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== History ==
== History ==
The ''LS3/5A'' is a commercially produced loudspeaker driven by the need of the [[BBC]] to monitor and assess broadcast programme quality. It was derived from the ''LS3/5'', which was conceived and developed by its engineering department in the early 1970s, when it was under the stewardship of Dudley Harwood.<ref name=hfa1979bbchomeservice/> The BBC specifically set out to design a speaker to achieve natural overall sound quality and good [[dynamic range]] for monitoring broadcasts in tight space confines.<ref name=hfa1979bbchomeservice/><ref name="BBC RD 1976/29"/><ref name=stereoph1989atk1/> There were no commercially produced small loudspeakers available at that time that met the requirement for naturalness and sonic neutrality.<ref name=hfa1979bbchomeservice/><ref name=hfcritic200705/>
The ''LS3/5A'' is a commercially produced loudspeaker driven by the need of the [[BBC]] to monitor and assess broadcast programme quality. It was derived from the ''LS3/5'', which was conceived and developed by its engineering department in the early 1970s, when it was under the stewardship of Dudley Harwood.<ref name=hfa1979bbchomeservice/> The BBC specifically set out to design a speaker to achieve natural overall sound quality and good [[dynamic range]] for monitoring broadcasts in tight space confines.<ref name="BBC RD 1976/29"/><ref name=hfa1979bbchomeservice/><ref name=stereoph1989atk1/> There were no commercially produced small loudspeakers available at that time that met the requirement for naturalness and sonic neutrality.<ref name=hfa1979bbchomeservice/><ref name=hfcritic200705/>


As the broadcasting unit was about to order another batch of the monitor, it was found that the supplier had modified the drive units, meaning the ''LS3/5'' design had to be fundamentally revised.<ref name=hfn199003/> The BBC's Designs Department was called upon to adapt the product in light of the supply changes.<ref name=hfn199003/> Modifications were made to adapt to the new drive units and deal with the altered resonance pattern, and the ''LS3/5'' became the ''LS3/5A''.<ref name=hfa1979bbchomeservice/><ref name="BBC RD 1976/29"/>
As the broadcasting unit was about to order another batch of the monitor, it was found that the supplier had modified the drive units, meaning the ''LS3/5'' design had to be fundamentally revised.<ref name=hfn199003/> The BBC's Designs Department was called upon to adapt the product in light of the supply changes.<ref name=hfn199003/> Modifications were made to adapt to the new drive units and deal with the altered resonance pattern, and the ''LS3/5'' became the ''LS3/5A''.<ref name="BBC RD 1976/29"/><ref name=hfa1979bbchomeservice/>


The BBC then licensed the product to a small number of private sector companies.<ref name=hfa1979bbchomeservice/><ref name="BBC RD 1976/29"/> Production began in 1975. In 1987, there was a reassessment of the product due to consistency issues in the manufacture of the mid–bass driver.<ref name=hfn199003/> As a result, the drivers were modified and the crossover changed. The overall impedance of the crossover fell to 11 ohms from the original 15 ohms.<ref name=tas20081202/><ref name=stereoph1989atk5/>
The BBC then licensed the product to a small number of private sector companies.<ref name="BBC RD 1976/29"/><ref name=hfa1979bbchomeservice/> Production began in 1975. In 1987, there was a reassessment of the product due to consistency issues in the manufacture of the mid–bass driver.<ref name=hfn199003/> As a result, the drivers were modified and the crossover changed. The overall impedance of the crossover fell to 11 ohms from the original 15 ohms.<ref name=tas20081202/><ref name=stereoph1989atk5/>


At that time, John Atkinson remarked in ''Stereophile'' on the design's exceptional longevity, saying: "It is virtually unknown for a speaker to be still available, virtually unchanged, 14 years after [its introduction]".<ref name=stereoph1989atk1/> The various official versions of the ''LS3/5A'' from various licensees sold in significant numbers in its life of over a quarter of a century. Sales estimates range from 60,000<ref name=hfcritic200705/> to 100,000 pairs.<ref name=tas20081202/><ref name=hfn200106kk/>
At that time, John Atkinson remarked in ''Stereophile'' on the design's exceptional longevity, saying: "It is virtually unknown for a speaker to be still available, virtually unchanged, 14 years after [its introduction]".<ref name=stereoph1989atk1/> The various official versions of the ''LS3/5A'' from various licensees sold in significant numbers in its life of over a quarter of a century. Sales estimates range from 60,000<ref name=hfcritic200705/> to 100,000 pairs.<ref name=tas20081202/><ref name=hfn200106kk/>
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== Speaker ==
== Speaker ==

=== Name ===
=== Name ===
The product name is derived from BBC naming convention: "LS3" designation meant it was a loudspeaker intended for outside broadcasting, as opposed to the "LS5" loudspeaker, intended for studio monitoring.<ref name=hfa1979bbchomeservice/> The number after the stroke is the model number, the ''LS3/5'' is "number 5" outside-broadcasting loudspeaker. The letter that follows denotes alterations to the original specification, of which there was only one in this instance after the ''LS3/5'', thus the "A" in this instance.<ref name=hfn199003/>
The product name is derived from BBC naming convention: "LS3" designation meant it was a loudspeaker intended for outside broadcasting, as opposed to the "LS5" loudspeaker, intended for studio monitoring.<ref name=hfa1979bbchomeservice/> The number after the stroke is the model number, the ''LS3/5'' is "number 5" outside-broadcasting loudspeaker. The letter that follows denotes alterations to the original specification, of which there was only one in this instance after the ''LS3/5'', thus the "A" in this instance.<ref name=hfn199003/>


