Linn Tukatan

 Linn's little Katan standmount from the 90s and early 2000s has an excellent reputation, particularly in active form, and quite right too, its not the last word in refinement but the music it produces is very enjoyable indeed.  In Linn part number terms, it is fitted with the 038/2 tweeter and 039/1 mid-bass driver.

 

 

Its predecessor is the Tukan, is similarly small, but lives in a more conventionally shaped cabinet.  It has the older drivers - the tweeter being the 015/x family and the mid-bass the 016/2.  It has a reputation as being a very "fast" speaker, but there's a certain hardness and lack of friendliness to the sound. Its also considerably bass shy compared to the Katan.

Curiously, when taking either of these speakers active (aktiv in Linnspeak) they both use the same analogue active filter cards, despite their very different drivers.  So the crossover points, slopes and relative loudness of the drivers are shared.

Also, the driver cut-outs in the cabinets are identical allowing the drivers from the Katan to be fitted into the Tukan cabinet.  So I gave it a go.  Even with the passive crossover, the Tukatans are a huge improvement on Tukan, being more flowing, warmer, far smoother in the treble and they now have that Katan musicality and friendliness.

Here are the Tukatans:

 

Inevitably, of course, a set of Exakt filters had to be created and were built pretty quickly.  Below is the FR resulting for Tukatan Exakt (ignore below 120Hz as the room is having too much influence there).  A great fun pair of speakers!

Product Review: Songcorder Software by Meraki Acoustic

The Linn DS (digital streamer) family is, at the time of writing, just over 13 years old.  The first internationally recognised true HiFi company to take streaming seriously, Linn launched their top of the range Klimax DS as a market leader.  There have been several iterations since, all versions able to be upgraded to the current specification.

But the family has grown since then.  There are pure DS players (network connection, streaming capability, onboard stereo DAC), DSMs (all the above plus pre-amplifier capability, including analogue inputs) and other DSMs that do what DSMs do but have a built-in stereo power amplifier. Spanning the complete range too - from the designed-to-be-hidden Sneaky, through Majik, Akurate and Klimax ranges.  Most recently the  modular Selekt DSM has been launched which can be all sorts of combinations of streamer, pre-amp, all-in one stereo, all-in one surround sound and more.  Surround modules can be added to DSMs too. Then we throw in the choice of outputs - traditional stereo analogue, Linn proprietary Exakt digital link to Exaktboxes or Exakt integrated speakers and a combination of analogue & Exakt on some units.

That's probably pretty confusing to the uninitiated, and understandably so. But there's even more to it than that. Software. Without software these players would be expensive (or very expensive) decorative (or in some cases not so decorative) items.  The software that makes them operate is vital.  But one of the beauties of the Linn DS / DSM is that the software continues to evolve. And every DS / DSM since that first one back in 2007 is capable of being upgraded to today's software versions. And Linn releases the software updates without charge. That's right, a 13 year old product is still being upgraded by Linn on a frequent basis - and it doesn't cost the original, nor subsequent, owners a penny.  Buyers need to keep that in mind when they think Linn gear is too expensive. Some of these software releases have unleashed even greater sound quality and musical enjoyment from the streamers, not just new functionality.

So even though Tidal and Qobuz streaming services weren't available back in 2007, they are available on the DS/DSM today through those software updates. As is the ability to tune the output of the music to counteract the worst impact of the room on your music.

Why do I mention all of this? Well where there is software, there needs to be ideas. Creative ideas. Ways to make hardware perform tasks that weren't originally envisaged. New ways to exploit, new services to offer, new functionality for the user. And that's where Meraki Acoustic comes into the Linn DS/DSM picture.

Many of the DSM devices have a built-in analogue turntable input - MM or MC - and this was the inspiration behind the Songcorder app from Meraki Acoustic. The DSM turns that incoming analogue turntable sound into a digital signal. What if there was a way to capture that digital signal, feed it to a computer and capture it as an audio formatted file? Could that be a way to digitise all that precious and delicate vinyl? Could a DSM customer capture their favourite music in format that doesn't wear out? Would they finally be able to get that vinyl only release from 1976 into a digital file to listen to on the move, in the car, in rooms without a turntable?

The answer is yes - with Songcorder.  Meraki kindly sent me access to a copy to download to investigate further.  As most will know, although I have a turntable, its not the main source in my system.  Even so, I thought it would be interesting to give Songcorder a try.

