"What a refreshingly honest blog about listening to music through hi-fi. So happy to see views based upon the enjoyment of music rather than so-called sound 'quality'." - Peter Comeau, Director of Acoustic Design at Mission / Wharfedale

Friday 10 June 2016

Linn Exakt and PMC Twenty.26. World First Review Part Three - Set Up and Listening

Part Three of a Three Part Review

Part One Here

Part Two Here

If you’ve read the above first 2 parts of this mini-saga, then you’ll be aware that we’re part way through the story of moving Audiophile Musings’ system from passive Klimax electronics into Majik 140 speakers towards Linn Akurate Exakt and PMC Twenty.26 speakers.

The Exakt kit was a mix of new and ex-demo and consists of:
  • Akurate Exakt DSM (an Ethernet connected streamer, digital pre-amp and box of tricks that converts all digital signals into Exaktlink protocol before passing this along to the Exaktbox) – AEDSM; 
  • A Cat 7 cable to connect AEDSM to Akurate Exaktbox 10; 
  • Akurate Exaktbox 10 (a digital crossover which contains 2x Linn Exakt engine processors and 10 independent digital to analogue converters (DACs) and outputs 10 channels of analogue ready to be amplified) – AEBOX10; 
  • 6x Linn Silver analogue interconnects connecting the AEBOX10 to the power amps; 
  • 8x channels of Linn Akurate 4200/1 power maps (4200 has 4 channels so after moving from M140 speakers to PMCs, 2x channels are not used for the stereo parts of the system, the 2 spare channels are used to power the centre speaker of the complete 5.1 set up) – A4200/1;
  • 4x 2.5m of Linn K400 speaker cable to connect the power amps to the speakers (initially for the Majik 140s);
  • 2x 2.5m of Linn K600 speaker cable to connect the power amps to the speakers (later, for the PMC Twenty.26 speakers) 
  • Linn Konfig software running on a Windows laptop.

Trevor of the House of Linn came to set up the system, starting with the Majik 140s. We had to do that as the Linn Exakt software filters for the PMCs weren’t available at the time – see Part One of the story for the thinking behind making the jump to Exakt, even before the PMC filters were available. After all the Klimax gear was disconnected, we started on unpacking all the boxes for the new kit and did a bit of shelf dusting whilst we were able. One of the aspects I really appreciate about Trevor’s work is the attention to detail around taking care of the kit. Everything is handled with care and respect, he removes his watch and nothing is left to chance in terms of laying everything out in a logical order etc.
So the DSM is set up on the rack to replace the KDS/2 streamer and the power amps and Exaktbox are installed on the centre rack between the speakers, under the TV. Of course, all installed on Cyrus Isoplats. The Linn software and documentation give diagrams on connecting up the power amp channels to the back of the Exaktbox. Because there are 10 channels on the Exaktbox and because there are many different speakers supported by the software, the connections to the power amps are very much dependent on the speaker in use. So the back of the Exaktbox is just labelled channels 1 to 10 – it’s the diagrams in Konfig that show you how to connect up. Konfig then needs the speaker serial numbers entering and it downloads the correct filter profiles for that particular make and model of speaker. The filters apply all the correct frequency cut-offs and phase corrections tailored through software for the speakers in use. For the Majik 140, channels 1 to 4 and 6 to 9 are used. These Exaktbox outputs were hooked up to 2x Akurate 4200/1 4 channel power amps using Linn Silver interconnects (these have silver coloured sleeves, but the conductors are copper). One power amp was used per left / right channel.

Akurate Exaktbox 10
Linn Konfig is fired up on the laptop and work starts on configuring the system. First up is to select the speakers for the Exaktbox – select the model from the drop-down lists and then enter the serial numbers – choosing which speaker (left or right) will use each set of channels (1 to 4 or 6 to 9). Then all the room information for SPACE room optimisation can be input (dimensions, materials, window positions etc etc), or the existing room information is retained, which is the position we were in. SPACE was left switched off and we spent the best part of an hour re-positioning the speakers in the room. There was only about 10-15mm change in position in the room to get the best sound from their previous position.
At this point, SPACE optimisation was calculated and applied. It was pretty much spot-on – a result which is markedly better than using SPACE in a non-Exakt system. In Exakt, the optimisation is called SPACE+ and is applied in the Exaktbox (rather than in the DS in analogue systems). This uses fewer compromises (for example, the position of individual bass / mid-range drivers and the bass ports are much more accurately modelled in SPACE+) and seems to give a great result. We messed a little with the SPACE settings, but ended up back at those calculated by the system. Impressive.
So the Exakted M140s using Akurate level electronics are a major improvement on the same speakers driven passively by the higher-up-the-range Klimax electronics. Some may find this difficult to take, particularly those heavily invested in Klimax gear. But here we have a system that performs both musically and technically far better and by selling on the Klimax components, actually left me financially better off. Why do I find it better? Well tighter timing, massively better imaging, bass control, a naturalness to the vocals and completely involuntary foot tapping. Given that Linn equipment already sounds very well controlled – to the point where some listeners find them too controlled and lacking in liveliness and wanting them to “let go” more – then its possible to see how Linn have developed Exakt to take this one step further. Did the electronics improve over time? Did they “burn-in”? I’m not sure that they did. Certainly, not enough for me to have noticed. But then it was only the AEDSM that was new – the Exaktbox and power amps were ex-dem and as such would’ve experienced “burn-in”, if such a thing exists with these systems. What is noticeably though, is the warm-up effect. The system sounds great when first switched on, but there’s definitely an improvement at somewhere between 20 and 30 minutes of use. The sound “fills out” and becomes both warmer, deeper in the bass and yet just as controlled. It’s a nice effect, but it would be much better if the system sounded this way from the start. I try to find the time to run the system for a while before sitting down to a focussed music listening session.

