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Historic LS3/5a - how to identify them

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  • Historic LS3/5a - how to identify them

    I've been contacted by an industry professional who sat in front of LS3/5as for years. Now he's removed the grille from his pair, he's asked for a visual comparison between our ex-BBC LS3/5as of similar vintage.

    To be clear: all Harbeth LS3/5a were of the "computer optimised design", the so-called 10 ohm type, for which we were the launch manufacturer. The first generation of 3/5, the so-called 15 ohm version, the bulk of which were made by Rogers, featured a bass unit cone heavily loaded with dope, a liquid semi-flexible, semi-transparent rubber compound. It was applied during manufacture of the B110 by KEF, and applied quite crudely with a paintbrush to both sides of the cone. This doping was revised to being applied as a fine mist by aerosol in our and all second generation, 10 ohm LS3/5a.

    Whether the public like it or not, when they now invest in early '15 ohm' LS3/5a, including all Rogers ones,they must be prepared for a cosmetic finish on the B110 bass unit which is, by modern Apple-esque consumer electronic standards extremely amateurish. But in the day, the damping layer was mandatory to achieve the BBC specification, and anyway, nobody removed the grille.

    So, I've gone through the Harbeth LS3/5a archive of traded-in (mainly) Rogers LS3/5a (traded-in against Harbeth Monitor 20s) and here are a few typical examples. Not pretty, but perfectly fuctional.

    (To follow)
    Alan A. Shaw
    Designer, owner
    Harbeth Audio UK

  • #2
    The LS3/5a lore seems to distinguish between earlier 15 ohm and later 11 ohm versions.
    Was there also a 10 ohm version, or is the 11 ohm designation inaccurate?
    http://www.audiocostruzioni.com/r_s/...s_shootout.pdf
    http://www.g4dcv.co.uk/ls35a/pics/HFC3_LS3.pdf

    Comment


    • #3
      Noted, thanks.

      I think it's important to distinguish between the original BBC-designed LS3/5a, designed when the BBC was mandated by the Governors to be involved in loudspeaker design (i.e 1928-1985 approximately) and post-BBC-design iterations of original BBC-designed speakers.

      In the mid 80s the BBC management formally and decisively axed any further in-hours development of 'BBC loudspeakers' by BBC staff using BBC technical resources (as they remained in this era), and the team retired, and the resources such as the anechoic chamber were scrapped. So, even if there was a complete reversal of the BBC's interest and desire to design loudspeakers, rather than take a sales royalty on speakers designed by others and badged BBC licensed (which is very much an ongoing revenue-income activity for BBC enterprises), considerable funds, building and people resources would have to be found by top management (under ministerial supervision) to put the BBC back in the loudspeaker business. And that simply is unimaginable in an environment where BBC funding from the governement has been constricted.

      Hence, the BBC's strategy these past years to allow enterpreneurs to approach them to make reinterpretations of legacy BBC designs using whatever skills, techniques and parts the commercial designers wish. What appears to be licensed is the BBC's name, a protected and registered Trade Mark, and not the BBC's top-down design. Hence, the latitude for commercial entrepreneurs to reimagine a classic BBC design, which would in fact be necessary as identical components to those of 25 years ago are no longer available. Such products compete in a relatively small global marketplace where the marking of the product with the BBCs commercial licence is deemed crucial to making any sales inroads.

      This reimagination of the original BBC designs has, understandably, produced measured frequency responses and sound presentations which range from a subtle variation on the classic designs to being a significantly different 'take', as is demonstrated by the very different published frequency responses. This has fuelled the second hand market for genuine classic original models, especially the 3/5a, where the buyer can - for the right money - be pretty sure he is directly buying-into the handywork of Dudley Harwood and his team at BBC Research Dept in the 1960s and 70s.

