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An interesting claim regarding op-amp "rolling" from a comment (by a former ASR member) left on Erin's U-Toob review:Erin's corner has a very good review of the amp. It may explain why some users of digital amps have reported experiencing different results to what you would expect after just seeing one set of measurements/review.
"On the op-amp thing... (edit: In relation to these mini-amps) Get a copy of the NE5532 spec sheets and look at the various curves and ratings. Two things become readily apparent ... the chip has uneven gain below about 1 volt of input (which is where we use them!) and they don't even specify differential input specs because the two inputs are diode clamped together giving a maximum of 1.2 volts across the two inputs. (On the TI data sheet take a look at graphs 5, 6, and 7) Now you have your difference... a cheap as chips chip with uneven gain and very uneven input characteristics vs. any other chip that does not suffer these limitations. The real difference in op-amps with these small amps is NOT putting in an expensive chip ... it is getting rid of the stock chips. I commonly pull out all the NE5532 chips supplied and put in either RC4558 or TLO72 ... under $1.00 each in lots of 10. Yes that first step does make a noticeable difference ... beyond that, not so much."
Perhaps one of the multitudes who, unlike me, have the EE smarts to properly interpret said "spec sheets" would like to comment on that comment. Is the NE5532 actually a poor (or at least suboptimal) component choice for "chip amp" input stages?
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