NVA's Overall Philosophy
Generally, we have never been keen on producing conventional literature, because it's usually just glossy expensive paper full of pretty meaningless specifications which have little bearing on how good the sound of audio equipment is when playing music. If you buy hi-fi equipment on the basis of what a manufacturer says about himself (including us!) you really do deserve what you get.
As an alternative, one of our dealers suggested that we try to explain good design and how to recognize it. People probably won't believe this, but really the basics are very straightforward. A famous British amplifier designer is supposed to have said, "Good amplifier design is not the things that you do right, but the things you don't do wrong". I really wish I had said it first, because it's amplifier design in a nutshell. You can come up with all the new circuit configurations under the sun such as feed forward, low feedback, class A to Z, but ignore the common sense ground rules, and you will have a sonic bag-of-nails capable of being blown away by a couple of EL34's in a 1950 Williamson tube circuit. I am afraid 80% of the amplifiers built today fall into this category. The thing that never stops amazing me is that so many audiophiles keep falling for it. There is nothing like a good story to have people hocking the next three years' spare income on the latest all-singing, all-dancing creation. Not only that, a good story sells magazines as well, which just exacerbates the problem.
Here are my ground rules:
After that it is all down to experience, and fine-tuning the design to your own taste. It is easier to get a half-way decent sounding amp using Vacuum State Logic (warm glass bottles) than Solid State Logic (hopefully cool lumps of plastic) because there is less to do wrong (Neanderthal Logic). That is why so many people have jumped on the valve bandwagon. All things being equal, bits of doped silicon encapsulated in metal or plastic (transistors) potentially are capable of doing more things with music, i.e. wider (frequency), larger (amplitude), cleaner (distortion and noise) for less cost. Remember though, the more you try to do, the exponentially easier it is to do it wrong.
If you can get most of it right, then think very carefully before you try to get the very last bit, because you may be too clever and ruin everything you've gained thus far.
This explanation is all very simplistic of course, and common sense and experience must apply as well. For example, a Class A circuit is a lot simpler that the equivalent Class B or AB. Ergo, applying my logic it should be better. Wrong, unless you spend a fortune on the power supply, which then makes the amplifier grotesquely expensive and heavy. The problems of current demand by the amplifier outweigh the simplicity. If I could buy 1000VA transformers not larger than 4" square, and weighing less than two pounds for £10, and if I could get good and consistent output transistors (i.e. not FETs) that could sink 20 amps, and either, not get hotter than 70 degrees C doing so, or stand 150 degrees C without going into self-destruct mode, I would produce Class A amplifiers. I will not produce them just because they have become some reviewers latest buzz word.
Every amplifier has its own sonic character, which is very much down to the musical parameters that are most important to the designer. The process is very much "lose on the swings, gain on the roundabouts". I once knew an amplifier designer, in fact I employed him back in Tresham Audio days to produce a professional FET power amplifier, who saw no necessity for listening to the amplifier at all. It was only after he left, and some ears were applied to the design that it started to sing, not as much as the best hi-fi amplifiers, but it went very loud and was virtually indestructible.
My greatest hang-up is information retrieval - musical information, especially dynamic separation. I will always go for information even at the expense of upsetting the "make everything bounce and swing with the tempo" brigade. My other priority, which seems to be out of favour at the moment, is neutrality, or as I prefer to call it, lack of the irritation factor.
Richard Dunn, Founder and Owner, NVA
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