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lateral mosfets vs. bjts in audio amplifier design

S

Sjouke Burry

Eeyore said:
So you'd be happy with the -3dB @ 20Hz and 20kHz of the 60s and 70s ?

Graham
Click to expand...
As you cant hear the quality difference anyway,
why not???
Oh I forgot those people with VULCAN ears, who can hear
the difference beween oxygen content in cables.......
or gold plated mains sockets.....
 
E

Eeyore

Sjouke said:
As you cant hear the quality difference anyway,
why not???
Oh I forgot those people with VULCAN ears, who can hear
the difference beween oxygen content in cables.......
or gold plated mains sockets.....
Click to expand...

Whilst your examples are inderd absurd, a flat frequency repsonse is not.

I work in pro-audio - you don't. I hear things you can't. To me you're simply a deaf ****
and competely irrelevant.

Graham
 
E

Eeyore

Jan said:
So far so good.


That remains to be seen, 'hearing' is for the largest part the processing in the brain.
Now that makes me wonder ....


Now it gets really bad, dinner was burned?


You decisively won the unpopularity contest again.


I wonder, if any of your customers put up with all that.
You are not involved in sales I guess.

Sales person: Our engineer says: "To me you're simply a deaf **** and competely irrelevant.'
That will do it.
Print it on the front of your amps.
Click to expand...

Well, I'm in high demand in the audio sector (amongst others).

There must be SOME reaon for that whether it it be my intellect, hearing or both.

Graham
 
E

Eeyore

You've been reduced to that level have you ?

Yes, a GREAT way to denigrate a superior designer. Let's see how many believe you since AFAIK
you never desisigned a commercial audio power amp that can regulsrly be found on ebay.

Graham
 
K

Kevin Aylward

Eeyore said:
Ditto. It's crazy to throw away that advantage.



Indeed so. Mind you, I actually *limited* my LF gain because it was
so huge already ! It didn't need any more. THD didn't start to climb
on the 1200B design until about 2-3 kHz. Knowing what I do now, I'm
sure I could do better than that. This was 20 years ago you know.
Click to expand...

Yeah, I was only a young pup at 21 in 1982. Obviously the err.. new bit in
the mosfet 1000 was err.. my idea to include the extra emitter follower
buffer from the hitachi design. It took me 3 weeks to realise this rather
obvious bit, for subtle reasons. Like:

Consider adding more and more output devices. Say the nchan is 600pf gate
souce, with 40pf gdrain. So, ignore the 40pf as an approximation. Now actual
capacitance is approx Cgs/(gmRL) and now inconvieniantly forget that the
approximation is now suspect with this new value. Now mentally keep adding
|| devices without actually doing the bloody sums...like oh.. gm goes up
with cap.. so er..net cap stays the same...me thinks, so drive current and
gain loading stays the say, ...f&**S*&^% forgot the approximation of Cgd now
fails and keeps adding on right on up there...


Kevin Aylward
www.kevinaylward.co.uk
www.blonddee.co.uk
www.anasoft.co.uk - SuperSpice
 
K

Kevin Aylward

John said:
With the qualifier "a bit of", sure. So there are now, and never have
been, any original circuits.


Like diff pairs, current mirrors, cascodes, are all the same

To get extreme performance, and to sell things for big multiples of
cost, you have to do something new and take some risks. The risks
should be concentrated only in the places where there is payoff. The
scut stuff, power supplies and firmware and cooling and simple
controls, should indeed be as low risk as possible.

YES.

Incremental fiddling of existing technology is a good way to get
bare-survival levels of margin, and even that takes luck.
YES


There are two variables in that relationship, not one. Moderate risk
could produce big profits. Everything fun is risky.
Click to expand...

Like shagging you best mates wife...indeed.
There are no

Yours, maybe. Not mine. I hate to copy circuits, even my own.
Click to expand...

I don't. I will use anything if it works,and can be shown to be reliable.


Kevin Aylward
www.kevinaylward.co.uk
www.blonddee.co.uk
www.anasoft.co.uk - SuperSpice
 
K

Kevin Aylward

Yes it is, but I truly don't have the time to through this all over again..
Have a read of
http://www.kevinaylward.co.uk/replicators/intelligence.html, especially at
the end of the page.
In the dim recesses of time, an idea flashed into being which was
unique and was fleshed out electromechanically into our being here,
now, so _that_ circuit wasn't stolen.

On a more mundane level, some of us work through the problems of
design without resorting to directly infringing the work of others,
whether that prior work exists or not.
Click to expand...

