Want to know about valve amps? Well here it is...
Ian, it's all a learning curve, mate! :lolsign:
For me a *good* valve amp (and I mean GOOD, as there's a fair bit of shit out there that I wouldn't entertain giving the 'side' a bad name) sounds much more like real music than any solid-state amp I've heard so far. That last rider is very important, as there could be some sand amps out there which are as good as the Copper valve amp I use, or even better. Experience suggests not, but I'm not so closed minded as to rule out the possibility.
In my experience, a good (completely hard-wired) valve amp sounds more like real music because designs facilitate a simpler signal path, i.e. there are less components in the circuit to influence or 'colour' the signal and add a 'signature' - and if the circuit is 'right' in the first place, then that is always a good thing. I'm not saying that even the best valve amps are completely neutral sounding, of course not, but in my experience (to date), the musical presentation of a valve amp when done well is more faithful to the sound of real music than what is capable from its solid-state counterpart. As ever, though, I'm up for being proven wrong!
Simplicity of the signal path is one of the reasons why SET amps can (and often do) sound sweeter and 'purer' than push-pull designs, although as ever in hi-fi, that's not the end of the story! There are many SET amps I've heard which I admire but none so far that I could live with, particularly considering the hugely varied styles of music I like to listen to, and sometimes at considerable volume! The K.I.S.S (keep it simple, stupid) principle is though without doubt the best approach when designing equipment of any nature, provided that it is accompanied with the use of the highest quality components most suited for a specific application, within the correct implementation of a particular circuit. This is usually a recipe for success. For me, good KT88 P/P designs do it best.
Often some expensive, supposedly 'high-end' valve amps are the victim of their overly complicated circuits (too much stuff in the way of the signal path) and the use of unnecessarily expensive 'bespoke' components which can when used wrongly do more harm than good. Unfortunately, in order to justify their (sometimes) ludicrously high price tags to appeal to brand-conscious 'badge snobs', some 'high-end' valve amps must be seen to be packed full of the most expensive components available and housed in the most elaborate cases, even if in many instances they're simply 'over the top' and unnecessary; the results in the process often being little more than statements of 'audiophile jewellery'.
Building a good valve amp is about getting the circuit right, keeping it as simple as possible, and using the best components for their correct application - *and* (and this is a big one) using the biggest (in terms of specification), highest quality mains and output transformers you can find to fit the case intended for use.
Quite simply, in terms of influencing the signal and reducing noise, transformers can never be too big! The power supply is the single most important area of ANY piece of equipment, and no more so than in a valve amp. It is my opinion that the criticism often directed at valve amps being 'soft' in the bass or not giving music 'pace, rhythm and timing (PRAT)', compared to the best solid-state amps, is because the transformers used aren't up to the job and are simply not good enough. It may not be that simple in some cases (over-complicated circuits are also a factor), but it's almost certainly at the root cause of the problem. OTL designs seek to solve the problem by not using any transformers, but they too impose their own compromises.
I am completely convinced that anyone who says that valve amps miss so much musical information or don't 'boogie', or any other nonsense like that I've heard from certain people, say so because they simply haven't heard a really good one! You know who you are ;)
The solid-state amps that I've heard *so far* and used in the 25+ years I've been into high-end hi-fi, at prices ranging from a few hundred pounds to many thousands of pounds, when compared to the TD push-pull Copper amp I'm currently using, sound 'grey', flat and lifeless in comparison, with a 'grain' and 'edge' superimposed onto the signal that is IMO alien to how real music sounds. There is a signature present in the reproduction of all types of music through solid-state amps which to my ears sounds quite false and unnatural, regardless of how 'musically adept' some can be in particular areas.
The problem for me with even the best solid-state amps is their lack of dynamic range and their rather 'flat' presentation of recorded music as a result. It is because of the superior dynamic range on offer from good valve amps that music is 'unrestricted' and allowed to flow naturally, 'breathe' freely, and have the colour and expressiveness which separates the 'real' thing from a cardboard cut-out of such.
*That*, in a nutshell, is what I think GOOD valve amps do over their solid-state counterparts :)
Marco.
