LS3/5a - Hi-Fi Choice Review

Please note: This review was written by Martin Colloms and appeared in the 1986/87 Hi-Fi Choice Loudspeaker Yearbook. Please be aware that I haven't been able to contact the holders of the original copyright. If you are the owner of the original copyright, please contact me, and if necessary, I'll remove it from this site.

Three manufacturers are currently licensed by the BBC to produce LS3/5as, and all must stick to the Corporation's tight specifications. Designed as a miniature broadcast monitor for cramped spaces, by offering a fine sound quality in its own right it has stood up to much larger competition for more than 10 years. Mounting on high stands well clear of room walls at approximately ear level provides best results.

A sealed plywood box of 5.5 litres volume, the 3/5A is a two way system employing selected KEF drivers, a 110mm Bextrene cone bass/midrange and a 19mm plastic dome treble unit. An elaborate and costly crossover is employed to equalise the drivers to a strict specification.

Sound Quality

The LS3/5a has consistently done well in previous live-versus-recorded sessions and fairly well on analogue-programme sources. However, with digital material, problems which were only hinted by analogue material were now clearly apparent, making the design sound more dated. Several areas attracted criticism - the bass lacked extension and sounded 'boomy' in the upper bass register, while the mid had a noticeably 'hard', 'nasal' quality and the treble seemed forward with a grainy, 'zitty' effect at the extreme top end. Some 'tubby', wooden and boxy colorations were also evident, with only moderate rendition of stereo depth.

However, it continued however to provide good voice detail and articulation, with a reasonably accurate tonal balance. Comparison between the Goodmans and Spendor versions showed great similarity while a much older model from Audiomaster (no longer in production) sounded slightly dimmer by comparison, with less mid nasality. However the difference was small by speaker standards.

Lab report

Sensitivity was low, measuring 81.5dB/W and necessitating a minimum amplifier power of 30W per channel. A 50W maximum is suggested although with care 100W amps may be used. The bass rolloff -6dB point measured 57Hz, quite good for the size, while pair matching was very good (all three current makes). The impedance curve never dipped below 7.5 ohms, so the design qualifies as an easy 10 ohm load. Modest 96dBA maximum sound levels are possible.

Reference curves were taken for the Goodmans and Spendor samples and showed good agreement with the reference unit, though the 1.2kHz prominence seems to have become more pronounced over the years. This perhaps reflects a change in the B110, although it is still within specification. By modern standards the response looks a trifle lumpy, though in its time this system was regarded as a very smooth performer.

Conclusion

At risk of offending the BBC, we feel that the 3/5A is due for a revision; as a working broadcast tool it no-doubt does its job, but as a piece of value engineering it is beginning to fall behind. Other speakers have shown a progressive reduction in price as well as an improvement in sound quality, but the LS3/5a has steadily increased in price more or less in line with inflation. Nevertheless, on the most recent listening test the LS3/5a scores were sufficient to retain recommendation!

First reviewed: Rogers 1978, Goodmans and Spendor, 1983 (retested 1984, reassessed 1985/6). Current typical price £220.

GENERAL DATA

   Size (h x w x d)..............................30 x 18.5 x 16cm
   Weight...................................................5.5Kg
   Recommended amplifier power per channel
      (for 96dBA per pair at 2 metres minimum)..........30 to 50W
   Recommended placement....................high stand (or shelf)
   Frequency response within ± 3dB (2m).............90Hz to 20KHz
   Low frequency rolloff (-6dB) at 1m........................59Hz
   Voltage sensitivity
      (ref 2.83V, ie: 1 watt in 8 ohms) at 1m............82.5dB/W
   Approximate maximum sound level (pair at 2m).............93dBA
   Third harmonic distortion (90dB at 1 metre)..........very good
   Impedance characteristic (ease of drive).............very good
   Forward response uniformity..........................very good
   Typical price per pair inc VAT............................£220
  

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