Connecting REL sub to Uniti Nova

Do not just shove the wires into the back of the Nova.
It is possible to buy "piggy-back" banana plugs, where you can plug multiple connections in. 
However, Naim discourage the use of plugging in anything other than Naim speaker cables as the amps are (or used to be) designed to use the speaker cable of the correct capacitance, which is thrown out by plugging in other equipment.
If you must use high level into your sub, it's better to plug in at the speaker end.
Otherwise use the low level inputs.
I doubt having L-R will make any difference. The low levels are virtually non directional and both channels "usually" carry the same bass anyway. Even if the bass sound moves from speaker to speaker, it's only the very deep lows that are handled by the sub anyway.

The traditional Naim approach, as Blythe says, is to connect to the speaker terminals, not the amp terminals. This means splitting the Neutrik cable so that two wires connect to one speaker, and one to the other. 

However, my dealer, who is a long standing Naim and Rel dealer, insists that this is unnecessary, and connection at the amp end is fine. Either way, the best connection would probably be to solder the thin Neutrik wires into the same bananas as the main speaker cables. Piggyback banana plugs would be another (easier) option. 

The single low level terminal sounds odd to me, I would avoid it if you can. 

It’s very simple. For a high level connection, connect to the back of the speakers. For a low level connection use the two sub out RCA connections on the back of the Nova. 

can you not get a cable that is two phono to one so you can use the summed low level output form the nova?

Yours for 99p.

You should ONLY use one of those (or a Y cable for that matter) IF it incorporates a resistive combiner with an appropriate impedance.

Thanks. For the benefit of neophytes such as myself, what is "a resistive combiner with an appropriate impedance"?  

I did correspond with REL, and one thing they said was that although I could use stacking banana plugs in order to use high level inputs, "NAIM has several different ways of grounding in play right now" and accordingly it would be safest to connect low level.  Any idea what this means?

By "low level" one can assume REL mean the pre-out at pre-amp level.  Apart from the subwoofer interconnect, all you'll need is a stereo to summed mono lead or a stereo to mono adaptor. 

That’s what I said above, but Huge said it needed special resistors. Does it really?

As I understand it that depends on the length of the lead. At least that was Naim’s recommendation for the N-Sub, with a traditional Naim preamp, but maybe it’s slightly different with the Nova. 

hungryhalibut posted:

That’s what I said above, but Huge said it needed special resistors. Does it really?

It does indeed, or you are effectively shorting the left and right line outs together... which may or may not  cause a detrimental effect to the line out stages

AFAIK the resistor were needed when you took the pre-out signal from a Naim power supply - IIRC, it was 100R, which helped avoid instability.  You still needed to be sure that the interconnect was not too long or too capacitive. Naim did sub leads of 5m and 10m length, both with 100R resistors fitted, which I guess is as good a guide as any here.

I don't know about the Nova, but it may have been designed with a long sub i/c in mind - best check with Naim if unsure.

This all seems more complicated than I expected.  I asked a cable manufacturer about this, and here is what they said:

"It's possible that the integrated amp [i.e. my Nova] might be able to run a summed signal out of one of the connectors, especially if they are labelled as subwoofer outs. Might be worth a look. Most sub content these days is center panned anyway. In general you do not want to run two signals into one input, even with a resistor inserted."

I am beginning to think I need a subwoofer with L and R inputs, and not just the single input like the REL has. Ugh.

As I understand it, the single input on your sub is really intended for the .1 channel of a 5.1 or similar AV system, and is effectively a mono input. The suggestion that one channel of the Nova sub out could be connected to it doesn’t sound like a good idea to me, as it will only give you one of the two stereo channels. I think you’d be better off using the high level connection, which is probably going to give you better sound quality in any case. 

The problem with the high level input is that it is extremely inconvenient - would need custom cable to wire the REL to the (banana only) speaker terminals of my speakers because it is apparently not possible or advisable to connect to the Nova, unless stacking bananas would be OK. (Would they?)

I’m sure stacking bananas would work fine. If you want to be purist about it, you may get a better connection by soldering both the main speaker cables and Neutrik cables into the same bananas, which should be a simple enough job for anyone who can solder properly. If I were you I would get some stacking plugs for now, to enable you to get the sub set up and adjusted properly. Chances are you will have to move it around the room to find an optimum location. Once you are happy with the position, you then have the option of cutting the Neutrik cable to length, so that might be the right time to get it soldered properly. 

For what’s it worth I have started using a B.K. sub, (a small scale quality English Hi-Fi manufacturer) and I have found feeding stereo signal level from an output on my 552PS provides significantly better  and tighter results than using a high level output from my amp. I think Naim amps are fussy on their loudspeaker connections...

I know it doesn’t help with OP and their mono input REL... but I thought I’d share... it’s really great to get deep low end without the all the faff of placement and compromising with trying to get this from your main speakers

Apologies if I am barking up the wrong tree, however REL produce a cable called Bassline Blue and specifically a version for Naim amps.

The relevant page on the REL website states:

"What’s In a NAIM? These same benefits are available to most NAIM owners—especially the older, classic models. These units feature an unusual output impedance that is quite complex. REL worked closely with NAIM engineers to model this behavior and arrived at a special circuit built into each NAIM cable that replicates this impedance so that it is safe to run Bassline Blue on early NAIMs. We even sourced a wonderful stackable banana plug that makes it so easy to use the cables, just plug them in to NAIM’s flush-mounted chassis banana sockets and then plug your speaker cables directly into the rear of our stackable banana plug."

I have no idea as to whether or not it is your answer.

ATB,

Mike

Thanks. That quote seems to be focused on older NAIM amps; I wonder if the Nova presents the same issues? Also, as I read it, I think the point is that this "bassline" cable (which is almost as expensive as the REL unit itself) is an upgrade over the standard REL cable, and there's a NAIM-custom version that enables you to use it with older NAIM amps.  The issue i still have is how to connect the REL T/5i to my Nova. It sounds like attaching stacking bananas to the REL Neutrik cable, plugging those into the pre-outs on the Nova, and then plugging my loudspeaker cable into the stacking bananas might work.  However, REL has told me that "NAIM has several different ways of grounding in play right now and accordingly it would be safest to connect low level."  I do not know what this means. 

I would say the advice from REL is a little suspect if given that way.. there is one method of Naim grounding for their devices and that is related to the signal grounding via the preamp powersupply and using one source as absolute the ground feeding the NAC, clearly the NAC PSU grounding is not relevant for integrated products..

The Naim amp / speaker terminals are nothing to do with grounding... but so as to maintain Naim’s level of performance on their amps they are quite specific about speaker cable and speaker impedances (or more accurately reactances) ... it might be the REL subs are interfering with the amp or possibly driving instability.

Low level connection means taking a preamp output to feed the sub, or using a sub signal feed. On the separates for example, the NAC powersupplies have multiple audio outputs, so it’s quite straightforward to feed an alternate amp or sub. Other devices have a dedicated sub signal output.

Simon-in-Suffolk posted:

The Naim amp / speaker terminals are nothing to do with grounding... but so as to maintain Naim’s level of performance on their amps they are quite specific about speaker cable and speaker impedances (or more accurately reactances) ... it might be the REL subs are interfering with the amp or possibly driving instability.

That is presumably why Naim recommended that the N-Sub was connected to the speaker end rather than the amp. They also suggested that this might give better sound quality than a low level connection. 

This conflicts somewhat with my dealer’s advice, which is that connecting a Rel sub to the amp output terminals is the way to do it. He’s been a Naim and Rel dealer for many years, so he should know.