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5881a 2007-08-06 15:27

el34配3/5A,类似的经典,传神,到位.


LS3/5a喇叭
 英国BBC的LS3/5a喇叭真是个奇迹,从上市至今已20多年了仍畅销不衰,现在还有Rogers、HARBETH、Spendor和KEF四家在生产销售LS3/5a。历史上最高时有七、八家英国音响公司同时生产和销售LS3/5a,可见其非凡的魅力所在。

 LS3/5a有小小的身驱和貌不惊人的外观,然而,它的声音太迷人了──饱满丰润的中频、细腻甜美的中高频、极佳的平衡感等,尤其是它在重播音乐时有一种非凡的音乐味和感染力,使听者醉心醉意。或者说,假如您不知道什么是音乐感和平衡感为何物,听听LS3/5a就明白了。LS3/5a 可以让您长时间沉醉在优美的音乐之中而不能自拔,使用过LS3/5a的人都有一个感慨:有LS3/5a相伴时,是音响旅程中听CD唱片最多的一个时期。然而,LS3/5a必定是20年前的设计产品,有它的局限性,诸如:高、低频两端的延伸、透明度与解析力、动态与瞬态反应等用今天的美学眼光来看是明显不足。LS3/5a的不足之处比起它的优点来显得太微不足道了。今日的喇叭可以做得很传真,但又有几个能像LS3/5a那样做得很传神的。传真容易传神难,传真则又传神就更难了。从这个意义上讲,LS3/5a是永远的经典!

 国内流行真空管机,比较“百花齐放”,真空管机用什么型号功率管的都有:6L6、EL34、6550、KT88、 KT100、2A3、 300B、211、845等等,经过这几年的大浪淘沙,市场所用功率管也渐趋明朗,基本上维挽在EL34(推挽机)和300B(单端机)两大类之间。我认为这不是一种简单的淘汰和定型,可以说是集功率管的特性、品质、声音、性价比及市场的综合体现。

 玩真空管机是先从“听”开始,即感性认识先于理性认识。通过聆听各种型号功率管的真空管机后发现: EL34管品质稳定、功率中等,但是声音表现却是超群,音乐表现非常人性化,像一个很有教养的淑女,既温柔大方,又不失粗旷和羞涩。基本上,不管什么型号、品牌、线路的真空管机用上EL34后让人失望的机会很少,再加上EL34管的售价只有KT88的1/4;300B的1/10,可以说,EL34是最超值、最靓声、最实用的真空管,难怪乎,欧洲生产的真空管机基本上是EL34机的天下。有幸的是,从接触真空管机的那一刻开始,我一直是EL34真空管机的积极推广者和使用者。

【靓声组合】:

 很多发烧友包括港台的都比较推崇用300B真空管机推LS3/5a,似乎成为一个主流。LS3/5a是一个动态、声压及承受功率有限的喇叭,然而,灵敏度又很低(只有82.5dB),所以,LS3/5a是一个大盒却又不能大声唱歌的喇叭,否则,LS3/5a的扬声器便会时时“打底”失真。从这个角度来讲,用LS3/5a听音乐的范畴是很窄的,大动态、大场面、大声压的音乐是不适合用LS3/5a来欣赏的。而300B真空管机有和LS3/5a类似的特性,较小的输出功率使其不可能听一些大动态、大声压的音乐。假如,用300B真空管机去推LS3/5a时,那么这种组合只能被定义为:适合听一些室内乐、弦乐人声小品等动态场面不太大的音乐范畴,还有就是300B真空管机的音色和LS3/5a并不十分相投。

 做个比喻:EL34真空管机很像一杯浓郁的蜂蜜水,而300B真空管机就像一杯清新的冰糖水。同样,LS3/5a就像浓郁的蜂蜜水般,HL-5 反倒像清新的冰糖水样,以我搭配的结果,我较喜欢用EL34真空管机去推LS3/5a的声音表现。虽然没有用300B真空管机那种清澈、细致、高贵的音色,但用EL34真空管机胜在声音更加丰润流畅,更佳的平衡感及更加宽阔的听音范围。可以说,300B真空管机的优点和不足是极为鲜明的,而EL34真空管机相比之下,优点没有300B真空管机那么 “优”,但缺点也没有300B真空管机那么“显”,我认为,EL34真空管机把LS3/5a的整体表现给提高了,主要是两者性情相投,音色相同所致。在这一点上,台湾省发烧友较认同用EL34真空管机去推EL3/5a。香港《发烧音响》杂志上一位发烧友写过文章称:EL34真空管机是 LS3/5a喇叭的第一佳配。

【总 结】:

 用EL34真空管机去推HL-5喇叭就没有用300B真空管机那么自然感人;同样,用300B真空管机去推LS3/5a喇叭也没有用EL34真空管机那么丰润迷人,这反映了不同的音响美学观,也说明了搭配的重要性。认真仔细地了解清楚每件音响器材的个性特点,搭配出适合自己口味的声音和特色,再一次证明了音响器材搭配的重要和美妙。

一个小小的传奇 ----



BBC LS3/5A





很难找到任何一个方盒子,如同BBC LS3/5A一般,能勾起如此多的情绪反应,或是制造出这么多的迷思与误解。光是它的名字,就引起了困惑,而实际上它只是单纯的遵循了BBC的器材编码方式。依循此一方式,音箱cabinets最前面的两个字母以CT代表,分音器filters为FL,而喇叭loudspeakers则为LS。编码中的3 表示此一设计主要是供外制转播(outside broadcast-OB)所用。如果此一编码为5,则代表供录音室广播用,如LS5/9即是。在斜线后的5则是型号。LS3/5即取代较早的OB喇叭如 LS3/1。所以我们可以理解LS3/5是当初开始制造时的编号。编号最后的A则是后来加上去的,用以表明第一次也是唯一一次的设计修正。如果有后续的修改的话,则会以B来标示,但那从未发生,也不太像会发生,其原因后文将述明。