=== Design ===
=== Design ===
For its [[outside broadcasting]] (OB) monitoring, the BBC was faced with need for a small speaker suitable for near-field monitoring of the frequency range from 400 Hz to about 20 kHz. The principal constraints were space and situations where using headphones is unsatisfactory, such as in mobile broadcasting vans.<ref name=hfa1979bbchomeservice/><ref name="BBC RD 1976/29"/><ref name=stereoph1989atk1/> There were no commercial constraints.<ref name=stereoph1989atk1/> The BBC Research Department, then situated at Kingswood Warren, were responsible for development work.<ref name=bbcatkingswood/> They were able to answer a request for a prototype in under a week because it resembled an experimental loudspeaker that the department had already developed for some preliminary acoustic scaling tests.<ref name=hfn199003/> The speaker had to be voiced by ear, octave by octave, because scale test results were inapplicable to a model of this size.<ref name=hfcritic200705/> Engineers took measurements; comparisons were performed against the LS5/8 – a large "Grade I monitor" already in use at the time – and with live sources.<ref name=bbcatkingswood/> Estimated development costs of the order of £100,000 were said to have been incurred at the time.<ref name=bbcatkingswood/> OEM drivers from [[KEF]] were selected, and approximately 20 units of the ''LS3/5'' were produced in-house.<ref name=hfn199003/>
For its [[outside broadcasting]] (OB) monitoring, the BBC was faced with need for a small speaker suitable for near-field monitoring of the frequency range from 400&nbsp;Hz to about 20&nbsp;kHz. The principal constraints were space and situations where using headphones is unsatisfactory, such as in mobile broadcasting vans.<ref name="BBC RD 1976/29"/><ref name=hfa1979bbchomeservice/><ref name=stereoph1989atk1/> There were no commercial constraints.<ref name=stereoph1989atk1/> The BBC Research Department, then situated at Kingswood Warren, were responsible for development work.<ref name=bbcatkingswood/> They were able to answer a request for a prototype in under a week because it resembled an experimental loudspeaker that the department had already developed for some preliminary acoustic scaling tests.<ref name=hfn199003/> The speaker had to be voiced by ear, octave by octave, because scale test results were inapplicable to a model of this size.<ref name=hfcritic200705/> Engineers took measurements; comparisons were performed against the LS5/8 – a large "Grade I monitor" already in use at the time – and with live sources.<ref name=bbcatkingswood/> Estimated development costs of the order of £100,000 were said to have been incurred at the time.<ref name=bbcatkingswood/> OEM drivers from [[KEF]] were selected, and approximately 20 units of the ''LS3/5'' were produced in-house.<ref name=hfn199003/>


The BBC had initiated tendering to have the ''LS3/5'' made under license.<ref name=hfn199003/> As the broadcasting unit was about to order another batch of the monitor, it was found that in the course of their product development that KEF had modified the drive units, and the ''LS3/5'' design had to be revised due to fundamental changes in resonances. A number of important changes were made to adapt to the new drive units.<ref name=hfa1979bbchomeservice/><ref name="BBC RD 1976/29"/> The tweeter of the ''LS3/5'' suffered from a treble lisp and was fragile because it was exposed. A suitable protection grille was found that made the tweeter more robust and helped cure the lisp. The crossover also had to undergo change, and the ''LS3/5'' became the ''LS3/5A''.<ref name=hfn199003/>
The BBC had initiated tendering to have the ''LS3/5'' made under license.<ref name=hfn199003/> As the broadcasting unit was about to order another batch of the monitor, it was found that in the course of their product development that KEF had modified the drive units, and the ''LS3/5'' design had to be revised due to fundamental changes in resonances. A number of important changes were made to adapt to the new drive units.<ref name="BBC RD 1976/29"/><ref name=hfa1979bbchomeservice/> The tweeter of the ''LS3/5'' suffered from a treble lisp and was fragile because it was exposed. A suitable protection grille was found that made the tweeter more robust and helped cure the lisp. The crossover also had to undergo change, and the ''LS3/5'' became the ''LS3/5A''.<ref name=hfn199003/>


The KEF ''B110'' mid&ndash;bass unit is a 110mm speaker with a doped [[bextrene]] cone and a neoprene surround. The KEF ''T27'' tweeter has a 19mm [[mylar]] dome fitted and is with a perforated protection grille.<ref name=stereoph1989atk1/> The loudspeaker cabinet, measuring {{convert/3|31|x|19|x|16|cm|in}}, is made using {{convert|12|mm|abbr=on}} [[birch]] plywood strengthened at every joint with beech braces, and heavily damped. Although there was no specification for the wood of the original ''LS3/5'' cabinets, the BBC closely specified wood types in defining the ''LS3/5A'' due to concerns that other hard woods &ndash; specifically [[Parana pine]], with which the BBC conducted tests &ndash; would cause noticeable colouration (i.e. detract from sonic neutrality) due to interaction with a resonance of the bass drivers.<ref name="BBC RD 1976/29"/><ref name=hfcritic200705/>
The KEF ''B110'' mid&ndash;bass unit is a 110mm speaker with a doped [[bextrene]] cone and a neoprene surround. The KEF ''T27'' tweeter has a 19mm [[mylar]] dome fitted and is with a perforated protection grille.<ref name=stereoph1989atk1/> The loudspeaker cabinet, measuring {{convert/3|31|x|19|x|16|cm|in}}, is made using {{convert|12|mm|abbr=on}} [[birch]] plywood strengthened at every joint with beech braces, and heavily damped. Although there was no specification for the wood of the original ''LS3/5'' cabinets, the BBC closely specified wood types in defining the ''LS3/5A'' due to concerns that other hard woods &ndash; specifically [[Parana pine]], with which the BBC conducted tests &ndash; would cause noticeable colouration (i.e. detract from sonic neutrality) due to interaction with a resonance of the bass drivers.<ref name="BBC RD 1976/29"/><ref name=hfcritic200705/>


