The LS3/5a – a midrange to die for Part I

I will not repeatedly report all about the history of this legendary BBC monitor again, there is nearly all information about the historical aspect scattered on the internet. My intention is to write about the different  models and incarnations of them, the amplifiers (may it tube or transistor) to drive these little shoeboxes, as also about the very important room placement which implies also some explanation of their construction.

The early period

If you talk to LS3/5a devotees, you will always educated about the two most outstanding models, namely the Rogers Gold Tag 15 Ohm and the Chartwell I (also15 Ohm)….why is that? Both models are almost the oldest of the whole breed, and both are nearly vanished from the used market – and if you will find one, there is a good chance, that it is not anymore in its original condition, as also very, very expensive.

There are some facts about the oldest versions of the LS3/5a and their different licensees, namely Rogers, Chartwell and also Audiomaster, which were all together in the forefront of building the BBC mini monitor, that has to be told. In the beginning of the 70ties (last century) all the licensees had to build their own crossover circuit – everything was done to meet the exact BBC specs, but the way it was done was into the responsibility of the different manufactures. So Rogers and Chartwell wound their specific autoformers in house during this period, and they both opted for different parts be it the foil capactitors used  or the brand of the different resistors needed – and even in the layout there were slight differences to be detected. Both used the same chassis delivered from the British manufacturer KEF, the legendary first version of the T27 tweeter identifiable because of the blue and black colour of the connection wires, as also the first version of the B110 woofer. But the implementation was rather different – both came out with a construction precisely matching the BBC specs – but both speakers sound a little bit different. The Rogers Gold Tag might have the warmest bass response of all LS3/5a, as also a magic midrange which is able to render the most three dimensional stage. The Chartwell in comparison had a tight bass response with a delicious rendered treble and higher presence  which is sooo smooth, that you would not detect at first the analytical abilities this model has to offer. The Chartwell is more about the monitor utilization in a control room were the Rogers is perfect for casual listening. Both have a tremendous smoothness in their presence and treble rendering as also the amazing ability to get the midrange right. It is an unforgettable experience to listen to a well recorded vocal trough this mini monitor speakers.

As KEF always had problems to produce the chassis, be it the B110 woofer or the T27 tweeter, without the slightest variation, all models share a circuit in their crossover, were the bespoke autoformer offered 4 taps to accommodate for variations of the speaker chassis delivered by KEF. One LS3/5a manufacturer stood out, which was Spendor. They opted against such a solution, instead they did the most rigorous selection of the delivered speaker chassis, and used only those, which were compatible with the specs of their crossover. This is maybe the reason for the phenomenal openness this first Spendor Gold Tag 15 Ohm model distinguished itself. It is maybe the most precisious and uncoloured treble performance of all LS3/5a ever built.

All those early models share the same sensitivity of around 83db/1W/1m and they all have nearly the same frequency response (with just very tiny variations) as also the same electrical parameters – but they all differ in their dynamic and micro dynamic abilities – something the BBC had not standardized too much.

The second period

After the first years a lot of things changed in the history of the LS3/5a – Chartwell broke and was bought up by Rogers which delivered now LS3/5a speakers with a Chartwell Logo as a sort of high end version of the monitor, which was not really profitable, so that they stopped it after the different parts and pre manufactured crossovers (still made by Chartwell) were depleted. These so called Chartwell II is somewhat a mixture of the Rogers White Tag brought out by the latter using their own parts, and an original Chartwell – all of the Chartwell II versions differ in small details may it the crossover construction or the selection of their chassis. All of these Chartwells have in common, that they are built with a Rogers enclosure. Rogers itself used the second generation of the KEF chassis to built their own Black Tag LS3/5a, also very, very rare today, which was the last version were Rogers implied their own autoformers, later White Tag models8 do not no the exact serial number) used Drake manufactured autoformers, Drake delivered them also to any of the other licensees. With the White Tag Rogers, we are facing now a different B110 woofer, which is called the white belly version. The reason for that is a characteristic white glue surrounding we will find around the dust cap of the B110. The White Belly period was maybe the last well regarded epoch, were the best 15 Ohm LS3/5a were manufactured. After that period the different licensees began to deliver a somewhat cheaper quality, which also reflects in a lower price tag, because nobody wanted to pay serious money for such a little speaker except the studio professionals – but on the other hand this little gem was very costly to produce.