There can hardly be another single box which as provoked as much emotive comment,or given rise to so many myths and misunderstandings,as the BBC LS3/5A。The very name has caused confusion,but in fact it simply follows the BBC's coded equipment format。In this,cabinets have the prefix 'CT',filters 'FL',and loudspeakers 'LS',hence the first two letters。The figure '3' in the code indicates that the design is primarily for outside broadcast (OB) use。A figure '5' would mean studio broadcasting,as LS5/9。The number '5' after the stroke is the model number,the LS3/5 supplanting previous

OB speakers like the LS3/1。So we arrive at LS3/5 which was the title of the initial model。Later the 'A' was added to indicate the first and only design alteration to the original specification。Any further specification change would result in a 'B'; but that hasn't happened,and isn't likely to,for reasons which will become apparent。



此一喇叭的设计概念,是为因应BBC的某些制作环境:当以耳机监听并不能令人满意,而又没有足够空间来使用Grade I监听喇叭时。Grade I监听喇叭是用来调整广播节目较具决定性的音调平衡,或麦克风的摆位等。现役的Grade I监听喇叭是LS5/8与LS5/9。Grade II 监听器则可用以监听节目的品质,但音调平衡或麦克风摆位等则一般属于Grade I喇叭的工作范围,除非别无选择。设计者因此体认到:前述情况将需要一种小型的Grade II喇叭,而为达成体积小巧的目的,牺牲部分低频响应与响度便无可厚非。此种喇叭较可能的使用者为:电视外制转播车的主控区,这些制作者需要以较正式混音时低的音量做监听。

The concept of this speaker was to suit those BBC environments where monitoring on headphones was not satisfactory and yet there wasn't sufficient room for a 'Grade I' monitor。A Grade I monitor can be used for critical tonal balancing of programme material,setting of microphone positioning,etc。Current Grade I monitors are the LS5/8 and LS5/9。A grade II monitor may be used for checking the quality of programme,but balance and mic positioning are normally Grade I-checked unless there is no alternative。It was recognized that what would be required was a small Grade II unit with some sacrifice of bass response and loudness reproduction,this being justified for the sake of achieving compactness。The likely users were,for instance,the production control areas of television OB control vans,where there producer needs to listen at a lower level than that used for the actual mixing。



当时市面上并没有现成合适的商业产品,因此BBC设在Kingswood Warren的研究部门就被要求设计一对这样的喇叭。才不到一个星期,原型机就被做出来,并进行实地测试与评估。之所以能这么快,是因为LS3/5的设计,是脱胎于一对实验性喇叭,该喇叭已经在Kingswood被用来做一些音频比例测试(acoustic scaling test)的初步工作。

There was no suitably available commercial unit,and so the Research Department of the BBC was asked to design one,at its headquarters in Kingswood Warren。Less than a week elapsed between this request and the first prototype being offered for field trials and evaluation。This came about because the LS3/5 was based around an experimental loudspeaker which had been developed for some preliminary work on acoustic scaling tests at Kingswood。



当时是以1/8比例的模型,并在1/8的波长(也就是8倍高的频率)下录音,某些音响技术的优缺点就可以被评估出来,而不必花大钱建构1:1的环境。当然,正因为如此,这也暗示了整个模型的再生过程所使用的器材,从放音机,喇叭,麦克风到录音机,都要能在极高的水准下运作,其所处理的频宽为 400Hz到100kHz,以便能正确模仿一般频宽的40Hz到15kHz。

By using one-eighth scale models,and one-eighth wavelengths (IE,8-times frequencies),recordings can be made by which the merits of particular acoustic techniques can be assessed without the expense of a life-size environment。

Naturally,though,this implies that the entire model reproduction chain,of tape player,loudspeaker,microphone and recorder,must be capable of operating at very high quality with a frequency range of 400Hz to 100kHz,in order to be able to model accurately a typical bandwidth of,say,40Hz to 15kHz。



照片中就是BBC在1972至1980年间所使用的的这种模型喇叭,它代表了模制过程(modeling process)的一大进步。虽然它在音质及最大输入功率方面有其局限,这种小喇叭的组件却被认为具有足够高的水准,能满足户外广播所要求的特殊小型监听器。因此,这种组合就被称为LS3/5,并显示出当初的模型实验者其实已经获致很好的成果。

Pictured is the model speaker the BBC used from 1972 until 1980,which represented a major step in the modeling process。Although it had its limitations,primarily in terms of its tonal quality and maximum power handling,components of this small loudspeaker were found to be of a sufficiently high quality to help fulfil the demand for the unusually compact monitor needed in outside broadcast use。This was therefore packaged and called the LS3/5 and showed the model experimenters to have achieved good results。



BBC自行制作了一小批这种喇叭,使用在电视转播车的控制室中,并提供了令人满意的效果。而后BBC终于面临一种状况:需要邀请外面的厂家在认证许可下制造LS3/5。实际上,Rogers在1974年2月19日发出了一则新闻稿,骄傲的宣称将在该年4月的SONEX ’74大展中展示这种新喇叭。他们附上了一张照片与一组临时的规格:25瓦的输入功率,频率响应80-20,000Hz +/-3db,或是60-20,000Hz +/-4db。分频点设在3k Hz,低音单体为110m Plastiflex doped Bextrene 音盆,高音单体为27mm半球型Mylar振膜。定价为一只52英镑外加营业税!

