Hi guys, I would like to add one or two Rel T5x subs to my Nait 5si, I have already read all the treads regarding the connections but I still have a doubt. So if I use just one sub I can connect it directly behind the Naim using Designcable’s high level cables and so far everything is ok. My doubt is if I want to connect 2 subs by connecting them directly behind my B&W speakers which are bi-wiring. I attach a photo to help you understand better. Where will I connect the Rel cables? on the high or low terminals? with bananas or swords? Or stripped cable? But there is the AQ jumper. Thanks everyone, please explain it easy.
Hi, if you want to connect to the amp I would talk to Designacable. I imagine they could make up a pair of mono cables, one for each sub.
Alternatively use the cables supplied by Rel with their subs to connect to the speakers. You could put banana plugs on them and connect to the spare banana socket on your speakers.
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perfect, you’re great! So I thought about having some cables made by Designcable but I also read that the standard Rel ones are excellent when connected to the speaker, I just need to shorten them because I will put the subs at the foot of the speaker. So as you say, either I buy banana terminated cables or I put bananas on the stock Rel ones and connect them to the free terminals of the speakers. Right? I wouldn’t want to explode anything 
With the subs close to the speakers I would connect to the speaker sockets using either bananas or spades, whatever is best for your speakers.
I suggest that you keep the cables long at first so that you can experiment and determine the optimum position for the sub. Cut the cable after you have made your final decision on its location.
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designacable rel-twincore-subwoofer-cable-for-dual-stereo-sub-setups
I think I’ll take these, already finished and to be inserted directly into the free connectors behind the speaker
No commercial links in the Hifi Corner please. Thanks.
Sorry I don’t know. Pocture is possible?
That would be a neat solution, although you could just get some banana plugs and put them on the cables that Rel supply with the subs.
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Sounds like you just want to connect each sub to the binding posts on the back of each main speaker in which case, and as others have suggested, you can simply replace the spade connectors on the supplied Rel cable with 4mm banana plugs.
You could also consider making your own cable and keep your original Rel cables unaltered.
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Thanks, these are all possible solutions. The important thing was first of all to understand which connectors to insert the cables behind the speakers. Does the already finished solution require that the red and yellow cables are already joined?
You need to connect both the red and the yellow wires to the positive and the black to the negative, on each speaker. It’s all in the manual - just substitute amplifier for speaker.
I wouldn’t bother buying cables, just remove the spaces and solder on 4mm plugs.
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I’ve contacted mine via the speaker post’s terminal with spade connection ,I tried the amp end but didn’t like the hum it produces so went this way and no hum.
Right sub with right speaker and left sub with left speaker .
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Sorry, was the hum noise audible because you were using the REL series cables or those specifically for Naim?
Using the REL cables
They are not shielded so can pick up other interference from power cords and things , maybe I was unlucky, they do sound a lot better though from the speaker terminal.
I read that the stock Rel cables when mounted behind the amplifier lead to this hum noise. That’s why they created the bassline cable for Naim
Not quite shure on that as I’ve not seen the naim cable from REL so can’t help you on that one sorry.
It is possible that the hum is related to the formation of a ground loop rather than interference. I believe there is some information on the Rel website about how to easily solve that problem. A ground loop can be created when two pieces of equipment are separately connected to the mains power and also connected to each other through a ground wire. In your case the two pieces of equipment are your amplifier and the subwoofer. This can form an electrical circuit which is a closed loop that runs between the two pieces of equipment and then returns through your mains circuit. You can think of that ground loop as a large loop antenna and the hum is caused that antenna picking up the electromagnetic noise in your home usually at the mains frequency of 50 or 60Hz. A potential simple solution is to plug the subwoofer and amp into the same mains outlet to reduce the length of the ground loop, make the “antenna” smaller and reduce the hum. In my experience this works only about 50% of the time. I hope that helps.
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Connecting directly behind the speaker connectors should avoid this. Right?
Not necessarily since you will have a ground loop whether you connect the subwoofers to the amplifier or to the speakers. However, it is possible that the change in the wiring configuration reduces the amount of electromagnetic induction in the loop since you are, in effect, changing the geometry of the “antenna”. I suggest you take a look at the Rel website which does address the issue of ground loop hum and how to eliminate it. To the best of my recollection the solution they suggest is either to “float” the ground to the subwoofer or connect the ground to the chassis of the amp. The former approach breaks the ground loop circuit while the latter probably works by reducing the voltage between the nominal ground on the amp and that of the subwoofer. Again, the Rel website has the details and options and you should look there since my memory is not perfect.
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