external sound card, RCA in out USB

[Katia]

Hello everyone, I apologise for my bad English and my total inability in these matters.
My only requirement is just to record the audio coming out of the mixer (2 RCA left/right) with the PC.

Currently from the REC OUT output of the mixer (2 RCA left/right) I go into the PC's internal sound card (Sound Blaster Z) with the jack connection (1 x 3.5 mm.) The problem, however, is that when listening to the recording, there is ‘noise and disturbance’ that is not acceptable.

I have tried a (RCA) TOSLINK output device connected to the optical input of the PC's existing internal sound card, but I am not satisfied.

I would like to stop using the PC's internal sound card.

I'm looking for an external sound card (in RCA out USB) but can't find it.
What do you recommend without spending a lot?

Thank you all | Katia from Italy

 

[staticV3]

Hi @Katia! Welcome to ASR.

I believe what you're looking for is an audio interface.

Julian Krause on YouTube has lots of in-depth reviews of audio interfaces.

How much are you looking to spend?

 

[Katia]

Hi @Katia! Welcome to ASR.

I believe what you're looking for is an audio interface.

Julian Krause on YouTube has lots of in-depth reviews of audio interfaces.

How much are you looking to spend?

Hi @staticV3 , around 100$, maximum $150

 

[staticV3]

Hi @staticV3 , around 100$, maximum $150

For starters, you could try the Behringer UCA202/UCA222.

Its RCA inputs are a double-edged sword though.

On one hand, you can use regular RCA cables.
On the other hand, if the noise and disturbance that you're hearing is caused by a ground loop, then these will not help you.

In that case, you would need an audio interface with differential XLR/TRS Line in (e.g. Scarlett 2i2), along with special XLR/TRS to RCA cables:


These would filter out the ground loop noise.

Thing is, I'm not aware of any place that reliably sells such cables with the right construction.

Ideally, one would buy an XLR->XLR (or TRS->TRS) cable and manually replace one end with RCA, paying close attention to which wire goes where.

 

[AnalogSteph]

Currently from the REC OUT output of the mixer (2 RCA left/right) I go into the PC's internal sound card (Sound Blaster Z) with the jack connection (1 x 3.5 mm.) The problem, however, is that when listening to the recording, there is ‘noise and disturbance’ that is not acceptable.

You probably have a much more fundamental problem: a ground loop in the setup that is wreaking havoc on unbalanced audio connections. What you are looking for would most likely not help you at all.

Would you mind listing the model of mixer and what all is connected to it? And I mean everything. I bet that there is a second connection to earth/ground lurking in there somewhere. Now you could be throwing a ground loop isolator at the problem but maybe there's a better solution still.

BTW: There's no shame in letting the likes of DeepL help you out here and there.

 

[Katia]

For starters, you could try the Behringer UCA202/UCA222.

Its RCA inputs are a double-edged sword though.

On one hand, you can use regular RCA cables.
On the other hand, if the noise and disturbance that you're hearing is caused by a ground loop, then these will not help you.

In that case, you would need an audio interface with differential XLR/TRS Line in (e.g. Scarlett 2i2), along with special XLR/TRS to RCA cables:
View attachment 403164View attachment 403165View attachment 403166

These would filter out the ground loop noise.

Thing is, I'm not aware of any place that reliably sells such cables with the right construction.

Ideally, one would buy an XLR->XLR (or TRS->TRS) cable and manually replace one end with RCA, paying close attention to which wire goes where.

You probably have a much more fundamental problem: a ground loop in the setup that is wreaking havoc on unbalanced audio connections. What you are looking for would most likely not help you at all.

Would you mind listing the model of mixer and what all is connected to it? And I mean everything. I bet that there is a second connection to earth/ground lurking in there somewhere. Now you could be throwing a ground loop isolator at the problem but maybe there's a better solution still.

BTW: There's no shame in letting the likes of DeepL help you out here and there.

Hi @staticV3 and @AnalogSteph,
I apologise for the delay in reading your kind comment. I am a journalist and just after this post I left for Valencia in Spain to report on the flooding. I found a truly apocalyptic scenario!

First of all, thank you for your valuable comments.

I will give you a further indication: the 'noise' during recording is not caused by the mixer's RCAx2 output, but by the PC's internal sound card. Because "to understand" I did a test. I connected, the same RCAx2 output and with the same cable, to the line input of another mixer and the sound was clean.

