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Differences In Audio Components That I've Heard And Not Heard
wrote:
You have asked from a place of affirmed confusion a series of
questions about amps. That one has questions is good, that questions
can be posed about a thesis doesn't harm the thesis, and that one
might not accept the answers does nothing to the correctness of the
thesis. The amp that doesn't exceed it's specs for a given speaker,
with regard to current reserves, headroom, distortion, etc. will most
likely not be different from another similar amp in a listening alone
test as to being able to discriminate which is which. The concept of
threshold comes in here also, various amp artifacts which rise above
a certain amplitude,ie. threshold, can be percieved and those which
do not can not; as established in tests to determine such things.
Various types of signal distortion are examples. The concept often
bantered about of "mid high" are meaningless when the above
conditions are met. A "mid" amp that doesn't exceed design
parameters nor produce artifacts above known thresholds can not by
listening tests alone be distingushed from those "high" amps often
found on "reccomended" lists.
Being an analog circuit designer, I know many different possibilities of
making a power amplifier.
You can use MosFets or BJTs in the O/P stage, for example a couple of
expensive complementary hand selected Sanken transistors (2SA1216, 2SC2922)
or get a good power IC like the TDA7293V. On the other hand there are cheap
quasi complementary stages at a fraction of the cost. The same is true for
capacitors and opamps.
Most characteristics show up in measurement data, but what really is the
sonic difference between 0.0002% and 0.05% distortion or IM?
We just have the so called "Hi-Fi" criterion, which at its time was a
challenge, but is now satisfied by almost any equipment. Despite some
attempts like THX there has been no other qualification of high-end vs. good
(or whatever) distinction, which would allow the user to categorize his
gear. The only data he has is the price-tag, and this has been abused by
many companies, so credibility is low. So it comes down to Brand names, and
that is what the industry wants(see the Bose thread).
I myself feel in the same dilemma, even with all the electronic knowledge
and experience, because I really cannot say where the standards have to be
put. It comes down to subjective listening, which apparently gives different
results as we can see in all these posts here. I learned to be careful to
avoid prejudices based on beliefs which lead to simple black/white
categorizing like "all amps sound equal".
I have used a Behringer small mixer to convert unbalanced to balanced lines,
and there certainly is a tiny little change of sound if you use the channel
inputs or the tape return inputs (IMO the latter sound "better"). It is
difficult to discover, but since you can switch back and forth with just 2
buttons simultaneously pressed, it is a relativly easy comparison. Now-
there should not be any difference, but there is. I did not verify this by
measurement, but I believe it should be possible. Maybe some opamp is
oscillating at a very high frequency or whatever, with a normal loudspeaker
measuring system(DLSApro) I could not find a difference though.
I would have categorized myself belonging to the "objectivists", but after
this experience I have become careful with my judgement.
--
ciao Ban
Bordighera, Italy
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