42/110 driving Castle Severn 2 /87 dB 8ohms

Dear Naim brains trust.

Ive some castle Severn 2s in good condition sitting around. Out of interested would an old 42/110 drive these well? I would also need speaker cable…Would I be tied to A4 or A5 and any length upper/lower length limits I need to work within…

Castle Severn 2

  • System type|2-way
  • Enclosure type|Bass-reflex
  • Frequency response ± 3dB|47 - 20000 Hz
  • Nominal impedance|8 Ohm
  • Amplifier Requirements|25 - 110 W
  • Sensitivity (2.83V/1m)|87 dB
  • Tweeter|25 mm (1 in.)
  • Woofer|150 mm (6 in.)
  • Weight|16 kg / 35.2 lbs.


Rob D

The 110 will have no problems with these. The old amps need the right length of cable for stability so a minimum of 3.5m of A5 (or A4 if you can find some in good condition) on both channels will be needed.


Thanks James.

Would you go A4 or A5?

I just missed out on a Nait 2 which are like hens teeth here in Australia. I just picked up a 42/110. I am intrigued how these will perform next to my other sn2 and probably more fairly 122x/hicap/150x…Will get the 42/110 serviced but will be interesting to see how they perform having been in storage for 25 years.

Many thanks

A5 is better but very stiff. A4 is more flexible but hasn’t been made for quite a while. Linn K20 and Cable Talk 3 were good alternatives and looked and performed very much like A4. I used to use the Cable Talk 3 in my old Olive system between a 140 and a pair of Royd Sinatras.

Try and get the Naim SA8 speaker connectors if you go the A5 route. It places less stress on the sockets on the amp even though on the 110 these are panel rather than PCB mounted.

Once serviced, you will have a classic combination which should be a lot of fun. My first pre-amp was a 42.5 (the dual rail supply capable version of the 42) and that kept me very happy for quite a few years until a 72 came along.


The 42/110 is a classic. The caps in the 110 can hold up surprisingly well over the years so it may still sound pretty good, although a proper service will really bring it back to its former glory. As James advises above, make sure you use the right speaker cable - A5 is ideal, at least 3.5m per channel, but better with a bit more, I find. A4 is a cheaper alternative - not as good as A5, but still fine for your purposes. Use properly soldered Naim SA8 speaker connectors at the amp end.

It’s also very worthwhile to upgrade the original grey SNAIC4 to a later and current black SNAIC4. It will have ring lock DINs instead of latching ones but if you just wind them all the way back, they still fit just fine, but won’t lock, so be careful not to accidentally unplug when powered up.


Thanks Richard.

I’m intrigued more than anything on the 42/110 with the Severn 2s.

Once I get my hands on the units I will get serviced. That will ultimately determine what if any work is needed. Then I can start playing around and working out the best combinations.

How does the 42/110 fair with a hicap dr?

If the NAC42 is an original (as opposed to a 42.5) then a Hicap DR is a bit tricky to use and requires either a custom 5-4SNAIC or modification of the NAC42 to NAC42.5 spec. The PSU to use with an original 42 is the SNAPS, or better still, a period Chrome Bumper Hicap which still has the single rail 24V output on the second DIN. Note that many of these had the single rail 24V output removed as part of a service - that way you would get better performance on the dual 24V output.

1 Like

From my (very limited) experience of them, the Castle Severn 2 are a fairly benign load and a 110 should drive them to the best of its ability, however…

Acoustically they’re not a particularly good match if you’re looking for the characteristic ‘Naim style’ sound. The Severns (like many Castle speakers) are quite neutral and give clear insight into the music but don’t give a particularly dynamic style of presentation. If their style of presentation suits you, this may be a near ideal combination.

The Severns will easily show the benefits of a later SNAIC and a PSU upgrade as recommended by Richard (a recommendation that I wholeheartedly support - Richard really knows his stuff).

In addition to the Naim speaker cables, the DNM speaker cables are also suitable: they match the electrical requirements of the amp and the acoustic characteristics of the speaker without further reducing the apparent dynamics of the presentation, but they are a bit ‘bass light’ by comparison to the Naim cables.

1 Like

Currently in terms of speaker matching

NDX2/SN2/ Focal 1028 be
122x/hicap/150x on Martin Logan 35xl
42/110 going to Castle.

Out of curiosity what speakers would be safe bets with the bottom 2 systems. I picked up the ML’s looking for something more lively that wouldn’t need to be treated as carefully as the old Severn 2s. They aren’t too far away from the Focals in sound signature, just maybe a diet version. The Severns are sweet little all rounders but are fussy on placement and can be further tuned using spacers on the lower plinth.

I would try the Castles with the 42/110. They should balance nicely Given the characteristics of the components. Naim amps of this period we’re really designed with an analogue source in mind so matched wrongly can sound a bit relentless, not helped if they need a service too. See what you think and report back - your ears, your preferences.

1 Like


Yes, I had a 42/110 for many years, drove a variety of speakers: Altec Lansings & Kan Mk1 so should drive your speakers reasonably well.

You might still be able to update the 110 to a 140 and as Richard D said, adding a HiCap requires a mod to the 42 to 42.5, the correct 4/5 cable or a SNAPS. Either way the external PSU does make a difference, I eventually changed to a HiCap with a 62 which is similar and that worked well with the 110.

The speaker cable I would look at is Witch Hat N2 which is nice and flexible, or their Pantom if you wish to spend more.

1 Like

Little update the 42/110 ended up selling for repair so I side stepped…

Ive just picked up a Nac72 and will keep my eyes open for NAP140.


I had a pair of Severn 2s for a year (with audiolab amps). They were very easy to drive, took a while to position though. They seem to like a bit of space round them or they sounded a bit sluggish. Once in the right spot they were a nice relaxing listen. Your setup should sound good with them, enjoy!

1 Like

Out of interest is the general consensus to go 72/hicap/250 (olive) if you aim to max the 72 performance? Or is the 72/Hicap/140 a better partnered system…?

Do the same speaker cable conductance properties apply to the 140/250 as we discussed earlier for the 110 or I can change things up a bit more in the Olive series?

Its going to be interesting how the final system punches vs my current SN2 or 112x/Hicap dr/150x based systems…Lets see what comes available used.

With all varieties of the Olive amplifiers it’s important to use electrically appropriate speaker cables (high inductance / low capacitance)

Such as:
Naim SL
Witch Hat Phantom
Witch Hat N2
DNM Reason
TQ Black
There may be others that are suitable, but not many actually publish the necessary specifications; these cables listed are either specified to be OK or measured to be OK.

There are also some cables that people have used OK, but these are not guaranteed to be OK in all circumstances: this includes some of the Chord speaker cables.

1 Like

Can a Olive 250 be powered by a Hicap Dr as an interim?

All versions of the 250 have their own power supply, and so don’t need (and can’t use) a HiCap. However, the preamps mentioned in this thread - 42, 42.5, 72 - can all be powered by any generation of HiCap, and will work fine. Whether the HiCap DR is a good sonic match for these older preamps is another question. For what it’s worth, I used a Classic HiCap (the most recent generation, but not DR) with an ancient 72 for a while, and I found it excellent.


Wouldn’t the 42 need a CB Hicap with 12V rail or is my understanding of how they work going fuzzy already?

1 Like

I picked up a 72 olive because the 42/110 I was eyeing ended up selling as spares/repair.

My understanding is that the 42 can be powered by either a SNAPS or a HiCap but that, with the latter, it will only use one of the two 24V rails. The later 42.5 uses both rails of the HiCap. The 42 was before my time (my first Naim pre was a 32.5), so I’m open to correction on that.