Supernait 3 Left Channel Hum

Having a weird issue with a Supernait 3 and was hoping that someone could shed some light on this. I’m getting a hum intermittently out of the left speaker with no sources connected. Sources are a Naim CD player and Naim tuner that are connected with the appropriate 5-pin Naim cables. Through troubleshooting I’ve determined that it doesn’t matter if either source is connected or no sources are connected. At first I was plugged directly into a Panamax power conditioner and thought that was the culprit. Went straight into the wall, still there. Ran an extension cord to a different room/receptacle, still there. Hum does not change with volume. What is really throwing me here is that when the amp is first switched on, there is a slight hum from both channels. Wait for a while and it disappears from the right channel. Unplugging either the positive or negative speaker lead from the amplifier’s left side obviously makes it stop and is gone initially when re-inserted. Then it comes back. No sources connected 5-pin or analog. I did meter about 28 ohms of resistance between the Panamax chassis and the Supernait, so I connected a piece of 16 gauge wire between the ground lugs on each piece and experienced no change. Speaker cables are Audioquest that are premade and measure 0 ohms straight through and speakers measure 6.8 ohms tested through the speaker leads or directly from the binding posts on the speaker. I’ve never had to do this before but I decided to measure resistance at the amp’s output terminals while the amp is powered on and the speaker leads are connected to the speakers. When the right channel is not humming, I measure 40 ohms at those terminals. When the left side is humming, I measured around 110 ohms. Unseating a speaker lead from the left side and re-inserting makes the hum stop and the resistance drop to around 40 and it climbs back up and starts to hum. I’ve been around this stuff for 20+ years and have never seen this. For clarification, this is the first Supernait that I have touched.

Perhaps @NeilS has some idea here.

I do have some limited knowledge of this issue, it’s down to the speaker cables throwing the amplifier into oscillation.
If your left & right speaker cables run parallel to each other - try separating them by 5 - 10cm & see if that helps.

Regards
Neil.

1 Like

I’ll give that a try, thanks. I didn’t want to coil excess speaker cable in a circular bundle too close to power leads and end up with a problem. I’ve never had this issue before and was scratching my head as to how noise was being picked up or introduced post amplification. The towers are placed out at the sides of the cabinet and the speaker cables are laid parallel to the wall and each other behind.
Ellis

Hi
It’s best not to coil cables at all.
Excess speaker cable should be folded back and forth.
:+1:t2: