In article <h2spb4$jcl$1@news.albasani.net>, The Natural Philosopher
<tnp@invalid.invalid> wrote:
> Jim Lesurf wrote:

> >> The adoption of power FETS with much better frequency responses,
> >> negative temperature coefficients and low switch on delays made that
> >> almost a non problem.
> >
> > Must admit I never liked power FETs for audio as the ones I tried
> > years ago all liked to hoot at HF, had a habit of current limiting,
> > and shoved capacitance where I didn't want it. But again this was in
> > the 1980s so I imagine they rapidly improved and have been fine for
> > some years.
> >

> That was merely a question of adapting your driving circuits.

> A bit of gate resistance cured the hoot, and you just ended a lot of
> gate current to wake them up..

Plus having engineered in another RC rolloff, probably with some included
inductance. :-)

Yes, I did find that stopping the hoot that way was easy. Alas, my
experience at the time was using that time-honoured method (as per grid
stoppers of a pervious age) then fouled up the performance in some other
way. So you then spent your time chasing other problems. There were other
'solutions' but again I decided they just shoved around where a snag popped
up.

I'm sure FETs got better and this became a non-problem. But I decided in
the 1980s that at that time they were more of a pain than bipolars,
particularly when the japanese started producing some really superb audio
power ones. so you could almost forget about secondary breakdown and
carrier storage. And at that time I'd have needed quite a few FETs in
parallel to get me the peak currents I wanted and the bipolars cheerfully
provided. That was the days of apogees, etc. 8-]

> The 80's was when I gave up the whole game as not paying a decent wage,
> and turned to computers for income...

I went back into academia. If you can't beat em, teach em... er, I mean,
learn more. :-)

> > Overall, I'd be happy to use amplifiers that employ either bipolar or
> > fet if the designer has produced a decent result.
> >

> Well.. yes.

> As with most things 'Hi-Fi' turned from being a high value specialist
> product sold to at least the semblance of a discerning public, to a mass
> market price sensitive product, where bullshit sold more amps than
> quality,.

> Personally I blame socialism. Too much disposable income in the hands of
> people with no taste and even less discretion ;-)

I tend to point at the dealers who valued an exclusive dealership with a 40
percent markup over actually selling gear that simply did the job with no
hype or an inflated price. But I guess 40 percent of a high price, and no
local competition, was simply too tempting.

And of course 'reviewers' who moved to fantasy island when writing their
articles. :-) The result was a decade or more where anyone who doubted
the magic brands and bull was obviously not to be taken seriously. Hate to
think how much damage that did to many makers and engineers who simply
wanted to produce decent kit, but weren't in the magic circle. Jim Sugden
springs to mind as an example I recall of someone who decided that the bull
made the game one worth walking away from.

The remains are with us still. e.g. Mains cables that cost over a 1000 quid
and have pretty blue lights on them to 'improve the sound', etc. <sigh>

> Having said that, I no longer do, nor do I really care much about the
> quality of the audio equipment I have.

It matters a lot to me for the reason you give below...

> In the end, I want to listen to the music, not the equipment.

That's why I still care about the audio gear I use, and that I should use
it in an optimum way. It allows me to enjoy the results more. But I do that
in ways that do make engineering sense to me. Not by buying eyecandy or
jewellery for audiophiles. :-)


> Being 'in the business' ruined the experience of a live rock concert for
> many years..

Fortunately I realised after a few years that I was focussing on things
like watching waveforms on a scope or trying to hear the quack from LS
cones to find problems, not listening to music. Once I'd realised this I
changed tack. I now rarely buy equipment and mostly just enjoy the music.

Most of the main gear I use for audio is decades old. Still works fine. And
unlike a lot of modern kit is easy to fiddle with if needed.

I do still experiment and try to learn more, though. Most recent example
being a look at using Linux boxes for playing audio. I was not surprised to
find some problems, but pleased that they could be sorted out OK. If anyone
is interested, the results are here

http://www.audiomisc.co.uk/Linux/Sou...Computing.html

However I do wonder how many people are listening to systems that are
fudging up the sounds without them knowing this or that they can be
improved. I was able to generate and measure test files to find the
problems. But I guess most people can't/don't do this, and then presumably
either think it is OK or if not, may blame something else.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
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