NAIM SBL Loudspeakers: From SNAXO Active to Linn Exakt: Guest Contributor

Here's something a little different.  The first ever "guest contributor" post on AudiophileMusings.  Below is Clive Gidney's experience of working with SpeakerFilters on development of Linn Exakt filters for the Naim SBL loudspeakers.

Full disclosure: the lead designer at SpeakerFilters is also the "editor at large" of AudiophileMusings.  Note the article below is entirely Clive's own words without any edits.  Enjoy, and thank you Clive for your contribution.

NAIM SBL: FROM SNAXO ACTIVE TO LINN EXAKT by Clive Gidney

At the beginning of the year, having been running a pair of SBLs with a pair of 250s sort of bi amped (one for left channel only & one for right - just because I had 2 x 250s & hadn't got round to swapping them for a pair of 135s) I decided that it was time to do the proper thing & go active. 
 
 
 
 So SNAXO  & Supercap added and this gave a significant improvement in detail, soundstage, PRaT & all the things that SBLs are famous for... But I was still left with the feeling that they are a bit forward & a bit bass light. In fact a non audiophile friend described them as "a bit shouty".  And yes - I'd done all the set up things, as close to a solid brick wall as the skirting board would allow, re-sealed the bass loading box etc.
 
Then a couple of months ago I was at Brian & Trevor's in Manchester for a musical evening  listening to a Linn/Kudos Exakt active system thinking this system sounds amazing (although I would have liked to hear it with Naim power amps) but the transparency that the Exakt technology brought, which performs the crossover in the digital domain, was breath-taking. In the interval I remarking to one of the other attendees how great Exakt was & that I wished it was available for SBLs! And he said "I write Exakt filters for speakers that Linn doesn't support" OMG!! That person was Neil Hallworth of speakerfilters.com
 
So we embarked on the Exakt SBLs project.
 
Step 1 was to physically measure the SBL cabinets, the position of the drive unit centres, the front baffle slope etc. These numbers were then plugged into Linn's system to enable Linn's Space Optimisation to be enabled. That is available now for free for anyone using a Linn DS or DSM with SBLs via Konfig! 
  
Step 2 involved Neil calling at my house to take some electrical measurements of the drive units to measure their impedance.
 
Step 3 Neil then took these measurements together with some information on the crossover frequencies & slopes obtained from Naim to work some digital magic to create a first cut of the digital Exakt crossover filters. In fact he sent me three versions with different crossover slopes, 2nd order, 3rd order & 4th order. It was very quickly apparent that the 3rd order (which is what Naim used) was the best. The 2nd order sounded congested in the mid-range while the 4th order sounded as though there was a hole in it. He then sent me a 3rd order v2 without telling me what he'd done. When I tried it, it was clear that this was an improvement over v1 with better definition & spatial separation. The sound stage was more clearly defined & I was in heaven. The slightly bright & comparatively bass light presentation was gone without losing any of the strengths of musicality & PRaT that SBLs are renowned for. Neil assured me that there would be more to come in step 4 but I was so impressed that my SNAXO & Supercap were already up for sale!
 

 
Step 4 Neil called again to fine tune the filters. Firstly we agreed that in taming the brightness, they had lost a little of their sparkle. Now apparently, the sound waves emanating from all drive units have an interaction with the speaker cabinet front baffle and to compensate for this, within the Exakt crossover Neil had created a 0.8 dB treble filter. Now I'd been advised by John Jackson (ex Naim Senior Test & Service Engineer & currently Witch Hat Lead R&D Engineer) that the SBL cut away foam grill was designed to overcome the treble baffle interaction issue. So Neil removed the filter, updated the Exaktbox & sparkle was back. Hi hats shimmered, room acoustics were tangible, the space around instruments & performers improved. 
 
