1 (edited by stanzanim 2018-09-26 09:15:04)

Topic: A/D Noise issue (grounding related?)

The setup is as following
- DAW is a W10 miniITX desktop PC with madiface ASIO USB drivers
- the DAW is also connected to a Panasonic plasma TV via HDMI
- connection is through USB to the RME ADI2 PRO
- the RME ADI2 PRO is in USB mode or preamp mode
- the analogue balanced inputs of the RM ADI2 PRO are connected to the output of a pre phono (Aqvox Phono 2 CI MkII which is a balanced pre phono)
- the analogue balanced outputs of the RM ADI2 PRO are connected to the input of a pair of monoblock amplifiers. Inputs of the monoblocks are single-ended RCA and an adapter xlr2rca is used

Scenario A.
- the USB cable from DAW to RME is disconnected
I can play vinyl without noise in preamp mode (USB mode of course cannot operate)

Scenario B
- the USB cable from DAW to RME is connected
Vinyl playback is affected by low frequency noise in both preamp and USB mode

The DAW and the RME are connected with a two pole (no ground) plugs through the AC/DC adapter
The phono preamp is connected to the AC socket (internal PSU and AC/DC)

Since scenario A works fine I would exclude earthing / grounding issues between the turntable and the phono preamp

I am trying to fix scenario B.

Thank you for your help

DAW: W10 mini PC (i5)
Server: JRiver 30+Dirac+Acon Declick
DAC: RME ADI2 PRO Speakers ATC SCM50ASL

2

Re: A/D Noise issue (grounding related?)

Unclear description:

> Aqvox PH2 mk2

Is that the Aqvox Phono 2 CI MkII? Is see it has Earth connection and a Ground Lift switch.

>  The DAW and the RME are connected with a two pole (no ground) plugs through the AC/DC adapter

And your monitor? Also is that a laptop used as DAW? Does the hum go away when used on battery?

Regards
Matthias Carstens
RME

Re: A/D Noise issue (grounding related?)

What happens to the noise if you connect the rme only to usb (so remove preamp from input to rme)? How are you listening? Headphones? Is there an amp connected? If yes what happens if you disconnect it from the rme?

Vincent, Amsterdam
https://soundcloud.com/thesecretworld
BFpro fs, 2X HDSP9652 ADI-8AE, 2X HDSP9632

Re: A/D Noise issue (grounding related?)

If I remove the preamp (i.e. disconnect the Aqvox from the A/D inputs of the RME) no problem: I can listen digital files w/o noise at all. The noise appears just when I use the A/D inputs with USB connected

I do not use phone output at all

Thanks much

DAW: W10 mini PC (i5)
Server: JRiver 30+Dirac+Acon Declick
DAC: RME ADI2 PRO Speakers ATC SCM50ASL

Re: A/D Noise issue (grounding related?)

MC wrote:

Unclear description:

> Is that the Aqvox Phono 2 CI MkII? Is see it has Earth connection and a Ground Lift switch.

>  The DAW and the RME are connected with a two pole (no ground) plugs through the AC/DC adapter

>And your monitor? Also is that a laptop used as DAW? Does the hum go away when used on battery?

I will try the ground lift switch (I did not try yet indeed)

I do not have a monitor but the DAW (a W10 mini PC) is connected to a panasonic plasma TV by HDMI.

I do not use a battery (it is a desktop PC) but I can try with a laptop

thanks

DAW: W10 mini PC (i5)
Server: JRiver 30+Dirac+Acon Declick
DAC: RME ADI2 PRO Speakers ATC SCM50ASL

Re: A/D Noise issue (grounding related?)

Try a headphone connected to the ADI just for testing. The ground loop likely happens between the TV (via HDMI shielding) and the PC, both of which are connected via 3-prong power-plugs (earth/safety line).

Re: A/D Noise issue (grounding related?)

Update: I disconnected the HDMI from TV to DAW. No joy
I will try the headphone output tonight
Thanks

DAW: W10 mini PC (i5)
Server: JRiver 30+Dirac+Acon Declick
DAC: RME ADI2 PRO Speakers ATC SCM50ASL

Re: A/D Noise issue (grounding related?)

When you disconnect the TV, how did you listen to the noise? If you connected speakers that use a 3-prong power-plug then you are back to a ground-loop. Sometimes it can help to switch wall sockets or to use a multi-socket if multiple earth connections are present. What happens is that the travel distance for the different noise signals are shifted slightly so that they may either amplify or attenuate due to phase differences. I can reproduce this by using different sockets for my computer display when I create a loop in combination with powered speakers and PC.

If you are using balanced cables for your speakers then you can try to break/disconnect shielding on one side of the cable. On XLR cables this is pin 1.

Re: A/D Noise issue (grounding related?)

Network cable (LAN) connected to the PC/Notebook/DAW can cause ground loop problems and noise. It is recommended to use UTP network cable (Unshielded Twisted Pair) between network switch and PC/Notebook/DAW.

Re: A/D Noise issue (grounding related?)

The amp itself can also be ground noise sensitive, which I guess is the case, since there is no noise on the headphones when connected to usb and the rest. So the noise comes via the ground from the laptop to the amp, but is not from the RME. As Timur said, removing the ground from the amp or disconnecting ground in the xlr cable might help.

Vincent, Amsterdam
https://soundcloud.com/thesecretworld
BFpro fs, 2X HDSP9652 ADI-8AE, 2X HDSP9632

Re: A/D Noise issue (grounding related?)

Thank you. I will try to disconnect the ground shield at the monoblock end of my single ended cables

DAW: W10 mini PC (i5)
Server: JRiver 30+Dirac+Acon Declick
DAC: RME ADI2 PRO Speakers ATC SCM50ASL