SOUND ON SOUND

[chanyam]

Hope it helped, get back to us when you can.

No worries - I work remote so I can be a bit distracted during my day job :D

[blinddrew]

If you've got an intermittent fault, as it would appear, I'd start by checking the xlr cable, then check how well it's actually connected at each end. Sometimes the manufacturing tolerances can be a bit iffy on cheaper cables.

[Sam Spoons]

Reading back over this a couple of things need clarifying.

You mention using the onboard sound card (Realtek) but also the Presonus via USB?

You mention taking the "mic out" from the Persons into the mic in on the onboard sound card?

a couple of questions :-

Is the computer a laptop or desktop or what?

What are your monitors?

[chanyam]

Reading back over this a couple of things need clarifying.

You mention using the onboard sound card (Realtek) but also the Presonus via USB?
You mention taking the "mic out" from the Persons into the mic in on the onboard sound card?

Ideally (and initially) I had the Presonus AI plugged into my desktop PC via USB cable only. That produced the high pitched whine so then I decided to try using the analog output on my AI to see if if was the A\D converter on my AI that was producing the whine. So, in order to do that, I took the microphone out on the AI and ran that to the mic-in on my desktop PC's on-board sound card (which is a Realtek chipset). This worked - no whine when recording in this way - but not ideal as I don't have a way to monitor the audio now since I'm using the mic out on the AI.

I used the microphone out instead of the main out on the AI because the sound level was low coming out of the main out and if I used the microphone out, I could boost the audio level by turning up the gain on the microphone on the AI.

a couple of questions :-

Is the computer a laptop or desktop or what?

What are your monitors?

I am on my desktop PC. In order to eliminate the possibility of ground loop or interference from multiple monitors, I switched the AI (via USB) to my laptop running off of battery. Recording this way still produced the whine.

My laptop, FWIW, is a Microsoft Surfacebook (first gen) and I use the built-in display (no docking stations).
For my desktop PC, I have two 24" Dell Ultra Sharp monitors. I don't know the exact model numbers.

Hopefully all of that made sense :)

[chanyam]

If you've got an intermittent fault, as it would appear, I'd start by checking the xlr cable, then check how well it's actually connected at each end. Sometimes the manufacturing tolerances can be a bit iffy on cheaper cables.

I've unplugged and re-plugged the XLR at both ends a couple of times and tried my best to make sure that both connectors were seated well, but its not made a difference thus far. I've ordered a Lyxpro XLR cable to see if that solves the issue.

[ef37a]

If you've got an intermittent fault, as it would appear, I'd start by checking the xlr cable, then check how well it's actually connected at each end. Sometimes the manufacturing tolerances can be a bit iffy on cheaper cables.

Yup, and I would run the same 'silent' test sans mic, phantom power on and tap the AI moderately hard with fingers on and around the top by the XLR. You might you see have a 'dry' solder joint in the earth circuit causing the HF AC from the 48V DC-DC converter to break through.
If no show repeat the exercise with mic connected but this time tap mic (this will of course cause alarming spikes in the signal but no harm. Can you also beg or borrow a dynamic mic? The Behringer XM8500 is only about £15 but is remarkably good and it is always handy to have a spare mic.

Dave.

[Sam Spoons]

I'm a little confused, you refer to the 'microphone out' from the Presonus but it doesn't have one, do you mean the 'Phones" output? If so what kind of cable are you using?

Are you in the US? If so is your desktop computer earthed/grounded properly? The kind of noise you are experiencing sounds typical of an ungrounded system or possible a 'pin 1 problem'

When I mentioned monitors I meant monitor speakers, sorry, my bad I should have made that clear.

[chanyam]

If you've got an intermittent fault, as it would appear, I'd start by checking the xlr cable, then check how well it's actually connected at each end. Sometimes the manufacturing tolerances can be a bit iffy on cheaper cables.

Yup, and I would run the same 'silent' test sans mic, phantom power on and tap the AI moderately hard with fingers on and around the top by the XLR. You might you see have a 'dry' solder joint in the earth circuit causing the HF AC from the 48V DC-DC converter to break through.
If no show repeat the exercise with mic connected but this time tap mic (this will of course cause alarming spikes in the signal but no harm. Can you also beg or borrow a dynamic mic? The Behringer XM8500 is only about £15 but is remarkably good and it is always handy to have a spare mic.

Dave.

Holy hell! I did both silent tests again and the first test (no mic) didn't produce any sounds or change when tapping over the XLR port. The second (with mic) was a different story. When I first started the recording, the whine was there. As I tapped, it went away. It slowly started coming back so I started tapping again and this time it went away and stayed away - so I guess that's that. Crappy XLR cable. The LyxPro cable should be arriving today. Thanks everyone!!

[chanyam]

I'm a little confused, you refer to the 'microphone out' from the Presonus but it doesn't have one, do you mean the 'Phones" output? If so what kind of cable are you using?