The BBC then licensed the product to a small number of private sector companies in exchange for royalties and the hope of supply contracts.<ref name=hfa1979bbchomeservice/><ref name="BBC RD 1976/29"/> David Prakel in ''Hi-fi Answers'' suggests it was a costlier speaker to build than imagined because tight specifications meant a high failure rate in production &ndash; the BBC had specified "the finest, most expensive ingredients and representing an investment of hours of skilled labour".<ref name=hfa1979bbchomeservice/> Martin Colloms notes that: "Hardly any component in either enclosure or driver may be substituted without the blend suffering audible disturbance. This is because the ''3/5A'' sets such a high standard for tonal balance that errors which would pass unnoticed in an ordinary speaker are readily exposed".<ref name=hfcritic200705/> Production began in 1975.
The BBC then licensed the product to a small number of private sector companies in exchange for royalties and the hope of supply contracts.<ref name="BBC RD 1976/29"/><ref name=hfa1979bbchomeservice/> David Prakel in ''Hi-fi Answers'' suggests it was a costlier speaker to build than imagined because tight specifications meant a high failure rate in production &ndash; the BBC had specified "the finest, most expensive ingredients and representing an investment of hours of skilled labour".<ref name=hfa1979bbchomeservice/> Martin Colloms notes that: "Hardly any component in either enclosure or driver may be substituted without the blend suffering audible disturbance. This is because the ''3/5A'' sets such a high standard for tonal balance that errors which would pass unnoticed in an ordinary speaker are readily exposed".<ref name=hfcritic200705/> Production began in 1975.


=== Construction ===
=== Construction ===
J. Gordon Holt indicates that most of the cost lay inside the case, having been spent on a complex equalizer and phase-corrected crossover.<ref name=stereoph1977gordon1/> However, John Atkinson notes in ''Stereophile'' that the cabinet ([[loudspeaker enclosure]]) alone "costs the manufacturer the same as the retail price of a typical {{sic|massmarket}} speaker".<ref name=stereoph1989atk1/> It has an internal volume of approximately 5 litres.<ref name="BBC RD 1976/29"/><ref name=hfcritic200705/> The internal cabinet walls are heavily damped, only specific speaker drivers manufactured to strict tolerances may be used. There were other measures to control diffraction and ensure tonal neutrality.<ref name=hfa1979bbchomeservice/><ref name="BBC RD 1976/29"/>
J. Gordon Holt indicates that most of the cost lay inside the case, having been spent on a complex equalizer and phase-corrected crossover.<ref name=stereoph1977gordon1/> However, John Atkinson notes in ''Stereophile'' that the cabinet ([[loudspeaker enclosure]]) alone "costs the manufacturer the same as the retail price of a typical {{sic|massmarket}} speaker".<ref name=stereoph1989atk1/> It has an internal volume of approximately 5 litres.<ref name="BBC RD 1976/29"/><ref name=hfcritic200705/> The internal cabinet walls are heavily damped, only specific speaker drivers manufactured to strict tolerances may be used. There were other measures to control diffraction and ensure tonal neutrality.<ref name="BBC RD 1976/29"/><ref name=hfa1979bbchomeservice/>

⚫
The 13-element crossover includes an inductor for the treble section with seven positions that allows adjustment to match level of mid to treble sensitivities.<ref name="BBC RD 1976/29"/><ref name=hfa1979bbchomeservice/><ref name=hfcritic200705/> The design also specifies high quality screened air-gap inductors and film capacitors.<ref name=stereoph1989atk1/><ref name=hfcritic200705/> The circuitry provides equalisation in both high and low frequency sections.<ref name="BBC RD 1976/29"/><ref name=hfcritic200705/>