      Cosmetically, the original 3/5a woofers, made by KEF, were smothered in hand-pained dope, and one of the first decisions I made when I started on designing the Harbeth P3ESR woofer (that gestation period was about five years, off and on) was to make the cone as clean and presentable as possible. That became a reality with our RADIAL™ cone material because the inherent mechanical properties, and stiffness, obviated doping. But if you want one of the original 73-88 (or thereabouts) LS3/5as, you have to accept that the heavily painted woofer cones were functional not pretty.
      Alan A. Shaw
      Designer, owner
      Harbeth Audio UK

      Comment


      • #4
        Here are a few photos (plus one magazine picture) from our ex-BBC stock of original Rogers first generation "15 ohm" LS3/5as. As you can see, there is quite a variation in the cosmetics of the bass unit becaue of the thick, hand painted (with a brush), PVA dope applied front and back of the cone. PVA is a thick, water based rubbery liquid (think white wood glue), and according to the ambient temperature when it was applied (i.e. time of year) the colour, brush strokes and bubbles will vary. The PVA is not in any way a structural element: the cone and surround are pre-glued before the dope is applied. Although the water soluble PVA is willing to lay on the bextrene cone with it's slightly sand-blasted rough cone, where the water-based PVA met the rubber surround, it was naturally repelled.

        On the woofer's assembly line, the inexperienced operator's mistake was to over-apply PVA to rim joint as they 'load-up' the dope around the cone/surround joint so that it couldn't run away from the rubber, but if you remember the rules of circumference of a circle, you'll appreciate that a small increase in dope quantity all around the rim joint would add dramatically to the mass. So that had to be avoided. What tended to happen in practice was the opposite: the operator initially plopped a known quantity of PVA near the neck and worked it up towards the rim and then swiftly back towards the neck, repeating several times. This tended to result in an accumulation of the thick PVA in the neck area where it was easier to top up (or remove) to meet KEF's weight specification, and a 'creep back' from the rim joint, sometimes visible sometimes not so. The PVA coating was most certainly not uniformly thick, and didn't need to be to meet KEFs spec. We found it much easier to make for KEF their B110 SP1228 (and variants), becasue they had dramatically reduced the dope, front and back.

        Harbeth manufactured quite a range of KEF woofers for KEF under a material-supply kit arrangement for them to KEFs QC, and we know quite a lot about their methodology. KEF did not control the cosmetic appearance of the woofers because for their needs, the total doped-up mass of the cone (to 0.1g tolerance) was the critical must-meet parameter, and we had to invest in extremely accurate and stable digital scales. Again, depending upon the weather and how fast the dope 'flashed off' (cured), we sometimes had to apply a dab or two of extra dope to bring the total cone weight up to the spec. That again made cosmetic uniformity impossible.

        All of those doping needs were sidestepped by the better cone material (RADIAL™) we use in the P3ESR, and now in all Harbeths.
        Attached Files
        Alan A. Shaw
        Designer, owner
        Harbeth Audio UK

        Comment


        • #5
          Dear Alan,

          I have this pair, manufactured by Swisstone Electronics Ltd., 11 ohms, 30 watts programme.

          "What are they" among the LS3/5a?

          From what I read (in Wikipedia) Rogers, the first lincensee, went bankrupt - before producing the LS3/5a - and was bought by Swisstone (an off the shelf company), which manufactured a large part of the units produced under the BBC lincense.

          Kind regards,

          Cesare
          Attached Files

          Comment


          • #6
            No, Rogers Ltd. were a vibrant and very much alive trading company that produced thousands of LS3/5a before Swisstone took them over. Certainly, at the time that your '11 ohm" versions were made (sometime after 1988), Swisstone Electronics were in charge, and then after that the assets were purchased by a Chinese group, who still own the brand and, presumably, the brand's Trade Mark in the UK and elsewhere.

            You might like to know that under UK Company Law, one day after the formal insolvency of a UK-registered Ltd. company (ABC Co.), it is allowed that the exact same company name (or, of course, a slight variation, to taste) can be re-registered (ABC Co.), but is given a new company Registration number by the UK government. The average person wouldn't spot that in the small print of the headed paper.

            The newly "re-registered" company need not have any connection whatsoever with the defunct one, never have corresponded with them nor met the directors, have no investment interest in the old company of any kind, and have no assets or paperwork of the old company, not even a pencil.

            It's a good marketing move though as it creates the impression in the casual reader's mind that ABC Co. lives on, and that somehow a fomal handover of technology has taken place. The reality is that the re-registration is an on-line paperwork exercise requiring nothing more than a credit card to complete in a few moments. No questions are asked as to the existence of the previous company, association with similarly named companys, its winding-up, nor relationship (if any) between the new registration and the old. The process is treated as an entirely fresh name dosconnected from any history of the company name's use - a rather casual arrangement.

