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I was looking to build something like this because I didn't know it existed since my searches came up empty until I found out what a direct bax was.

This direct box from Amazon allows me to take TRS audio output from the computer and convert it into XLR and I can take a XLR to TRS cable so I can connect it to the condenser microphone input on my V8 sound card.

Direct box/audio amplifier direct box/audio amplifier

XLR to 1/8 TRS XLR to 1/8 TRS

V8 sound card inputs V8 sound card

And yes I did know there's a place to input computer audio as an accompanied device/music. Voice changer doesn't work on accompany devices only microphone input.

How do I convert an unbalanced 3.5mm TRS audio output from computer to balance 3.5mm TRS input to sound card /mixer?

Dean
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  • I think you need to put time into a picture that shows the entire system as a whole for each separate purpose you intend. If there is only one purpose, but it is a complicated purpose, then the drawing will just be one complicated drawing. But if you have two (or more) simpler uses then you should draw up something for each one, separately. That's what I'd like, anyway. I'm trying to untangle your words into a picture and I can't honestly say that I've been successful. Maybe that's just me, though. But I do get the first idea you presented. I'm just not sure that's what you really want to do. – jonk Sep 29 '22 at 05:00
  • Does your condenser mic need phantom power? – JYelton Sep 29 '22 at 18:34
  • Ok, disregarding the mic for the moment (USB provides it power)... You're asking how to change the function of a 3.5 mm jack on your computer (or audio interface) from one thing to another? That's going to be specific to the manufacturer (some computer motherboards allow you to change audio jacks from input to output, or from stereo to surround, etc.). To be honest I don't think you are asking an electrical engineering question, but rather more of a "how to use a commercial product" question, which is off-topic. – JYelton Sep 29 '22 at 21:04
  • Dean, don't stress too much about a question being closed. Feel free to ask another question that's more specific. This one was a little tough to discern the engineering requirements early on. – JYelton Sep 30 '22 at 00:03
  • Please do not just replace your entire question with a rant about people being unhelpful. I've rolled it back to what it was before. People did not answer your question because it's difficult to understand what the system you're talking about even *is*, or what you need done with it. – Hearth Sep 30 '22 at 17:01
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    Edits to your post are not a violation of your First Amendment right -- it's part of how the site works, which you agreed to when you signed up. – Null Sep 30 '22 at 17:28
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    @Dean My profession is test engineer for power electronics systems. I have nothing whatsoever to do with computer audio connector standards and know very little about them. I do, however, know that there is not in general a way to change an output into an input. Some devices may support that, but there is no general standard way to do that. – Hearth Sep 30 '22 at 17:33
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    I would also like to note that freedom of speech in the United States, which I assume is what you mean as you mention "first amendment", specifically means *the US government* can't restrict your speech. Private entities, such as myself or the company that owns StackExchange, very much can. – Hearth Sep 30 '22 at 17:34
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    @Dean I am here because I choose, on my own free time, to help moderate this site so that people can get the help they want. And to provide that help myself, where possible. I know nothing about computer audio systems, so even if the answer is very simple I wouldn't likely know it, *because I don't deal with them*. StackOverflow being hosted in new york has nothing to do with whether freedom of speech applies here, because *StackOverflow is a private company*. They are not owned or operated by any branch of the New York or US government. – Hearth Sep 30 '22 at 17:38
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    I don't understand why you're getting so upset about this. Your question was hard to understand and thus closed. You were asked to provide additional information to make it easier for people to understand, so that they could help you. You did not, so the question remained closed. I don't see why you're being so hostile. – Hearth Sep 30 '22 at 17:40
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    @Dean I can see at least two things that last sentence can mean. Either: You want to use the port on your laptop labelled "audio out" to connect a microphone to your laptop, or: you want to connect the "audio out" on your laptop to the "microphone in" on another device. The former is potentially possible but would depend heavily on the details of the laptop and may not be possible, while the latter can be easily found via your search engine of choice, as all you'd be asking then is how to convert line level signals to mic level. You were also asked to provide a picture, which you did not. – Hearth Sep 30 '22 at 17:52
  • @dean can you please ask a question and include it in the post, this is a Q&A site – Voltage Spike Oct 05 '22 at 14:20
  • I _am_ an audio and electronics engineer and I run a small recording studio. I have tried to provide some guidance, but the question was difficult to understand and thus why I voted to close. Despite that, I added an answer to try to help OP with some terms and concepts. I'm glad I missed all of the apparently deleted comments and edits to the question which completely change it from what was originally written. – JYelton Oct 05 '22 at 17:10
  • @VoltageSpike The question was asked a little bit ago and the question is in the title. Which is the only thing you should need. As it was what gave the answer above. The question has been answered by me. – Dean Oct 05 '22 at 18:31
  • @JYelton what is hard to understand about wanting computer audio to go to a place were a condenser microphone should be? As it's called a direct box. – Dean Oct 05 '22 at 18:32
  • Also @JYelton the first thing asked was how to take 3.5mm computer audio output and convert it to 3.5mm microphone audio input. I would think that anyone that wanted to connect their computer to their audio mixer so they can play music from their computer would know how to do something like that. Yes? If it's buying a device or making a circuit board which is what I wanted to do. – Dean Oct 05 '22 at 18:52
  • @JYelton I got my answer by having a intelligent conversation instead of someone forcing what they thought and came to a component that does what I wanted. It's called a transformer specifically made to convert computer audio to mixer audio. Unbalanced to balanced. Computer audio to condenser microphone audio TRS headphone audio to TRS condenser microphone input. That was all the different explanation I used to help you guy get on track. But I was shut down with a question closed. – Dean Oct 05 '22 at 20:17
  • @Dean As I said earlier, don't be too bothered by question closure. It's just a means to redirect you to either edit the question or ask a new one that addresses the issues. This is not a forum, it is a Q&A. You could have added comments to the answer I provided to try to correct misunderstandings, but instead you chose to edit your question multiple times including antagonistic remarks. Your attitude toward me is extremely unwarranted, so with that I kindly ask that you instead go find a forum which is probably more what you're looking for. – JYelton Oct 06 '22 at 19:38