⚫
The 13-element crossover includes an inductor for the treble section with seven positions that allows adjustment to match level of mid to treble sensitivities.<ref name="BBC RD 1976/29"/><ref name=hfcritic200705/><ref name=hfa1979bbchomeservice/> The design also specifies high quality screened air-gap inductors and film capacitors.<ref name=hfcritic200705/><ref name=stereoph1989atk1/> The circuitry provides equalisation in both high and low frequency sections.<ref name=hfcritic200705/><ref name="BBC RD 1976/29"/>
=== Signature sound ===
=== Signature sound ===
Typical of speakers of similar size, the ''3/5A'' has little or no low bass. But the design reinforced its lower register by a boost at around 160Hz, giving the subjective impression that the speaker is more bass-rich.<ref name=harbethmeasure1/><ref name=stereoph2007atk1/> Reviewers have noticed the sound being a little bright at the treble registers, or that the speakers "reproduce the high-end roughness of solid-state amplifiers mercilessly" thus suggested partnering with valve amplification would be advantageous.<ref name=stereoph1989atk2/><ref name=stereoph1984/><ref name=stereoph1977gordon2/> A slight nasal quality in the midrange has also been noted in the earlier versions<ref name=hfcritic200705/><ref name=stereoph1977gordon2/> which seems to have been cured in Stirling's "V2" ''3/5A''.<ref name=stereoph2007atk1/> The accuracy and stability of its stereo imaging and its clean midrange reproduction are also appreciated qualities.<ref name=stereoph2007atk1/><ref name=stereoph1984/> John Atkinson suggests in ''Stereophile'' in 1989 that the ''LS3/5A'' is ideally suited to the reproduction of program having a limited dynamic-range requirement, for example chamber music;<ref name=stereoph1989atk2/> he said in 1993 that the ''LS3/5a'' "has never boogied and never will; it's just too polite ever to cut the mustard on rock, or even [[straightahead jazz]]".<ref name=stereoph1993atk1/>
Typical of speakers of similar size, the ''3/5A'' has little or no low bass. But the design reinforced its lower register by a boost at around 160&nbsp;Hz, giving the subjective impression that the speaker is more bass-rich.<ref name=stereoph2007atk1/><ref name=harbethmeasure1/> Reviewers have noticed the sound being a little bright at the treble registers, or that the speakers "reproduce the high-end roughness of solid-state amplifiers mercilessly" thus suggested partnering with valve amplification would be advantageous.<ref name=stereoph1989atk2/><ref name=stereoph1984/><ref name=stereoph1977gordon2/> A slight nasal quality in the midrange has also been noted in the earlier versions<ref name=hfcritic200705/><ref name=stereoph1977gordon2/> which seems to have been cured in Stirling's "V2" ''3/5A''.<ref name=stereoph2007atk1/> The accuracy and stability of its stereo imaging and its clean midrange reproduction are also appreciated qualities.<ref name=stereoph2007atk1/><ref name=stereoph1984/> John Atkinson suggests in ''Stereophile'' in 1989 that the ''LS3/5A'' is ideally suited to the reproduction of program having a limited dynamic-range requirement, for example chamber music;<ref name=stereoph1989atk2/> he said in 1993 that the ''LS3/5a'' "has never boogied and never will; it's just too polite ever to cut the mustard on rock, or even [[straightahead jazz]]".<ref name=stereoph1993atk1/>


=== Constructors ===
=== Constructors ===
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== Reception ==
== Reception ==
Despite not being a "commercial product" at the outset, the ''LS3/5A'' was commercially successful in its twenty-something-year life,<ref name=timeline1/><ref name=timeline2/><ref name=stereoph2007atk1/> from 1975 until approximately 2000, when the availability of KEF drive units came to an end.<ref name=stereoph2007atk1/> Figures of their sales differ, possibly due to scope and cut-off: when it ceased production in 1998, "some 100,000 pairs were in circulation, with 3000 pairs sold in its last year alone", according to Paul Seydor writing in ''The Absolute Sound'';<ref name=tas20081202/> in 2001, Ken Kessler similarly estimated in ''Hi-fi News'' that 100,000 pairs had been produced.<ref name=hfn200106kk/> In 2007, Martin Colloms reported "more than 60,000 pairs of the original ''LS3/5A''s were made".<ref name=hfcritic200705/> John Atkinson noted that it had sold in excess of 60,000 up to 1988, of which Rogers represented two-thirds.<ref name=stereoph2007atk1/>{{#tag:ref|US retail prices/pair: $430 (1977), $450 (1984), $650 (1989), $999 (1993), $1295 (1996), $1695 (2007). Manufacturers: Rogers Loudspeakers Ltd., Mitcham, Surrey, England (1977, 1989); Spendor loudspeakers, Redhill, Surry, England (1984); Harbeth Acoustics, Haywards Heath, West Sussex, England (1993). KEF, Maidstone, Kent, England (1996). Stirling Broadcast, Somerset, England. (2007)<ref name=stereoph2007atk4/>|group="Note"}}
Despite not being a "commercial product" at the outset, the ''LS3/5A'' was commercially successful in its twenty-something-year life,<ref name=stereoph2007atk1/><ref name=timeline1/><ref name=timeline2/> from 1975 until approximately 2000, when the availability of KEF drive units came to an end.<ref name=stereoph2007atk1/> Figures of their sales differ, possibly due to scope and cut-off: when it ceased production in 1998, "some 100,000 pairs were in circulation, with 3000 pairs sold in its last year alone", according to Paul Seydor writing in ''The Absolute Sound'';<ref name=tas20081202/> in 2001, Ken Kessler similarly estimated in ''Hi-fi News'' that 100,000 pairs had been produced.<ref name=hfn200106kk/> In 2007, Martin Colloms reported "more than 60,000 pairs of the original ''LS3/5A''s were made".<ref name=hfcritic200705/> John Atkinson noted that it had sold in excess of 60,000 up to 1988, of which Rogers represented two-thirds.<ref name=stereoph2007atk1/>{{#tag:ref|US retail prices/pair: $430 (1977), $450 (1984), $650 (1989), $999 (1993), $1295 (1996), $1695 (2007). Manufacturers: Rogers Loudspeakers Ltd., Mitcham, Surrey, England (1977, 1989); Spendor loudspeakers, Redhill, Surry, England (1984); Harbeth Acoustics, Haywards Heath, West Sussex, England (1993). KEF, Maidstone, Kent, England (1996). Stirling Broadcast, Somerset, England. (2007)<ref name=stereoph2007atk4/>|group="Note"}}


