if i was to build an amplifier what are the main types of distortion
you think i will come across and what could be done to reduce or avoid
them
Assuming you mean a power amp and not a preamp, there are a few
general concepts. One of the nastiest types is crossover distortion,
which happens in push-pull output stages when there isn't enough
bias; there is a gap where a sine wave goes to zero, stays there until
the other half of the push-pull starts conducting, and then resumes.
It makes lots of odd-order hamonics, but the real problem is that it
is worse (as a percentage of signal) at lower levels.
At high levels on any amp you can get clipping distortion if you
overdrive it, which is odd-order and generally unpleasant.
(Well, unless you are into heavy-metal guitar, exclusively!)
On any amp with top-bottom asymmetry, such as anything
that is *not* push-pull, you tend to get more even-order
distortions. The golden-ears crowd is fond of Class A
amps, which exhibit tons of distortion (few percent) but
they like the more pleasing sound of even-order harmonics.
Then there is slew distortion, where the sharp vertical
edges of square waves can't be followed fast enough, so
you get trapezoids or triangles instead.
Any of these distortion types can/will also cause intermodulation
distortion, where an input of two tones gives not just
the orginals and their harmonics, but also "inharmonics"
based upon the sum and difference. Nasty sound, since
the new frequencies are unrelated to the note being played.
And on, and on......
Bob Masta
dqatechATdaqartaDOTcom
D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com