The download was easy as was install on my up to date version of Windows 10 running on a Dell Latitude E6440 laptop which has a 3 year old Core i5, 8GB of memory and an SSD.  I tested it along with my Ariston RD80sl / Linn Basik Plus / Goldring 920 turntable and my Linn Akurate Exakt DSM through its built-in MM phono stage. The instructions recommend a wired connection for the computer running Songcorder and for the DSM - wifi being "potentially" troublesome.  In practice I found wifi to be almost always troublesome so stuck with an ethernet cable throughout, which was totally stable. Your DS or DSM must have Songcast enabled for Songcorder to do its thing.  It must also be listed in the compatible devices list here: https://meraki-acoustic.com/songcorder/#Compatibilty

If you're as old as I am you'll remember pressing pause and record on your tape deck, gently lowering the stylus onto the record and then pressing the pause button before the track started - the way we used to be able to play our own music in the car or the kitchen or later on a Walkman or similar.  Well Songcorder is similar in concept - whatever you're playing through the DS or DSM will be captured and recorded as a digital file ready for use with your streamer or loading to your DAP.

Once installed and fired up, this is the simple interface: 

Select your wired connection in the Network Interface drop down, select the Linn DS/DSM you want to record from (the software found all 3 Linn devices on my network) and select which directory you want to drop your recording into, and that's it. Nothing fancy but nothing complicated nor confusing - refreshing.  I really like the simplicity.  Start your turntable playing and click on that big red button. Done. Of course, you need to keep on top of what's going on.  You could record a whole album side and leave it at that. Or you could then use some software tools to break down the side into individual tracks. Or you can do what I did and capture individual files for each track on the LP.  When recording you get the simple screen below, just click Stop when you're done.

For each vinyl recording Songcorder creates a file at 24 bit 192kHz resolution using my Akurate Exakt DSM - I suspect that this is the resolution used by Linn when converting analogue to digital. Recordings from earlier Majik DSMs would be resolved at 24 bit 96kHz due to its lower resolution ADC stage. Songcorder generates what looks like a unique filename in FLAC - a widely supported format that can be converted to other forms by many of the popular digital music file handing programs available. You'll need a music file editor (I use TagScanner but there are lots of choices) to rename the tracks and input your own meta data such as Artist, Album, Track, Year, Genre etc.

Only one element of Songcorder I didn't enjoy is that it goes back to its default folder every time, rather than remembering where you prefer to capture your recordings. Its a very minor point and doesn't take away from the fact that this is a superbly simple tool that does exactly what it sets out to do.  The good news is that this gave me the opportunity to test the bug reporting process and happy to say that work is underway to address this as I type.

Sound quality is excellent - when playing back a vinyl recording, as far as I could tell, there was no degradation from the original analogue conversion I was listening to as recording took place. 

Whilst vinyl is the inspiration for Songcorder - to preserve those rare recordings or to create back up copies, for example, I did find that Songcorder will capture any stereo audio input on the DSM that's connected by toslink, SP/DIF or analogue inputs. Streaming works, but HDMI was less successful - theoretically it should work with stereo unencrypted content, but I didn't find any. Streaming works equally as well as the analogue input and captures the file in the resolution of the original source.  Of course an anlogue stereo output from such devices would work. Songcorder picks up the signal before any of Linn's SPACE Optimization or Exakt processing is applied.

Of course, one should be careful about copyright issues and only capture music already owned, or material that is free from copyright. 

An impressive piece of very effective software - I was so pleased by its performance I have purchased a copy, an equally smooth and simple process. At the time of writing the software cost a mere 20 Euros and is highly recommended.

LINN Exaktbox-i: Photo Comparison Between Majik (Pre-Katalyst) and Akurate Katalyst Versions

Linn's carefully hidden Exakt separates system consists of the following key components:

An "Exakt ready" streamer / pre-amp (such as Klimax DSM / Akurate System Hub / Majik DSM amongst others)

A proprietary Exaktlink cable which uses standard Ethernet cables

An Exaktbox which is essentially a digital active crossover and digital signal processor, amongst other things (such as Akurate Exaktbox10 / Klimax Exaktbox)

Power amps, which can be from Linn or any other manufacturer.

