• Interface output → OMTP/CTIA converter → [Male TRS ↔ Female TRRS adapter] (reversed)→ TRS Male² cable → Splitter on mic side : Fail
• Interface output → TRS Male² cable → OMTP/CTIA converter → [Male TRS ↔ Female TRRS adapter] → Splitter on mic side : Fail
• Interface output → [Male TRS ↔ Female TRRS adapter] (reversed) → OMTP/CTIA converter→ TRS Male² cable → Splitter on mic side : Fail
• Interface output → TRS Male² cable → [Male TRS ↔ Female TRRS adapter] → OMTP/CTIA converter → Splitter on mic side : Fail
• Interface output → [Male TRS ↔ Female TRRS adapter] (reversed)→ TRS Male² cable → OMTP/CTIA converter → Splitter on mic side : Fail

• Plugging TRRS Male² cable didn't change anything from TRRS, since the interface output is TRS, so discard this option right away. Just wanted to try in case voodoo stuff would happen 😇
• Partially insert of jacks, in all previous cases: Fail; the app stopped recordings most of the time, as it does when a mic is unplugged, bc it "fake-detected" 1 in & out. Yet, I remember & of these tests gave a successful signal while unplugging, but not on a steady position! Which gave me the hope it would work on below experiments...

→ Now, I was convinced the solution hinged on building a custom cable, as it might be a matter of ground placement/commuting/shunted...
→ My TRS cable cut on 1 hand for experiments, gave me 5 headaches, just to figure out which wire was what, since it had 5 non standard colored wires... By trying & error, found out the L, R, & all the others considered as Ground, so joined together.
→ Now, on the TRRS screwable adapter: considere the correct wiring (for TRS cable) is: L wire ↔ T ; R wire ↔ R1 ; Ground ↔ R2 ; Ø ↔ S
→ For tests, L & R are reversible, since it's just a matter of signal/ø ; what could eventually make a difference in term of power/current/resistance (then detectability?) was L+R.

• Plugging (screwing) L, R & Ground properly (verified working), creating a straight TRS cable : Fail (of c, otherwise none of that would be necessary...)
• L wire ↔ T : Fail
• R wire ↔ R1 : Fail
• L wire ↔ T ; Ground ↔ R2 : Fail
• R wire ↔ R1 ; Ground ↔ R2 : Fail
• L wire ↔ T ; R wire ↔ R1 ; Ground ↔ S : Fail
• L wire ↔ T ; R wire ↔ R1 ; Ground ↔ R2 + S (Shunted) : Fail
• L + R wires ↔ R1 ; Ground ↔ R2 : Fail
• L + R wires ↔ R1 ; Ground ↔ R2 + S : Fail
• L wire ↔ T ; R wire ↔ R1 : Fail
• L wire ↔ T ; Ground ↔ R1 : Fail
• R wire ↔ R1 ; Ground ↔ T : Fail
• L wire ↔ T ; R wire ↔ R1 ; Ground ↔ : Fail
• L wire ↔ T ; Ground ↔ R1 + R2 + S : Fail
• L wire ↔ R1 ; Ground ↔ T + R2 + S : Fail

Conclusion: I'm officially utterly PISSED OFF If none of those worked, the only remaining explanation to me, is there is some difference between Mic in & any device output. But can't figure out which one.. Power? Couldn't try every step on the potentiometer obviously, but nor 0, nor low, neither high gain did change a thing. Resistance? I tend to think so.

👉 "So the next step for us is to figure out how to hotwire the signal from the PC to the external Mic and trojan horse it " 👍, PC being USB interface's monitor output in my case (even though having the signal going through the PC is applicable as well). Any TRS output basically.
Ideas?

 

[americanaudiophile]

In general you can't change an output into an input (or vice versa). Has nothing to do with cables or connectors. Completely different circuitry required for completely different functions. It's not like USB which requires a driver to know how to function.

 

[hang-the-9]

There are XLR to 3.5 mm adapters with phantom power https://www.amazon.com/Saramonic-Sm...ocphy=9001809&hvtargid=pla-539946877175&psc=1 Never tried one so can't say how well they work or what brand is better.

 

[Luckybob]

In general you can't change an output into an input (or vice versa). Has nothing to do with cables or connectors. Completely different circuitry required for completely different functions. It's not like USB which requires a driver to know how to function.

I agree with that, only bc you said "in general" . 😄 It happens I know I don't fall in a general case, & what I'm looking for is out of what could be considered normal use. Which is why I'm looking for technical way to make it work, if there ever is.

I found this as a very insightful topic: https://www.quora.com/Can-putting-a-speaker-output-into-a-microphone-input-harm-either
I didn't find it before posting, yet that gave me a lot of specific answers I was looking for. The only difference with my montage is I deal with a headphone output, instead of speaker output (since I assumed the speaker amp would deliver far too high power as a signal, for it to be delivered properly with no clipping or damage).

I'll just say, from my understanding, yes in & out devices are different, with completely different circuitry required, yet the signal they're interpreting is not necessarily that different, it's analogical in both directions, only the electrical properties & routes/poles on the connector (TRS here) differ. Therefore, there is no reason it shouldn't be compatible, once both these criterias are managed accordingly to each device.
I assumed it could be directly compatible, since I already kind of achieved it, the other way around (regarding my set up): rerouting the output of a headphone amp to the mic input of my Focusrite, on the instrument side. It's not perfect, & you have to be picky with the power level, but it definitely works!

Thx for the input anyway... No pun int... ok it was intended 😅

 

[Luckybob]

There are XLR to 3.5 mm adapters with phantom power https://www.amazon.com/Saramonic-Sm...ocphy=9001809&hvtargid=pla-539946877175&psc=1 Never tried one so can't say how well they work or what brand is better.

This, actually, is a valid solution, which perfectly fits the purpose! Thx, I almost "forgot it" (in my focus on this set up), even though I happen to own this device... I should have used it as a description of what the mean I'm looking for had to achieve...
The downside of the Saramonic is it requires a 9V extrnl battery, while I wanted a set up I could let plugged as such indefinitely without worrying about any battery to change, so that hours of worry-free usage would be possible. & using the Saramonic on-the-go while keeping the home set up with the Focusrite, was my retained solution..

Thx for the reply!