What of the PMCs? Well at this point I was kind of thinking the M140s would be around for a while longer whilst saving up for Akubariks. But it wasn’t long (about 3 weeks) and the PMC filters were released. So time to give it a whirl. Some correspondence with Linn suggested that they had found the PMCs a little bright and tiring too and had tailored the Exakt filters to take out a fair amount of treble energy. So the work was done to convert the speakers (see part 2 here), the M140s were replaced by the PMCs.
But its not a straight swap of course – everything was powered down to start with. First, documentation was consulted and the PMC wiring diagram was identified. Now channels 1-3 and 6-8 of the Exaktbox are in action. 2 channels of the power amps were disconnected from the Exaktbox and the speaker cables were changed out from 2x K400 for K600 (3 pairs of cables in one sheath). Next the AEDSM and Exaktbox were powered up (NOT the power amps) – once they were visible on the network then Konfig was opened on the laptop, the correct PMC speakers (curiously, there is choice of 1x Twenty.26 or 2x Twenty.26 available – this is for those who wish to use one Exaktbox per channel – apparently for sound quality purposes, but I doubt that’s something I’m going to consider in the near future – one of the major benefits of the PMCs is the ability to run them off one Exaktbox, including the 6 channel Klimax version). So 2x Twenty.26 was selected and SPACE switched off. I then connected up the bass power amps to the bass drivers and powered up, listened to a couple of minutes of music to check bass information was coming out of the bass drivers. Then the mid-range was added, checked and finally the treble was connected up and checked for treble output. This sequence is important to make sure that drivers are not damaged. The great news was that everything worked as it should. A major relief that the speaker conversion has been a success.
The system was then played and speaker positioning commenced, taking about an hour to start with, then tweaked again after a couple of hours. Like the M140s, the .26s ended up positioned only 10 to 15mm away from their position when using a traditional system.

So a little time was spent listening with SPACE+ turned off, then the position of the PMCs entered into the Konfig room information and SPACE+ optimisation was applied. Like the M140s, the PMCs benefitted from the improved modelling in SPACE+. The room optimisation notches applied by the Linn calculations are excellent, again I found that tweaking them made no improvements, in fact, deviations messing stuff up really. After a few weeks of use, the only change I made at the room optimisation end of things (ie the bass) was to add a 0.9 dB bass “shelf” to add a little weight over the full bass range. What of that sometimes tiring top end? Well the effect of the Linn Exakt filters are easily spotted – with the treble much more in keeping with the rest of the frequency range. A nice change and one I stayed with for a week or so, but eventually dialled in a -1.8dB treble shelf (after much experimenting with values above and below this). Now we have, to my ears at least, a well-balanced frequency range.
One more area that didn’t sound right to me was a harsh edge on vocals – particularly female vocals. There’s nothing to play with here on Linn Konfig so I experimented with a few cables and found something quite astonishing – the supposed perfect digital signal going along the Exaktlinks makes a difference. This doesn’t make much sense, but its probably about noise getting into the Exaktbox – I’m sure its nothing to do with data corruption. So changing from a standard Cat 7 ethernet cable between AEDSM and the Exaktbox to a Chord C-stream (their most basic streaming cable) lost the sharp edge on the vocals and I can’t hear any downsides. Strange but true.

