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I'm trying to get a multipurpose audio setup going on my PC which could include but isn't limited to audio recording and VOIP (gaming, streaming, skype, etc.).

I have a Focusrite Scarlett 6i6 pre-amp/mixer with an Audio Technica AT2035 plugged into it. I'm trying to find a good balance between microphone gain, mixer output, and PC settings to get proper audio levels with good sound which would include reducing background noise and electronic noise from the PC.

Since games and other devices don't support ASIO for their audio input I had the idea to take the signal from a physical line out on the 6i6 and plug it into the line in on my PC.

This lead me to get the capabilities I was looking for and now I'm trying to get the audio levels just right and don't know what equipment or software I need.

What I've done is turn down the line In level in Windows to reduce electronic noise and turn down the microphone gain to reduce background noise. This results in a nice but quiet signal. I found that plugging in my headphone amp between the pre-amp and the line in input on the PC helped significantly but there still isn't quite enough power.

Should I get a full blown amp? A more powerful headphone amp? Am I going about this completely the wrong way and there is a software based solution that can solve my problem?

Details on how the Scarlett Works (from what I can tell)

The Scarlett does indeed appear as a standard line in device on the PC. This can act as an audio input for all sorts of applications.

The downfall of using this approach is that since I'm only inputting the audio of a single microphone the audio comes through only on the left channel - enter some of the nicer features of the Scarlett.

The Scarlett includes mixing software for all its various inputs which then lets you route any combination of the inputs to any combination of outputs. This allows me to route the input from my single microphone into both left and right channels.

These outputs can be leveraged digitally through USB as ASIO devices (from what I can tell) and software such as FL Studio can detect and use them, but various other softwares seem to not be able to leverage these as they aren't identified as "recording devices" in Windows which is what the other softwares seem to be looking at.

Enter my fix - routing the mix to a physical output allows me to physically connect the line out on the Scarlett to the line in on my PC getting me the mixed audio I am looking for.

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...and turn down the microphone gain to reduce background noise...

That's patently counterproductive. The gain on a solid-state mic preamp should always be set as high as possible without clipping; that's the whole point of the preamp. In particular, the lower you set the gain, the higher the effective noise level will be, because any boost later on will amplify not only the mic signal but also all noise introduced in earlier circuitry stages.

However, a decent large-diaphragm mic has so much output that even with the preamp set up way too low there really shouldn't be much electronic noise. Is it perhaps something else you mean by “background noise”? CPU Fan noise or something like that? Obviously, the correct way to deal with such issues (apart from, making the environment quieter!) is to place the mic better, perhaps talk closer with a pop screen. — If you're in a really high-noise environment, then a large-diaphragm mic is not the ideal choice; supercardoid small-diaphragm condensers or dynamic mics can give you much better signal-to-background ratios; that'll generally outwight the superiority of the large-diaphragm's sound.

Next... obviously, this thing with plugging the signal to the analogue line in of the PC sound card is a really rather ugly hack. Are you sure you can't properly use the Scarlett as an outboard sound card for all your applications? Many comparable interface do that just as well as the can do low-latency ASIO.

If you must use the line in, you should turn up the Scarlett's output as high as possible, and then again balance the line in so it just doesn't clip yet. Only if it clips even at the lowest gain setting, turn down the 6i6 output.

All that done, you should get a usable level to work with, and noise shouldn't be too much of an issue either. (If the are strange nasty chirps/burst in the signal: that'll be interference from some switching power supply, picked up through the ground loop you've created by connecting the interface and PC with both USB and line. Solution: best of course, get rid of either of them, but you can also just isolate the line.) Note however that even a clean, well-levelled signal sounds rather quiter than anything you hear in modern recordings / broadcasts: these generally process the signal, mainly with compression and EQs. Switching from a solid-state preamp to a slightly saturated tube model would also help in this regard.

You definitely shouldn't need to plug a headphone amp between the 6i6 and the PC line in, that's ridiculous. If the Scarlett works properly, it should offer plenty enough signal to feed any line input. (And anyway, the main purpose of a headphone amp is not to boost signals but to buffer the headphone impedance.)

  • Regarding the background noise, yes I meant sounds like the CPU fan which is why I called out electronic noise separately. Gain impacts the background (fan) noise while the PC levels impacts the electronic noise is what I've found. – SpartanDonut Apr 4 '15 at 6:09
  • Added an update that further explains my experience with the Scarlett and what it does and how I seem to be able to leverage it. I did manage to get something a lot closer to what I want, by adjusting the mic position to be a bit closer yet, though I still have the headphone amp plugged in and cranked to max. I'll play with this a little more without the headphone amp and see what results I can get. Thanks for all the feedback. – SpartanDonut Apr 4 '15 at 6:18
  • Thinking about it I was trying to solve the wrong problem the wrong way. Let me know if this makes sense - just use a splitter on the mic input so that the single mic gets input into both channels? Then I wouldn't need to do any mixing and the USB signal should be good enough. – SpartanDonut Apr 4 '15 at 7:20
  • Doing research I think the more common term for splitter is probably "Y cable" - it looks like this is probably an ok route to go. – SpartanDonut Apr 4 '15 at 7:37
  • Yeah... simply using both mic inputs in parallel is a rather strange solution too, but I don't see what could go wrong. The mic will see only half of the usual impedance, but since a condenser is active this should make an audible difference. The Scarlett might get confused suppliying both outputs with the same 48V phantom power, but probably it would just work fine. Just make sure you use a Y-cable that actually splits both of the balanced wires – the standard (TRS) kind of Y-cable does not do that, but only sends each of the wires to one of the (unbalanced) outputs. That wouldn't work. – leftaroundabout Apr 4 '15 at 11:45
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Im adding to this, except the room / ambient noise that stuff may produce (cars passing , cpu fans etc) i think you are refering to digital hashing noise, what you said as electronics noise lowering the windows volume will not fix this, this is a largely known issue and there are some ways to only try beating it. Some people never beat it and it has to do with proper grounding and proper electricity signal flow.

I think though that you can be lucky addressing this issue if you use balanced connections at every connection.

This is also a known issue with focusrite.

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