A small number of these units where made in house by the BBC and used in television mobile-control-rooms where they gave satisfactory service。The BBC got to the stage of inviting applications to make the LS3/5 under license by outside manufacturers。Indeed,Rogers issued a press release on 19th February 1974 which proudly announced that they would be exhibiting the new design at SONEX '74,an exhibition to be held that April。They offered a photograph and a provisional specification:25W power handling with +/-3dB 80-20,000Hz and +/-4dB 60-20,000kHz。Crossover frequency was quoted at 3kHz and the units were a 110mm bass driver with a Plastiflex doped Bextrene cone and a 27mm Mylar dome tweeter。The price,&52 each plus VAT!



尽管如此,当时也出现了一些早期的问题。虽然BBC对KEF生产的B110低音单体有信心,但当他们随后需要一批供内部使用的LS3/5时,发现低音与高音单体已经历经重大的改变,必须要重新设计才能接续生产。因此,这款喇叭就被交给当时在大波特兰街的BBC设计部门,要求将它修改到合适。

Alas,though,there were to be early problems。Although the BBC had confidence in the KEF B110 bass unit at the time,when a subsequent batch of in-house LS3/5s was needed it was found that the low and high frequency units had undergone significant changes and a re-design of the speaker would be required before production could resume。

Accordingly,the speaker was passed on to the BBC's Designs Department,then located in Great Portland Street,with a request to modify it so that it would once again be suitable。



当时的问题来自三方面:被改变后的B110单体,以不同于前的方式刺激箱体,导致染色的产生。这染色不仅来自低音单体,也来自音箱; 高音单体则产生出明显的’唇齿’音(lipsy)。

The trouble was in three areas; the B110 had changed,exciting the cabinet in a different way,producing a coloration both from the LF unit and the cabinet; and the HF unit had developed a pronounced 'lipsy' quality。



为了确保音箱的共振不会引起问题,两面侧板都以沥青垫增加其阻尼,上下箱板也做相同的处理,但更铺上两层。此外,一种PVC边料被加在低音单体的框架上,其作用是将低音单体与前障板隔离(de-couple),并使接缝密封。为降低箱内空气共振,所有的箱内壁都再铺上聚亚胺脂发泡材料。箱体并加以密封,以防止在高音压时空气渗漏产生杂音—实际上甚至连螺丝孔也被做成不透气的。箱体的问题也与软木材巴拉那松木制的肋条有关,这些肋条连结前障板与背板,但因为不够硬无法有效支撑,改以榉木代替。而背板的规格也重新制定,由原本的云杉木三夹板改为多层的桦木夹板,如此可避免云杉木常有的空隙。修改后的音箱被称为 CT4/11A。

In an attempt to ensure that cabinet resonance would not cause problems,the side panels had each been damped with a bituminized pad,and the top and bottom panels likewise,except that two layers were required here。In addition,a PVC edging was applied to the chassis of the LF unit and to de-couple it from the front panel and seal the join。In order to damp the air modes of resonance inside,all internal surfaces were lined with polyurethane foam。The cabinet was sealed to prevent air leaks,which might produce extraneous sounds from the high pressures produced - indeed even the screw holes were made airtight。The cabinet problems were associated with the softwood parana pine fillets which connected the back panel to the front; these had an insufficient impedance and were therefore replaced with beech。The back panel was re-specified from the precious sandwich of spruce to multi-ply birch,thus obviating the voids often associated with spruce。This then became the CT4/11A。



藉着此一修正机会,高音单体的高频唇齿音也被加以处理。当时认为这个裸露的KEF T27 SP 1032高音单体很容易在工作场所打包捆绑时受到损害,故决定加上一层保护金属格栅,并在Celestion HF2000单体上找到一个,稍事修改后即可适用。另外T27高音单体的振膜很小,其扩散方向近乎无指向性,故其外围以一圈固定在前障板上的厚毛毡条加以围绕,意在防止音箱突起的边缘干扰造成声音不连贯(acoustic discontinuity)。而前面网的效果也在设计中被考虑进来,因此聆听时必须要装上面网,以避免高音域的不平顺。

The opportunity was also taken to sort out the treble lisp of the tweeter。It was felt that this unit,the KEF T27 SP1032,was vulnerable because it was exposed and could easily be damaged during rigging at a venue。It was decided to incorporate a protection grille and a suitable one was found,with some modification,from a Celestion HF2000。The tweeter is surrounded by a thick felt-strip mounted on the baffle in order to prevent acoustic discontinuity presented by the edge of the cabinet setting up an interference pattern,since the T27 radiating surface is small and the radiator nearly Omni-directional。The addition of the protection grille was wholly beneficial as it raised the output at higher frequencies and help cure the lisp。The effect of the Tygan cover on the front was taken into account in the design,and the loudspeaker should always be used with the grille on,to avoid discontinuities in the upper presence region。



在做了这许多修正之后,分音器也必须要调整,因此以FL6/23取代原来的FL6/16。经过所有这些变动,LS3/5的第一个修正版于焉诞生- --LS3/5A。这最后加上的’A’有其必要,因为尽管LS3/5A的声音近似于LS3/5,其差异却大到无法各取一只配对做立体声聆听。既然只有少量的LS3/5曾被制造,这一改款并未造成太大的问题,只有约20只LS3/5必须停用。