            The matter of Registered Trade Marks is another thing altogether. This is well regulated andf very formal, and the ability to register as a limited company ABC Co. Ltd. (or any variation of that name) confers no legal right watever to use ABC as a brand name. Others may have, for example, a legitimate historical interest in the brand name ABC and its protection in their own favour. Manufacturers in a situation where they are making unauthorised use of a Registered Trade Mark would be best advised to quietly settle the matter with the Registered Trade Mark owners sooner rather than later.
            Alan A. Shaw
            Designer, owner
            Harbeth Audio UK

            Comment


            • #7
              Originally posted by A.S. View Post
              The matter of Registered Trade Marks is another thing altogether. This is well regulated, and the ability to register as a limited company ABC Co. Ltd. confers no legal right watever to use ABC as a brand name, if ABC is already a Registered Trade Mark. Manufacturers in such a situation would do well to take note of that and settle the matter of the unauthorised use of a Registerd Trade Mark with the Registered Trade Mark owners sooner rather than later.
              Volkswagen was the recipient of a rather rude awakening in that regard during their attempt to acquire the assets of Rolls-Royce automotive business.
              Apparently someone neglected to perform adequate due diligence to confirm who it was that controlled the rights to the use of the Rolls-Royce brand name.

              Comment


              • #8
                Originally posted by IMF+TDL View Post
                Volkswagen was the recipient of a rather rude awakening in that regard during their attempt to acquire the assets of Rolls-Royce automotive business. Apparently someone neglected to perform adequate due diligence to confirm who it was that controlled the rights to the use of the Rolls-Royce brand name.
                Yes, I heard that they are still paying a royalty. It can be quite a shock to discover that you've naively helped yourself to someone else's Registered Trade Mark especially when you've built a marketing campaign on it.
                Alan A. Shaw
                Designer, owner
                Harbeth Audio UK

                Comment


                • #9
                  I must say that there is so much drivel talked about the LS3/5a, about the bass units and crossover in particular, The actual manufacturer's opinion about the realities (and the tiny profit and pitiful reward versus effort) has been substituted by myth and misunderstanding which seem to feed themselves. There are legion of experts, it seems, not one of which has ever made the speaker or been party to the specification, QC, marketing and relationship (or not) with those who one could expect to control 'standards'.

                  It must never be forgotten that the LS3/5a was never conceived of nor used as a premium monitor. Quite the opposite, as premium BBC monitors of the era were coded 'LS5', the LS3 designation telling immediately that this was a product never intended for front line monitoring. The variablilty between specimens, as shown in my video of the card index file and its frequency response contents at the BBC Research Dept. affirmed the whole story, objectively.

                  Is there any other audioproduct which exhibits such a relationship between fact and folklore? I hope not. Amongst the long list of manufacturers of the original 15 ohm and 11 ohm LS3/5a from Rogers through to KEF branded, the only two companies who have actually manufactured the original B110 bass units using the original processes, materials, tooling and to the designer's drawings are KEF and Harbeth, Harbet's factory being an off-site resource to KEF when the final KEF UK production line closed and transferred to China.

                  At that time, KEF contracted with Harbeth to manufacture a number of drivers, including UniQ, at Harbeth's facility using KEFs tooling, so we and KEF are in a unique position with regard to the reality of B110 production. And also, only KEF and Harbeth have the blueprint full drawing sets for the B110 defining every detail of assembly of the woofer.

                  But what do we know? Clearly nothing.
                  Alan A. Shaw
                  Designer, owner
                  Harbeth Audio UK

                  Comment


                  • #10
                    "But what do we know? Clearly nothing."

                    Thanks for last post Alan.

                    Many audio fans or music lovers, also audio reviewers (i.e. potential customers, audio press) still mistake "BBC heritage", which is scientific approach to audio products for mindless duplication of old (and sometimes very specific) designs, frequently engineered for purposes not encountered in domestic circumstances.

                    Let's read the introduction to the report of the Team of BBC Engineers, who created this small professional monitoring loudspeaker - http://downloads.bbc.co.uk/rd/pubs/reports/1976-29.pdf

                    I personally never lived in "television mobile control room" or in radio booth as well as probably remaining 99,(9)% of everymen.

                    Is any more explanatory necessary for what purposes this monitor was designed?

                    This is the biggest audio myth ever produced since introduction of phonograph.