So what of the overall sound of the system? Well at this point, with SPACE+ set up and the cable change above, what we have is a very musical result. The changes I noted going from M140 to PMC in the traditional system are all relevant here, but without any noticeable downsides. The PMCs go deep but are better controlled, vocals really come across with nuances and texture and treble is both full of detail and subtlety. On top of this, Exakt brings a sense of the recording space, speed, masses of information and a step change in the separation between instruments. And I can listen for hours. And hours. And hours, and I do so.
From what I remember of the Exakted Akubariks (at this point about 5 weeks ago in a different room, and about 3 or 4 months ago in Canada), then the PMCs are at least their equal in terms of detail retrieval and subtleties. But they have a different approach to life – they’re very much more lively – they drive a rhythm along with more conviction and a sense of fun, but they do this without being out of control or aggressive. Perhaps the PMCs don’t go quite so deep as the Akubarik, but this is very room dependent so there’s no real direct comparison here. So all was well, but the story doesn’t stop there.
About 3 weeks after Exakt conversion, there was a new software release (for the detail people, it was Exakt compiler version 16). This made no changes to the filter settings for the PMCs, but it changed the way in which the Exaktbox processes and applies those filters. At first, I didn’t quite believe what I was hearing. It took the best part of a day to get past the initial size of the change. That this magnitude of change could happen through software, and to move on to all the little subtle changes that came with this release is an eye-opener. First, and most obviously, was the massive improvement in the sense of imaging and space of the sound. I’m guessing that this is down to much more effective phase alignment processing and it is astonishing in its effect. The speakers truly disappear and instruments and voices are absolutely defined in space – very stable and very believable. The context of the recording is much more obvious – particularly live tracks where the sense of the recording space is portrayed into the listening room. I would liken the size of this software driven improvement being equivalent to moving from ADS/1 to KDS/1. And it was free. Remarkable.
But all this separation, sense of space and believability allows through so much more detail and subtlety. And it’s across the frequency spectrum. Bass lines on Daft Punk’s "Giorgio Moroder" (from the Random Access Memories album) reveal themselves to be even more complex than before and as the crescendo builds at the end, all that complexity remains in control with no tendency towards harshness. Throughout the track there are numerous synth sounds that move from bleeps and blops to being clearly identified sounds that evolve within each note – adding texture and flavour to the track. At the end, the click evolution is much more obviously about a note generated with a very “square” profile. " Get Lucky" (also from Daft Punk's Random Access Memories) is revealed as being much more complex than just a good bit of dance-pop. The lead vocal is clearly more “breathy” with words like spinnin’ now being spinnin-uh, with the uh part only just discernable, but clearly there. Midway through the track the bass line drops out and there’s a buzzy synth underlying the main theme – but it is now audible as a vocoder vocal sample that’s been stretched and twisted. These might seem like minor points, but together they add up to a track that’s much more musically enjoyable – one worth sitting down and concentrating upon rather than being some kind of background or party track.
The echo of the venues on Fink’s live album (entitled "Wheels Turn Beneath The My Feet") is both more obvious and decays away for longer without crashing into or blurring the following notes. The sound of hammer on anvil is right there about 3 feet out from the speakers, just left of centre and about 3ft off the ground in Funkerman’s "Speed Up" (ATFC Remix from the Speed Up EP). Mary Gauthier’s hatred and ire in "Falling Out of Love" (on the "Mercy Now" album) are laid bare whilst the heat pipes hiss. On all of this music, even though there is this very clear separation of individual instruments, there’s no doubt about this being a presentation that still hangs very much together as a joined up performance. Very soon, you get wrapped up in the messaging and mood of the music, enjoying the expressions and flavours, ignoring the hifi, which tends to just disappear.

As you might have gathered, I’m very impressed with the implementation of Linn Exakt with PMC Twenty.26 speakers. The approach Linn has taken to produce digital crossover filters, phase correction between and within drive units and time-aligning the signal has paid massive dividends. The combination of Exakt and PMC really pushes these speakers to compete in a price bracket two or three above where they are as a passive speaker. They sound different to, but very much in the same performance league as Exakt Akubariks. And they’re different in a way that brings more life and fun to the music, but in a way that’s not tiring or wearing – but listenable for hours. And boy do those hours fly past quickly!

 Now we can look forward to Linn releasing this as an official conversion – it’s a pity that the Twenty.26 will be in the shadows a little now that Twenty5.26 is about to hit the market – the gestation time seems too long to have hit the market at the right time. On the flip-side, think of all those traded-in Twenty.26s that will be hitting the market ripe for the transformation that Exakt can bring to them…

For those that heard Exakt in the early days and weren’t impressed, or for those who thought/think that a Klimax badged system MUST be better than an Akurate badged system, I urge you to think again and give Exakt another listen.

Post Script: Since the initial implementation, my Klimax Twin amp has been added into the system – I use this for the mid-range where it seems to bring the best improvements, having tested it across the board. Taking the mid-range from Akurate level to Klimax level amplification has helped at a little more subtlety and detail, but its not a huge uplift – more of a nice to have, given that the amp was already in my possession. If another becomes available at a sensible price I would add it into the bass before the treble.

Now with added Twin
Post Post Script: I'm now wedded to the PMCs for the longer term, so Twenty.21 have replaced the Linn Katans (formerly there were Linn Majik 109s prior to this recent wholesale change) as rear speakers and a Twenty.C has replaced the Linn Tukan (again, formerly a Majik 112 for a number of years) as the centre to complete the 5.1 set up. I must say, the Twenty.C is in a different league to the Majik 112 - a very impressive centre speaker


  1. Fantastic read Neil despite a fair bit being very technical for my brain. I'm seriously impressed with the work you've done and how you've conveyed this to your audience. Congratulations.

  2. Thanks Neil
    Always a good read you must come down and have a listen now the chord Music cable is in the system
    Took two seconds to convince me

  3. You're welcome gents, thanks for the feedback

  4. Six years later, I’m about to buy my first Linn system. It’ll be a Selekt as system hub with Exaktbox-I driving 140’s. This write up was actually about the only thing apart from dealer praise I could find on the specific subject!