Having carried out these changes,the crossover had to be adjusted to compensate and the new type,FL6/23 replaced the original FL6/16。Sporting these alterations the first variant of the LS3/5 was born - the LS3/5A。The 'A; suffix was necessitated because although the LS3/5A sounded similar to the LS3/5,the differences were significant enough for it not to be possible to use a mixed pair for stereo listening。Since only small quantities of the LS3/5 had been built,this did not present much of a problem and only 20 units had to be considered obsolete。



对那些并不完全熟知它的人而言,此一设计至今可说仍高度维持了当初的样子,除了这些年来一些微小的改进外。这些小改进将后续提及。

For those not fully acquainted with it,the design is still now very much as it was then,with just a few slight enhancements which came about over the years,as will be explained。



在1977年产生了一些明显的问题,而几乎每个夏天,制造者的不良率都会稍稍提高。80年代初期做了一个修正,当时单体悬边的凹陷 (surround-dip)似乎稍微被更动了。解决之道为将负责控制它的分频共振器(crossover resonator)调整到一较低频率并更改制振电阻(damping resistor)。任何一个这类的修正都由BBC发布给当时的制造厂家并并入执照中。当时并对高音单体并联电容(coupling capacitor)的数值做了一些修正,这是整个平衡调整的一部分。当高音单体的材质更动时,它的’Q’值也跟着变动,并在频率响应上产生一个轻微的偏斜(tippling)。此一并联电容影响电路的型态并决定其制振为过度或不足(under or over damped)。为调整高音域的平衡,对FL6/23上一个tapped transformer的输出做了调整,并且改变并联电容以维持其分频点。

There were a few noted difficulties in 1977,and almost every Summer saw the reject rate at the manufacturers rise slightly。The early 1980s saw a change when the surround-dip was seen to have moved slightly。This was resolved when the crossover resonator controlling it was tuned to a lower frequency and the damping resistor changed。Any alteration like this is issued by the BBC to the current manufacturers and is incorporated into their license。There have been also some adjustments to the value of the tweeter coupling capacitor; these are part of the relative balance adjustment。As the material of the tweeter alters,the 'Q' changes and there is a mild 'tippling' of the response。This coupling capacitor affects the shape of the network and decides whether it is under or over damped。To adjust the treble balance,an output from a tapped transformer on the FL6/23 is adjusted,and the coupling capacitor changed to maintain the crossover frequency。



重新评估

Re-assessment



1987 年的重大修改已经在专门杂志中被广泛报导过了,而这次的变动主要却来自于制造厂商的要求。经过这许多年以后,授权厂商之一Rogers的Richard Ross解释道,虽然当时制造LS3/5A使其听起来与测量起来均符合规格是可行的,且可以被接受;但单体符合容许误差的良率却有变动,尤其是低音单体。因为LS3/5A的特殊设计,虽然B110单体符合KEF的规格,刚好却有一种特点,那就是在这种喇叭设计上最关键的部分,此一单体的误差却最不稳定。在炎热的夏天,低音单体的不良率可以从10%到85%。从授权厂商的经济观点而言,这是无法被接受的。

The major re-assessment of 1987 was widely reported in the specialist press; but this time the alterations had been requested primarily by the manufacturers。As one of the licensees,Richard Ross of Rogers,explained,over the years,whilst it had been possible to make an LS3/5A which sounded and measured within spec,and which was acceptable,the number of units,in particular the woofers which were within tolerance varied。Because of the particular design of the LS3/5A,the B100s,although being to KEF's standards,happened to have the point where their tolerance was most variable occurring at the most critical point in the speakers design。In hot summers the reject rate of the bass units could be anything from 10 to 85 per cent,and,for the licensees,this was not satisfactory from an economic standpoint。



在授权厂商发现难以制造品质划一的单元的同时,BBC也有他们自己的问题。在1987年年底,成品品质似乎朝向能被接受的底限飘移。确切的说,它们被发现在 1k Hz附近的八度有2db的隆起,而这正是影响声音平衡的关键地带。之前的LS3/5A在这一频率通常也稍微隆起,但现在它隆起的程度却开始使人不悦。必须要强调的是,它仍然可以在Grade II监听喇叭的要求中运作,但以Grade I的标准而言,就无法被接受。

At the same time as the licensees were finding it difficult to make consistent units,the BBC was encountering their own problems。At the end of 1987 it was noticed that the units were tending to drift towards the limit of acceptability。

Specifically,they were found to be about 2dB up at a octave around 1kHz,a particularly critical area for balance。There had always been a slight lift on the LS3/5A here,but now it started to become objectionable。It should be stressed that the units were still operating within limit for a Grade II monitor,but would have been unacceptable in a Grade I。



这件事的关键又发生在悬边导致的频率凹陷上(surround-dip),它的确切频率随着时间而有数百Hz的飘移。而这又与箱体共振产生牵连,到了必须采取行动的地步。非得做一些变动,使这种喇叭能被制造得可让BBC接受,且品质划一,符合他们所需。

The crux of the matter was again the 'surround-dip',the precise frequency of which varies by a few hundred Hertz over time。This had become interactive with the box resonance to the extent that action was needed。A change had to be brought about so that speakers could be manufactured which the BBC would find acceptable,to provide them with a consistent loudspeaker they designed,and wanted。