@AnalogSteph the mixer Is this https://www.dnrbroadcast.com/airence-usb
and use the REC OUT output (the USB connection is used with another PC for broadcasting).
I had the grounding of the electrical system checked and the values were good

You need something that,
receives the analogue audio from the mixer and then sends it to the PC, preferably with USB (without using the internal sound card) or with a Toslink optical cable (using the internal sound card)

Thanks again and have a good weekend everyone

 

[AnalogSteph]

I apologise for the delay in reading your kind comment. I am a journalist and just after this post I left for Valencia in Spain to report on the flooding. I found a truly apocalyptic scenario!

I'll believe that right away. From what I hear it seems like the flooding we had in parts of Germany about 2 years ago but on a much bigger scale.

@AnalogSteph the mixer Is this https://www.dnrbroadcast.com/airence-usb
and use the REC OUT output (the USB connection is used with another PC for broadcasting).

From here:

power supply

Every Airence unit, Main and Extender, is individually powered by a 12V switched-mode power supply.

That looks awfully IEC Class I to me.

So I reckon there's a ground loop between the mixer and PC, which is wreaking havoc on your unbalanced audio connection. That's a systemic problem and not the soundcard's fault, much like I suspected. Not having any more (impedance-)balanced outputs on a mixer like that is a bit of a dumb design, especially since 1/4" TRS jacks don't take up any more space on the back panel than RCAs and the few extra parts required cost cents. They would still be useful as unbalanced outputs if you were to plug in some TRS to RCA cables, so it's not like any functionality would be lost.

You could pursue either of two avenues:

1. Install a ground loop isolator (audio isolation transformer) between the mixer and PC input. (Note, they cannot typically drive any major cable lengths on the output side. Also, with any kind of magnetics you tend to get what you pay for. I don't know what's available for you down there but around these parts I might buy an "IMG STAGELINE FGA-102". This may be similar electrically to the trusty Behringer HD400, so if you don't mind getting matching cables - 2 pcs. RCA to 1/4" TS and 3.5 mm stereo to 2x 1/4" TS -, you could also use one of those. I hope the recording output is happy driving a 600 ohm impedance, which is the one downside of this kind of transformer. It can drive a modest length of cable in return, I would say maybe 1.5 m and not a lot more. Actual 10/20 kOhm isolation transformers tend to be so sensitive to capacitive loading that they pretty much have to live inside the device with the input; in return you can get better common-mode rejection with these.)
2. Run a - presumably DIY - unbalanced to balanced cable into an audio interface of your choice, as suggested by @staticV3 in post #4. I would recommend the "old" Focusrite Scarlett 2i2 3rd gen that's on clearance right now then, though if need be the more basic Swissonic UA-2x2 ought to work alright, too.

 

[Katia]

Thanks @AnalogSteph I have just returned to Italy.
Between tonight or tomorrow I will read you carefully and follow your instructions. Thank you very much.

 

[repsych]

Hello everyone, I apologise for my bad English and my total inability in these matters.
My only requirement is just to record the audio coming out of the mixer (2 RCA left/right) with the PC.

Currently from the REC OUT output of the mixer (2 RCA left/right) I go into the PC's internal sound card (Sound Blaster Z) with the jack connection (1 x 3.5 mm.) The problem, however, is that when listening to the recording, there is ‘noise and disturbance’ that is not acceptable.

I have tried a (RCA) TOSLINK output device connected to the optical input of the PC's existing internal sound card, but I am not satisfied.

I would like to stop using the PC's internal sound card.

I'm looking for an external sound card (in RCA out USB) but can't find it.
What do you recommend without spending a lot?

Thank you all | Katia from Italy

Hello everyone, I apologise for my bad English and my total inability in these matters.
My only requirement is just to record the audio coming out of the mixer (2 RCA left/right) with the PC.

Currently from the REC OUT output of the mixer (2 RCA left/right) I go into the PC's internal sound card (Sound Blaster Z) with the jack connection (1 x 3.5 mm.) The problem, however, is that when listening to the recording, there is ‘noise and disturbance’ that is not acceptable.

I have tried a (RCA) TOSLINK output device connected to the optical input of the PC's existing internal sound card, but I am not satisfied.

I would like to stop using the PC's internal sound card.

