Naim NAP 200 overheating / Kudos KS1 speaker cable

[MJS]

Try re-dressing the cables, if possible.
Series resistance won't contribute to a Naim amp being unstable, capacitance will. A log thin cable with closely spaced conductors may well have enough capacitance to upset it. A service won't necessarily fix this - alternative cables might, an inductor on the output probably will.

 

[Molyvos]

Thanks again for all the advice. Will definitely look into a service for the NAP. Not sure what redressing the cables means (sorry), but I had a good chat with the dealer this morning and the guy I spoke to agrees that it is likely to be the resistance over the long length causing the problem. Of the many cables they sell it seems Naim is not one of them, so he is going to check the specs and locate a suitable alternative. If none found, I can return the Kudos for a full refund. Any recommendations for suitable 9m cables within a similar price range (upto £40/m) would be appreciated.

 

[kensalriser]

Look for some second hand NACA5, plenty of it around.

 

[wd40addict]

Sadly Kudos don't publish the capacitance specs for KS-1, but it's clearly going to be higher than shotgun style cables like A5 & Tellurium Q.

Anyone out there own a capacitance meter and some KS-1?

 

[omers]

Why would series resistence cause this? Think of it as a less efficient loudspeaker with higher impedance (and lower damping factor from the amp).
Do you listen very loud?

 

[Molyvos]

Why would series resistence cause this? Think of it as a less efficient loudspeaker with higher impedance (and lower damping factor from the amp).
Do you listen very loud?

I don't think so? Depends on the source, but had the dial on the 202 at around the 8 o'clock mark I think. But used the same level for both cables, and the amp only became hot with the KS1.

 

[wd40addict]

It will be the capacitance as @MJS says above. Naim's lack of an output inductor makes them sensitive to cable capacitance and potentially radio interference.

Note how the special BBC NAP250s were fitted with an inductor. Presumably the BBC wanted unconditional stability with any cabling...

 

[omers]

I don't think so? Depends on the source, but had the dial on the 202 at around the 8 o'clock mark I think. But used the same level for both cables, and the amp only became hot with the KS1.

8 oclock is normal, I'm not saying it's not the cable, but that the problem is probably capacitance and surely not resistance.

 

[andyr]

My system is NAP200, NAC202, LP12, Linn Tukans, and having just moved house I needed some longer speaker cables that were less bulky and easier to manoeuvre than NACA4/5.

Reading various posts online I settled on what I thought would be ideal: 9m lengths of Kudos KS1, with Naim connectors on amp end and banana plugs speaker end, with jumpers.

However, within about an hour of listening to music from TV (connected to AV in DIN on 202 from TV headphone socket) the 200 cut out and was extremely hot to the touch. Turned everything off and tried again next day with a portable music player (A&K Kann) attached to 202 Aux 1 via Din and same thing happened again.

Has anyone experienced the same issue with this cable, or is it more likely that the amp has developed a fault? Prior to unpacking after the move it had been boxed and put in the loft for around 18mths, although had caused no problems over many years use before that.

Many years ago, when I had my spkrs at one end of an 8m long room (and my amps up the other end - so 11m of NAC A4 cable) ... my 250s used to regularly cut out due to heat loading, when playing Pink Floyd fairly loud.

So I moved the amps behind my spkrs (and had 11m interconnects, instead) ... and the problem went away.

So I would suggest that Naim amps are super sensitive to the 'C' and 'L' load that your spkr cables provide. The sure-fire solution is move your NAP200 to where your spkrs are; if that's not acceptable ... then it would seem you need to:
a. buy a non-Naim amp, or
b. use Naim spkr cable.

 

[Darth Vader]

With the older Naim amps its essential to use suitable cable. Naim do not use a full Zobel/Thiele network in the early amps and this means that they are liable to oscillate in the RF. This may cause the output stage to over heat and blown tweeters have sometimes been seen.

The NACA5 has high inductance and its this that sort of provides the missing inductance that completes the Zobel network.

Avoid any fancy cable with tight twists or coax of any sort. Simple spaced parallel wires should be OK.

DV

 

[stevec67]

It will be the capacitance as @MJS says above. Naim's lack of an output inductor makes them sensitive to cable capacitance and potentially radio interference.