Atkinson notes in 2007 that the sound of the speaker had not dated whilst many other speakers of the 1960s and 70s had. He guessed that ''LS3/5A'' remained competitive due to the exhaustive considerations and top engineering talent that went into its design.<ref name=stereoph2007atk1/>
Atkinson notes in 2007 that the sound of the speaker had not dated whilst many other speakers of the 1960s and 70s had. He guessed that ''LS3/5A'' remained competitive due to the exhaustive considerations and top engineering talent that went into its design.<ref name=stereoph2007atk1/>


== Product revisions ==
== Product revisions ==

=== 1987&ndash;1990 ===
=== 1987&ndash;1990 ===
It had become apparent in around 1987 that a number of units already in the field were not up to specification.<ref name=hfn199003/> In particular, it was becoming increasingly difficult to obtain KEF drivers of acceptable tolerances, particular the woofer. Measurements of the 1–1.5kHz peak of some units produced at the time were up to 6dB higher.<ref name=tas20081202/> KEF underwent a program to improve consistency of both drive-unit and the associated crossover, and if possible to improve the product further, but without altering frequency characteristics or tonal balances.<ref name=stereoph1989atk1/> In the end, it was decided to change the woofer's neoprene surround to one employing a vinyl compound;<ref name=stereoph2007atk1/> greater use of computer would be made for measurement of drive units. Upon its redesign to accommodate the changes, overall impedance of the crossover fell to 11 ohms from the original 15 ohms. KEF then also manufactured and supplied in matched kits to put an end to the blame cycle.<ref name=tas20081202/> Martin Colloms had suggested in ''Hi-fi News'' in August 1988 that the BBC had consented to a revision of the design to ensure that targeted production levels could be maintained.<ref name=stereoph1989atk1/>
It had become apparent in around 1987 that a number of units already in the field were not up to specification.<ref name=hfn199003/> In particular, it was becoming increasingly difficult to obtain KEF drivers of acceptable tolerances, particular the woofer. Measurements of the 1–1.5&nbsp;kHz peak of some units produced at the time were up to 6dB higher.<ref name=tas20081202/> KEF underwent a program to improve consistency of both drive-unit and the associated crossover, and if possible to improve the product further, but without altering frequency characteristics or tonal balances.<ref name=stereoph1989atk1/> In the end, it was decided to change the woofer's neoprene surround to one employing a vinyl compound;<ref name=stereoph2007atk1/> greater use of computer would be made for measurement of drive units. Upon its redesign to accommodate the changes, overall impedance of the crossover fell to 11 ohms from the original 15 ohms. KEF then also manufactured and supplied in matched kits to put an end to the blame cycle.<ref name=tas20081202/> Martin Colloms had suggested in ''Hi-fi News'' in August 1988 that the BBC had consented to a revision of the design to ensure that targeted production levels could be maintained.<ref name=stereoph1989atk1/>


In 1990, the BBC authorised licensees to manufacture models capable of being biwired, but stipulated that the performance in single-wired mode must meet the original specification.<ref name=stereoph1989atk1/>
In 1990, the BBC authorised licensees to manufacture models capable of being biwired, but stipulated that the performance in single-wired mode must meet the original specification.<ref name=stereoph1989atk1/>


=== 2005 &ndash; birth of ''LS3/5A'' "''V2''" ===
=== 2005 &ndash; birth of ''LS3/5A'' "''V2''" ===
2001 Stirling Broadcast obtained a BBC licence to produce legacy 11-ohm ''LS3/5A'', but had to rethink the product when KEF finally ceased manufacturing the drive units in about 2000.<ref name=stereoph2007atk1/><ref name=tas20081202/> Using drivers from SEAS and Scanspeak, Derek Hughes developed for Stirling a new crossover that enabled the new proprietary drivers to mimic the response of the original KEF drivers they replaced.<ref name=tas20081202/> Specifically, the ''T27'' was replaced by a 19mm doped fabric dome tweeter. The mid–bass unit is a formed polypropylene co-polymer cone to which a damping coating has been applied and given a synthetic rubber roll surround. The crossover has three settings of relative high frequency level, in steps of 0.5dB. Each crossover is tuned to the specific pairs of drive units.<ref name=hfcritic200705v2/> While Stirling's revision deviates technically from the specification, the company took steps to research and test to ensure the ''LS3/5A'' sound was preserved, "warts and all". Stirling added a "V2" to the designation when the product was launched in 2005 in an act of transparency, even though its ''LS3/5A'' has the endorsement of the broadcaster.<ref name=tas20081202/><ref name=hfcritic200705v2/>
2001 Stirling Broadcast obtained a BBC licence to produce legacy 11-ohm ''LS3/5A'', but had to rethink the product when KEF finally ceased manufacturing the drive units in about 2000.<ref name=tas20081202/><ref name=stereoph2007atk1/> Using drivers from SEAS and Scanspeak, Derek Hughes developed for Stirling a new crossover that enabled the new proprietary drivers to mimic the response of the original KEF drivers they replaced.<ref name=tas20081202/> Specifically, the ''T27'' was replaced by a 19mm doped fabric dome tweeter. The mid–bass unit is a formed polypropylene co-polymer cone to which a damping coating has been applied and given a synthetic rubber roll surround. The crossover has three settings of relative high frequency level, in steps of 0.5dB. Each crossover is tuned to the specific pairs of drive units.<ref name=hfcritic200705v2/> While Stirling's revision deviates technically from the specification, the company took steps to research and test to ensure the ''LS3/5A'' sound was preserved, "warts and all". Stirling added a "V2" to the designation when the product was launched in 2005 in an act of transparency, even though its ''LS3/5A'' has the endorsement of the broadcaster.<ref name=tas20081202/><ref name=hfcritic200705v2/>


== Notes ==
== Notes ==
{{Reflist|group="Note"}}
{{Reflist|group="Note"}}

== References ==
== References ==
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Revision as of 15:27, 2 December 2013

Late model (c.1998) LS3/5A from Spendor, one of the BBC licensees

The LS3/5A is a small loudspeaker created by the BBC to equip their outside broadcast vans with small studio monitors with which to ensure quality of their outside broadcasts. The speaker is known for its transparent and natural sound.

