Mk1 pxos with mk2 sbls

Hi, I'm new here having got enthusiastic about chrome bumper over the last year or so. My current setup is a nac42.5 powered by a snaps-cap (a snaps converted to a hicap by naim some years ago i was told) and a pair of kef c60s (mint - on stands) powered by a nap140. The sound is probably the best I've heard... Bearing in mind I've just moved to a bigger flat and it could just be acoustics and speaker placement.

Anyway, i have visions of going axo having bought a pair of mk2 sbls which came with a matched naxo2-4 for a good price, pxos not included. However, unable to afford the extra hicap and get my other nap140 serviced at the moment, i found a pair of mk1 pxos for £50 so got those.

Well, I'm not liking the sound generally. I know sbls need tinkering and maybe even the seal needs redoing. Could it be the nap140 on its own not up to the job though? Or does anyone know if the mk1 pxos are much different to the mk2 pxos and might not be compatible?



Ali B

Original Post

Alex, SBLs need stripping down and doing right - that means new gaskets, the lot - if they're to sound right.  There are no shortcuts with SBLs, they require total commitment to perform properly.  Anything less and you can end up with boxes sounding like a bag of nails.

Oh, and just to clarify - the dual-railed SNAPS is not the same as a HICAP.  Performance-wise it's more of a half way house between the standard SNAPS and the HICAP.  

Thanks, Richard.

Tbh, the guy that sold it too me did say it was more of a flat cap than hicap, yet, the improvement in sound was excellent when i plugged it in.

I have me time coming up so the sbl rebuild will have to go on the list then. It was already a consideration.

I also look forward to seeing what the hicap sounds like, when i get one.

Any info on mk1 vs 2 pxos?


My concern is the drivers themselves really.

The LF/MF driver seems to distort quite easily at times. This could be related to a bad seal with the box below.

Yet, the HF also sounds harsh at times and they're in a box of their own.

Asking Naim themselves is an excellent idea...




A little update & also another question...

I contacted Naim & the mk1 sbl pxo is exactly the same as the mk2. Or rather, the only changes were the drivers.

My other question is about the CB nac42.5 - i was under the impression that the 42.5 used the 2x 24v rails from the hicap to power each channel. (1&2/L&R)

However, someone says that the .5 nacs utilise the 2nd rail for the phono side.

Is that the case?

I also have a NAXO2-4 (yet to be implemented) & that requires a hicap for 2x 24v rails. So now i'm wondering, are they for each channel or for each frequency range (HF/LF)?

Moderated Post: I have edited your post and removed the web link. Please note forum rules - no discussion of DIY or unauthorised modifications to Naim equipment.  

Alex, On the mechanical side, when I first got my used SBLs I did a complete rebuild as being the only way to ensure their mechanical integrity. You probably know already, where they are sited is vital. Make sure they are not tilted forwards or back. If you are lucky, as I was, your gaskets will be intact, so all you will need is 8 sticky aluminium pads (available from Naim) and a tube of Loctite 595 silicone sealant (available from RS).

On the electrical side, though I've not heard active SBLs,  would not your NAC, a CBHC and a CB NAP250 into your SBLs give you an all time classic set? You could then just get on with the rest of your life in audio peace.


ARB76, those Mk1 paxos are really old and really need replacing. However, I believe Naim are now out of stock. An email to confirm might be a good idea. As you have an active crossover I would be tempted to go this route although it could be costly. Although you say you have Mk2 SBLs it would be worth having a dealer check them over and perhaps even pay them to do an install if possible.

I will be using SBLs until one of us pop our clogs, truly great speakers if you get them working well. I have a replacement pair just in case! Good luck and keep us posted on progress.


PS. They really need a top notch source!

Ian and Richard thanks you.

In that case, it's a redundant rail as I have no phono cards currently fitted.

The naxo will remain a mystery ��

Thanks, Christopher.

I'm going to start the sbl rebuild soon, some useful info there, much appreciated.

My current system (all CB) is: nac42.5 powered by a snaps cap and a nap 140 powering a pair of old kef c60s (mint). The kefs are 4ohm 200w and it all sounds rather good.

I have a 2nd nap 140 (needs service), naxo 2-4 and sbls waiting to join the party.

Will go for another hicap to power the naxo. Extra cables and interconnects too.

