Re: perceptible audio distortion

Phil Allison wrote:
"Tim Wescott"
Phil Allison wrote:
"Glenn Gundlach"

The other
classic annoyance is the crossover notch. Keep in mind it sounds a LOT
like a rubbing/sticking voice coil. Also, some old opamps have
crossover problems as well.

** Really ?

Maybe only the uA709 with zero bias on the output followers.

I know it's more than that, if for no other reason than I never used that one.

My memory is dim, but I know that it's at least the 741,


** Nope - not a trace.

possibly the LM358 and its relatives,


** Only if misused with cap coupling.

See page 8 of http://www.national.com/ds/LM/LM124.pdf

and some other then-jelly-bean amplifiers from the early '80s.

** All the popular audio op-amps date from the 1970s.

uA741 = 1968
LM101 = 1968
LM301A = 1969
uA748 = 1969
RC4558 = 1974
LF355 = 1975
TL081 = 1975
TL071 = 1976
NE5534 = 1977


..... Phil


When I get the spare time I'll go re-run some experiments. I know I've seen this more than once, but possibly at higher than audio frequencies?

At any rate, watch this space. I expect to get sufficient time right after I help my second kid through college: 2025 ought to be about right.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html
.

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