However, there is an option to combine the last 2 elements - the Exaktbox and the power amps.  This is called an Exaktbox-i and combines 8 channels of DAC / digital active crossover and 8 channels of power amplifiers in Linn's normal just-a-bit-narrower-than-standard box.  There's really only one of these in the range, but it has evolved in the 4 or 5 years it has been available:

1 - Intitially it was a Majik Exaktbox-i containing Majik level DACs and 100W power amps, all in the Majik level casing

2 - Then it was re-badged the Akurate Exaktbox-i but still contained Majik level DACs and 100W power amps, but now in the more substantial Akurate casing.  This version was very short lived, soon replaced by:

3 - Akurate Exaktbox-i with Akurate level Katalyst architecture DACs but sill with Majik level 100W power amps in Akurate level casing

As is often Linn practice, those who bought the earlier products don't get left behind when there's an upgrade.  So it is possible to have a Majik Exaktbox-i upgraded to Akurate Katalyst Exaktbox-i internals but retaining the Majik casing.  The first Akurate Exaktbox-i can also be upgraded but I expect most of those were done pretty much automatically as there was a deal where the cost to upgrade was only the difference in price between Katalyst and non-Katalyst versions.  It would be very odd to find one of these that hadn't been upgraded, given the small price to do so.

I've been using an original "pre-loved" Majik Exaktbox-i for a while for Exakt filter design activities.  For some reason, now seemed to be the right time to take that up to Katalyst specification.  So that has allowed me to make comparisons between the circuitry of the non-Katalyst and Katalyst versions.

A similar comparison of the Akurate Exaktbox10 (April 2018) is here.

Much has been written about the musical capability of the upgrade from Linn's previous generation DAC to the Katalyst DAC, and I can't think of anyone who has anything but praise.  An example is here regarding the upgrade in Linn's onboard active Akubarik speakers.  So I'll not write about that here as it is well trodden path. With the upgrade being applied to the Exaktbox-i back at the Linn factory, there's no ability to directly compare the 2 products back to back.

To the photos.  Note that every single audio board (DACs are combined with the power amps) and the Exakt processing board are changed in the upgrade - the photos with the green circuit boards are the Majik non-Kat version, the black circuit boards are the upgraded Kat version.  The PSU and the casework is untouched, save for the addition of a Katalyst sticker on the underside.

Externally the box is unchanged

BEFORE AND AFTER UPGRADE COMPARISON PHOTOS:

The most obvious difference from an overall perspective is the change from green to black and gold boards

Each side of the enclosure has 4 channels of power amps (the chips bonded to the heatsink are the obvious components) and 2x stereo DACs.  The DACs above are the cross-shaped cluster of an oblong chip surrounded by 8 smaller chips

Here you can see the difference in the DAC architecture - now we have the 2x stereo DACs which are the 2x flat square chips - the board layout is very different

The "flyover" board down one side of the enclosure is the Exakt processing board.  The above original layout has 3x FPGA processors - the large flat square chips. The one on the left is the "master" processor with the other 2 processing 4 channels each

On the new board there is one more powerful FPGA chip in the centre doing the work formerly done by 3x separate chips

Board labelling for channel 5 to 8 DAC / power amp board has been relocated

Relocated labelling for the Exakt board

The increased complexity and density of the components surrounding the DACs is clear in this comparison.  The Katalyst DAC has multiple different regulated power supplies which probably explains this increase in components

SOME KATALYST ONLY PHOTOS:

Xlinx FPGA that does all the Exakt processing

DACs and power amps for channels 1 to 4 live in the shadow of the Exakt board

Building a Nindex Speaker - Part 3 Crossover Design, Measurements and Listening

PART 1 OF 3 HERE
PART 2 OF 3 HERE

As explained back in Part 1, the speaker is intended only to be operated in active mode with a Linn Exakt system. So a bit of an explanation of Exakt first.

In a traditional hifi system, an amplifier feeds a full range signal to the back of the speaker cabinet, then a passive electrical system inside the cabinet (the crossover) splits the signal into the correct frequency ranges for each of the drive units to handle.  This crossover is made of high power components which sap power from the signal, have wide tolerances and introduce their own problems such as phase errors.
In Linn Exakt, the full range signal from a digital source is fed to a component called an Exaktbox. In here the signal is split into the frequency range appropriate to each driver in the digital domain - this means it is done far more accurately than can be achieved in the speaker's own passive analogue crossover. The Exakt system allocates a DAC (digital to analogue converter) to each speaker driver and then the signal is passed to a power amplifer for each driver.  This is then connected directly to the appopriate driver in the speaker cabinet without any further components getting in the way, so the amp has better control over the movement of the driver.
So Exakt has very precise control over what gets to each driver and it introduces no phase errors of its own.  In addition to this, the system corrects for any phase errors within each driver and any frequency response "features" of the driver by applying an opposite signal to the error. Finally it also introduces time delays to drivers that are closer to the listener, in order to better time align the sound getting to the listener's ears. Some information here plus if you Google Linn Exakt you'll get lots more information and opinion.
Personally, I call it Linn Lessinexakt, but I don't suppose that would go down well in the marketing department...

