Annoyng problems with Subwoofer and Superuniti

The yellow needs to connect to the positive on the back of the left speaker, so that you get bass from both channels through the subwoofer. 

Should I open the Rel cable to separate the yellow!!!!!: However, even without the yellow, the bass is deep and big.

 What worries me is that bad noise connected to the pre out: it is difficult to explain, It is similar to those nois in FM radio when the signal is low. You believe that it is appropriate for contact my dealer? Has anyone had similar problems?

Without the yellow connected you will only be getting bass from one channel through the REL. I have no idea about the funny noise with the low level connection, but it's always been my understanding that connecting the REL to the back of the speakers is the best way to connect it.

Anto68 posted:

Hi, I hope that my English is acceptable to all of you.

I encountered a serious problems these days with my SU to which I connected a sub Rel by 4/din-2RCA cable from pre out amp: I heard a annoyng eletrical noise from my speakers at loud volume but at moderate also: lowering the level control from the SUB the noise has disappeared. Then I tried to connect the sub in Hi Level directly to the right Speaker connections and it seems that the problem does not occur.

What' happens with the SU pre/out level? Do you think it possible that the SU pre-out section has serious problems or is it just the electrical incompatibilities between the Lo level circuits of the sub and the SU amp?

 

Its fine to use the loudspeaker high level connections as described by earlier posters.

If you want to use the low level connection, then I would use the sub output phono sockets rather than the DIN pre/out, although I don't know how the internal circuitry differs, if at all.  The other thing to try would be the ground switch which is next to the outputs. If your pre is grounded and the SU switch is set to chassis rather than floating, you may get an earth loop which could explain the noise you mention.

best

David

Anto68 posted:

Should I open the Rel cable to separate the yellow!!!!!: However, even without the yellow, the bass is deep and big.

 What worries me is that bad noise connected to the pre out: it is difficult to explain, It is similar to those nois in FM radio when the signal is low. You believe that it is appropriate for contact my dealer? Has anyone had similar problems?

Unless you're using some kind of DSP device a high level connection, using the yellow wire (as shown in the REL manual) and as HH mentioned, is the way to go. If you follow Naim's recommendation you will strip the cable and connect the RELs wires to your speaker binding posts and NOT at the back of your SU's speaker terminals. There is some debate about this but I strongly suggest you follow Naim's advice. After all they design and build our gear.

David Hendon posted:

 

 The other thing to try would be the ground switch which is next to the outputs. If your pre is grounded and the SU switch is set to chassis rather than floating, you may get an earth loop which could explain the noise you mention.

best

David

this is interesting, I'll do a test

Thank's David

you will strip the cable and connect the RELs wires to your speaker binding posts and NOT at the back of your SU's speaker terminals. There is some debate about this but I strongly suggest you follow Naim's advice. After all they design and build our gear.

 

I know, I read the information, even Richard Dane had warned me.

However open the cable to separate the yellow lead is not easy, I should have it done by a professional technical

Surely all you need is a pair of scissors or a sharp knife? It's no harder than wiring a mains plug. 

Hungryhalibut posted:

Surely all you need is a pair of scissors or a sharp knife? It's no harder than wiring a mains plug. 

From experience I would suggest sharp, tiny scissors over the knife. With the latter, unless you're a surgeon, you risk cutting through the wires.

Wouldn't a decent pair of adjustable wire-strippers be preferable for this job?

Hungryhalibut posted:

Surely all you need is a pair of scissors or a sharp knife? It's no harder than wiring a mains plug. 

Some people are just not comfortable with things like this, me included, so exhortations like this are probably less than helpful.

To the OP, did you select "all outputs" in the speaker submenu on the SuperUniti when you had it connected by DIN?

SJB

I take the point, but it's really very easy. Once you've split the first inch of so of the outer insulation you can usually just pull on the separate wires with one hand and the insulation with the other, and it will simply peel off. 

If that is too scary, perhaps you could smile sweetly at your Hifi dealer? It's only a five minute job. 

Sloop John B posted:

To the OP, did you select "all outputs" in the speaker submenu on the SuperUniti when you had it connected by DIN?

SJB

 

Yes of course, otherwise the sub would not work: noise occurs for both output the pre/out and  sub output phono sockets therefore there should be no differences between these circuits.

This problem should not occur in normal use; when I am at home will try to switch the ground signal. At moment is on chassis

There is only 1 RCA input in Rel model T7 so I use an adaptator 2RCA in 1 RCA to SUB: a low-quality adapter, perhaps this is the problem.

I will use the Hi level connection but I want to be sure that the amp has no faults

Reading old posts, Richard Dane recommended to connect the sub in low level with a  "slugged" cable. What does it mean? I can not find a translation in Italian.

I bought a Naim camble, 180 euro : It is not designed for optimal use?

I think a slugged cable is one in which there is a ferrite ring (or slug) over part of the cable which helps to stop RF signals from being transmitted along the cable from one piece of electronic equipment to another. 

The use of slugs in the pre to sub application is a counsel of perfection and I doubt that it is necessary in most domestic situations. Your Naim cable should be fine, just the way they made it.

best

David

I believe a slugged cable includes a resistor to correct whatever happens when a preamp is required to drive a long cable, rather than anything to do with RFI. If it's a proper Naim cable designed to drive a sub then it will be ok, but if it's a standard interconnect it won't be, unless it's short. 

Changing the SU's earth switch is probably the first thing to try. 

Anto68,

If you are reluctant to strip the yellow wire from the cable, you could run an additional wire between the speakers to attach the yellow wire to the opposite speaker.  Any speaker cable will be fine, nothing heavy or expensive.   At the very least, this could be a cheap, simple experiment to hear what improvement to the sound may be achieved.

Charlie

Amusingly, when I googled "slugged cable" the only remotely relevant answer it pointed me to was HungryHalibut's answer in this thread.

He may well be right. Only Richard can tell us for sure what he meant!

best

David

Anto, the "slugged" sub cable has resistors fitted to make it easier to drive. 

See! See! I was right! Too many years with Naim equipment. 

Ground loop problem.

REL is also eartherd.

You will need an isolating transformer.

If it was a ground loop it would be a 50Hz hum, rather than the type of noise that the OP seems to be hearing. It's a bit hard to speculate, but I don't think you can state confidently that it's a ground loop and therefore an isolating transformer is required. 

Hungryhalibut posted:

If it was a ground loop it would be a 50Hz hum, rather than the type of noise that the OP seems to be hearing. It's a bit hard to speculate, but I don't think you can state confidently that it's a ground loop and therefore an isolating transformer is required. 

It was a mere suggestion

Salient points, please correct me if I'm wrong ...

When connecting to the low level input of the sub via the sub our RCA or the Preamp out DIN:

1  The noise is coming from the main speakers, not the sub
2  The amount of noise is related to the volume setting of the sub not the volume setting of the SU
3  When connecting the sub to the terminals of the speakers, there's no noise problem
4  It's noise not 50/60Hz hum

If the above are true, then I suspect one of the following:
A)  there's a fault on the low level input of the sub
B)  your low level cables to the sub are running very close to a mains cable carrying a noisy mains signal (e.g. from PLAs)
C)  your low level cables to the sub are running very close to the speaker cables
and this issue is injecting noise into the signal path of the SU, just before the power amp.