                    ATB

                    Comment


                    • #11
                      Indeed. And living proof of the highly specific nature and design remit of the original 'BBC Monitor' is the bass output limitations of the LS3/4, LS3/6, known commercially as the Roger BBC Monitor and BC1. I lost track of the number of these bass units I burned-out as a novice audiophile in the 1970s because they were designed for nearfield listening not at 3m away, in the domestic home.

                      Furthermore, because they were designed for nearfield listening (i.e. at a stretch you could actually touch the speakers in use in the studio), they ....
                      • were played rather quietly in their intended application as a studio monitor
                      • had a very generous bass characteristic built-in which subjectively compensated for the low listening level, as per psychoacoustics ...
                      • which became overwhelmingly rich when played louder than intended, 3m away, at home

                      It was no surprise then that as time passed, by the mid 1980s, the media's love affair with the genere was finally shaken by the miserable reviews of the LS5/9, after which BBC management pulled the plug on any further official BBC loudspeaker design work. To be fair to all sides, the LS5/9 was designed with an extremely tight and specific remit (to sound as close as possible to the much bigger LS5/8, itself a highly specific and non-commercially viable sound), not in any sense to be a neutral, fresh thinking, clean-sheet-of-paper design. For commercially marketable designs, there were many 5/9 alternative choices in the 80s, and many of them good too.

                      Needless to say then with that history, from inspection of public accounts filed with the UK government (by law), neither Rogers nor later clone 'reimagination' manufacturers have made a penny profit from their enterprise despite years of marketing. That leaves customers, fascinated by the quasi-heritage in a most vulnerable position, since trading losses cannot be sustained year after year.

                      It's a simple rule, pointed out by Dudley Harwood to me which can't be far off the truth: 'Be careful. Nobody involved in manufacturing of the BBC monitors has achieved anything other than losing the shirt off their back....'.
                      Alan A. Shaw
                      Designer, owner
                      Harbeth Audio UK

                      Comment


                      • #12
                        If you listen 'up close and personal', then you'll be listening to your 'BBC monitor' as it was intended to be used.

                        If you are listening at a distance, in a normal domestic room, then you're going to need something that takes the BBC monitor concept and properly adapts it for domestic use. Such as the Harbeth line-up. Not a clone of a historical design intended for near-field use, but an innovative development which correctly balances the bass/mid and top and permits the speaker to be played excitingly loud without distress.
                        Alan A. Shaw
                        Designer, owner
                        Harbeth Audio UK

                        Comment


                        • #13
                          The "up close and personal" approach along with the playing quietly is the main reason why the LS3/5A is so very popular with collectors in the Far East.

                          Quite why they are so popular is a mystery to me, having heard several pairs over the past 10 years or so. The P3ESR beats them hands down in all areas and is a far more practical speaker for domestic use. Not only that, you can buy a couple of pairs of the little Harbeth for the average price of a beaten up LS3/5A.

                          Another thing I don't understand, is how companies can get away with producing 'LS3/5A clones' ? These use different drivers, crossovers and cabinets to the LS3/5A, so how can they be 'clones' ?

                          Comment


                          • #14
                            Originally posted by hifi_dave View Post
                            The "up close and personal" approach along with the playing quietly is the main reason why the LS3/5A is so very popular with collectors in the Far East.

                            Quite why they are so popular is a mystery to me, having heard several pairs over the past 10 years or so. The P3ESR beats them hands down in all areas and is a far more practical speaker for domestic use. Not only that, you can buy a couple of pairs of the little Harbeth for the average price of a beaten up LS3/5A.

                            Another thing I don't understand, is how companies can get away with producing 'LS3/5A clones' ? These use different drivers, crossovers and cabinets to the LS3/5A, so how can they be 'clones' ?
                            Well, having actually sat around the table with the BBC's legal department in recent memory, I can give you the essence of the set-up, these days.

                            The BBC operate an open door to would-be licencees, that is, anyone anywhere can apply to make a product onto which they wish to place the BBC Registered Trade Mark. If you yourself fancy making a modern interpretation of a classic 1930s BBC microphone, or mixing console or loudspeaker, the door is open to you. Let's assume that you like the idea of remanufacturing the BBC ABX microphone. You'd have discovered that none of the original parts are available, the inventors long deceased, and no documentation available, so your starting point would be to enquire if the BBC could provide you with drawings etc. You'd find that none would be available.