Digital Design

As a consequency of the Linn Exakt approach, the Exaktbox system can be programmed to address pretty much any loudspeaker available, as long as there is someone who can measure the speakers and then carry out the design work to be loaded to the Exaktbox.  This is the service I offer under the SpeakerFilters brand.

There are several stages involved in creating the filters:

• Physical measurement of the speakers which are then uploaded to Linn's database
• Acoustic measurement of the passive speaker prior to modification to get a view on its existing characteristics (not part of this design work as there's no existing passive design to measure)
• Electrical measurement of the speaker drive units (in and out of the cabinet if a ported design)
• Translation of the electrical measurements into the parameters expected by the Linn Exakt Design system
• Creation of initial crossover points and slopes, along with approximate attenuation of individual drivers - usually based on the passive crossover design
• Acoustic measurement and listening with lots of experimentation to get the right mix of measured results and the best listening experience - this is the most time consuming with lots of iterations

So these were the next steps to the project.

Electrical Measurements

These are based on pretty straightforward impedance sweeps - showing the impedance in relation to the input frequency range from 20Hz to 20kHz - the generally accepted range of human hearing.

An example of the bass driver in the Nindex project is shown below:

The upper (red) line shows the phase response of the driver, the lower (blue) line shows the impedance curve which is fairly typical of a driver in a sealed cabinet - the peak is the driver's resonance frequency when mounted in the cabinet. By analysing various elements of this trace, the "thiel-small" parameters for the driver can be derived and fed into the Exakt design tools.

Looking at the response curves of the TM1-A array, it was a fairly straightforward choice of where to start with for the crossover points:

Mid Range Dome Frequency response - shows that the crossover points need to be above 850Hz at the lower end and below about 7500Hz at the top end (when the off-axis response starts to fall away)

The tweeter has a very wide response range and looks like it could handle from 1500Hz or so upwards - so it would be a good design to use with a larger mid-bass in a two way system.

I started with nominal crossover points of 1500Hz and 7000Hz, both with Butterworth 4th order crossovers - for those of you concerned about such steep slopes, remember that, unlike a passive crossover, the Exakt digital crossover doesn't introduce phase distortions based on the steepness of the slope. So the slope can be adjusted to suit integration requirements and the subjective listening experience.

The first acoustic measurement to take is just a quick sweep to check if the relative volumes of the drivers are somewhere near close.  Using the bass driver with attenuation of 0dB I usually put in -3dB for a mid-range and -4dB as the starting point.  Then work from there, usually by ear first, then refining with acoustic measurement. Its possible to hear changes of as little as 0.1dB which most people find very surprising until they hear it for themselves.

Then starts the refining of the crossover points - but only one at a time of course - listening for where the instruments sound more believeable but most importantly where the music itself is more engaging plus best for the most stable central imaging but widest overall spread of image - its not scientific, other than staying within the sensible ranges for each driver.  A crossover point is a nominal value - once this seems about right, more listening is done to various combinations of each driver roll-off point and therefore which mix is right and how steep the slopes might be.  For the bass to mid crossover, its easy enough to hear changes of around 25Hz in the values.  For mid to tweeter, I usually work in chunks of 100Hz.

Design work was completed using a Linn Majik DSM/3 network streamer / pre-amp and a Linn Majik Exaktbox-i which combines 8 channels of Exakt processing, 8 DACs and 8 power amplifiers - a remarkable bit of kit all in one box. The Exaktbox is the pre-Katalyst DAC version (at time of writing and design work - the upgrade is planned for the future).