The key with these old beauties is not to rush in. There are some bargains to be had if patient.

Stuart, thanks.

What makes you believe the sbls are MK1 and not MK2 like the seller said? Naim would have a record if I gave them the sns I hope.

I got them with the naxo, minus pxos. I got some sbl pxos at a good price elsewhere and the guy said they were from MK1 sbls. I wondered if there was a difference.

Some good info. Thank you

arb76 posted:

With ref to the Naim serial number webpage, the sbls i have were manufactured in 1999 which makes them mk2 drivers i believe.

Yes. Mine are a year earlier with mk2s.

I'm in a flat too. I made an effort to spike down onto the concrete floor. They do not rock. Makes a huge difference.

What will your source(s) be for these active SBLs?


I was thinking of getting some granite plinths/slabs for the SBLs to sit on. Good idea?

My source will be a turntable one day, i haven't got the time to do some proper research at the moment, nor the money to finance it. 

I'm afraid i'm a streamer for now - i have a iEast & a Neet wifi receiver - different dacs . I think the iEast gives a better sound - lossless files.

ARB76, I personally would not use slabs under them. Get them level with absolutely no rock into your floor, perfectly level etc. Search here for the many and various threads on how best to set them up. They will reward you with every set up improvement, better source and amplification. But they will also reveal any weakness in your system. If they sound bad or harsh best not blame the speakers until you have checked everything else.

Get them right and they are simply superb! How are the grills? If shabby the best replacements are from Tomtom at about £180 just for info.


The grills appear original and are in very good condition.

If anything, the MF/LF grills sink in a bit but, maybe they would anyway.

The odd strip of retainer has been replaced with some velcro hook type strip but, they all stay in place.

I wonder if anyone's tried putting them on plinths. Trouble is my floor's rubbish - has asbestos tiles on top of concrete, some of which are loose. No safety worries with special underlay, which I have.

Going price is approx £80 a pair. Sort of thing that can have a dramatic effect for a small amount. Good or bad, is worth a punt. I can always sell them on if bad.

The adventure ensues...

You don't want anything under the SBLs. A concrete floor is perfect, just get the tiles stuck down properly. 

I suggest that you get the source for your system sorted out. The iEast is a £45 streamer/DAC, which is hardly ideal with top end speakers and a good amplifier. Rather than worrying about active I would get the source sorted out as your first priority. An NDX would be a good place to start if you want a good streamer. 

The landlord would not incur the fee, option B activated.

Obviously a £2500 ndx will out perform a £45 streamer. But, we're talking about 30 year old hifi, as good as it still is. My objective is to go vinyl.

For the price difference it doesn't offer the reward in the relative short term.

The ndx is 6 years old, a big amount of time in the computer game.


I'm not saying i definitely can't get them level & firm, they're not in use right now so i've not put that much attention into it, yet, there's still a potential 'loose layer' between the sbl spikes & the concrete.

The plinths was just a thought, i still might give it a bash. It's no big expense at this level & i can sell them on for not a lot less than i'll pay for them. Maybe i'll lose £20 in the exercise... when you guys are proved right ;-)

I'll be sending the NAPs off for service first, they need to be sweet & matched before going active. I need to spend the money on that sort of thing before considering a big upgrade in source.

I like the plan. Treat this as a restoration project, get everything sorted and then put them in place. They really are worth the effort, but it is an effort as they will reward the hard work and planning. Looking forward to a future thread describing how they sound.


Christopher_M posted:

On the electrical side, though I've not heard active SBLs,  would not your NAC, a CBHC and a CB NAP250 into your SBLs give you an all time classic set? You could then just get on with the rest of your life in audio peace.


A brace of 250s driven by a SNAXO-Supercap could be even better

(another) Chris

Suzy Wong posted:
Christopher_M posted:

On the electrical side, though I've not heard active SBLs,  would not your NAC, a CBHC and a CB NAP250 into your SBLs give you an all time classic set? You could then just get on with the rest of your life in audio peace.


A brace of 250s driven by a SNAXO-Supercap could be even better

(another) Chris

Ah! But how would I know what active SBLs sound like?!

My only concern for the OP is that he walks before he runs. At the same time, I can see his enthusiasm for his project and it's horrible to try to dampen that.


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