Next we played with the actual crossover frequency. With v1 the bass/mid roll off & treble roll on were at the same point 2.4khz which we'd got from one Naim source. In v2 the bass/mid was rolled off at 2.3khz & the treble rolled on at 2.5khz (from a different Naim source) So we tried widening the gap by 50hz either way - not as good. Leaving the bass/mid where it was but bringing the treble back again - immediate improvement!
 
Adding baffle filters for the bass/mid drivers for both the length & width of the cabinet added further improvements and the subtlety  of the changes that could clearly be heard was mind blowing;  -0.5 dB - too much, - 0.25 dB, not enough so we settled on - 0.4 dB. Adding a 1.5 dB lift in the bass from 0-60 hz - too much, 1.2 dB - still too much, 1.0 dB - bingo! In all we went through 17 variations fine tuning the Exakt crossovers in just over two hours. Imagine trying to do that with resistors & capacitors in the analogue domain!
 
The end result? Absolutely stunning. If you thought going from passive to active with a SNAXO was a big step... from SNAXO to Exakt is like having seven league boots on! Really, it's that good. 
 
Oh, the cost?  Well  I'm going to make a few assumptions. If you're already active with SBLs, then presumably you've got a good front end - LP12 around Akurate spec, a Naim NDX minimum, maybe NDS, or a Linn Akurate DS/DSM Katalyst, Naim 82/Supercap or more likely 52/Supercap, SNAXO / Supercap.
Hardware. You keep whatever power amps you're using - in my case a pair of olive Nap 250s which will retain your signature sound. Ideally you'll need a Linn Akurate System Hub which becomes your pre amp - £2700 new or about £1600 pre owned, & a Linn Akurate Exaktbox Katalyst which is where the majik happens (see what I did there) - £5000 new or I picked one up pre owned with 4 years warranty for £3200; And, you'll need a set of  Exakt filters from speakerfilters.com  which are just £295. These  can be tested for a free 2 week  trial period before purchase. Total cost  about £5400 pre owned or ~£8000 going new
But you can recoup say £1500 on your NDX, or £2000 on your Akurate DS, £2000 on your 82 /Supercap & £1500 on your SNAXO /Supercap = £5/5500 so approx. cost  neutral going pre owned And if you've got a 52 or an NDS you might even have some cash left over


A huge shout out for Neil of speakerfilters.com for all the work designing & refining the filters. 

Clive. 

Kudos and Exposure Collaborate on Active Crossovers

Its a long saga...

Kudos have been enthusiastic about active electronics to drive their "Super" and "Titan" range speakers for around 3 years.  There are Linn Exakt digital crossover configurations for their speakers and a Devialet option too.

In parallel, a project was underway to develop a Naim SNAXO active crossover too.  It rumbled on for a couple of years, with previews at a number of shows that proved the solution to be a good idea.  it would, of course, have encouraged existing Naim amplifier owners to not only buy a SNAXO, but also to buy extra amplifiers.  You'd think that Naim would be keen on that.  But, for whatever reason, Naim have chosen to shelve the project for the foreseeable future.  There are some Naim dealers that will modify existing SNAXOs for Kudos use, but that's not exactly mainstream.

But now the news, for non-Linn and non-Devialet users, is much better.  Kudos and Exposure have announced a collaboration to produce an active crossover for Kudos speakers.  This will be a stand-alone unit that will allow the customer to choose any pre-amp and any power amp combination.  Excellent. I look forward to hearing the prototype at the 2019 Bristol Hifi Show.

https://www.stereonet.co.uk/news/exposure-launch-xm-cd-player-and-preview-vxn-crossover

CHESTER HIFI SHOW 2017 - NAIM SNAXO AND KUDOS ACTIVE TITAN 707 - SOUND OF THE SHOW

KUDOS T-707 WITH NAIM SNAXO ACTIVE SYSTEM

Kudos have been the best room at this show for the past 3 years (even when launching their most modest floorstanders they've made a great sound here) so, with the T-707 just launched at the Bristol show about 3 weeks ago, anticpation was high, opportunity to disappoint therefore equally high, I suppose.