Linn Majik DSM/3

Linn Majik Exaktbox-i

Here's the data that I ended up with for the Nindex:

Bass Driver

• Roll-on = 10Hz
• Slope Type = Butterworth
• Slope Gradient = 4th Order
• Roll-off = 1100Hz
• Slope Type = Butterworth
• Slope Gradient = 3rd Order
• Attenuation = 0dB
• Time Alignment = 0

Mid Driver

• Roll-on =  1600Hz
• Slope Type = Butterworth
• Slope Gradient = 3rd Order
• Attenuation = 4.0dB
• Time Alignment = -119 microseconds
• Roll-off = 4800Hz
• Slope Type = Butterworth
• Slope Gradient = 3rd Order

Treble Driver

• Roll-on =  6700Hz
• Slope Type = Butterworth
• Slope Gradient = 3rd Order
• Attenuation = 9.1dB
• Time Alignment = -87 microseconds
• Roll-off = 28000Hz
• Slope Gradient = 4th Order

In the simplest terms, the resulting graphic looks like this below. Note that this is the electrical output required to achieve the crossover points and a flat response from each drive - so the curves aren't straightforward because Exakt is allowing for the characteristics of the drivers themselves.  Plus, in this image there are actually some filters hidden from view but having an effect - for example there is a small lift below 60Hz to add a little bit of weight to the bass.

The electrical outputs to achieve the crossover points

I then, by habit, add some "protective" filters to each driver - they're not shown above, but I'll put in a low pass filter for the bass driver than allows frequencies between 0Hz and 3000Hz. For the tweeter, for example, I'll add a high pass filter from 3000Hz upwards.  For example for the bass:

Example "safety" filter for the bass driver

Baffle step is a phenonmenon that means when a certain frequency and above reaches the edge of the baffle, it diffracts and becomes amplified for the listener - this is often cited as the reason that studio monitors are built into walls, to avoid any edges. This is obviously not possible for a speaker designed in a box so its best to put in step filters at the frequencies calculated on the baffle width and height.  So those calculations are done and appropriate filters added - with attenuation levels that are guessed to start with (they're often of a similar value between designs with the size of the attenuation rising as the frequency rises) and are typically in the range 0.2 to 2.5dB.  I usually start the step curve a little before the intended frequency and keep the slopes at a nice and gentle 2nd order. Here's the step for the mid driver which kicks in about 15Hz before the calculated point and is attenuated by 1.5dB:

Mid Range Baffle Step Filter

At this point, for confirmation of the rough acoustic measurements and subjective work, I'll take an acoustic 20 to 20000Hz sweep to make sure there are no glaring errors - preferring to work this way rather than relying entirely on measurements.

So now we have a pretty flat response through the design process, a choice of crossover points that give the best subjective sound and imaging.  Of course, in the background of all this the Exakt system has applied the calculations to each driver to deliver minimum phase errors, but all of that is invisible to the designer.

Now its time to do some detailed acoustic measurements and iron out any signficant frequency response anomylies in the drivers themselves.

I use REW software for acoustic measurements, paired with a calibrated UMIK-1 microphone connected to the laptop by USB. The laptop is dedicated to only the audio work, runs Windows 7 and pretty much nothing else. No fancy audio programmes nor drivers or anything else that will potentially add noise or unwanted processing effects.  For design work I always measure the speaker on-axis vertically with the tweeter as that is usually the most directional driver.  Horizontally I will measure on-axis and 30 degrees off axis.

My intention with this design was to get the 30 degrees off-axis frequency response pretty close to flat.  This will mean that on-axis the speaker will sound a little "bright" in that the treble output will be higher than the rest of the audio range.  This is deliberate to allow the speaker to be pretty much optimal with just a very small amount of toe-in.  Then for those who like a little more brightness or for older listeners whose hearing is starting to tail-off at the higher frequencies, a little more toe-in of the speaker will bring that change in balance.

Measurements are taken at 300mm to allow the mic to pick up the full frequency range but to minimise the effects of room reflections.  Not having an anechoic chamber to work with means that measurements below about 110Hz need to be completely ignored as they are prone to standing waves in the room.  Any tweaking below 110Hz is done purely by ear.

The camera angle makes this look more, but this is measuring 30 degrees off-axis in the horizontal

The software provides a sweep from 20 to 20,000Hz and measures the output from the speaker, corrected for the calibration of the microphone. I ignore all readings below 110Hz.

