On Mon, 15 Nov 2004 21:11:55 +0000, Andre Jute wrote:

lots to read, but still snipped!

http://www.geocities.com/mixtel99/index.html


The above free web space site is now also accessible via a free domain
name: (Its nice to do things on the cheap sometimes!)

http://www.projectedsound.tk

If anyone has any pics that they would like me to put up on there for
the others to look at then please email me. There is still quite a bit of
space left I think.

--
Mick
(no M$ software on here... :-) )
Web: http://www.nascom.info

On 15 Nov 2004 21:11:55 -0000, er
(Andre Jute) wrote:


At 3W a 300B is just idling. In fact, we don’t
want to design it down to there because that would take it out of its aurally
pleasing band.

Aurally pleasing band? But I thought this was an 'ultra fidelity'
amplifier? Isn't it aurally pleasing all the way down?

So, because we are not production engineers with cost accountants hungrily
watching us, we shall use the 300B and allocate some of its surplus capability
to making an amp so quiet that it will shame the creaking ali heatsink on your
melted sand amp.

Melted sand amp? Oh, you mean all that glass..............


These two articles about calculating how much power you need, KISS 102 and
KISS 103, are the most controversial in the entire set.

I don't see much controversy. I do see some basic inaccuracies.

You will hear a lot from the silicon brigade about orchestral crescendos measuring
105-108dB rather than the 90dB that is traditionally accepted. It depends where
you measure, right in front of the big bass drum or in a good seat.

Nothing to do with 'the silicon brigade', simply measurements made in
real concert halls, from the front stalls. Look them up in books on
acoustics. Show me *any* reference that says 90dB is 'traditionally
accepted'. This is plain misinformation, feeding your flea-power
prejudice.

That is why I say that if you want the musical nirvana that comes from an ultra-fi
tube amp, you must without fail first get high-sensitivity speakers. It is
far easier to make an ultra-fidelity amplifier with a small directly heated
filament triode tube (DHT for directly heated triode) than to make any bigger
tube amp sound anywhere near that good. The economical cut-off point in my

Ah, so now we *are* concerned with economy, and we are forced to use
less than ten watts. All is clear...............

Beyond 25W go only those with huge experience and fat bank accounts who can
count a good number of clever electronics engineers among their friends. It
very soon becomes cheaper to get the sensitive speakers you should have bought
or built in the first instance!

Except that very few highly sensitive speakers have flat frequency
respoinses. Hey, maybe that's why the best speakers are not highly
sensitive?

Unless you own superior panels, the chances of a really insensitive loudspeaker
not sounding like it pulls your music through porridge cooked with slurry (that
is, liquefied cow dung) is pretty small.

Utter rubbish! Some of the best speakers around have low sensitivity,
indeed the ATC SCM 10 is horrifically insensitive at about 80dB/w/m,
but sounds wonderfully clean and clear.


Good loudspeakers around the 90dB
mark and up are available to buy and to build. The premise of this entire series
is that you have the right speakers before you start designing and building
an amp to drive them. The best amp in the world will not make wretched speakers
sound better.

Indeed so, since all good amps sound the same, i.e. just like the
input signal. That's your own definition of 'fidelity', remember?
However, 90dB/w/m speakers will require at least 30 watts to produce
realistic orchestral peaks, and 100 if you want a decent safety
margin.

Once you own sensitive speakers, the 300B is actually the most economical compromise
you can build.

Not really, you could always build a good SS 30-watter, very simple
and cheap to do with power ICs. :-)

It is ironic that, with very few exceptions, poor loudspeakers announce themselves
by being incapable of being driven by 8W SE 300B or 16W PSE 300B.

Actually, hardly *any* good speakers *can* be driven to realistic
levels by such amplifiers.

Okay, now you have the right speakers and you know how much power they will
demand, so we can proceed to design the amp.

Good, let's leave aside the basic inadequacy, and get to the
interesting bit! :-)

--

Stewart Pinkerton | Music is Art - Audio is Engineering