It was a blue light version with blue and white graphics. It was the MF review sample which Alvin Gold (I think it was him) declared as the best p[ower amp in the world. Its rails had been hoiked to 68V. I’m not sure what the production setting was but Tim sent me his hand drawn schematic for it and that says 60V. It used 63V capacitors so one would usually expect the rails to be about that value - not that I expect a 5V breach was doing that much harm.
I’ve seen pics of the internals of other A370s that looked very different. I don’t think the PCBs would have been changed, just the power supply lumps in the middle. I wouldn’t describe any of them as a model of assembly, with the input capacitors dangling on wires and the inrush current resistors hanging in mid-air too, in spite of there being tapped holes for them on the back surface. These things don’t make much of a difference individually, but something that Naim seems to understand is that regimented assembly makes things consistent! It almost doesn’t matter whether you’ve got the perfect layout, just that it’s repeated identically and you don’t have a dozen random variables on the loose - one day popping up and untraceably changing the sound.
The swept volume of the bass unit essentially sets the peak output the speaker is capable of, so you would expect size to be an important factor - and indeed it is. There is an immutable relationship between bass extension, cabinet volume and sensitivity. You can have extension in a small cabinet but you’ll have low sensitivity and if you want high sensitivity then you’ll have to sacrifice bass extension; which is what your example does and what we got years ago with the Wharfedale E Series.
Although this is essentially set by the maximum excursion and the area of the bass driver(s) it is complicated by the shape of the bass rolloff and, in hi fi at least, there are only so many shapes that are considered reasonable - all of them largely approximating to something flat prior to the bass rolloff. When looking at peak output, the design process for drivers above this is to ensure that they don’t artificially limit the peak level. Though you’d generally have to be pretty crass to manage this, 19mm tweeters in some systems might well be getting close if crossed over low enough.
Viewed a bit less technically, the louder your system is to go, the larger area bass unit you’ll need. If we’re comparing apples with apples, that will generally translate into larger cabinets (else the Q will go too high or the port alignment will be out) so you would expect any speaker capable of high spls to be physically large, if not very large. As an example, Andrew Jones’s TAD Reference Ones are half a meter wide, 1.3m high and 0.7m deep. The two 10" bass units have pk-pk linear excursions of 30mm (essentially 10x what you can get from a B139 in an Isobarik) and they only claim a peak level of 115dB. Trying to achieve that with more normal bass units (even exceptional ones) would result in an even more monstrously sized cabinet with perhaps 4 drivers, probably of an even larger size.
I’m afraid size and peak output are very much related.
I didn’t suggest otherwise, though it is not a simple direct relationship as it also depends on driver design (to which you also allude in your post), and on cabinet design principles, so one speaker of a given size can be more efficient than another with the same frequency response. (Speaker design is something in which I have great interest and first studied before embarking on my hifi journey, many years ago). Add to that the fact that people have speakers with very different degrees of bass extension, and you cone back to my point that size per se is no indication of efficiency (sensitivity). And then we have no idea how close to the speakers the individual mentioning 110dB listens. These are the reasons for my original picking up of your question about size…
NIOSH and Decibel X give exactly the same reults on my iPhone.
In Holland the use of hearing protection is mandatory for employees from 85 dB(A)
Seems a good reference for the start of the danger zone.
N.B that I assume is average not peak level, and is not unique to Holland, sounds up to 85db(A) average not being subject to statutory control.
Peak levels may be well above that, the statutory limit being 137dB(C) - something highly unlikely to be encountered in a domestic hifi system, e.g. listening at 2 metres from a pair of very efficient 100dB/W sensitivity speakers would require over 2KW peak amplifier power.
You can listen to sounds at 70 dBA or lower for as long as you want. Sounds at 85 dBA can lead to hearing loss if you listen to them for more than 8 hours at a time. Sounds over 85 dBa can damage your hearing faster. The safe listening time is cut in half for every 3-dB rise in noise levels over 85 dBA.
As a lover of small ‘bookshelf’ speakers, I’ve always found that at a certain volume level things just ‘come to life’. I usually turn it up in search of dynamics - especially on tracks that on listening on ‘normal’ systems from my youth such as my old Sony Discmans and CD Walkmans that I know well sound light (Metallica’s black album for instance).
I’ve actually just taken my NDX2 out of my system and am currently experimenting using an Classé CP-800 preamp USB from an Intel NUC running Roon Core. Definitely more insight with system in this configuration. I have a unique set of Bowers & Wilkins 805 D2 Maserati edition sourced from a friend which I absolutely adore, combined with an old Ruark CL300 sub. Turn it past a certain level and there is an energy and presence which is lacking otherwise.