THIS WEEKEND! The Best UK Hifi Show of the Year.

 Coming this weekend - the Wam Show!

At a new base near Barnsley, the show put on by enthusiasts for enthusiasts.

40 or so home systems brought together in an hotel for the weekend, you'll get to experience systems you'll never hear at commercial shows provided for you by people who are not trying to sell you anything. From budget to exotic, from vinyl to streaming, from vintage to brand new, from mass manufactured to DIY. Plus charity auction and raffle plus the bring and buy stall.

There's nothing else like it on the planet.

29th October 2023 from 9.30am

Holiday Inn, Barnsley Rd, Dodworth, Barnsley S75 3JT

Tickets available here:  https://show.hifiwigwam.com/

A Tale of Three Amplifiers - Linn, Lejonklou and Naim(ish). GUEST REVIEW BY CLIVE G.

 Something a little different this time - a review of three power amplifier choices by occasional guest contributor Clive, one of the moderators of the popular Linn Hifi and Music Enthusiasts Facebook group.  Over to you Clive...

I'm fairly happy with my system, but, well, there's always room for improvements & I'd been
thinking maybe an amp or speakers upgrade.
 
My system at the time of writing comprises: -
Linn Klimax System Hub (Classic);
Linn Klimax Exaktbox with Organik DACs;
2 x Naim Olive 250s with Avondale HCR200 regulators & Witch Hat Phoenix amplifier boards;
Naim SL2s supplemented with a BK Electronics Double Gem sub;
English Electric 8 Switch & QNAP TS-251+ NAS drive;
Witch Hat Morgana interconnects & Spectre speaker cable;
Dedicated consumer unit with 5 x spurs in 6mm sq twin & earth & 6mm sq equipment leads
 

 
 
Maybe for those not in the know, I should explain the Linn System Hub & Exaktbox. The system hub
is a streamer only - it just controls the playlist from my NAS drive or streaming service (Qobuz or
Tidal) & other inputs (TV Box & Chromecast) and acts as a pre-amp with digital volume control. It has
no DAC and passes a digital stream of music and instructions to the Exaktbox. The Exaktbox is a digital crossover & 6 channel DAC (using the latest Linn Organik DACs). The advantage of having the crossover in the digital domain is that it can be far more accurate that an analogue crossover (I used to have a Naim SNAXO but this set up is far superior). The analogue outputs of the Exaktbox are fed to power amps - one for each speaker drive unit - so 2 x 250s in my case, SL2s being a 2 way speaker design.
 
In the past I've compared an Naim Olive 250 vs Naim Classic 250DR vs Linn Akurate 2200. I felt that the 250DR was more detailed but the Olive 250 more musical. Comparing Linn to Naim - Linn allowed all the separate elements of the music to be followed & analysed whereas Naim felt more like a band
performing. Both good - just a difference of presentation.
 
So I was interested a couple of months ago when I had the opportunity to compare, in passive
configuration, one of my modified 250s vs a new White Logo Naim 250 vs Linn Klimax Chakra Twin at a dealers showroom using a Linn Selekt Edition streamer with dual mono Organic DACs & Kudos 707s. When you consider the price differential Olive 250 with Avondale & Witch Hat boards ~ £1.7-2k vs New Naim 250 £5.7k vs Klimax Twin £9.4k you'd think it would be a fairly uneven contest... But was it?
First up was the New White Logo Naim 250 - bags of detail & pace but I found myself analysing the music rather than enjoying it. My feet stopped tapping! Switching to my modified Olive 250 & the foot tapping was immediately back. Sure it was a marginally less informative, but ultimately more enjoyable. Finally the Linn Klimax Twin. This was somewhere between the two. A bit more detailed than the Olive 250, more musical than the New White 250. But was it worth the £18.8k price tag for the upgrade (remember I need a pair of them)? I didn't think so - maybe a used pair but I would want to hear one in my home system.
So where did this leave me? Neil of Audiophile Musings & Speakerfilters has suggested to me a few
times that I should try Lejonklou Tundra 2.5 amps in place of my Naim 250s. For those of you who
haven't read Neil's previous posts about these amps - Fredrik Lejonklou used to work with Linn beforedeciding that he could build better amplifies for a much lower price. The Tundra Stereo was
first released in 2012 & is now in its ninth iteration in version 2.5 which sells for just under £3.25k.
Neil offered to lend me a spare Tundra he has to try in my system, which coincidently is for sale, so
no hidden agenda there (editor's note: it was a completely above board agenda, as it happens!). At the same time I've borrowed a Klimax Twin to try at home.
 