I'm looking for an external sound card (in RCA out USB) but can't find it.
What do you recommend without spending a lot?

Thank you all | Katia from Italy

Ciao Katia, I have used the NAD PP3 for that process. It may be available on the second hand market. Mine is ten years old cost US$60.

 

[Katia]

Ciao Katia, ho usato il NAD PP3 per quel processo. Potrebbe essere disponibile sul mercato dell'usato. Il mio ha dieci anni e costa 60 $.

thanks for the advice @repsych
I searched but the PP 3 model is no longer available. On the NAD website there is the PP 4 model, which costs about $250, however.

 

[Katia]

I'll believe that right away. From what I hear it seems like the flooding we had in parts of Germany about 2 years ago but on a much bigger scale.


From here:

That looks awfully IEC Class I to me.

So I reckon there's a ground loop between the mixer and PC, which is wreaking havoc on your unbalanced audio connection. That's a systemic problem and not the soundcard's fault, much like I suspected. Not having any more (impedance-)balanced outputs on a mixer like that is a bit of a dumb design, especially since 1/4" TRS jacks don't take up any more space on the back panel than RCAs and the few extra parts required cost cents. They would still be useful as unbalanced outputs if you were to plug in some TRS to RCA cables, so it's not like any functionality would be lost.

You could pursue either of two avenues:

1. Install a ground loop isolator (audio isolation transformer) between the mixer and PC input. (Note, they cannot typically drive any major cable lengths on the output side. Also, with any kind of magnetics you tend to get what you pay for. I don't know what's available for you down there but around these parts I might buy an "IMG STAGELINE FGA-102". This may be similar electrically to the trusty Behringer HD400, so if you don't mind getting matching cables - 2 pcs. RCA to 1/4" TS and 3.5 mm stereo to 2x 1/4" TS -, you could also use one of those. I hope the recording output is happy driving a 600 ohm impedance, which is the one downside of this kind of transformer. It can drive a modest length of cable in return, I would say maybe 1.5 m and not a lot more. Actual 10/20 kOhm isolation transformers tend to be so sensitive to capacitive loading that they pretty much have to live inside the device with the input; in return you can get better common-mode rejection with these.)
2. Run a - presumably DIY - unbalanced to balanced cable into an audio interface of your choice, as suggested by @staticV3 in post #4. I would recommend the "old" Focusrite Scarlett 2i2 3rd gen that's on clearance right now then, though if need be the more basic Swissonic UA-2x2 ought to work alright, too.

Thank you @AnalogSteph for the detailed explanation

Summarizing to confirm that I have understood:

1. I purchase IMG Stageline FGA-102 which I connect to LineIN (left/right) with 2 RCA cables (maximum 1 meter) from the mixer output;
2. I purchase Swissonic UA-2x2 (or Scarlett 2i2 3rd gen) which I connect with these 2 cables (rca from lineOUT left/right of IMG Stageline FGA-102 and Mono jack Ø 6.3 to Swissonic UA-2x2 combo input)
3. Then I use a USB cable from the Swissonic UA-2x2 to the PC and receive on the PC the audio from the mixer (without using the 2 Line outputs 6.3 mm balanced jack of the Swissonic UA-2x2)

Do I understand this correctly?

 

[Randyman...]

If you want to keep it simple, and the sonics from the current PC setup are acceptable minus the ground-loop noise, then the IMG Stageline FGA-102 (or any good galvanically isolating RCA transformer) is likely to solve most of your problem by itself.

Re-reading, it appears @AnalogSteph was likely suggesting the transformer on it's own (his #1) - not in conjunction with a USB interface (his #2).

 

[Katia]

If you want to keep it simple, and the sonics from the current PC setup are acceptable minus the ground-loop noise, then the IMG Stageline FGA-102 (or any good galvanically isolating RCA transformer) is likely to solve most of your problem by itself.

Re-reading, it appears @AnalogSteph was likely suggesting the transformer on it's own (his #1) - not in conjunction with a USB interface (his #2).

Thanks @Randyman... but only with the IMG Stageline FGA-102 maybe I could solve only for the audio that the PC receives from the mixer.
Instead I would like to solve also the problem of the audio “with noises” that the mixer receives from the PC. For this maybe better to also buy Swissonic UA-2x2 (or Scarlett 2i2 3rd gen) so I can use the USB connection of the PC

Before placing the order, I am waiting for @AnalogSteph to conform to me the products mentioned in my previous comment

 

[AnalogSteph]

Would it be possible for you to use two of the microphone inputs for the PC? If not, you'd probably be best off skipping the audio interface altogether and just buying two FGA-102s, one for each direction. (Or two HD400s with some of the RCA to 6.35 mm TS cables you listed.)

So cabling would be as follows:
Mixer rec out L/R --> stereo RCA cable --> FGA-102 #1 LINE IN L/R --> FGA-102 #1 LINE OUT L/R --> stereo RCA to 3.5 mm cable (<= ~1.5 m) --> SB Z Line-In
Mixer (RCA) input used for computer <-- stereo RCA cable (<= ~1.5 m) <-- FGA-102 #2 LINE OUT L/R <-- FGA-102 #2 LINE IN L/R <-- stereo RCA to 3.5 mm cable <-- SB Z Front/Headphone Out

Or for Behringer HD400s:
Mixer rec out L/R --> 2 pcs. RCA to TS cable --> HD400 #1 INPUT 1/2 --> HD400 #1 OUTPUT 1/2 --> stereo TS to 3.5 mm cable (<= ~1.5 m) --> SB Z Line-In
Mixer (RCA) input used for computer <-- 2 pcs. RCA to TS cable (<= ~1.5 m) <-- HD400 #2 OUTPUT 1/2 <-- HD400 #2 INPUT 1/2 <-- stereo TS to 3.5 mm cable <-- SB Z Front/Headphone Out

Your SB Z is basically adequate (2 Vrms in and out, high input impedance, decent/good dynamic range), I would only look into an audio interface if the mixer routinely outputs levels high enough to clip the input and there is no other way to avoid this. According to its specs, it's got a nominal output level of +6 dBu, and if I'm not mistaken this should be at -9 dBFS so it could go up to +15 dBu (~4.35 Vrms, almost certainly 6 dB more than the input will accept).

You could obviously try writing to DNR's support inquiring whether they're got any more elegant solutions (I can't imagine you're the first to have this particular problem), this may take a while though as I imagine they'd be closed for the weekend now.

 

[Katia]

Thank you, very clear.

To better evaluate: in my previous comment I indicated another solution (following Your previous directions) that I like better because I would enter the PC with the USB

Should I decide to use that previous solution, can you confirm or correct the 3 points I indicated?

Thank you @AnalogSteph

 

[Katia]

Would it be possible for you to use two of the microphone inputs for the PC? If not, you'd probably be best off skipping the audio interface altogether and just buying two FGA-102s, one for each direction. (Or two HD400s with some of the RCA to 6.35 mm TS cables you listed.)

So cabling would be as follows:
Mixer rec out L/R --> stereo RCA cable --> FGA-102 #1 LINE IN L/R --> FGA-102 #1 LINE OUT L/R --> stereo RCA to 3.5 mm cable (<= ~1.5 m) --> SB Z Line-In
Mixer (RCA) input used for computer <-- stereo RCA cable (<= ~1.5 m) <-- FGA-102 #2 LINE OUT L/R <-- FGA-102 #2 LINE IN L/R <-- stereo RCA to 3.5 mm cable <-- SB Z Front/Headphone Out

Or for Behringer HD400s:
Mixer rec out L/R --> 2 pcs. RCA to TS cable --> HD400 #1 INPUT 1/2 --> HD400 #1 OUTPUT 1/2 --> stereo TS to 3.5 mm cable (<= ~1.5 m) --> SB Z Line-In
Mixer (RCA) input used for computer <-- 2 pcs. RCA to TS cable (<= ~1.5 m) <-- HD400 #2 OUTPUT 1/2 <-- HD400 #2 INPUT 1/2 <-- stereo TS to 3.5 mm cable <-- SB Z Front/Headphone Out

Your SB Z is basically adequate (2 Vrms in and out, high input impedance, decent/good dynamic range), I would only look into an audio interface if the mixer routinely outputs levels high enough to clip the input and there is no other way to avoid this. According to its specs, it's got a nominal output level of +6 dBu, and if I'm not mistaken this should be at -9 dBFS so it could go up to +15 dBu (~4.35 Vrms, almost certainly 6 dB more than the input will accept).

