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Computer noise through system and RME ADI-2 Pro Questions

Holmz

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Two things changed last week.
1) Got the RME ADI-2 Pro in the mail
2) Got a 3mm to RCAs lead to facilitate playing the iPad through the system.

So I hooked up an RME ADI-Pro and it would not record in any quality way.
I spent a day copying the SSD in a MacBook Pro (MBP) and upgrading the OS.
I could get to not sound bad with an Intel NUC running windows.
And a second NUC running Linux I would also not get to record.

I copying the MacBook’s SSD to a new SSD and upgraded the OS.

Then while the SSD was being copied I noticed that there was a lot of computer noise to coming through the system.
So I removed that 1/8” to RCA cable, but the noise was still there on a TV input.
It took removing the USB connecting the RME to MBP for it to go away.

I went out Saturday to get another brand new USB cable, and finally I was able to flash the RME.
Plugged the MBP into the same power strip as the audio gear.
Still heaps of computer noise coming in, and without anything coming in the background SINAD/lever is -45 to -50 dB, so it is not a clean 24 conversion.

Questions are:
  1. How does one prevent the digital computer noises?
    1. (Getting a new MBP battery so I can run it for more than a couple of minutes.)
  2. How does one change the sample rate of the ADI-2 PRO? It is on 44.1kHz, and I would like to go higher on ADC
 

KSTR

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Re.1)
Could you please give detailed info how your gear is connected to each other, to the mains, and to other electronic items? That would help to nail down the key question where the error, the noise generated, manifests itself exactly.

Most typically this would be the analog signal cable(s) from/to the RME. A typical "Ground Loop" issue. Use balanced cabling right from the source, even if that is unbalanced, will mitigate the effect of the offending "balancing current" running along the GND/shield. With balanced, the signal conductors do not see this current.

Re.2)
Not familiar with Macs but obviously the application needs to tell the USB driver the requested sample rate which in turn will tell it to the RME so that it switches to that rate. The moment you click "record" should be the latest possible point in time where this needs to happen.
Is the RME set to auto or USB mode, and clock set to internal?

As a DAC, does the bittest pass (RME offers downloadable files to check the bit depth used)?
 
OP
Holmz

Holmz

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Thanks @KSTR


Re.1)
Could you please give detailed info how your gear is connected to each other, to the mains, and to other electronic items? That would help to nail down the key question where the error, the noise generated, manifests itself exactly.

Most typically this would be the analog signal cable(s) from/to the RME. A typical "Ground Loop" issue. Use balanced cabling right from the source, even if that is unbalanced, will mitigate the effect of the offending "balancing current" running along the GND/shield. With balanced, the signal conductors do not see this current.

230v —> 115v transformer —> Power strip.
Preamp, amp, RME and computer plugged into powerstrip.
Preamp has 2 sets of RCA outputs called line-1, and 1 set of XLRs outputs called line-2

RCAs are going out to the RME’s analogue input, which is not Line-level, but rather are volume controlled.
(And hence, I need to turn the amp off if I want to drive the RME closer to full scale by rotating the volume clockwise.)

the computer is plugged into the same 115v power strip with a short USB connected to the RME.

The noise is not a hum, but a “buzzt… Buzzt, buzzt, buzzt. Buzzt like cell phones used to do near into a car radio. So like 2KHz or something “up there”.
I’ll try cutting a file tomorrow.

There are only XLR outputs from the RME, whereas the inputs are RCAs.
I will get some XLRs tomorrow to connect the RME to the Preamp as a source and then can tell whether there is still there is still computer noise with the RCAs disconnected.



Re.2)
Not familiar with Macs but obviously the application needs to tell the USB driver the requested sample rate which in turn will tell it to the RME so that it switches to that rate. The moment you click "record" should be the latest possible point in time where this needs to happen.
Is the RME set to auto or USB mode, and clock set to internal?

It does not appear to…
When the RME starts up it says “USB Active”
And shows a fixed 44.1kHz on the display.

On OSX there is no provision to set the rate in “system Preferences” “Sounds” but apparently my friend, who is running OSX 12, has a midi setting which has sample rate.



As a DAC, does the bittest pass (RME offers downloadable files to check the bit depth used)?

I did not see those downloads… but I can do this myself as I am intending on ingesting the files into my own s/w once the stuff sounds OK when playing back the recording on computer.
 