First thing was to put my system back to passive as I only had one Tundra & one Twin. It's a fairly
straight forward job with SL2s as they have external passive crossovers and put the Exaktbox into
pass through mode so the DACs are being used but not the digital crossover. I then played five of my
favourite test tracks to get a feel for how it sounded passive. The overall character remained
unchanged although a little of the precision of the timing & sound stage was missing but still very
enjoyable.
 
Before putting the Tundra into my system, I'd been warned that:
a. They have less gain ~21dB compared to the Naim/Linn ~29dB so I would have to turn the
volume up +8
b. They take about 20 minutes to warm up - not after being switched on, but 20 minutes actually playing music to come fully on song, not that they are bad initially, they just get better with playing.
So when I first switched to the Tundra, I tuned the volume up & played the five tracks through
before going back to the beginning for a serious listen. The first thing that struck me was how similar
the sound was to that which I was used to. The Tundra has similar PRaT that Naim amps are famous
for. The Naim maybe had a smidge more authority on bass lines, the Tundra maybe a smidge more
transparency in the mid-range… But I would be hard pushed to choose one over the other - both are
very enjoyable.
 
Next up was the Klimax Twin. I was immediately taken by how much better it was than the Akurate
2200 I'd heard a few years ago. Previously I've found Linn amps great if you want to listen to all the
individual strands of the music, whereas Naim amps present the music as a whole performance.
While this is still true, the Twin is much more similar to the sound I am used to from my Naim amps
& more enjoyable for it. The Twin is a maybe smidge more detailed & informative but the Naim has
more swing & induces more foot tapping. Apart from the wallet bending price of a pair, I could
probably live with the Klimax Twin… if I hadn't heard my 250s or the Tundra.
 
I was able to have both the Tundra & the 250 in my system rack at the same time so it was only a
minute or so to swap from one to the other to do a tune dem. So having warmed the Tundra up again, in an effort to differentiate between it & the Naim, I played some tracks that I don't know on
one then the other. Now the differences became a bit more apparent. While the 250 still had a little
more weight & authority in the bass lines, where the Tundra really excels is in conveying the
emotion in the music. It's difficult to explain in words but I feel that I can really hear the musicians
putting their heart & soul into the performance, whether they are vocalists, guitarists or a
saxophonist you just get the feeling that they are giving it that bit extra. The listening experience is
just that bit more… well musical, more fluid although it still wasn't night & day differences.
 
A few days later I had a friend round who has no interest in hifi but enjoys music, particularly to
dance to rather than sitting down listening at home. First I played a couple of tracks she wouldn't
have heard previously using the 250 before switching over to the Tundra. Her initial reaction was
that the presentation of the two was quite different. The 250 was laid back & enjoyable whereas the
Tundra was more up front & in your face. She didn't like the way that the Tundra demanded her
attention, demanded to be listened to. Interesting. Then we played a number of tracks that she
knew from dancing switching back & forth between the two. Now her preference switched to the
Tundra, hearing the additional nuances it brought to the experience, describing it as more engaging
as though the musicians were performing just for her. By the end of the evening she said that both
were enjoyable but on balance although the Tundra is more demanding, she felt it is also (a bit)
more engaging.
 
So am I swapping my modded Olive 250s for Tundras? Hmmm! The 20 minute warm up is a bit of a
downer. Most mornings, I have a listening session that's, at most, ½hr while I have a cup of coffee
after I've done my morning workout & there would be that nagging doubt that the amps are not
performing at their best for the majority of that time. Additionally, I've been in discussions with John
Jackson (ex Naim & Witch Hat) about an further mod to my 250s to add another regulator to power the amplifier board to create a Phoenix Plus board if you like and elevate the performance further.

So the jury is still out.
 
At the end of the day, the Tundra is a very musical amp & should certainly be on your shortlist to
audition if you are in the market for amps at this sort of level. In my view it's considerably more
musical than the latest generation Naim 250 which, to me, is very hifi, which is great if that's what
you are looking for but for me, Naim have lost the PRaT that they were renowned for. I also
preferred the Tundra over the Klimax twin which, considering its ~⅓ of the price, makes the Tundra
something of a bargain. And if you have a standard Naim Olive 250, again the Tundra will be an
upgrade. At the end of the day, you could argue that my Naim 250's are no longer Naim amps - all
that remains of the original amps is the case, transformer & the sockets.
 