You could obviously try writing to DNR's support inquiring whether they're got any more elegant solutions (I can't imagine you're the first to have this particular problem), this may take a while though as I imagine they'd be closed for the weekend now.

Whereas if I follow this advice instead, I have to order:

n°02 Behringer HD400 (this)

n°02 one stereo jack (TRS) 6.3 mm <> dual RCA cable (this)

n°02 dual jack (TR) 6.3 mm <> one stereo jack (TRS) 3.5 mm. (this)

Right? @AnalogSteph

 

[AnalogSteph]

To better evaluate: in my previous comment I indicated another solution (following Your previous directions) that I like better because I would enter the PC with the USB

The problem is that you would be no better off doing that. As long as the mixer and PC are disagreeing about their respective ground potentials, the unbalanced connection back to the mixer is always going to be problematic, no matter whether the audio is coming from an internal soundcard or an external USB audio interface. Even in the other direction, using the audio interface only helps you when you've got the right cabling to go with it that most likely is not an off-the-shelf item (as described in post #4).

Whereas if I follow this advice instead, I have to order:

n°02 Behringer HD400 (this) V

n°02 one stereo jack (TRS) 6.3 mm <> dual RCA cable (this) X

n°02 dual jack (TR) 6.3 mm <> one stereo jack (TRS) 3.5 mm. (this) V

Right? @AnalogSteph

The middle item is incorrect. You need two of these instead (one 5ft/1.5m max, one as long as you like).

Should you ever decide to get an audio interface later, you can just keep the HD400s and everything on the mixer side, just the two 3.5 mm cables would have to make room for four of these.

Looks like you could order at least the HD400s from here. They also have plenty of Cavi RCA - Jack 6,3mm and Cavi RCA - Jack 3,5mm to choose from, now that you know what you need.

(Thankfully I know just about enough Italian to get around on websites as a result of my italopop affinity, which always is kind of an anomaly in my collection. A lot of that is quite indie... and then there's my 6 Annalisa albums.)

 

[Katia]

Thank you very much indeed @AnalogSteph for the correction and for everything. Kudos for Your professionalism and accuracy.
Your Italian and choices of Italian music are pleasing.
That website is among the best as value for money, I have already bought many products.
I will proceed with the order and let you know after installing if the problem has been solved.
Thanks again and have a good Sunday

P.S. Thanks also to @Randyman... @repsych and @staticV3

 

[Katia]

hello @AnalogSteph
The material has arrived, I have connected everything and .... THE NOISE IS GONE !!! Thank you!!!
But now I realised that compared to your instructions I made a mistake: the audio coming out of the PC to the mixer was not connected to output B (Headphone Port) but to output C (Front L / R) of the sound card. See attached screenshot.
Can I leave it like this, or is output B (Headphone Port) preferable?

Secondly, in doing some careful testing I noticed that the mixer (this https://www.dnrbroadcast.com/airence-usb), even with all channels switched off and/or down, has a steady hum with a peak every 4/5 seconds! Could it be because of the poor power supply that you have already pointed out in a previous comment!
What could I plug in before plugging in the power supply?

 

[AnalogSteph]

The material has arrived, I have connected everything and .... THE NOISE IS GONE !!! Thank you!!!

Unsuprisingly so, but it's always good to know that theory and practice line up.

Can I leave it like this, or is output B (Headphone Port) preferable?

I'd generally prefer the headphone output. It should be driving the HD400 with ease which may not be quite the same with the line-out, and its output impedance is lower which is always a good thing when driving transformers.

Secondly, in doing some careful testing I noticed that the mixer (this https://www.dnrbroadcast.com/airence-usb), even with all channels switched off and/or down, has a steady hum with a peak every 4/5 seconds!

Please explain where exactly this hum occurs. Is it in the PC recording or the monitoring setup or headphones or what? (You might have yet another ground loop going outside of what you just fixed, or a 3.5 mm cable with a bad ground connection.) Is there any change when unplugging the USB?

Even the common-mode rejection of a HD400 has its limits should one side have a ground potential that's at like half the mains voltage. I don't see how that would be the case here though. I assume the PC is a regular old desktop / tower PC that takes the same IEC power cords as the mixer?

You wouldn't happen to have a multimeter around...? Doesn't have to be anything fancy, you can get a plenty decent unit for 20-30€ or something and pretty much the most basic DMM would do here.