Hello all. Looking for some help. I have a Supernait 3 I just got. I use B&W 7 series standmount speakers and a REL T/7x subwoofer, along with a Keith Herron phono pre-amp and a technics 1200 turntable.
When I had my old Arcam 50W amp, I used the Hi-level REL connection and attached the REL with the 3 wires to the binding posts on the amp, grounding it to a black binding post. All was good.
With the NAIM Supernait 3, if I use the REL HI-level connection and ground the REL to the speaker inputs, using stackable bannana plugs, I get a loud hum out of the subwoofer. I tried all that was suggesed on the REL videos:
Disconnecting the ground cable and covering it with electrical tape (no ground ).
Grounding with an RCA from the REL to the amp, to an un-used RCA in on the amp, with the REL ground wire not attached to anything and covered with electrical tape.
Grounding the REL to the ground screw of the Supernait
None of the above works to cancel the hum. In fact when I am doing (1) & (3), the hum from subwoofer stops but I get a very loud hum out of my speakers. I tried plugging the subwoofer into the house outlet using a ground lift adapter and that achieved nothing. My Speakon connection cord for the REL is not in close proximity to any power cord.
I am out of ideas. Anyone else have any? Thank you!
Naim amps don’t have added inductance on their outputs - stability being provided by the speaker cable (see FAQ for more details on this). Hence high level connection of a subwoofer to the amp terminals is not recommended as it can cause all sorts of issues from poor performance, to humming, to even causing the amp to shut-down. With Naim amps you need to connect to the back of the posts on the speakers - that way the amp doesn’t “see” the high level connection.
I use the regular low pass connection from my Rel T5x to my SN2. Less hassle.
If you are getting a hum from the main speakers, you could try the Floating-Chassis switch on your Naim source. I had to change the position on mine when I installed the REL.
I would recommend connecting the REL via a DSpeaker Anti-Mode 8033 S-II.
Not only will this fix the hum issues, it will also correctly align the sub’s output to your room.
Use a short stereo pair of RCA leads from the SN to the Anti-Mode, then a longer RCA cable to the sub.
I have a loan t7x at the moment, using the arrow wireless system, from the SuperNait 3 speaker output as recommended by my dealer. Seems to work fine. I’m guessing the wireless connection removes the load seen by them amp?
The Anti-Mode has the advantage that when you ask it to calibrate itself, it tunes the feed to the sub to control room resonance peaks in the sound (resonance peaks which the sub would otherwise generate).