Thank you to Neil Hallworth for the loan of the Tundra, & Nigel Moore for the loan of the Klimax
Twin

Inside Linn's Akurate Kontrol/0/D Pre-Processor (Exotik DA)

 In the early years of the 21st Century Linn was still fully on board with multi-channel audio / surround sound with the Akurate Kontrol product.  They're back into surround again now, with the optional module of the Exakt DSMs - albeit with a lack of choice of centre speakers and no subs at all in the range - perhaps they'll arrive soon?

Introduced in 2006, the last dedicated (audio only, no video switching) pre-processor from Linn was initally branded Exotik and with the digital processing option, the Exotik +DA. About 3 years later, when Linn rationalised their products into three distinct tiers - Majik, Akurate and Klimax - the Exotik was re-branded as Akurate Kontrol. To distinguish this from the later stereo only Akurate Kontrol/1, the product is generally referred to as Akurate Kontrol/0. Part way through its life the power supply was changed to Dynamik which was also offered as an upgrade to existing products, hence the full nomenclature of the version in these pictures is Akurate Kontrol/0/D.

It was an excellent sounding processor and acquitted itsself well enough for stereo music to justify its place in the Akurate tier.  Covering Dolby ProLogic, Dolby Digital and DTS, it was equipped to offer audiophile grade cinema sound.  It was never directly replaced when Linn decided building its own fully licenced products was no longer cost effective at their sales volumes.  The latest foray into surround relies upon the use of a module built by a partner supplier.

The excuse for opening up this particular version was for the conversion to the workshop system colourscheme...

Before

General View

The digital board (the " +DA" on the Exotik version)

Main board - notice top left that its origins are from the much earlier Kinos pre-processor product

This small board allows the user to choose between MM phono, MC phono or line level on one of the analogue inputs

Rear of the front panel / display

Across the main board

Mainboard dustscape

Refinished for the workshop system

Exaktbox Comparison. Something to Consider When Choosing Which Exaktbox To Use: Stereo or Dual-Mono?

EDIT, 2018:  PLEASE NOTE THAT THIS POST WAS WRITTEN PRIOR TO THE /1 UPGRADES FOR AKURATE AND KLIMAX EXAKTBOXES - THE "KATALYST" VERSIONS.  THE FOLLOWING ARTICLE RELATES TO /0 EXAKTBOXES AND IS NOT RELEVANT TO /1 EXAKTBOXES

How exact is Exakt?  Well, you’d think, from the branding, that it would be as exact as Linn could make it.  A recent online “conversation” revealed that all is not exactly as it might seem.  And its all down to processing power.

A quick review of Exakt – it’s Linn specific set of processes in the digital world that changes the signal being fed to a digital to analogue converter (DAC) specific to each driver in the speakers to allow the sound coming out of that driver to correct for room nodes (like boominess), for manufacturing tolerances (in the higher range of Linn speakers), time for the signal to travel to the listening position, to make sure that driver only gets the part of the frequency range particular to that driver, to correct for phase alignment issues between drive units at the crossover point and to correct for phase errors within the drive unit itself.  All very much in real time (it takes about 45ms).  Clever stuff.  But that takes a fair amount of processing power, something that happens inside a Linn Exaktbox which takes a feed from the Linn digital streamer / pre-amp, does all that processing and feeds the signal to multiple DACs – one per speaker driver – which then feeds to the power amp per driver and then onto the speaker driver.

So all of the above, applied to a pair of speakers that have 3 drivers per speaker (known as 3-way), requires 6 channels of processing and DACs.  As this is a particularly good “use case” to illustrate the differences between stereo filters and dual-mono filters, that’s what I’ll step through in this post.

Linn make an Exaktbox that has 6 channels (in fact, there are 2 of these, one at Akurate level, the other at Klimax level).  So, that it makes it very easy to choose an Exaktbox to suit a pair of 3-way speakers right?  3 drivers x 2 speakers = 6 channels.  So Exaktbox 6 (Akurate or Klimax level) will do the job.  Well yes.  And no.  Why not?  Well, we need to take a look at what’s in each of those boxes.  Exakt processing is done in a processor called an FPGA, and the number of FPGAs you get per Exaktbox varies according to which version in use.  Take a look at the diagram below.  On the left, Exaktbox 6 (Akurate or Klimax, for this discussion they’re identical on the Exakt processing side), and on the right the Akurate Exaktbox 10 (actually called Akurate Exaktbox without the 10, but lets not get into branding choices here!).  Clearly, there are 6 DACs in the Exaktbox 6 and 10 DACs in the Exaktbox 10.  But, more crucially for this post, the Exaktbox 6 has 1 Exakt processor, the Exaktbox 10 has 2 Exakt processors.  Note that these diagrams are simplified for the purposes of illustrating this comparison and test (for those who are really interested, in Exaktbox 6 there is a "Master" processor and 1x "Slave" processor, in the Exaktbox 10 there is a "Master" processor and 2x "Slave" processors).