The BBC granted licences to a small number of British firms, who would manufacture the product from 1975 to 2000 and beyond. The product underwent a change in 1987 due to consistency issues in manufacturing, and again in around 2003 when original parts from KEF ran out. Upwards of 60,000 pairs of the speaker have been sold.

History

The LS3/5A is a commercially produced loudspeaker driven by the need of the BBC to monitor and assess broadcast programme quality. It was derived from the LS3/5, which was conceived and developed by its engineering department in the early 1970s, when it was under the stewardship of Dudley Harwood.[1] The BBC specifically set out to design a speaker to achieve natural overall sound quality and good dynamic range for monitoring broadcasts in tight space confines.[2][1][3] There were no commercially produced small loudspeakers available at that time that met the requirement for naturalness and sonic neutrality.[1][4]

As the broadcasting unit was about to order another batch of the monitor, it was found that the supplier had modified the drive units, meaning the LS3/5 design had to be fundamentally revised.[5] The BBC's Designs Department was called upon to adapt the product in light of the supply changes.[5] Modifications were made to adapt to the new drive units and deal with the altered resonance pattern, and the LS3/5 became the LS3/5A.[2][1]

The BBC then licensed the product to a small number of private sector companies.[2][1] Production began in 1975. In 1987, there was a reassessment of the product due to consistency issues in the manufacture of the mid–bass driver.[5] As a result, the drivers were modified and the crossover changed. The overall impedance of the crossover fell to 11 ohms from the original 15 ohms.[6][7]

At that time, John Atkinson remarked in Stereophile on the design's exceptional longevity, saying: "It is virtually unknown for a speaker to be still available, virtually unchanged, 14 years after [its introduction]".[3] The various official versions of the LS3/5A from various licensees sold in significant numbers in its life of over a quarter of a century. Sales estimates range from 60,000[4] to 100,000 pairs.[6][8]

In the early 2000s, due to the parts being discontinued, the 3/5 had technically reached the end of the road.[9] However, Stirling Broadcast, one of the last batch of licensees, completely redesigned the product based on the audio signature of the original, and launched the LS3/5A v2 with the full endorsement of the broadcaster in early 2006.[6][9][10]

Speaker

Name

The product name is derived from BBC naming convention: "LS3" designation meant it was a loudspeaker intended for outside broadcasting, as opposed to the "LS5" loudspeaker, intended for studio monitoring.[1] The number after the stroke is the model number, the LS3/5 is "number 5" outside-broadcasting loudspeaker. The letter that follows denotes alterations to the original specification, of which there was only one in this instance after the LS3/5, thus the "A" in this instance.[5]

Design

For its outside broadcasting (OB) monitoring, the BBC was faced with need for a small speaker suitable for near-field monitoring of the frequency range from 400 Hz to about 20 kHz. The principal constraints were space and situations where using headphones is unsatisfactory, such as in mobile broadcasting vans.[2][1][3] There were no commercial constraints.[3] The BBC Research Department, then situated at Kingswood Warren, were responsible for development work.[11] They were able to answer a request for a prototype in under a week because it resembled an experimental loudspeaker that the department had already developed for some preliminary acoustic scaling tests.[5] The speaker had to be voiced by ear, octave by octave, because scale test results were inapplicable to a model of this size.[4] Engineers took measurements; comparisons were performed against the LS5/8 – a large "Grade I monitor" already in use at the time – and with live sources.[11] Estimated development costs of the order of £100,000 were said to have been incurred at the time.[11] OEM drivers from KEF were selected, and approximately 20 units of the LS3/5 were produced in-house.[5]

The BBC had initiated tendering to have the LS3/5 made under license.[5] As the broadcasting unit was about to order another batch of the monitor, it was found that in the course of their product development that KEF had modified the drive units, and the LS3/5 design had to be revised due to fundamental changes in resonances. A number of important changes were made to adapt to the new drive units.[2][1] The tweeter of the LS3/5 suffered from a treble lisp and was fragile because it was exposed. A suitable protection grille was found that made the tweeter more robust and helped cure the lisp. The crossover also had to undergo change, and the LS3/5 became the LS3/5A.[5]

The KEF B110 mid–bass unit is a 110mm speaker with a doped bextrene cone and a neoprene surround. The KEF T27 tweeter has a 19mm mylar dome fitted and is with a perforated protection grille.[3] The loudspeaker cabinet, measuring Template:Convert/3, is made using 12 mm (0.47 in) birch plywood strengthened at every joint with beech braces, and heavily damped. Although there was no specification for the wood of the original LS3/5 cabinets, the BBC closely specified wood types in defining the LS3/5A due to concerns that other hard woods – specifically Parana pine, with which the BBC conducted tests – would cause noticeable colouration (i.e. detract from sonic neutrality) due to interaction with a resonance of the bass drivers.[2][4]

The BBC then licensed the product to a small number of private sector companies in exchange for royalties and the hope of supply contracts.[2][1] David Prakel in Hi-fi Answers suggests it was a costlier speaker to build than imagined because tight specifications meant a high failure rate in production – the BBC had specified "the finest, most expensive ingredients and representing an investment of hours of skilled labour".[1] Martin Colloms notes that: "Hardly any component in either enclosure or driver may be substituted without the blend suffering audible disturbance. This is because the 3/5A sets such a high standard for tonal balance that errors which would pass unnoticed in an ordinary speaker are readily exposed".[4] Production began in 1975.