1 Answers1

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Your question is likely to be closed because it's not strictly on-topic (about electrical engineering) and instead is more about how to use/connect audio equipment and computer. You may find that an audio Q&A or forum is a better fit.

That said, I'm adding an "answer" since I think it may still help you out.

First things first, diagrams are a wonderful and necessary way to communicate what you are trying to do. An electrical schematic is what we use most of the time here; wiring and block diagrams as well.

Is this the V8 audio interface you're using?

V8 audio interface, front

V8 audio interface, back

Image source

You said in comments that you have a USB condenser microphone. Condenser microphones use a capacitive plate to capture sound, and require power. It is using power from the USB port to do this, but this also means it acts like a device that your computer will effectively treat as an independent audio source. In some cases (depending on your computer or software), you may not be able to utilize two different audio interfaces or sources at the same time.

The audio interface provides a "dynamic" and "condenser" mic input and my best guess is that it provides phantom power (what we call the 48V power) to a condenser mic plugged into that jack. However, your mic is incompatible with that because it is a USB microphone. (Most professional audio interfaces use XLR and allow you to enable phantom power as needed per-channel.)

I think what you're asking is how to use the USB microphone with the computer, running its signal through whatever software you're using for processing, then send the signal out, and then back in through the V8 interface. However that is super complicated (again, depending on your OS) and might not work at all. Your computer will see the V8 and USB mic as two separate interfaces.

If you are using a DAW that allows you to receive audio from multiple interfaces or sources (ASIO interfaces, for example) then you may be able to simply treat the USB mic as a selectable source, and just integrate it in your DAW as you would any other audio source.

Finally, to address just the physical question about adapting 3.5mm TRS: There are a few ways in which TRS can be used. For your stereo output, generally:

  • tip is the left channel
  • ring is the right channel
  • sleeve is ground

TRS headphone or stereo out pinout

Image source

On your V8 interface, it will likely be balanced audio where:

  • tip is "hot"
  • ring is "cold"
  • sleeve is ground
  • (Phantom power applied between hot and cold)

TRS balanced audio pinout

Image source

With this information you may be able to create an interconnect cable. I can recommend Rane's Sound System Interconnection article for various wiring diagrams and best practices.

I think — even if you had the correct interconnect — that you will have other issues trying to accommodate both the USB mic and audio interface at the same time. However, that's just speculation so I'll leave it at that. Hopefully some of this information gives you some solid terms to search for and determine a solution that works best.

JYelton
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