Now, the Exaktbox 10 has to be capable of running 2 speakers of up to 5 drivers per speaker (5-way).  So, for the sake of argument, lets assume that a 5-way speaker will use 100% of each Exakt processor in the Exaktbox 10.  This might not be true, but it keeps the discussion relatively simple – believe it or not! So, with 2x mono Exakt filters – one mono filter per speaker – both Exakt processors will be fully busy:

 

But we’re talking in this post about 3-way speakers, which probably need less processing power than a 5-way speaker filter.  Again, using an assumption that is purely that, I’m going to say that a 3-way speaker will consume 3/5s of the processing power of a 5-way speaker.  So then we have the 2 Exakt processors in an Exaktbox processor, running a pair of mono 3-way filters might look a bit less busy than the above example.

Now, if we take those left and right Exakt filters out of the Exaktbox 10 and put them into the Exaktbox 6’s single Exakt processor, what happens?  Well, it gets a bit over full.  I know these are all approximations and assumptions, but its just to illustrate what’s going on here.  The principle applies, regardless of the precise percentages of capability.  So we then have an Exaktbox 6 single processor that’s too full, you can see here that stacking up the 2x mono filters into the single processor doesn’t fit:

So what to Linn do to make it possible for an Exaktbox 6 to support 2x 3-way full range speakers?  Well, they don’t run the 2x mono filters like the Exaktbox 10, they run a cut-down stereo filter.  In order to achieve this, the stereo filter does less complex (and therefore less accurate) processing so it will squeeze into the space available in a single processor:

 

And what does that mean for sound?  Well, it’s less accurate, as you might expect.  Hence, Exakt is sometimes less exact than it might be.

Experiment

Its taken a while for this experiment to happen in Musings’ listening room.  Why?  Well, it took a while for Linn to get around to releasing the “dual mono” Exakt filters for the PMCs amongst others such as Linn’s own Keilidhs.  So if you were running an Exaktbox 6 or an Exaktbox 10 for PMCs back in May 2016 (like me), then you’d not hear much of a difference between them as they were both running the compromised stereo Exakt filters.  In fact, the Exaktbox 6 sounded slightly better due to the greater space and better circuit layout inside the box.  But this was a small difference and has nothing to do with the Exakt filters in use.

Let’s be clear here, even the compromised stereo Exakt filters, with my PMC Twenty.26 speakers, Exakt brought a step change in performance to the system.  See my review here of my first impressions of these speakers with Exakt.  Those impressions were written with stereo Exakt filters in an Exaktbox 10, per the diagram below:

But a few weeks back, Linn finally released the dual-mono Exakt filters for the PMCs.  So the system was set up with stereo filter in the Exaktbox 6 and dual-mono filters in the Exaktbox 10.  As below:

Everything else in the system was kept the same – same Akurate Exakt DSM source, same Chord C-Stream cable for the Exaktlink, same 6x Linn silver interconnects and same 6x channels of Akurate power amplification and speaker cables.  The same SPACE Optmisation settings were applied too, leaving only the stereo vs dual-mono Exakt filters being the only difference between the 2 set ups.  Yes, there’s the better layout of the circuitry in the Exaktbox 6 to allow for, but earlier testing has shown that as being fairly minor (worth having, but not worth trading equipment for, if you already have an Exaktbox 10, IMHO).

Although it takes about 10 minutes to swap all the interconnects over between the 2 boxes (and power up each drive unit one at a time, starting with bass and working up the frequency range to ensure all the connections are correct), its pretty easy to hear the benefits that dual-mono filters bring.  As is often the case, its not that easy to describe, especially given how good the stereo Exakt filters are. But lets say there’s just a lot more of everything without adding any clutter at all.  What you think is very stable imaging, becomes even more stable, wider and deeper too.  What you think is lots of space between and around instruments is a good bit better defined.  Bass appears to go a bit deeper, but room nodes are not excited any more than they were.  Some sounds evolve with even greater texture through the lifetime of a note.  There’s another improvement in the flow and effortlessness of listening to the music and following the tune – without thinking about it.  Are there any downsides?  Not that I’ve noted, its all good.  At least its all good if you don’t think too hard about the financial implications, or the idea that, with even greater processing power in future iterations of Exaktboxes, that there might be yet more to come.  But let’s not go there just now!