BBC将这件事知会KEF,而KEF派其”特殊产品部门”(Special Products Division)来做因应。此一问题被追本溯源,发现SP1003 B110所使用的二稀橡胶Neoprene缺乏一致性,为此,一款新的B110因应LS3/5A而设计出来。这次使用一种PVC的悬边,其材质一致性较高,且对温度变化较稳定,但是顺服度较低。因此一个种新的蛛网状音圈(spider voice-coil)构造就被用来使这种新单体保持与旧单体一样的灵敏度,以获致相同的低频表现。这就是B110 SP1228单体。分频器设计通常是一个争论不休的领域,这当然也发生在LS3/5A上。几经修改,正如报导所言,但这种喇叭的主要规格与整体声音平衡却维持不变。

The BBC referred the matter to KEF,who set their Special Products Division to work。The problem was traced to variations in the consistency of the Neoprene used in the making of the SP1003 B110 and so a new B110 was specifically designed for the LS3/5A。This uses a PVC surround,more consistent and temperature stable than the Neoprene but less compliant。A new spider voice-coil assembly was therefore required to give the new drive the same sensitivity as the older one,in order to achieve the bass performance。This is the B110 SP1228。Crossover design is always a source of great debate and this has certainly been the case with the LS3/5A。Changes have been made,as reported,but the main specification and overall sound balance of the speaker have remained the same。





分频器

Crossover



关于这个主题,与LS3/5A有关的事足以写成一本书。它的复杂性显现在它的电路图中。L1与R1被用来等化轴线上的响应突起与低音单体的频率特性。而 C5,L2与R2这组则用来补偿另一个响应凹陷。针对高音单体,L3的作用为一分流指示器(shunt inductor)与自耦变压器(autotransformer),以便区别灵敏度的等级。C2是用以调整保持分频点的衡定,而R3则用来避免铃振 (ringing),并同R4与C6以调整高频端的频率响应。

A book could be written on this subject as far as the LS3/5A is concerned。The complexity is indicated in the circuit diagram。L1 and R1 are employed to equalize the rising axial response and frequency characteristic of the bass unit,while the group C5,L2,and R2 compensate for a hump in this characteristic。For the tweeter,L3 acts as a shunt inductor and as an autotransformer to allow for differing levels of sensitivity。C2 is adjusted to keep the crossover frequency constant and R3 is there to prevent ringing,with R4 and C6 to adjust the frequency response at the upper end。



SP1228 低音单体较先前的B110有着较平顺的响应,也因此需要较温和的分频等化。于是当时决定:分频器不能单只是重新设计,以补偿驱动单体的改变,而应将新技术也整合进来。基本上这个等化装置(equalization)与先前相当近似,其线路看起来也差不多。之前的设计使用前面提及的自耦变压器作为高通滤波器的一部分,且用来以1db为单位调整高音单体的音压。但是当高音单体的灵敏度越来越稳定(误差在0。5db以内)时,设计者发现可以改用一个较简单的衡定阻抗衰减器(constant impedance resistive attenuator),在+/-1db的范围内以每段0。5db的方式作调整。这个较简单的等化器(equalization)所带来的效应之一,就是整体阻抗由原来的正常15欧姆变为现在的11欧姆。

The SP1228 has a considerably smoother response than the older-type B110,and hence needs gentler crossover equalization。It was decided therefore that the crossover could not only be re-designed to compensate for the change to the drive unit,but could also incorporate new technology。In essence the equalization is very much the same with a similar looking circuit。The earlier design used the already mentioned taped auto-transformer as part of the high-pass filter and to adjust the level of the tweeter in 1dB steps,but it was noticed that as the tweeter sensitivity was becoming increasingly consistent (to within 0。5dB),a simpler constant impedance resistive attenuator could be used to give the +/-1dB of adjustment in 0。5dB steps。One consequence of the simpler equalization is that the overall impedance has been reduced from the previous 15ohm nominal to now 11ohm nominal。



KEF从整个响应频段分析了组件的误差值后,发现在最关键的一些地方缩小误差的容许值,可以改进其一致性。先前的喇叭单元相互间可能有2db的差异。举例而言,如果分频网路在关键频段为+1db,与之组合的喇叭单体也是+1db,二者就会加成为+ 2db。KEF于是决定采用电脑辅助配对,以利在一般情况下选取组件,使得若分频网路为+1db时,喇叭单体为-1db,最终得到0db的整体效果。这一新的分频器为FL6/38,SP2128/。

KEF analyzed the effect of component tolerances on the overall response and found that by tightening these in the most critical areas an improvement in consistency could be achieved。In previous units it had been possible to obtain a 2dB variation。For example,if the network was +1dB in the critical area and the accompanying drive unit was also +1dB the two compounded。KEF decided that by opting for computer-aided matching,it was possible to nominally select components so that if the network was +1dB a drive unit with a -1DB figure would be chosen to give 0dB overall change。The new crossover is the FL6/38,SP2128/



因此,KEF得以提供配对的组件给制造厂家,虽然该公司自己并不完整组装这种喇叭。目前所有三家授权厂家都使用KEF的配对组件。归根结底,我们必须要说KEF做得实在很好!BBC交付给他们一只1975年制造的LS3/5A参考标准单元No。6,而他们在1988年制造出的组件与之听起来如此接近,甚至符合Grade 1的标准,且能在品质更为稳定的状况下生产。因此LS3/5A的编号就被保留下来。

