Effect of (short) speaker cable length

If you are doubling up the biwire cable to use as single wire, you may be pushing it even further out of spec in addition to the effect of using short lengths. If I were you, I would get some proper single wire cable and do it right. There are some more flexible alternatives to NACA5. Sometimes, you can use the stiffness of A5 to keep it in place, and if you heat it with a hairdryer you can sometimes bend it and get it to stay in shape. 

Also, is the fireplace in use? Can you run it behind the hearth?

Rob, in my experience, it's always well worth doing this right.  Get the NACA5, go for at least 3.5m per channel - more off possible (it sounds better), and get it properly terminated (i.e. well soldered) with Naim speaker connectors. I run NACA5 around a hearth and its stiffness actually is an advantage as it means once bent into shape it stays that way.

You have a nice system that has cost a fair bit of money.  Don't spoil it by try to cut a corner in such a critical area.

Thanks Richard and Chris,

It sounds like I should be able to wrangle the NACA5 into place after all which is the only reason I didn't use it initially. I can hide excess cable under the cabinet that the kit is in so should I order say 5m rather than the 3.5m minimum?

Rob:  I also have Spendor A7s so you won't be able to use the Naim speaker connectors in the normal manner.  I've had to take them out of the plastic plug box.  Obviously they work fine at the amp end (NAP 250)

I'd be interested if there is anything better to use at the speaker end.

Rob, when we tested different lengths at the factory I definitely preferred 5m over 3.5m of NACA5.

As for what connectors to use the the speaker end, I would choose which ever ones have the most similar metalwork to the speaker sockets - the trick is to get the best metal to metal match between socket and plug.  You may need to ask Spendor to find out what sockets they use and their makeup.

Richard Dane posted:

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As for what connectors to use the the speaker end, I would choose which ever ones have the most similar metalwork to the speaker sockets - the trick is to get the best metal to metal match between socket and plug.  You may need to ask Spendor to find out what sockets they use and their makeup.

In terms of metal makeup, lest Richard’s phraseology leads to detailed technical questions, it is the contact surface that matters, which is often plating, rather than the underlying metal - no need to try to find out what the main structure is made from, nor any intermediate plating layers.  The aim is if possible to use plugs and sockets with the same plating metal, as that will prevent galvanic corrosion at a junction that for good signal transmission relies only on physical pressure of one contact surface against another. The more humid the atmosphere the greater the potential for deterioration- no issues at all in bone dry air.

I'll drop Spendor an email and report back

Can anyone think of a reason why 5m cables might sound better than 3.5m cables? Normally, one thinks of electrical signals losing information and power as cable length increases (although I'm not an electrical technician).

The length recommendation is down to the effect of the cable on the output stage of the power amp. This is soecific to the design of Naim, and a very small number of other amps. Naim also say that losses may occur with lengths above 20m, which I imagine is plenty for most people. 

All power amps need a series induction load as part of the zobel shunt circuit that is installed in all amps to stabilise the amp output stage.  NACA5 with its 1uH per metre is that induction load & Naim's 3.5 metres is in effect recommending a minimum 3.5uH load.    Most other amp manufacturers have an internal inductor as that part of the Zobel shunt circuit, the problem with this is it still needs a speaker cable with its inductance to be added & the end result can be too much inductance & result in HF roll off,  & why Naim suggest >20m is not recommended.    Naim (& a few others) choose to use only the speaker cable to provide the correct inductance & avoid that possibility.

Thanks - that is very helpful. Does that mean that perhaps the 14 year-old 2 x 8m Chord Rumour 2 speaker cables I'm using should be replaced by 2 x 5m of NACA5? Am I likely to hear the difference on my humble 272/150x/Arivas?

Also, that I should use the 4 original Naim black speaker plugs which I still have rather than the 8 banana plugs that are soldered onto the ends of my cables?

I would certainly use the Naim plugs at the amp end, and maybe a good time to check the cable for any corrosion or poor solder joints. Cutting off a few cm and resoldering can be worthwhile. Maybe your dealer will lend you some A5 too, and you can compare for yourself. 

Reply from Spendor.

Hi Steve

Thanks for your e-mail and for your kind words regarding your A7 speakers - glad you are enjoying them!

Spendor doesn't make a specific recommendation about the plugs to use - your dealer should be able to advise on this and will likely fit them for you too, if you ask nicely ...

Alternatively, spade terminals could be used - again, your dealer can advise on the appropriate type

Best regards

Rob Coe
Sales & Customer Support, Spendor Audio Systems Ltd

I've contacted my dealer (Moorgate Acoustics) and Paul is sorting me out tomorrow with the same type as they use in the shop.

I might have asked them a more specific question, such as ‘what plating is used on your speaker sockets?’ Then you can buy some that match. Many are either nickel or gold, and you could do worse than using the inexpensive Deltron bananas that come in either plating. Naim plugs with the box removed would also be worth using, in which case I would put some heatshrink round them to cover up the exposed metal. 

A problem is no one knows the spec's of Chord cables as Chord don't publish them.  I use 5m of Chord Odyssey (Rumour's big brother) & I have measured it at 3uH (for 5m).     I guess that Rumour-2 has a similar spec. & wherever the difference will be inconsequential.   So assuming your Rumour-2 is the same as Odyssey them 8m will be 4.8uH & near as knats do-do to spot on.  I would also add that if your SN2 is anything like my SuperNait (1) its extremely tolerant of speaker cables.   

Rather that change the banana plugs I would try it all first.  The big plus with the Naim plugs is to be had at the amp end, the 90 degree cable exit makes for a speaker cable that does not pull out easily from the amp,  so if that does become a problem with the Rumour plugs,  then a good thing to change to them,  I would not change them at the speaker end fro the reasons ChrisSU mentions,  dissimilar metals can be a problem over time.  I had a problem with the nickle plated Naim plugs in my 'gold' speaker binding posts,  I changed them to gold plated Deltron's,  job done.    

ChrisSU posted:

I might have asked them a more specific question, such as ‘what plating is used on your speaker sockets?’ Then you can buy some that match. Many are either nickel or gold, and you could do worse than using the inexpensive Deltron bananas that come in either plating. Naim plugs with the box removed would also be worth using, in which case I would put some heatshrink round them to cover up the exposed metal. 

You can see that the speaker terminals are gold-plated.  Moorgate will be supplying me with gold-plated plugs

This is news to me. Is it then the case that 5m Super Luminas sound better than 3m?

William posted:

This is news to me. Is it then the case that 5m Super Luminas sound better than 3m?

No one is saying that,  & as far as I have read no one has reported on testing different lengths.   Naim have not published the cable specs to my knowledge but would expect that the standard lengths they supply carry the correct inductance load(s)