Note how the special BBC NAP250s were fitted with an inductor. Presumably the BBC wanted unconditional stability with any cabling...

The BBC wanted a properly engineered amplifier that was stable with any cabling, not some princess and a pea prima donna that needs special treatment. The last thing you want it you're doing an OB is an amplifier that's sniffy about which cable you use. As MJS says it's a capacitance thing.

With the older Naim amps its essential to use suitable cable. Naim do not use a full Zobel network in the early amps and this means that they are liable to oscillate in the RF. This may cause the output stage to over heat and blown tweeters have sometimes been seen.

The NACA5 has high inductance and its this that sort of provides the missing inductance that completes the Zobel network.

Avoid any fancy cable with tight twists or coax of any sort. Simple spaced parallel wires should be OK.

DV

I think it's actually a Thiele network but the comment is correct. People routinely confuse Zobel and Thiele, they're both found in amp circuits. The reason that Naim specify 4m plus for cabling is to get sufficient inductance as a result of the length.

 

[Roog]

I think it's actually a Thiele network but the comment is correct. People routinely confuse Zobel and Thiele, they're both found in all circuits. The reason that Naim specify 4m plus for cabling is to get sufficient inductance as a result of the length.

This /\ :0)

 

[Roog]

The BBC wanted a properly engineered amplifier that was stable with any cabling, not some princess and a pea prima donna that needs special treatment.

Don't we all? :0)

 

[Roog]

Simple spaced parallel wires should be OK.

Agreed, in fact back in the days before Naim figured out there was easy money to be made out of cables they used to recommend two single core cables twisted loosely with 2 or 3 twists per foot, they even gave the RS components product code for the cable! (It was just normal single core wiring of either 2.5mm or 4mm cross sectional area, can't remember)

I expect some one can find an image of the advice sheet published by Naim at that time.

 

[Amber Audio]

Agreed, in fact back in the days before Naim figured out there was easy money to be made out of cables they used to recommend two single core cables twisted loosely with 2 or 3 twists per foot, they even gave the RS components product code for the cable! (It was just normal single core wiring of either 2.5mm or 4mm cross sectional area, can't remember)

I expect some one can find an image of the advice sheet published by Naim at that time.

Before Naim offered NACA4 and then later on as an alternative they recommended an RS cable - 357-946, it was 4mm and they said to twist it 4 times per metre, screen cap from old amp manual below.

This is the up to date version

RS PRO Red 4 mm² Tri-rated Cable, 12 AWG, 56/0.3 mm, PVC Insulation | RS​

uk.rs-online.com

 

[stevec67]

Agreed, in fact back in the days before Naim figured out there was easy money to be made out of cables they used to recommend two single core cables twisted loosely with 2 or 3 twists per foot, they even gave the RS components product code for the cable! (It was just normal single core wiring of either 2.5mm or 4mm cross sectional area, can't remember)

I expect some one can find an image of the advice sheet published by Naim at that time.

NACA 4 was a BICC cable intended for low voltage lighting around military camps, it's identical to Linn K20. I'm not sure when Linn and or Naim started getting it branded and charging a premium over the stuff sold to the MoD at a tenner per sodding great reel. Specially selected. Yes, sure, specially selected from the BICC catalogue. It's the right spec, it's the right price. Select it.

 

[Roog]

Before Naim offered NACA4 and then later on as an alternative they recommended an RS cable - 357-946, it was 4mm and they said to twist it 4 times per metre, screen cap from old amp manual below.

This is the up to date version

RS PRO Red 4 mm² Tri-rated Cable, 12 AWG, 56/0.3 mm, PVC Insulation | RS​

uk.rs-online.com

That's the one, thanks for the correction. I remember seeing a copy of the Naim advice sheet typed out!

Industrial Control panel wiring!

 

[Amber Audio]

 

[llatpoh]

It will be the capacitance as @MJS says above. Naim's lack of an output inductor makes them sensitive to cable capacitance

I believe that only applies to Chrome Bumper and Olive series, and not to the Classic series. For example, Naim has confirmed that on a NAP250 DR you can use pretty much any cable you want.