Therefore KEF was able to offer matched components to the manufacturing licensees even though the company does not manufacture the speaker in its entirety themselves。It so happens that all three current licensees use the KEF matched parts。At the end of a day it has to be said that KEF did a superb job。They were issued with a BBC LS3/5A reference unit (no。6) of 1975 vintage and produced a set of 1988 parts which sounded so similar that they were within Grade I limits,and could be made much more consistently。Hence LS3/5A remains。



Spendor过去都完全自行制造分频器组件,他们表示如果情况需要,同样能自行生产。他们现在使用铁粉电感(勿与纯铁ferrite搞混),且被准许不使用先前的矽-铁E & I绕线电感(E & I transformer winding)。E & I绕线(laminates)较为昂贵,因此他们也没放过向KEF购买配对组件的机会。

Spendor used to make their own complete crossover units and say that they could start again if they situation called for it。

They have now adopted the iron-dust inductors,not to be confused with ferrite,and have dispensed with their previous silicon-iron E & I transformer winding。The E & I laminates tend to be more costly,and the opportunity to buy the matched KEF sets was taken。



Rogers 多年来都使用各种纯铁与铁粉电感,因为他们的研究显示:鉴于在变换器(transformers)中微小的缝隙却有着高磁场束,而在纯铁 (ferrite)中有较大的空隙与许多磁性物质,因此与无线金属(radio metal)或单向结晶钢条(grain-orientated strip steel)比起来,这么做较经济,且有较佳的磁饱和品质。虽然绕径较多,且直流阻抗稍微增加,磁饱和的特性却相当的增强了。Rogers认为以现代的分频技术,与其制造一个有缝隙的无线金属扼流圈(radio metal choke),不如较单纯的制造一个有2%至3%误差的铁粉磁心电感。部分原因是因为这一设计很复杂,而任何可以使事情简化的机会都不容错过。

Rogers had for years used various ferrite and iron-dust cores,because their research showed that they were more economical and gave superior saturation qualities compared with the radio metal or grain-orientated strip steel,given that in the transformers there are quite small gaps with quite high fluxes,whereas in the ferrite’s there are big air gaps and a lot of magnetic material。Although there are probably a few more turns and the DC resistance rises slightly,the saturation properties are considerably enhanced。Rogers decided that with modern crossover techniques,it was simpler to make a 2 or 3% tolerance iron-dust core inductors than to make a gapped radio metal choke。This is partly because the design is complicated and any opportunity to make things less so should not be avoided。



就长期而言,也许BBC将这种喇叭的设计完全重新来过,还来得单纯些,可以命名为LS3/5B。但是他们不但不想,也没法承受这种替选方案,因为他们在全国各角落大约有三千五百只这种喇叭在使用中。而改变后的设计,又得保有与现有设计相近的声音,与相同的频率响应,因为未来的型号很可能与现役机种并肩使用。即便在今日,当一批喇叭被运到工作场所,他们是否出自同一代并不重要----它们都必须能被配对做立体声聆听。基本上这就是整个设计的目的,无论何时何地,在整个节目制作过程与使用中能保持一致性。总而言之,最近的修改并没有改进其规格,只是为了要在制造过程中提供较好的一致性,以维持这种喇叭的标准。此一标准现在回归到中性(median),所以听起来会与1987年耶诞节前最后制造的前一代产品有点不同,但是将会与更早的制品听起来一样。

It would perhaps have been simpler in the long term for the BBC to have completely re-designed the speaker,and to have produced a LS3/5B,but they did not want nor could they afford this option,since some three and a half thousand of the existing design were in use up and down the country。And design change had to produce similar results and the same response because future models would end up alongside existing ones。Even today,when a batch is taken to a location,it does not matter whether some are from one generation and some from another - they should all be capable of matching as stereo pairs。That in essence is the whole purpose of the design,consistency through production and during use,anywhere。To sum up,then,the recent changes have offered no enhancements in terms of specification,simply a means to provide better consistency in production to maintain the speaker's standard。This is now back on 'median' and so may sound a little different from those latter 'older models' of just pre-Christmas 1987,but will sound the same as earlier production runs。



在修改之后,阻抗稍微的有改变 --这可以由图中的模式看出来,它反映出Rogers的两种标准模式。当原本的阻抗为正常值15欧姆,新型号的正常值则接近11欧姆。检视列线图表 (nomograph),我们可以看到旧款的阻抗在15欧姆,它使用了旧的等化器与旧的低音单体,这单体的阻抗大约是7欧姆。新的低音单体有较低的直流阻抗,但是在配上新的等化器后,二者的曲线形状非常相近,尽管现在的平均数值较接近11欧姆。这仍旧意味着LS3/5A是由电压而非电流所驱动,因此扩大机要能有撼动电压的劲道(swing volts),并且有适当的输出功率,但不能是低输出阻抗者。

The impedance has altered slightly post modifications - this can be seen by the modulus shown,reflecting the Rogers' two standard models。Whereas the original was a nominal 15ohms the newer model is nearer to a nominal 11ohms。Looking at the nomograph,we can see the original as 15ohms,using the old equalizer and with the old bass unit which had about a 7ohm resistance。The new bass unit has a lower DC resistance but,with the new equalizer,the curves are very similar in shape,although the average level is now more like 11ohms。This still means that the LS3/5A is voltage rather than current driven and needs an amplifier that will swing volts and produces reasonable power levels,but not into low impedances。



因此,1977/78年制造的LS3/5A,将不在任何方面比1983年或现在生产的较好或较差。多数对平衡有所了解的人,认为这个系统与先前一样,而且在声音特性上提供与前相同的品质。

