You can correct the XLR wiring to lift the shield ground at the power amplifier end of the cable. That should be the correct and final solution. It will require that you modify the wiring on your custom XLR cables.
Low buzzing through speaks
Hello All,
Need some serious help here. So I just (upgraded?) from a Marantz AV8802A to a McIntosh MX122 preamp. I also just got brand new Revel Performa3 speaks all around (5 channel setup). I disconnect everything from the Marantz and then into the McIntosh, connect the speaks and I have a faint buzzing through all 5 speakers (that was not there previously). I have everything plugged into a Furman Elite 20pfi power conditioner which is plugged into a dedicated 20 amp circuit. My power amp is a Simaudio Titan HT200 5 channel. This is not going through the Furman but directly into the other outlet on the same 20 amp line. I even tried plugging the Sim amp into the Furman to see if that helped-no change faint buzz is still there. I have unplugged just about everything, and the buzz is still there. It is very faint and does not get louder when I turn up the volume. Again it is faint and you have to put your ear up to the speaks to hear but it is definitely there. I have tried so many things and nothing gets rid of it. It is not my cable box (I did have that issue previously with the Marantz but as soon as I unplugged the coax from the box it went away so I just bought a coax loop eliminator connected the cable to that and noise was all gone) as I unplugged that and started there.
Any help would be so sincerely appreciated????
Showing 3 responses by sleepwalker65
@kingbr circling back to the interconnect cables between the preamp and power amp, I have a new angle to look into. As you know, XLR plugs have three pins. Two are for the balanced signal, and the third is for the signal ground. You will also note that the XLR connector body (also known as the connector shell) is typically made of metal, and is therefore conductive to electricity. There is a golden rule in electronics to only use one path for any signal. Ground connections are often the most difficult to control, because there are different approaches to grounding. But for the sake of this discussion, let's leave it at the golden rule. Normally we consider the preamplifier in a HiFi system to be the place where all grounds originate. Therefore the other things (such as your power amplifier) should not allow a circuit to form through the shield ground, which is normally also the chassis ground. You will want to also keep the signal ground separated from chassis ground at all points from the preamp to the power amp. The shield is supposed to be electrically connected to only the chassis ground of the preamp. It must not be connected to the XLR connector shell at the power amp, or an undesirable current will flow through the shield, causing that buzzing noise you hear in your speakers. |
Don't know of any specific pre-made cables that would be up to the job, but I'd be surprised if custom / "premium" cable manufacturers would not offer options for ground lift on balanced cables. Considering your technical capabilities, just using RCA interconnects might be the best solution for you. |