The 11 Ohm period

This is the last period were original LS3/5a were manufactured. As KEF had too much variation in their chassis production, the BBC stopped the traditional way the LS3/5a was produced and opted for one standard crossover, made by KEF for all licensees, and some special selection procedere in which the manufacturers of the LS3/5a had to guarantee a low variation. In those years Harbeth started as a licensee in the LS3/5a scene and delivered as the first company in the history of audio a computer / laser technology to get a precise chassis selection. Harbeth was also the most outstanding company regarding the woodwork of the LS3/5a enclosure. I never had problems with a leaky enclosure of any Harbeth LS3/5a, which can not be said about the Rogers built quality in this period.

A not so well known fact is, that Rogers produced and labeled their speaker enclosures in advance – so they were somewhat surprised by the new BBC “rules” and as they already had a couple of speaker cabinets ready to ship, the kept the 15 Ohm badge at the back of the speakers but put the complete 11 Ohm hardware in those….born was the pseudo 15 Ohm Ls3/5a – which is today something for the collectors…

Another funny story might be the fact, that KEF as the only supplier for the famous chassis for the LS3/5a never made their own model of the little legend until they ceased the production of the B110 and T27 tweeter. KEF produced at the very end of the LS3/5a production their own limited edition – the KEF Raymond Cook Signature model.

The day after tomorrow

As KEF stopped producing any original chassis for a licensed LS3/5a the different manufacturers went on – for a long, long period of time there was no LS3/5a anymore available. Instead of that the market saw some BBC inspired constructions like the Harbeth P3 ESR or different Spendor models just to name a few. Meanwhile it was the last fashion to discredit the little British monitor, statements like “typical British mid bass bump”, “typical British mini monitor” was en vogue at the end of the 80ties and during the 90ties (last century). The typical British monitor sound was not anymore modern, manufacturers as Dynaudio developed the basic concept to new standards with their Contour 1.3 using their superb Esotar tweeters and the famous Dynaudio bass chassis. But during the 90ties a proper floor standing  speaker was the latest fashion, so that small 2 way monitor speakers were mostly entry level models for those who cannot afford a “proper” speaker. The situation changed with the High End audio scene in the far east. Those HiFi fans in the big metropolis share one big problem, and this is space….It is nearly prohibitively expensive to have a dedicated listening room in the big cities like Tokyo, Hongkong, Kuala Lumpur or Singapore….. The LS3/5a began  to establish a sort of cult status in that particular region of the world. At the specific forums dedicated to the little British queen you might find installations were we western devotees rub our eyes in disbelieve. You will detect Kondo Ongaku amplifiers driving some Chartwell I or vintage Marantz 2 monoblocks doing the same with Rogers Gold Tag speakers. Ultra quality front end products are used, Micro Seiki 5000 turntables with Ikeda carts, tape machines like the little Nagra IVs or top end CD players or DA converters can be observed – amazing….

Here and now

The industry started to think about the rebirth of the LS3/5a since a couple of years – because all the manufacturers from the past are also aware of the fact, that an original pair of Rogers Gold Tag or Chartwell I will reach prices in the used market which are ridiculous. Sums around 5000,- US dollars for a pair in mint condition is nothing special in our days – such evolution awakes the industry….