So what is the conclusion?  Well, Exakt isn’t always as Exakt as it could be.  And if you’ve got 3-way full range speakers like me, the Exaktbox 6 isn’t necessarily the “lower cost” route it might’ve been, as it involves a level of compromise.  But its also worth saying that the benefit brought by dual mono filters is worth having – if I knew this when starting out with Exakt, I would’ve saved up for the Exaktbox 10 over the Exaktbox 6.  It just so happened that the ex-dem Exaktbox available to me was the 10 channel version and it was part of the purchasing choice for a different reason – the option to go to the 5-way Akubariks, had I wanted to do that at some point in the future.  What does that mean for choosing an Exaktbox for other systems?  Well here’s the run down, as it stands at the time of writing, for a stereo pair of speakers:

• 1x Majik Exaktbox-i – 8 channels – 2 Exakt processors – capable of running stereo or dual-mono filters up to 4-way
• 1x Akurate Exaktbox 6 – 6 channels – 1 Exakt processor – capable of running stereo filters up to 3-way (and for some small 3-way speakers, that might be as much as is needed as the stereo filter is as good as the processing is going to get)
• 2x Akurate Exaktbox 6 – 12 channels – 2 Exakt processors – capable of running dual-mono filters up to 6-way (actually, this might be up to 5-way as that’s the maximum number of channels in currently released Exakt filters, but Linn would have to confirm)
• 1x Akurate Exaktbox 10 – 10 channels – 2 Exakt processors – capable of running stereo or dual-mono filters up to 5-way
• 1x Klimax Exaktbox – 6 channels – 1 Exakt processor – capable of running stereo filters up to 3-way
• 2x Klimax Exaktbox - 12 channels – 2 Exakt processors – capable of running dual-mono filters up to 6-way (actually, this might be up to 5-way as that’s the maximum number of channels in currently released Exakt filters, but Linn would have to confirm)

Some observations / thoughts:

• Linn should update the Klimax Exaktbox to further differentiate it from the Akurate Exaktbox 6 by adding a second Exakt processor.  The idea of a 6 channel Exaktbox that could run a pair of 3-way speakers in dual-mono is very attractive indeed and would be something to aspire to.  Currently, the cost of 2x Klimax Exaktboxes to run dual-mono 3-way speakers is just financially so far out of reach.  Or maybe produce another model called the Klimax Exaktbox 2 with 2x Exakt processors, priced slightly above the single processor version.
• The Exakt part of the Konfig interface doesn’t tell you which filters your Exaktbox is running.  Exaktbox-i and Exaktbox 10 will run dual mono filters by default, where they are available.  They will run stereo filters if dual mono are not available.  Multiple Exaktbox 6s will run dual-mono if the user / dealer install the mono filters into each one.  Either way, Linn really needs to make it obvious in Konfig precisely which filters are in use.
• Should I stick with dual-mono filters in the Exaktbox 10, or take the plunge and go with 2x Exaktbox 6s to get that last chunk of performance?
• Does a Klimax Exaktbox running stereo filters sound better or worse than 2x Akurate Exaktbox 6s running dual mono filters?  Maybe there’s someone out there with deeper pockets than me (or a dealer with the boxes to hand) who would like to experiment?
• Thanks to MaH at the Linn forum and some pointers to comments made by Linn's lead speaker designer, its clear that not all 3-way speakers will benefit from dual-mono operation over and above stereo filters.  For smaller speakers that don't need such a wide range of low frequencies to be corrected, then the stereo filter is all that's needed and Linn won't be producing dual-mono for those (an example might be the Majik 109).
• Does this apply to 2-way speakers?  Or does the lower processing requirement of 2-way speakers mean the stereo 2-way filters are just as comprehensive as dual-mono filters?  The bullet point above suggests that small 2-way speakers will probably have only stereo filters, but maybe the larger ones, such as Kudos Super 20 will still benefit from dual-mono filters due to their greater bass extension.

Conclusion

I like the effects of dual-mono filters in the Exaktbox 10 and will be sticking with them for the time being.  I was very happy with the system before the move to dual-mono, its just a very substantial layer of icing on my system cake!  I’m off to consume another slice…

FYI, for those systems using speakers with built-in Exakt processing and power amps, none of the above applies – this is because each speaker has its own Exakt processor on board and therefore, by definition, are running a mono filter each.