Construction

J. Gordon Holt indicates that most of the cost lay inside the case, having been spent on a complex equalizer and phase-corrected crossover.[12] However, John Atkinson notes in Stereophile that the cabinet (loudspeaker enclosure) alone "costs the manufacturer the same as the retail price of a typical massmarket [sic] speaker".[3] It has an internal volume of approximately 5 litres.[2][4] The internal cabinet walls are heavily damped, only specific speaker drivers manufactured to strict tolerances may be used. There were other measures to control diffraction and ensure tonal neutrality.[2][1]

The 13-element crossover includes an inductor for the treble section with seven positions that allows adjustment to match level of mid to treble sensitivities.[2][1][4] The design also specifies high quality screened air-gap inductors and film capacitors.[3][4] The circuitry provides equalisation in both high and low frequency sections.[2][4]

Signature sound

Typical of speakers of similar size, the 3/5A has little or no low bass. But the design reinforced its lower register by a boost at around 160 Hz, giving the subjective impression that the speaker is more bass-rich.[9][13] Reviewers have noticed the sound being a little bright at the treble registers, or that the speakers "reproduce the high-end roughness of solid-state amplifiers mercilessly" thus suggested partnering with valve amplification would be advantageous.[14][15][16] A slight nasal quality in the midrange has also been noted in the earlier versions[4][16] which seems to have been cured in Stirling's "V2" 3/5A.[9] The accuracy and stability of its stereo imaging and its clean midrange reproduction are also appreciated qualities.[9][15] John Atkinson suggests in Stereophile in 1989 that the LS3/5A is ideally suited to the reproduction of program having a limited dynamic-range requirement, for example chamber music;[14] he said in 1993 that the LS3/5a "has never boogied and never will; it's just too polite ever to cut the mustard on rock, or even straightahead jazz".[17]

Constructors

A total of 10 companies were ever granted licenses by the BBC to manufacture the model, a maximum of 3 at any given time.[18] Rogers was the earliest licensee, but went broke before ever producing one unit. The name was bought by Swisstone, who started manufacturing the Rogers 3/5A under licence in 1975.[19] Rogers' production accounted for the lion's share, of around 43,000 pairs by 1988, and 50,000 pairs all told.[9] Spendor's production amounted to about 22,000 pairs, Audiomaster 10,000. Dudley Harwood, the BBC engineer instrumental in the creation of the 3/5A, starts Harbeth. Although licensed since 1977, the company produced no LS3/5A for a decade.[19] Eventually, Harbeth accounted for 7,000 pairs.[8] Other licensees included Chartwell, RAM, Goodmans, KEF and Stirling Broadcast.[9]

Clones

The Linn Kan, considered a clone of the LS3/5A

In 1979, Linn Products created the Kan – a non-BBC specification bookshelf speaker that used a LS3/5A-sized cabinet and the same B110 driver from KEF.[4][17] Linn acquired a hundred pairs of cabinets from the supplier of the bankrupt Chartwell, and used them for the very first Kans.[20] The similarities end there as Linn chose the re-badged OEM D20-LP-1 from Hiquphon; they installed a very simple crossover into the box that transformed it into "one of the fastest and most involving wall mount miniatures ever", according to Martin Colloms.[4][17]

Jim Rogers, who set up J R Loudspeakers Ltd after the collapse of Rogers Audio, released the JR149 in 1977 using the same drive units as the LS3/5A in a cylindrical aluminium cabinet. A review of the JR149 in the May 1977 Hi-Fi News and Record Review found that the "general quality was very comparable" to the LS3/5A.[20]

KEF released its CS1 constructor kit to tap the home-build market. According to the product brochure, the kit includes "the same KEF drive units originally specified for the LS3/5A with a somewhat simplified dividing network giving a similar overall frequency response characteristic".[20]

Reception

Despite not being a "commercial product" at the outset, the LS3/5A was commercially successful in its twenty-something-year life,[9][18][19] from 1975 until approximately 2000, when the availability of KEF drive units came to an end.[9] Figures of their sales differ, possibly due to scope and cut-off: when it ceased production in 1998, "some 100,000 pairs were in circulation, with 3000 pairs sold in its last year alone", according to Paul Seydor writing in The Absolute Sound;[6] in 2001, Ken Kessler similarly estimated in Hi-fi News that 100,000 pairs had been produced.[8] In 2007, Martin Colloms reported "more than 60,000 pairs of the original LS3/5As were made".[4] John Atkinson noted that it had sold in excess of 60,000 up to 1988, of which Rogers represented two-thirds.[9][Note 1]

Atkinson notes in 2007 that the sound of the speaker had not dated whilst many other speakers of the 1960s and 70s had. He guessed that LS3/5A remained competitive due to the exhaustive considerations and top engineering talent that went into its design.[9]

