NAC A4/5 - Soldering, Plugs & "F" Connection.

Posted by: Adam Meredith on 01 March 2007

Before you start - NACA5 has ridge on one edge. Designate this conductor POSITIVE and ensure that, in every instance, this ridged side of the cable is connected to the positive (RED) socket.

NEVER solder speaker cables that are still connected to your amplifier.

It will help to have some form of jig or arrangement to hold the cable steady and locate the 4mm plugs while soldering and during the cooling period.

Either a couple of 4mm sockets in a plank of wood or just two 4mm holes (with the correct spacing). You should arrange a way of ensuring that the weight and stiffness of the cable does not move the solder joint while it is cooling.

N.B. in light of the additional advice below - you may wish to use two groups of two sockets/4mm holes.
MARK these +/- or RED/BLACK to reflect the socket arrangement on the back of your amplifier.


On Naim amplifiers (other than a pair of NAP 135s) - these are mirrored (take a look).

Good and sufficiently powerful soldering iron - pre-tin tip, apply to pin with cable firmly and neatly in place - feed in solder gradually, ensuring that the join is good and with no excess of solder above the pin.

Allow to cool without any relative movement between cable and plug (that's why you are using the pin holders and a clamp or similar - NACA5 can get very hot during soldering).

For best results - the pin should be free to wobble a bit in the re-assembled plastic holder so avoid using more solder than is required to fill the slot and bind the cable. This allows the plug to 'mate' properly with the socket - rather than being forced into a limited, two-point contact.

When soldering speaker cables you should first lay out the cable with the two amplifier ends (arrows pointing away from this end) together.

(It is a common error to take the entire length of cable and fold it in two to get the two correct lengths. A sensible move but this will, without correction, result in two cables that 'run' in different directions.

Dealing with the amplifier ends -
look at the rear speaker sockets on your amplifier.

On Naim units (Apart from NAP 135s) these are "mirrored". THINK.

When you replace the plastic case - will the correct (+,-) pins fit in the correct socket without resorting to contortion?

Get this right now.

At the speaker end - the sockets are likely to be UN-mirrored. Once again (and during life in general) THINK.


Imagine the cables coming up to their respective sockets.

Posted on: 21 April 2008 by Adam Meredith

For connection to Naim amplifiers or loudspeakers we strongly recommend that you use the supplied Naim plugs.


These are included, Free of Charge, with all new amplifiers and speakers.


Please ensure your retailer offers to use these for any speaker cable supplied. If not used immediately please retain along with link plugs, etc.


Naim right angle plugs are designed to make the best connection with the sockets we use.


You should be wary of mistaking elaboration (gold plate, locking plugs, etc.) with superior value or effectiveness.

If using speakers from another manufacturer, with different spacing between the sockets, Naim plugs can still be used.

Remove the plastic plug casing - use either soldered at right angles or straight in-line.

Care, especially with the right angle join, will need to be taken when the plugs are disconnected at the speaker end as there will be a risk of short-circuit.

Heat-shrink tube insulation can easily be used with the in-line joint. The right angle connection may take a little more ingenuity.

Posted on: 21 April 2008 by Adam Meredith
Speaker socket arrangement - rear of amplifier. (except NAP 135s).

Why are they switched around?
Originally Naim amplifiers had a "pro" use feel. Here amplifiers are commonly mounted rear panel out - to ease access to signal, power and speaker connections.
Turned around for domestic use - the orientation is the opposite to some people's intuition.
Posted on: 07 May 2008 by Adam Meredith

"F" connection.

Some loudspeakers offer the facility to access different parts of their crossover network by the removal of link plates on their rear panel. These plates often have a detrimental effect on sound quality quite out of proportion to their length.

The design is intended to encourage bi-wiring (or more) from a single amplifier.

The design can also be used to multi-amplify the speakers from several amplifiers.
This is NOT active use and NO Naim speakers are suitable for bi-wiring or bi-amping. Without the passive crossover Naim speakers will require an active crossover designed to match and feed only safe amounts of signal to each driver - especially the treble unit.

We would encourage owners to first try substituting small link wires in place of the supplied plates OR (preferable) have some cables made up with "F" connections at the speaker end (see thread below).

As ever - you will need to be careful to avoid shorting the + and - when the plugs are out of the speakers - detach at amplifier end first or switch off the power amplifier.

Posted on: 05 November 2010 by Richard Dane
An example of good soldering (Thanks to Peter Swain for the pictures);
Posted on: 05 November 2010 by Adam Meredith
... and two other ways to do it incorrectly.

Not enough heat for solder and flux to make the joint.
Posted on: 05 November 2010 by Adam Meredith
again little solder/flux flow and excess (ineffective) solder.