Are you in the US? If so is your desktop computer earthed/grounded properly? The kind of noise you are experiencing sounds typical of an ungrounded system or possible a 'pin 1 problem'

When I mentioned monitors I meant monitor speakers, sorry, my bad I should have made that clear.

Gah! You're confused because I am bumbling over terms as I pick this stuff up :). You're 100% correct, everywhere I said "mic-out on the AI" I mean "headphone out on the AI". Apologies! So when using the 1/4" TRS adapter to the 1/8" TRS cable that came with my headphones into the mic-in on my on-board sound card.

Yes, I'm in the states. My desktop PC has the 3 prong grounded plug, but this is also my work PC and my work requires a boatload of peripherals, so I am using something like 3 power strips and 4 different outlets. This is why I did the test on my SurfaceBook Pro running off of battery - to try and remove ground loop as a culprit. With the SurfaceBook setup, I had the laptop, the AI plugged into it via USB and that's it and was still getting the whine.

I don't have speakers - I use headphones (either via headphone out on the AI or USB from the PC)

Thank you for all the patience and wisdom these past few days!

[Sam Spoons]

:thumbup: Hopefully the new cable will sort the issue. Please keep us posted.

[chanyam]

If you've got an intermittent fault, as it would appear, I'd start by checking the xlr cable, then check how well it's actually connected at each end. Sometimes the manufacturing tolerances can be a bit iffy on cheaper cables.

Yup, and I would run the same 'silent' test sans mic, phantom power on and tap the AI moderately hard with fingers on and around the top by the XLR. You might you see have a 'dry' solder joint in the earth circuit causing the HF AC from the 48V DC-DC converter to break through.
If no show repeat the exercise with mic connected but this time tap mic (this will of course cause alarming spikes in the signal but no harm. Can you also beg or borrow a dynamic mic? The Behringer XM8500 is only about £15 but is remarkably good and it is always handy to have a spare mic.

Dave.

Holy hell! I did both silent tests again and the first test (no mic) didn't produce any sounds or change when tapping over the XLR port. The second (with mic) was a different story. When I first started the recording, the whine was there. As I tapped, it went away. It slowly started coming back so I started tapping again and this time it went away and stayed away - so I guess that's that. Crappy XLR cable. The LyxPro cable should be arriving today. Thanks everyone!!

Upon further consideration, I wonder if I have come to the correct conclusion. If the issues is actually the XLR cable, then why did going from the AI's headphone out to the sound card's mic-in work? If the issue is in the XLR cable, then shouldn't I hear the whine whether I go directly to the sound card or via USB?

To be clear (as I've already mucked a few things up in this thread :D ) -

When I say 'go directly to the sound card', what I mean is that I am using the headphone out on the AI to the sound card's mic-in and then in OBS I'm choosing the 'Realtek line-in' as my sound source. I'm still plugged into USB, but in this case, its just to provide power to the AI. In this scenario, I don't hear the whine.

When I say 'via USB', what I mean is that I am only connected to the desktop PC via USB and in OBS I am choosing the 'Presonus Studio24c line1/2' as my sound source. In this scenario, I do hear the whine.

If the XLR cable is the issue, it seems its earlier in the signal chain than either using headphone out or USB out for the audio, so I should hear the whine either way right? So does the fact that I don't hear it using the headphone out method mean that its not the XLR despite the fact that tapping the microphone makes the whine go away?

[blinddrew]

If you just hold, rather than tap, the XLR barrel (i.e. the metal bit) does that make the whine go away?

[James Perrett]

I'm still not totally convinced that the problem is the cable - it could well be inside the Presonus. Intermittent problems like this can be difficult to track down but at least you seem to be able to get it to come and go by tapping which confirms that it is a bad connection somewhere.

[chanyam]

So, as I guess I should have expected, its not very consistent, but here are some of the things I've observed after multiple recordings:

* sometimes holding and then releasing XLR barrel makes the whine go away
* I'm not sure why this didn't work before, but now removing and re-connecting the XLR will sometimes make the whine go away (but not always)
* when I hear the whine and then wiggle the XLR barrel in the input, the whine stutters in and out
* Now, unlike before, I sometimes get a recording that starts with a whine (until I fiddle around with something that makes it go away) and sometimes the recording starts out with no whine straight off.

This is most certainly progress as I can get the whine to go away, but its pretty frustrating that I don't know when its there or not or when I need to fiddle with something to make it go away. Maybe there's some way to real-time monitor the audio OBS is capturing - I'll have to look it up.

I bought this interface open-box from Pro Audio Star so maybe I'm just paying for being a cheap-ass :)

[chanyam]

I'm still not totally convinced that the problem is the cable - it could well be inside the Presonus. Intermittent problems like this can be difficult to track down but at least you seem to be able to get it to come and go by tapping which confirms that it is a bad connection somewhere.

well, the lyxpro cable is supposed to arrive today so I guess we'll be able to confirm the XLR cable theory soon enough :)