Active speaker issues (Adam Audio TV5)

[fordiebianco]

Dear All,

after the excellent review of the ADAM TV5s I acquired a pair for nearfield duty on my office desk, and indeed, they are lovely. Bit brighter than my LS50s who they are replacing, but certainly an inch more detailed.

Chain: Mac Mini -> USB -> Loxjie D10 v2 -> RCA cables -> TV5

This setup works beautifully, but: under the desk is my gaming rig, a hefty thing with oodles of oomph. As soon as this is switched on, the TVs hum and haw and screetch (mostly depending on what the graphic card seems to be doing).

Any ideas how to isolate them from the electromagnetic spam? This wasn't an issue with my Loxjie A30 amp and the LS50s.

Many thanks for your help

 

[dfuller]

That's interesting... I wonder if it's a ground loop? The solution there would be using a balanced DAC and the XLR inputs on the monitors.

 

[fordiebianco]

Hi,

the gaming rig is not hooked up to the DAC (first thing I tried). Can this be transmitted just though a AC adaptor?

 

[MrPeabody]

The first thing I would do is make certain to place physical distance between the video cable and the RCA cables from the DAC to the self-powered speakers. At the same time I would experiment by moving these two cables closer to each other, to give me insight into whether this is likely occurring due to noise emitted from one cable and picked up in the other, or due to something more sinister, i.e., a group loop. It could turn out that the solution is a better video cable.

If it does not seem to be noise transmitted through space from one cable to the other, then one thing that I might consider at some point is opening up the +5VDC and ground pins somewhere in the USB cable. Since this DAC evidently takes power from USB, you would then need to supply that power using the other USB port on the DAC, and using a powered USB hub. (With some USB hubs, USB is also used for the connection from the power supply to the hub, and in this case, you should be able to leave the hub out and connect the power supply directly to the other USB port on the DAC.)

I'm not confident how useful this would prove to be, but nevertheless it is probably the next thing I would try, if rearranging the cables did not have any beneficial effect, because if this isn't due to noise transferring through space from cable to cable, it is presumably due to noise carried out of the Mac Mini on the two non-data pins/leads of the USB output. While it may be possible to remedy the problem by changing something in the connection between the DAC and the speakers, my preference would be to isolate the DAC from the noise source.

 

[MrPeabody]

Hi,

the gaming rig is not hooked up to the DAC (first thing I tried). Can this be transmitted just though a AC adaptor?

I took a glance at the D10 and unless I missed something, it uses USB as its power source. If the video cable is not reactively coupled through space to the RCA cable, it is likely that video junk is reaching the DAC through the USB cable, but most likely through the power pins (+5VDC and ground) than the two data pins. This is why I suggested eliminating the power path from the Mac Mini to the DAC, which will be made easier by the fact that the DAC has an auxiliary USB port for power delivery. I suspect that this was done because the designers anticipated this very problem.

If you are thinking about the possibility of video noise reaching the speakers directly via the speaker's power connection, I wouldn't rule this out although I think it more likely that it is occurring via the two power pins/leads of the USB connection. It could be some of each. The TV5 uses an internal AC/DC converter (power supply), which doesn't inspire confidence in me, but I would still start from the assumption that it is most likely occurring via the USB connection. Unless it is occurring via coupling of the two cables, which would only likely happen if they are placed in close proximity to each other. I would obtain a good, clean +5VDC power source and connect it to the DAC via that auxiliary USB port, and break the power connection (both +5VDC and ground) in the USB connection from the Mac Mini to the DAC (after playing with the cables to make certain that they aren't simply placed too close together).

 

[cyruz]

First thing I would try, if all is connected to the same power strip, is to separate your audio stuff from the rest (possibly a different power socket).

 

[fordiebianco]

Dear All,

many thanks for your help. I am now powering the ADAMs from a different wall socket, and that already has improved things considerably.

Edit: actually it hasn't. Moving the DAC physically away from the gaming rig hasn't helped either.

Change in pitch is in response to change what's happening on screen (civilization VI) if you're interested.

 

[fordiebianco]

Have now tried different DAC with external AC adaptor, powered by a different wall socket. No change. Will try to exchange display port cable with extra insulation, but am not hopeful.

 

[cyruz]

You may have a ground loop through your main earth. Probably the only way to fix this is to use balanced connections. You can also try to power the DAC through a USB hub, as already advised by MrPeabody, but YMMV.

 

[fordiebianco]

Hi Chaps and Chapettes,

just wanted to feed back that a change to a DAC with balanced connections indeed did the trick. Switched the Loxjie D-10 to a S.M.S.L SU-8 and am now using balanced connectors: hey presto, all is well.

Many thanks for all your help.