No. See link above.


Kevin Aylward
www.kevinaylward.co.uk
www.blonddee.co.uk
www.anasoft.co.uk - SuperSpice
 
K

Kevin Aylward

Eeyore said:
I thought he was wrong about that. I confess I didn't look it up
again at the time but my 1200B does exactly the same as your approach
Kevin.

Graham
Click to expand...

Indeed. ALWAYS use full push pull source and sink. Resisters and current
sources are just not as good. The exception is probably when you are doing
extremely fast comparators when its a good idea to never let currents cut of
to zero. The difference in these cases is that the amp is designed for non
clipping use, the comparators for clipping!

Kevin Aylward
www.kevinaylward.co.uk
www.blonddee.co.uk
www.anasoft.co.uk - SuperSpice
 
R

Rich Grise

Well, I'm in high demand in the audio sector (amongst others).

There must be SOME reaon for that whether it it be my intellect, hearing
or both.
Click to expand...

Audiophoolery?

Thanks,
Rich
 
R

Rich Grise

On Thu, 23 Oct 2008 19:27:50 GMT, "Kevin Aylward"


Slightly relevant, and mildly humorous:

On page 45-14 of the 1972 "Reference Data for Radio Engineers" is a table
of random digits which is identical in each book.
Click to expand...

Maybe they assumed that each customer would only need one copy of the book? ;-)

And really, putting a different chart in each copy would be prohibitively
expensive.

Cheers!
Rich
 
K

Kevin Aylward

John said:
Random fiddling is a perfectly valid way to find new circuit
topologies. I do that all the time. Sometimes one has a hunch that
some circuit may exist, somewhere in circuit-space, and fiddles until
it emerges.
Click to expand...

Yes...

However, the brain rejects most of the fiddles before it even reaches our
consciousness, maybe millions of variations, such that it gives the illusion
that the ones that actually emerge are not fundamentally based on the
Darwinian machine algorithm.

Chemists only get to use 90-ish elements. Musicians mostly use the
same list of notes. Novelists use the same character set. But new
stuff happens.
Click to expand...

Yes new stuff can happen, but only if we assume that quantum randomness
kicks in somewhere in the brain, otherwise, its all classical mechanics,
like the current position and momentum determines the next.

If Bohmian Mechanics, is correct, then nothing is new.

Kevin Aylward
www.kevinaylward.co.uk
www.blonddee.co.uk
www.anasoft.co.uk - SuperSpice
 
R

Rich Grise

Yes new stuff can happen, but only if we assume that quantum randomness
kicks in somewhere in the brain, otherwise, its all classical mechanics,
like the current position and momentum determines the next.
Click to expand...

You're denying Free Will. "quantum randomness" is a term used by
"sciencists" to rationalize away the fact that everything has Free Will.
If Bohmian Mechanics, is correct, then nothing is new.
Click to expand...

Well, evidently, it's not.

Hope This Helps!
Rich
 
K

Kevin Aylward

John said:
---
I agree.

The thrill of "Eureka!" certainly seems to be more than just
incremental plodding toward a solution which emerges from the soup,
but Kevin's postulations are well founded in that whatever we build
we build upon the shoulders of our forbears.

There had to have been, however, something which started it all off.
Click to expand...

Actually no. there is no reason that there should be any reason for
anything. Some in physics are taking the view that the mass-energy just
appeared, from nowhere.

Physics is characterised by "The laws of physics". However, these laws can
only exist, presumably, if mass-energy exists. In a truly empty universe,
there can not be any laws that prohit anything. Therefor, in an empty
univese here is no reason why mass-energy cannot simple appear from nowhere


I favour this position, as I see no other reasonable alternative. When all
else is proven false, what remains must be answer..

Kevin Aylward

www.kevinaylward.co.uk
 
K

Kevin Aylward

Rich said:
You're denying Free Will.
Indeed.

"quantum randomness" is a term used by
"sciencists" to rationalize away the fact that everything has Free
Will.
Click to expand...

Not to me they don't. Its a matter of logical conclusion. Either they there
is a soul transcending physics, or there is not, if not there cannot be free
will.

The absence of Free Will is not really open to debate, in my view

http://www.kevinaylward.co.uk/replicators/freewill.html
Well, evidently, it's not.
Click to expand...

Whether it is or is not correct, has no baring on the fact that none of us
can possible have free will. Its fundermental physics


Kevin Aylward

www.kevinaylward.co.uk
 
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