So an LS3/5A circa1977/78 will not in any particular way be better or worse than one from 1983 or now。The consensus of opinion from those who understand balance,is that the system is the same and offers the same qualities as it always has in terms of its tonal characteristics。



进一步说,近期的制品可说更为平顺,因为高音的不平坦已经被去除掉了;而在使用新的悬边之后,染色也被稍为减低,却还不至于影响音调的平衡,因为对某一特定频段染色的察觉,其实关系到整个喇叭系统的平衡与等化。因此,比如说在1k Hz附近的音调染色若被减低到某一可查觉的程度,可能会因而强调出其他频段的染色。

In detail,the latest models are now marginally smoother because irregularities of the high treble have been sorted out,and the coloration has been reduced by a small degree with the new surround,but not so as to affect the tonal balance,because the perception of localized coloration is all part of the balance of the loudspeaker system and its equalization。So if the tonal coloration was reduced to an extent in,say,the 1kHz region where it was noticeable,it could highlight colorations elsewhere。



在真实的情况中,此一新的设计提供了较好的一致性,由KEF掌控以维持其标准。在规格上没有任何改进,但评论员们认为现在声音较前好些,因为它回归到中性。基本上它发出与前相同的声音。这一论点有BBC的实际测试做后盾,并伴随制造厂家对此一组件立体声能力的认可。

The new design offers only,in real terms,a better consistency,executed by KEF to maintain the standard。No enhancement in terms of the specification was made although commentators say the loudspeaker now sounds a little better because it is back on the median。Essentially it produces the same sound。This has been backed by tests carried out at the BBC and with manufacturers,with regard to the unit’s stereo capability。



从发出第一张执照至今,据估计总共约有六万对LS3/5A被制造出来,所以它能赢得举世注目倒也并不奇怪。在BBC这种喇叭备用来作各种用途,从一个人的OB,到几年前在Promenade演奏会中的实验性四轨传送中用来做控制与平衡,或在BBC 的地方电台提供主要的小房间监听。即使如此,此一设计也有它的缺点,例如它的分频器中要用到既被动又复杂的等化线路,以补偿因箱体与振膜太小所导致的低频损失。

The total number of LS3/5As made since the first license was granted is estimated to be around 60,000 pairs so it is not surprising that a huge interest has been generated around the world。In the BBC the speaker has found many uses from the one-man OB to the control and balance of experimental quadraphonic transmissions from the Promenade Concerts several years ago and in BBC Local Radio Stations,the design provides the main cubicle monitoring。Even so,the design has its fallbacks like the passive and complicated equalizer in the crossover to restore the loss of low frequency caused by the cabinet size and limited cone area。





授权厂家 Licensees



这种喇叭的历史,与获得授权制造它的厂家有着有趣的关联。

在BBC设在Chiswick的器材部门(Equipment Department)自行制作了最早一批产品之后,他们核准几家公司在特许下依合约制造,

The very history of the speaker has interesting connections with licensees who have been permitted to manufacture them。

After early production runs at the BBC's own Equipment Department in Chiswick,the Corporation permitted a number of companies to apply to produce the speakers under license,as it is obliged to do under its Charter。



执照收费被用来补贴当初开发的花费,而非仅是一种以大量生产降低单位成本的手段,而该笔款项由工程部 (Director of Engineering)而非BBC企业接收,因为BBC企业有其他由出版与录音等所得的商业收益。目前有四家厂商有生产执照,但实际上只有两家在生产。当初任职于BBC研究部门,且参与LS3/5A规划的H。D。Harwood所创办的Harbeth,与Rogers,Spendor,Goodmans 等厂家都获权制造。Goodmans实际上已经停止制造,且未在合约到期时重新申请,而Harbeth则尚未开始制造。

The license fee is a means of recouping the original development cost,not purely a way of cutting unit costs by mass-production,and the money is recovered by the Director of Engineering and not BBC Enterprises,the commercial arm of 'Auntie' which has taken over other money making areas like publications and records。Recently as many as four companies had licenses although in essence only two actually had a production line at that time。This situation came about when Harbeth,formed by HD Harwoodd who was working on the LS3/5A at BBC Research Department,was granted a license while Rogers。Spendor and Goodmans were also permitted to manufacture。Goodmans in fact had ceased production and did not re-apply for their license when the renewal time came,and Harbeth had yet to start making any。



另一家授权厂商Spendor,由晚年的Spencer Hughes与当初同在BBC工作的Dudley Harwood合组。他们最初并未申请执照。当时该公司处在工作满档的状况,但是在后续出现生产空档时,他们也加入申请,因为实际上Mr。Hughes非常了解这个设计与要注意的所有相关事项。

Another licensee manufacturer,Spendor,founded by the late Spencer Hughes who had worked with Dudley Harwood at the BBC,did not apply for a license at the first opportunity。The company was then already working to full capacity,but when a 'vacancy' next arose it did apply,encouraged by the fact that Mr。Hughes knew the design and all that would be entailed by association with it。



Rogers几乎从一开始就参与,并且目前拥有Chartwell品牌。Chartwell当初也是被授权制造LS3/5A的厂家之一。 Rogers的母公司Swisstone在1975与Rogers合并之后,在1978年又并购了Chartwell 这家先前的竞争品牌。Rogers随着大量市场需求而生产,在1979年宣告他们卖出了第一万对LS3/5A,并且宣称这是世界上最成功的小喇叭。而到目前为止,Rogers共卖出了33,534对。