Product revisions

1987–1990

It had become apparent in around 1987 that a number of units already in the field were not up to specification.[5] In particular, it was becoming increasingly difficult to obtain KEF drivers of acceptable tolerances, particular the woofer. Measurements of the 1–1.5 kHz peak of some units produced at the time were up to 6dB higher.[6] KEF underwent a program to improve consistency of both drive-unit and the associated crossover, and if possible to improve the product further, but without altering frequency characteristics or tonal balances.[3] In the end, it was decided to change the woofer's neoprene surround to one employing a vinyl compound;[9] greater use of computer would be made for measurement of drive units. Upon its redesign to accommodate the changes, overall impedance of the crossover fell to 11 ohms from the original 15 ohms. KEF then also manufactured and supplied in matched kits to put an end to the blame cycle.[6] Martin Colloms had suggested in Hi-fi News in August 1988 that the BBC had consented to a revision of the design to ensure that targeted production levels could be maintained.[3]

In 1990, the BBC authorised licensees to manufacture models capable of being biwired, but stipulated that the performance in single-wired mode must meet the original specification.[3]

2005 – birth of LS3/5A "V2"

2001 Stirling Broadcast obtained a BBC licence to produce legacy 11-ohm LS3/5A, but had to rethink the product when KEF finally ceased manufacturing the drive units in about 2000.[6][9] Using drivers from SEAS and Scanspeak, Derek Hughes developed for Stirling a new crossover that enabled the new proprietary drivers to mimic the response of the original KEF drivers they replaced.[6] Specifically, the T27 was replaced by a 19mm doped fabric dome tweeter. The mid–bass unit is a formed polypropylene co-polymer cone to which a damping coating has been applied and given a synthetic rubber roll surround. The crossover has three settings of relative high frequency level, in steps of 0.5dB. Each crossover is tuned to the specific pairs of drive units.[10] While Stirling's revision deviates technically from the specification, the company took steps to research and test to ensure the LS3/5A sound was preserved, "warts and all". Stirling added a "V2" to the designation when the product was launched in 2005 in an act of transparency, even though its LS3/5A has the endorsement of the broadcaster.[6][10]

Notes

  1. ^ US retail prices/pair: $430 (1977), $450 (1984), $650 (1989), $999 (1993), $1295 (1996), $1695 (2007). Manufacturers: Rogers Loudspeakers Ltd., Mitcham, Surrey, England (1977, 1989); Spendor loudspeakers, Redhill, Surry, England (1984); Harbeth Acoustics, Haywards Heath, West Sussex, England (1993). KEF, Maidstone, Kent, England (1996). Stirling Broadcast, Somerset, England. (2007)[21]

References

  1. ^ a b c d e f g h i j k l Prakel, David (August 1979). "BBC's Home Service", Hi-Fi Answers, pp67–9 (Courtesy link)
  2. ^ a b c d e f g h i j k BBC RD 1976/29
  3. ^ a b c d e f g h i j Atkinson, John (February 1989). "1989 Rogers version". Stereophile (Vol.12 No.2).
  4. ^ a b c d e f g h i j k l m Colloms, Martin (May / June 2007). "The BBC LS3/5a – Revisiting a Classic". Hi-fi Critic, pp.29–32 (courtesy link)
  5. ^ a b c d e f g h i Butler, Trevor (March 1990). "The Little Legend". Hi Fi News & Record Review (Courtesy link)
  6. ^ a b c d e f g h i Seydor, Paul (2 December 2008). "Stirling Broadcast LS3/5a V2 Loudspeaker". The Absolute Sound.
  7. ^ Atkinson, John (February 1989). "1989 Follow-Up". Stereophile. (Vol.12 No.2).
  8. ^ a b c Kessler, Ken (June 2001) "LS3/5A Shootout". HiFi News (courtesy link to reproduced content)
  9. ^ a b c d e f g h i j k l m Atkinson, John (April 2007). "Stirling LS3/5a V2, 2007". Stereophile (Vol.30 No.4).
  10. ^ a b c Colloms, Martin (May / June 2007). "The Stirling Broadcast BBC LS3/5a V2" (scroll down). Hi-fi Critic, pp.33–35 (courtesy link)
  11. ^ a b c "BBC Research at Kingswood Warren, the LS3/5 and LS3/5A". Ls35a.com
  12. ^ Holt, J. Gordon (17 March 1977). "BBC LS3/5a loudspeaker". Stereophile.
  13. ^ "Harbeth Measurements". Stereophile (Vol.16 No.12).
  14. ^ a b Atkinson, John (February 1989). "1989 Rogers version part 2". Stereophile. (Vol.12 No.2).
  15. ^ a b Olsher, Dick (August 1984). "1984 Spendor version". Stereophile (Vol.7 No.4).
  16. ^ a b Holt, J. Gordon (17 March 1977). "1977 BBC Version part 2". Stereophile.
  17. ^ a b c Atkinson, John (December 1993). "1993 Harbeth version". Stereophile (Vol.16 No.12).
  18. ^ a b "A timeline of LS3/5A manufacture". Ls351.com
  19. ^ a b c "The LS3/5A Timeline". Ls351.com
  20. ^ a b c "Inspired designs". Ls35a.com
  21. ^ Atkinson, John (April 2007). "BBC LS3/5a Specifications". Stereophile (Vol.30 No.4).

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