A bit of background - Kudos are big fans of making their speakers capable of working with active options from manufacturers such as Linn and Devialet.  Their current range leading T-808 has been played with passive electronics from Naim, Exakt active from Linn and active with Devialet at shows I've been to, in addition to active with Naim electronics being fed by an active Behringer crossover (which was good but not in the same league as Linn and Devialet).  The best of these was Devialet at Indulgence, although I understand the Exakt crossovers have been heavily modified since I heard them at the National Audio Show back in 2015.
The T-808 range topper comes in at £23k and is quite a large two-box cabinet.  So out of the range of most.  Kudos are now happy with the concept they used in the T-808 (e.g. the cabinet shaping, isobaric bass loading, complex flared porting, ability to easily run passive or active etc.) to roll-out the same concepts down the range into more accessible (!) pricing and suited to smaller (let's say, more UK sized) rooms.  So the T-707 scales down the 8" drivers to 7", uses one less of them, uses a single box cabinet and takes up less room in the room.  The 7" is a mid-bass that has another identical driver hidden in the cabinet, configured in isobaric mode.  For active use, 2 pairs of terminals are presented on the back panel so only 2 amp channels are needed per speaker.
A little more background - Kudos have been hoping to persuade Naim to provide a SNAXO active crossover for some time.  The design is now done (by Kudos with help from Naim) so hopefully it will just be a matter of time before it becomes available.  Naim really should do this - as we'll see below.

Today the system was Melco, NDS / 555, 252 / Supercap, SNAXO active crossover with Hi-Cap PS and 2x 250DR power amps.  Cables were, in the main, standard Naim fare (not hi-line) with the exception of the streamer to pre connection which was courtesy of Chord Sarum-T.  Sarum-T also provided connection between power amps and speakers, with the length of cables in use today just exceeding the price of the speakers themselves - at around the £13.5k mark.  Gulp.  The T-707 at Chester were finished in Tineo wood veneered sides - black oak, Tineo red and satin white are also available as standard.  Other finishes are options.

Let's get the negatives out of the way first.  There are really only 2 for me - the price, and that the room was playing its part a little today.  Boom was not really tolerable in the back row of seats, but the middle and front seats removed most of this, but there was still a touch too much.  It wasn't enough to distract though - just a hint that there's more to be had by a different set up, and Linn SPACE of course :)

If I said that I spent over 2 hours in this room, it might give an impression of just how enjoyable this Naim / Kudos active system is.  Music, music, music was what was heard in this room.  Track after track (with the exception of one rather poorly recorded Elvis track requested by a visitor) just flowed rhymically from these speakers.  Occasionally there are some bass details that aren't as well resolved as my Exakt/PMC system, but the overall set of compromises here is a much better mix.  Focal could learn from a big powerful sound that doesn't have to be over-bright, nor does a big speaker mean that instruments have to be over-large in the image.  It was impossible to drag myself away from the room - even for music I don't traditionally like.  As usual, the Kudos team encourage visitors to select music and they shy away from nothing.  This system just got on with playing tunes - there's a sense of joy in these speakers - I think the T-808 goes deeper, but somehow, in comparison with these 707s, they feel a little restrained - holding something back in case they get too excited.  The 707s feel much more like they want to get on with entertaining and being part of the party - but they still manage to be in control.  There's a sense of detail in there too, but its not the sort of detail that says "hey look at me", its just there when you seek it out.

Kicking electronic dance tracks? Hugh Masakela? Folk Rock? Sophisticated pop (think London Grammar)? Dire Straits? Mexican guitar duos? Deep electronica?  Just play whatever you like and enjoy.  For me, even more than the T-808.  I really look forward to hearing these with Klimax Katalyst Exakt.  Perhaps the Linn front end, a couple of Naim 250DRs and the T-707s could be a match made in audio heaven.  Maybe - it would be good to find out.

Top Shelf Stuff: SNAXO for T-707 on the left and its Hi-Cap PS on the right

A superb system.

FULL SHOW REPORT HERE