This then gives a picture of any interesting "features" of the frequency response of the drivers themselves, and, if there are any, where the drivers are perhaps overlapping too much, or leaving a trough due to not enough overlap.  Usually some quick adjustments to crossover points or possibly slopes get this sorted quickly.  The "features" of the drivers can be adjusted for with the Exakt digital crossover designs.

This is done by "modelling" the humps and dips in the response curve, then Exakt compensates electrically by applying the inverse to the signal delivered to the speaker.  So a 3dB hump at 1000Hz in the speaker will have an exact opposite - 3dB output applied at 1000kHz. It is possible to add bell curves, high or low pass and shelves. The height and width of a bell curve is adjustable.  It is possible to model each left and right speaker individually, or just go with a blend of the average of both.  In this project I worked on individual drivers - in commercial models it makes more sense to go with an average as there is little sense in trying to second guess the features of individual products out in the market.

So here is the resulting modelling for the left speaker with all the humps and dips modelled in for Exakt to correct for. It has to be said, apart from the need to add a lift from about 16000Hz upwards, the tweeter was the best behaved of the drivers.  Please be aware that I don't spend days and days dialling out every single ripple in the response curve. It would be rather unproductive - I focus on the main features and leave it at that.

The top line is the modelling of the "features" in the frequency response of the drive units.  The bottom 3 lines are the phase characteristics that Exakt has calcuated for correction.  Note, at this point the features include the effect of the cabinet, not just the drive units, so some of these could be due to the cabinet resonances mentioned in the build section (Part 2).

Top is the modelling of the frequency response of the drive units, including their "features".  The bottom is the Exakt modelling of the phase characteristics for correction

RESULT

So what is the ouput of all that work?

I've used 1/12th smoothing of the acoustic measurements to give a realistic idea of the reponse curve.  Below are 2 graphs to show why I'm mentioning this - if I was a speaker manufacturer, I would be tempted to publish the the 1/3th smoothing to make it look miraculously good!

Remember to ignore everything below 110Hz as there is too much room interaction.

Example with 1/3 Smoothing. Contrast With 1/12th Below. See how the above pretty much eliminates the room iteraction!  And those who really like their hifi to be "objectivist" rather than "subjectivist" sometimes forget that the numbers can be manipulated.  This is exactly the same data, just presented differently!

Exactly the Same Measurement But with 1/12th Smoothing - I use 1/12th in the results below

Single speaker result below - remember it is designed to be listened to off-axis.  Here you can see the more pronounced upper frequencies that would result in pointing the speakers directly at the listener compared to the intended only slight toe-in. Rotating the speakers with more toe-in allow a slightly brighter presentation if required.

Green line is on-axis response measurement. Red line is 30 degrees horizontal off-axis response measurement

 A word about phase correction with Exakt - one of its key selling points. It must be said that it is a phase error minimisation solution, it doesn't deliver a completely flat phase response.  However, I will provide a not to be named phase response example from a very well known domestic speaker maufacturer for comparison.  This is from their £16,000 speaker.  As usual, please ignore the measurements below 110Hz.  I do not post this comparison here to try and claim my project gets even close to being within sniffing distance of having a hint of the performance of the comparison speaker, but just to illustrate the effect of having no phase errors introduced by the crossover and the correction of phase errors within the drivers.

Nindex phase response, 30 degrees horizontal off-axis:

Phase Response of the Nindex Project Speaker

The dotted line in the above graph is the phase response of the £16k speaker

SOUND

So how does it sound?  Well, I'm not at all disappointed by the result. In fact, its rather enjoyable.  I don't think its the most dynamic speaker ever, but it does have a nice sense of flow - its definitely of the more laid back variety.  If you like most JBLs, you'll not like these.  Bass is tuneful but not "kicking", doesn't go massively deep but its pretty good for a box of this size.  There's no real noticable box artefacts, the treble is sweet and very detailed, the mids and vocals a touch polite but well articulated. Maybe it will appeal to those who prefer the BBC type of design?
Perhaps, at the next but one Wigwam Show (plans are already in place for the next one) you'll get a chance to come along for a listen.
Now perhaps its time to hook them up to the Akurate Katalyst / Lejonklou power amps in the main system and see how they get on.  Perhaps there'll be a post script later.

Finally, what's in a name. Well, not much thinking really. The base cabinet is an Index, but they're no longer Index, so they're Nindex. It works with the NINka drivers too. Kind of.

A few parting photos.  Thanks for reading!

PART 1 OF 3 HERE
PART 2 OF 3 HERE