Nick Gorham wrote:

Ian Bell wrote:
Nick Gorham wrote:


Agreed, but what I said was most designs are gain limited, not that they
had to be.



Fair enough provided you can justify that remark. Are you saying that is
just how ?current? SE designs happen to be? If so is there any reason for
this?

Ian

No, of course you can have as many stages as you want so as much gain as
you want, however its gets harder to apply global feedback with more
stages as you start to run into problems with phase shift.

Agreed but surely true of any topology?


The other side of the above statement, of course, is that the rationall
that goes behind the reintroduction of SE designs tends to frown on the
use of global feedback. It can be heard that increasing feedback will
tend to cause the sound to become closed and in some way deader.

I can understand that they will sound different and that different people
will prefer with and without feedback.

Now
some will prefer that effect, but in that case, the same sound can be
obtained by PP amps using feedback,

Interesting. IIRC PP systems can only produce odd harmonic distortion which
sounds more musical. I am not sure what the primary distortion mechanisms
are in valve SE designs but you statement infers it must be mainly eben
harmonics.

so there is little point in
accepting the other SE problems, including cost and efficiency if the
same percieved sound can be gained elsewhere.

However for those that prefer the result of SE with little or no
feedback, then the additional problems are seen as acceptable.

There is a element of fashion attached to SE design and currently, part
of that fashion is zero negative feed back.

Not entirely unexpected.


As I said, I am not trying to convince anyone of the "correctness" of SE
designs, but just trying to give some answers to the questions that were
raised. Which got onto feedback via the fact that without global
negative feedback its hard to make anything like a linear amp from non
linear devices.


And I am just curious to know more. I have no axe to grind either way.

Ian