We can buy today an original LS3/5a again, and it is made by Falcon Acoustic, which developed in the last years both KEF chassis again and built now the one and only real 15 Ohm incarnation of the little legend. Stirling Broadcast did the same with the 11 Ohm model a couple of years bevor Falcon came up with a proper reincarnation of the 15 Ohm LS3/5a. They use speaker chassis from Scan Speak and SEAS – and they did an amazing job to mimic the original sound which resulted in a BBC approval – so the Stirling are the one and only LS3/5a without original KEF speaker chassis or recreations of them, which ever got the “go” from the BBC. Stirling called their 11 Ohm reincarnation V2, which tells us, that they do not use the original KEF chassis (Stirling had also an older version with used the last KEF chassis available). The modern Falcon also received the blessing of the BBC, so we have two very addictive possibilities today to buy a brad new LS3/5a which is made to the BBC specifications.

If you are not completely into the puzzeling details to differentiate an original LS3/5a against some modified “Frankenstein” types – my advice is – get a new one…. It is far too risky to spent €3000,- – 4000,- for a Chartwell 1 or Rogers Gold Tag were nothing is anymore in its original state moreover the wooden enclosure….

Why is this little dwarf so special???

If you never listened to a well set up LS3/5a system, you wont believe, what these little shoeboxes are able to achieve. The miniatured size enables them to sound like a true point source speaker system. Hence these little monsters can disappear completely as a sound source, the instruments as also the center stage enfolds in your room in a fashion, that you might think about magic. The omnidirectional performance is one of the best I ever found on any speaker. You can almost enjoy them if they are listened with the back of the speaker pointing toward you….ok – that is a little bit overpraised – but you get, what I try to explain. The phenomenal omnidirectional characteristic means also, that you have to listen to them in a acoustical treated room, because such special behaviour of any given speaker will react in a critical way, if too much early reflections are mated with the direct sound pressure level. If you position them wisely, which I will explain in a minute, you can achieve a bass response you wont believe…. The speed and agility is breathtaking as is the unreal truthful rendering of the whole midrange. The resolution these little speakers are capable of is also astonishing. Mating them with a cheap amplifier and a mediocre CD player does not justice to them!!!!!!! They have the ability to grow with any upgrade you will make in your stereo system – may it the front end, the preamplifier or the amplifier….they are audio microscopes without being nasty – you can listen for hours without getting tiered…

If I should name the three most revealing speaker systems regarding midrange pureness, I would opt for the Quad ESL 57, the Western Electric 755 and the 15 Ohm LS3/5a!

Room placement

As any high performance speaker system also the little LS3/5a is very demanding about proper implementation in your HiFi system and room placement. If you have a rectangular room at your disposal please choose the long wall to place the speakers on it. In every rectangular room with the speaker positioned at the long wall we will have an energy maxima (room mode) at 40hz around 1 – 1,5m in front of the long walls. This might be a nightmare for an American floorstander like a Wilson Audio Whatt / Puppy system 7 – but it is the chance to do a miracle on a full range sound of a little mini monitor speaker system. The LS3/5a has a frequency response which reaches out to nearly 70hz – than there is a smooth roll off towards the deepest octaves. As the British queen is constructed with a sealed enclosure, the little speaker does not behave like a ported construction, which cuts off its sound pressure level at the resonance frequency of the ports. The LS3/5a will reproduce frequencies till nearly 30hz – but it will do that with no serious sound pressure level anymore – because we have a too little membrane surface and an enclosure with much too restricted volume. But if we can place the LS3a in front of the long wall in our listening room a couple of miracles will happen. First the 40hz mode in our room will be triggered by the speaker – so that we get a frequency response at the listening position, which shows nearly no drop in energy till around 45hz – and – which is even more spectacular – at the position were we have an energy peak around 40hz in our room, we will have a decrease in sound pressure level at around 130hz – and there the LS3/5a has its characteristic bass bump – which is cool for near field listening – but not so much appreciated if we listen to some classic music at mid field distances. So we gain two very important aspects – only with the fact that we choose the long wall of our room – we get bass reinforcement and we get rid of the 130hz bump. The bass reinforcement is also not comparable to the trick Audio Note UK is proclaiming in which their speakers have to be placed in a corner….the LS3/5a placement is much more versatile and elegant!