Trell

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I did not see those downloads… but I can do this myself as I am intending on ingesting the files into my own s/w once the stuff sounds OK when playing back the recording on computer.
The RME bit test is documented in the manual. When playing one of the test files you’ll get a passed displayed on the units display, if passed, and at what bit depth.

I seem to recall that the download link was available on the product page, but it is in the manual.


 

sq225917

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Do you use home plugs, Internet over mains, or have a router close by?
 
OP
Holmz

Holmz

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The RME bit test is documented in the manual. When playing one of the test files you’ll get a passed displayed on the units display, if passed, and at what bit depth.

I seem to recall that the download link was available on the product page, but it is in the manual.

I suppose I should look at the test file, but I am more interested in recording than playing.


Do you use home plugs, Internet over mains, or have a router close by?

Router in on the other room, with everything connected via WiFi.
so maybe 9 meters and a wall away.
 

NiagaraPete

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) Got a 3mm to RCAs lead to facilitate playing the iPad through the system.
Toss that away and get a lighting to USB. Use the RME as the DAC
 

NiagaraPete

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Not familiar with Macs but obviously the application needs to tell the USB driver the requested sample rate which in turn will tell it to the RME so that it switches to that rate. The moment you click "record" should be the latest possible point in time where this needs to happen.
Is the RME set to auto or USB mode, and clock set to internal? CD
MBP is not a great sound source but can be used. No special drivers needed but to change sample rates you need to do it manually via the midi app. You are much better off using the iPad.

Get one one of these to charge the iPad and plug into iPad and DAC.
 

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Wicky

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Re. 2) Have you opened the Audio MIDI Setup app? You can set your sample rate & bit depth there unless your software supports 'Exclusive Mode' where it will be controlled by the application you are using to generate the output.
 
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Holmz

Holmz

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Toss that away and get a lighting to USB. Use the RME as the DAC

I got the RME mostly to use it as an ADC.


Re. 2) Have you opened the Audio MIDI Setup app? You can set your sample rate & bit depth there unless your software supports 'Exclusive Mode' where it will be controlled by the application you are using to generate the output.

Nope, I have not seen that Audio MIDI Setup App.
Where is that located at?

I also have not really found a lot to use to record. There Is GarageBand, and I can turn off the metronome.
Ideally a recorder with an oscilloscope function would be good,
 
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Holmz

Holmz

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Thanks @Wicky - I got a new MBP changer yesterday and order a new battery for it.
And they had 6m long XLRs, so I got pairs of male and female XLRs.

After the coffee is in me, I’ll make up a set of short XLRs to go to the Preamp.
That should also help by adding a more solid ground to the Preamp via the XLR shell/sheild.

And post coffee I’ll look in Applications/Utilities
 

NiagaraPete

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Nope, I have not seen that Audio MIDI Setup App.
Where is that located at
Finder search audio midi setup. Your iPad is a much better audio source. It’ll switch sample rates for you.
 
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Holmz

Holmz

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Finder search audio midi setup. Your iPad is a much better audio source. It’ll switch sample rates for you.

I am not trying to use the ipad/MBP as a source.
I want to input analogue into the RME and capture the music to a digital file.
 

NiagaraPete

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I am not trying to use the ipad/MBP as a source.
I want to input analogue into the RME and capture the music to a digital file.
Yikes like stealing content?
 
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Holmz

Holmz

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Yikes like stealing content?

Yeah stealing it off my TT.

For instance how is one supposed to go through a DSP process without getting things into the digital domain?
I did not get an Octo DAC8 for an active XO just to have it sit in a box.
But I might move it on.
 

NiagaraPete

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Yeah stealing it off my TT.

For instance how is one supposed to go through a DSP process without getting things into the digital domain?
I did not get an Octo DAC8 for an active XO just to have it sit in a box.
But I might move it on.
Ohhh. Have fun with that. I sold my analog and went streaming.
 
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Holmz

Holmz

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I just finished up the set of XLRs about a foot long.
The RME is now on the shelf on top of the preamp.

There is no apparent noise anymore with the Output XLRs connected to the preamp.
Same MBP as the computer.

The RME’s analogue level went from -45-50 dB(FS) to about -80 dB(FS).

The only problem is the output level on playback and input level on record, so I’ll adjust it on the RME.
 
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