                            This is only a minor inconvenience to the process, because you would be encouraged to go away, and create your own 'take' on the original. As far as I was made aware, as long as the external appearance of the reinterpretation is broadly comparable to the original, that would meet BBC requirements. As for the choice of all and any of the piece parts used inside the design, these are wholly the choice of the re-designer. In parallel to this technical design process, you would have started on a Licence process, which would define, primarily, the sum you'd have to pay per unit to use the BBC name by association, although you would not be allowed to use the BBC logo.

                            As to who in the BBC is experienced enough, authorised, motivated, paid, competent in the specific area of product, has the time and inclination and crucially, test equipment to sanction your new 'take', was not explained to me to the point that I thought I would be cooperating with a like-skilled person. Furthermore, I do not recall that the Licence had/has an inbuilt mechanism for guaranteeing day by day, piece by piece QC, nor mandate any formal process (such as independently audited ISO9000 standards) to assure quality to the consumer. The process for formally auditioning the licenced product (assuming that it is a sound device) was not fully explained, but without the equipment and human resources that would have existed and accumulated over half a century at Research Department, Kingswood Warren, one had to take a view on the depth of such an analysis nowadays.

                            So, it appeared to me that the Licence was in fact a formal permit to use the BBC name on a product, the design of which is wholly up to the manufacturer. Hence, just looking at the bass units used in the various LS3/5as offered now in Europe and the far east, one sees tremendous technical differences in cone and surround colour, profile and inevitably, acoustic nature.

                            Perhaps most surprising is that there is no mandate for the re-designer to mimic the frequency response (and hence sound balance) of the original. The re-designer can set-about his re-design without the heavy burden of making a close copy of the original publicly available and recognised product. He could make his own interpretation according to his taste. In the case of the BBC-designed LS3/5a, the characteristic frequency response - very skilfully shaped by Dudley Harwood for psychoacoustic reasons - is well known: a hump in the bass followed by a shallow trough up to the presence region, and the tweeter band set down slightly. Reinterpretations I have looked at have a completely different overall bass/mid/top balance, and cannot sound interchangeable with the original.

                            So, as far as the consumer is concerned, the latitude for different reinterpretations of classic designs to yield a significantly different listener experience is considerable. Anyone in the market for a modern-take on a classic BBC design really does need to invest time and effort in actually listening for themselves to offerings, because the BBC system that assured that a Rogers/Harbeth/Spendor BBC LS3/5a sounded practically interchangeable has not existed for some twenty years.

                            It must be clear then that the decision we took at Harbeth in 1990, at the end of the original LS3/5a production era to develop an altogether better solution which we could control and nurture - the P3 series - has guaranteed a consistent user experience. The Harbeth P3 has been in continuous production for 27 years, which far eclipses the continuous production run of the original BBC-designed LS3/5a. This is a market area where we dominate.

                            Needless to say, we acquire and technically investigate competitive speakers on a routine basis. What astonised me about a recent reinterpretation of a mid-sized monitor is that I am convinced that the tweeters are wired out of phase. Whether this is a one-off issue to do with slack manufacturing QC, or poor design I cannot know, but the consequence is of a sonic hole in the crossover region where the tweeter and bass unit (normally) collaborate constructively. It is not possible to identify a Reference Axis, because no matter where the microphone is placed vertically, the bass/midrange and tweeter do not sonically integrate properly. One can only ponder about how either of these issue came about in an expensive loudspeaker.

                            On the subject of investigations and comparisons, we will shortly be hosting the first of many Dealer Days, where we'll be taking trade vistors through the process of speaker design and evaluation, the sort of factors the designer has to consider, what his objective are, culminating in giving visitor's the training to make hands-on technical measurement of a lifetime's accumulated speakers from our archives, or any they chose to bring along.
                            Alan A. Shaw
                            Designer, owner
                            Harbeth Audio UK

                            Comment


                            • #15
                              I first auditioned the LS3/5a sometime, I think, in the early 1980's. At the time, I felt it was the best of a pretty wide range of small speakers. When I actually needed such a small speaker in 1991 as part of a secundary system, I bought a pair (the improved 11 Ohm version) from the late Tomas Heinitz in early 1991, and have enjoyed them ever since, as desktop speakers in my home office, and sometimes as a main system when in small temporary accomodation.

                              However, I recently acquired a pair of P3ESRs, and they do indeed beat the LS3/5a hands down. I never bothered to audition any of the clones.

                              Comment

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