Now lets talk about the distance towards the rear wall….as I explained in the chapter above, it is nearly fixed, if we want to trigger the 40hz mode – which results in a position around 1,2 – 1,5m in front of the wall. So we do not start without having any clue – but that said – it is not in any way insignificant to dial in the proper distance. The LS3/5a will react in a very, very sensitive way….

Toeing in

The next critical parameter is the angle in which the speaker is pointed towards the listening position. Normally we would angle the speakers at 30° towards us, with a right triangle placement already achieved. But with the LS3/5a it is a different kettle of fish…..You can use a full angled placrment towards your listening position, which is always a good thing, if your room is very reflective. But if you have achieved a somewhat good domestic listening acoustic in you room with not too many reflective surfaces around the speaker – you can choose a different positioning model. In this model we use a toeing in of not more than 7° – which is nearly nothing…..

Now lets listen to some music with a strong center fill – a well recorded vocal surrounded by some natural instruments.  If we compare the 30° method against the 7° method we wont believe, what is now going on. With the 7° model we gain a lot – I mean A LOT more centerfill – a much, much larger stage, a better rendering of the recorded space as also a tremendous directional accuracy!!!!

Now close your eyes – what you will here is astonishing – and you never, never would believe, that such a small monitor is able to produce this large sized sound performance….The speakers disappear completely, the stage reaches way beyond the position of them, the depth of the stage is breathtaking and the center of the stage with the vocal on them is directly in front of you – right there, three dimensional and real!!! The deepest impact has gained now from around 70hz towards 45hz without any loss of detail or pureness, nor speed, these little monsters will render even Trentemöllers electro music in a fashion you never thought that this would be possible. You coupled the speaker up to your room – in a fashion, that you cared about the efficiency in doing so. You do not waist any of the produced sound pressure level the little monitor is able to give us….instead you use room acoustic phenomena like modes to get the most linear frequency response in your room. Please be patient – after the first listening session one might think it is done – but the size of the speaker base, the distance to the rear wall and the listening distance must be dialed in with a lot of care. At the end of this process you might be achieved a position, were you leave the equilateral triangle in favour of a slightly smaller speaker base – do not worry….

The Stands

The quality of the stands is nearly as important as finding the best position in your room. The LS3/5a are nothing special there, because any little monitor will gain enormous quality if paired with a proper stand. The best one you can buy is the Music Tools LS3/5a stand – and – normally I am no fan of “THE BEST” – but here it is a matter of fact. The Music Tools are reincarnations of the famous Foundation LS3/5a stands which are not anymore available. The speakers are positioned on top of these stands using 4 little balls of blue tack – please read it again – LITTLE BALLS…..;-))) The LS3/5a is constructed with an enclosure that is able to resonate – and this is meant to be like that. The whole enclosure is tuned in a way that those resonances wont effect the clean frequency performance of the speakers – so you must take care of that fact. If you use a big bubble of blue tack the speaker will be dampened – it is also a very bad idea to use any kind of spikes between the speaker and its stand… Please level the speakers precisely – our goal is, that both speakers have the chance to send their soundwaves in a coherent way towards us – if one speaker is tilted to the back, the other vice versa, this is not anymore possible. Please take care also of the indentical position of both speakers in your room….if one speaker is placed  closer to a side wall than the other – ist will destroy the whole balance of the stage! As the LS3/5a have such a tremendous omnidirectional performance, it is a good idea to leave a lot of space between the speaker and the side wall to avoid reflections which will work against the law of the first wavefront….As we use the long wall of the room, this might not be a big problem, if it is, you must decrease the listening distance as also the speaker base to gain more distance to the side walls.

In Part II wie will discuss some amplification possibilities as also some construction details in depth….so

stay tuned

E. Strauss