BBC monitors and replay loudness
I think that was a general observation at the time.
Originally Posted by DSRANCE
What nobody really appreciated (or even wanted to believe) was that they were criticising the BC1 rather harshly for what was in actuality a design feature. The first question to ask of a speaker design is 'what is the target listening loudness?'. If the answer is that it is designed to be used in studio control rooms at a replay loudness rather lower than the studio staff would like because of general commotion in the studio and/or the close proximity of other studios and worries over bleed-through of noise from one to another, then it's a legitimate design decision to lift the bass end output of the speaker. That's because our ears perceive bass strongly correlated to loudness: if the loudness drops even a little, the bass subjectively diminishes rather more.
Take that same speaker, optimised for 75-80dB studio monitoring and place it in the untreated home listening environment, set the listener to 2 -3m away from it (rather than in the relative near field), connect it to an powerful amplifier, turn up the replay volume to 90-110dB and you have a recipe for boom and excessive warmth. What do you expect?
Re: BC2 .... that had a 1.5" voice coil hence more power handling than the 1" BC1 to pander to those home users determined to use the speaker at higher spls. But it was said that what the 1.5" voice coil gained in power handling it lost in midrange quality.
Unsure what questions to ask when considering new loudspeakers? No chance of a demo in your own home? Then ask the above question and it will give you a good starting point about the suitability of the loudspeaker for your needs. There is, of course, no perfect speaker, but a match between your listening loudness requirements (e.g. late at night, easily irritated neighbours) and the speaker design philosophy is the correct starting point.
As a class, the 'BBC monitor' is designed to sound full bodied and natural at a lower listening level than most other speakers due to it's application heritage. If you see pictures of speaker brands proudly boasting their rock and roll application or heritage against a backdrop of a huge studio and whaling guitars, avoid them like the plague. That implies that they have been optimised for high replay levels >>> 100dB and will sound gutless and bass light at home at a normal loudness. The ear has to be given a little assistance because none of use replay at home at anything like full concert loudness. This has been known for the best part of 100 years and you can read about ISO226 here.
ISO226: see the upward tipping curves in the low frequencies? See that the are not parallel to each other? See that at the threshold of hearing (bottom red line) for 20Hz to sound as equally loud as 1kHz (the pivot point) there needs to be a massive boost of about 60dB? It's the difference between those curves that (ideally) needs to be considered to make a transistor radio sound like a full orchestra .....
Alan A. Shaw
Harbeth Audio UK