Apologies in advance, having scoured this forum I am still none the wiser, and haven’t found anything I can accept as substantive, but will try and keep this succinct.
I want to add a REL T5-X to my set up. The Naim variant of the bassline blue is prohibitively expensive so will rely on the supplied REL cabling.
The speaker terminals on the rear of my 250 are the 4mm sockets. My speaker cable is the WitchHat with naim plugs at the amp end, and bananas into the speakers.
Having read the REL manual I would need to affix the red and yellow wires the 4mm sockets and the black to a grounding plug or chassis screw on the amp.
I haven’t pulled the trigger on the sub yet as I’m unsure how integration will be possible.
My questions are:
1, will the bare wires (red and yellow) be able to be accommodated into the 4mm sockets with the naim plugs in place also? Just pull out the plugs and shove the wire into socket with the plug? Will I damage something?
2, there’s no grounding plug or visible chassis screws on the 250 to attach the black wire to - what do I do with the black wire?
Imagine that these 4 connections are on your right and left speakers rather than two ‘sides’ of the amp. So yellow/black to red/black speaker poles on one side, red to red on the other speaker. That’s it.
You can’t just shove bare wires into the sockets and hope that the banana plugs will hold them. If you want to connect at the amp end there’s a more reasonably priced version of the Naim Bassline Blue cable available from Designacable. Alternatively use the Rel supplied cable to attach to the loudspeakers as Bruce suggests. Rel appear to have changed their advice on connecting to Naim amps, suggesting that you should buy 2 subs instead of one because it’s only slightly more expensive than buying one sub plus their Bassline Blue cable!
Connecting to the speakers is a little more fiddly that other options. First, you have to split the outer sheath of the Rel cable so that you can run 2 cables to one speaker, and 1 to the other. Then you have to attach them: the best way to do this will depend on the type of sockets and plugs you have on your speakers and speaker cables.
Thank you. Food for thought. Won’t be going the two sub’s route. The official guidance on the designacable website states “…attach the black wire to which ever of the amplifier’s ground output terminals is convenient; plug the Speakon connector into the sub’s high level input…” my 250DR doesn’t have a ground terminal. Does this just mean put in any of the other two free terminals once the stackable yellow and red plugs are in place?
Appreciate this may be a question for them, and not you.
Seriously, listen to these guys. Hook the wires to your speakers. I tried the route of connecting to the back of my SN3 and all I got was ground loop hum, something terrible. Only way to stop it was connecting to back of speakers. I also started with one REL sub and quickly (a week later) added a second one. Two is where it’s at. Amazing what it does for the sound. Don’t waste your time trying to hook the REL wires to your amp.
A correctly connected sub will not hum when run straight from a Naim amp. It’s better to connect to the speakers, yes, but doing so just to avoid hum is not necessary. That is almost certainly caused by a ground loop somewhere in the system that needs to be addressed. The Naim specific cable from either Rel or Designacable is the best solution for direct connection to the amp.
Connecting one Rel to the speakers is a huge pain…need to slit the wire to stretch to both…and after doing so i had hum. Connecting to speakers does not magically solve a hum problem.
when i used an olive 72 preamp i connected the Rel to the amp with the Bassline blue for Naim cable and it also had hum. However, i cut the black ground wire, extended it with some old speaker cable, and grounded it at the 72 phono ground screw. Zero hum.
with my new 332 this same setup resulted in hum. I fixed it by going back to the original grounding at the amp. Zero hum. This means in this system the Bassline Blue for Naim out of box to the amp works absolutely perfectly.
With Rel you just have to try different things. That’s why there is a rel youtube video for just about every grounding scheme ever created. One of them will probably eventually work perfectly.
I have used a pair of REL subwoofers with NAP 250 and 300. You can connect the sub “hi-level” input to either the amp or the speaker. There are some amps where you must connect to the amp but Naim 250 isn’t one of them. It doesn’t matter if you connect the sub to the amp or the speakers; which ever is the easiest for you. The cable carries virtually no current compared to the regular speaker cables. The Rel has an input impedance of around 100k ohms compared to the speaker which is probably around 8 ohms nominal. This means that the Rel is just sensing the voltage across the speaker or amp terminals. I would not buy any special or upgrade cable because even the standard REL cable is overkill.
For info I contacted rel for my N50 and here are their suggestions which presumably applies to similar Naim amp setups (speaker option is to one speaker only, not both):
“The Naim Nait 50 uses a star grounding system, so you can’t plug the supplied high-level cable directly into the back of the Naim, you will most likely experience a ground loop hum via the REL.
Option 1 - Connect the high-level cable to the back of one of your speakers. Connect both the red & yellow (signal cables) to the positive terminal of the speaker, and then the black (ground) signal to the speakers negative terminal. This method negates the star grounding system, as the Naim will use the length of the speaker cable to ground the amp.
Option 2 – We work with a great company called Design-a-cable to make a dedicated cable that is designed to get around the star grounding system which you can order in a custom length to suit. It also has stackable banana plugs, so you can plug your own banana plug directly into the back of these. You can read all about it via the supplied link above.”
They also suggested their own cable if funds allow.