Rogers were involved almost from the start and now own the Chartwell brand,a company who also previously licensed to make the LS3/5As。The parent company,Swisstone,acquired the defunct Chartwell,a previous competitor,in 1978 having merged with Rogers in 1975。Manufacturing to quantity demands,in 1979 Rogers announced that it had sold its ten thousandth pair and proclaimed LS3/5A the worlds most successful small loudspeaker。With the Rogers total to date standing at 33,534 pairs。



Harbeth是最后获得授权的厂家,目前由Alan Shaw经营。在所制造的第一批样品通过BBC验证后,目前已可合格的正式生产。他们所生产的是经过电脑辅助测试的版本。

每家厂商都要通过开始制造时的抽样程序,使BBC确保喇叭的制造正确无误。授权厂商由最初制品中挑选出两只送交BBC。其中一只由BBC保存以做为该厂家之工作参考标准,另一只则被调校到符合BBC自己的参考标准,该参考标准喇叭出自BBC最初自行制造的一批。这第二只喇叭将会送还给制造厂,变成该厂随后所有制品的参考比较标准。

The latest company to be permitted to manufacture is Harbeth,now under the control of Alan Shaw。They had samples from their first batch passed by the BBC and are now eligible for full production; all are of the computer-optimized type。

This initial sampling process,a condition of all licensees,is to assure the BBC that their speakers are being made correctly。The licensee selects two units from the initial batch to send to the BBC。One of these is kept by the Corporation as that licensee's working reference,while the other is tweaked so that it matches the BBC's own reference,a unit from the very first in-house batch。This second speaker is then returned to the licensee and becomes the reference for all their subsequent units to be compared with。



较早被BBC授权的一些厂家则没有那么顺利。一般认为LS3/5A并不是一项容易做的产品,且必须配合合宜的行销。一些品牌会半路消失,正因为他们发现市场并不如预期中大;有的厂家则发现要达到BBC的严谨要求太困难。而这也可能是因为人们对要价250英镑的喇叭有更高的期望,如果没有正确的市场行销,要卖出去很困难。

Earlier companies to have been licensed by the BBC have not fared as well。It is agreed that the LS3/5A is not an easy product to make properly and must be marketed correctly。Some names have fallen by the wayside because they found the market was not as large as they forecast,and some found it too difficult to make to the BBC's tight tolerances。These problems could be because people expect more than they see for a ?250 loudspeaker,and that without the correct marketing,sales are just not realized。



像Audiomaster 这种品牌,在1976年4月开始他们的生产,只维持了短短的时间;而RAM牌的则从未面市:它们都在生产线完成前破产了。帮Goodmans制造分音器的 Falcon,曾为情况不妙的RAM制造了一批,却发现他们得自负盈亏,因为RAM根本没有立场付他们钱。JPW也曾有过一些动作,但从未具体化。

BBC对授权厂商产品的检验持续进行,而一些”见不得人的事”(nasties)也被发掘出来。其中一个例个子是:一只送来检验的喇叭有着比正常为厚的金属罩材质,造成了两个八度音程有1 1/2db的响应凹陷。不用说这只喇叭很快就被退还了!

Names like Audiomaster,who launched their models in April 1976,had a rather short lived license span while RAM never got any units out on the street:they went bankrupt before the production line got underway。Falcon,who were making crossovers for Goodmans,made a batch for ailing RAM company and then found themselves having to distribute the boards directly because RAM were not in any position to pay for them。A flurry of activity was seen from JPW but no quantities to speak of ever materialized。Constant checking of the licensees production is carried out,and there are some tales of 'nasties' being found。There's the case of a unit coming in for evaluation with a thicker than usual grille material causing a two-octave 1 1/2dB dip。Needless to say it was swiftly returned。



在目前的三家制造厂商中,Spendor表示虽然部分卖到英国,却有80%的产量是供外销用的,主要是欧洲,美国与远东地区,包括日本与台湾。 Rogers也外销到日本,欧洲,北美,香港与新加坡,而他们卖到日本的数量甚至超过英国; 在英国当地,除了一部分提供给BBC,经由hi-fi零售店卖出的也不少。尽管其他设计有着许多优点,LS3/5A在它的等级中始终维持着参考标准扬声器的地位。

Of the three current manufacturers,Spendor says that although a percentage of their production line ends up in the UK,80% of their sales are to the export trade,the areas being mainly Europe,the USA,and the Far East,including Japan and Taiwan。Rogers also export to Japan,Europe,North America,Hong Kong and Singapore,with more sales to Japan than to the United Kingdom even,where,while a quantity go to the BBC,the hi-fi retail outlets get through a fair volume too。Despite the advances of other designs,the LS3/5A remains a reference standard loudspeaker in its class。



谢词 Acknowledgements



我受助于BBC工程部以确保本文的正确性。在BBC中,T。Somerville与D。E。L。Shorter两位公认为现有的标准树立了基础。而 LS3/5A的研发则仰赖研究部门的Messrs H。D。Harwood 与设计部门的M。E。Whatton与R。W。Mills两位先生。我们对Whatton先生最近过世深表惋惜。

I am indebted to BBC Engineering for ensuring the accuracy of this article。Within the BBC the work of two people,T Somerville and D E L Shorter,must be considered as having laid the foundation for current standards。The particular work on the LS3/5A was carried out by Messrs H D Harwood of Research Department and both M E Whatton and R W Mills of Designs Department。It was with deep regret that we learned of the recent death of Mr。Whatton。


5881a 2007-08-07 11:03
ding--xia !

stanley 2007-08-09 13:43
好文,再up

xntglin 2007-08-10 16:28
好文


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