You could start with (and almost finish with!) "The Art of Eelctronics".
Simple Op-amps (741 variety) cannot be driven large-signal (ie +/- 10V outputs) above a few Khz or they will slew-rate limit.
Google is your friend ..........
Simple Op-amps (741 variety) cannot be driven large-signal (ie +/- 10V outputs) above a few Khz or they will slew-rate limit.
Google is your friend ..........
Actually google always tries to sell me stuff for $800 that can be had in post #1046 for $76. I miss Altavista search engine.
Lots of progress made in op amp slew rate, current drive, and noise specs, since 1980. 4558, 1 v/usec slew rate, 1.4 uV@1k noise, 2Kohm load minimum. LoFi sound in disco mixer. 33078, 5 V/usec , 4.5 nv/sqrtHz, 600 ohm load, pretty good sound, near same as 12AX7 tubes with metal film plate resistors.. RC4560, 5.5 V/usec, 1.2 uv@2k noise, pretty good but 25 ma drive current allows lower feedback resistor+higher capacitance values for less resistor noise. (the RA88a disco mixer has 1.5 megohm feedback resistor, high value resistors are noisy). KevinKr says even better results can be had with LM4562, 15 V/usec slew rate, .65 uV noise, 23 ma drive current. Looking forward to trying it.
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This is basic "the ability of the op amp to change based upon it's internal capacitance and current drive capabilities".
Unless you are referering to something else and I have missed your point!
I did say a "power op amp" in the earlier post and the frequency was within audio range. I still think it is relevent to this thread "opamps or tubes" linked to preamp stages. If I had been driving current I would have had a FET driver stage. It was just an observation! Things have moved on since I did this high speed opamps better current drive etc! indianajo has some excellent comments!
Regards
M. Gregg
"The output was good from the chip generator, however as I increased the frequency the output from the op-amp got worse and worse. I thought it was the scope chip but no. The output was good all the way up! I said I have got to try this through a small tube preamp. Guess what, the output was perfect no distortion all the way up!"
I was really commenting on the implied implication that the op-amp was rubbish and the tubes OK. Whereas I would suggest that the OA was simply being driven outside of its spec.
When "opamp rolling" (I think that is the right expression) it is so easy, without checking and 'scoping speed and oscillation issues, to simply conclude that there are vast differences in op-amp "sound".
I was really commenting on the implied implication that the op-amp was rubbish and the tubes OK. Whereas I would suggest that the OA was simply being driven outside of its spec.
When "opamp rolling" (I think that is the right expression) it is so easy, without checking and 'scoping speed and oscillation issues, to simply conclude that there are vast differences in op-amp "sound".
I agree, the temptation is to listen and make assumptions on sound quality when other issues may be the cause. Analogue Devices sound better though. LOL
Regards
M. Gregg
Comparing tube preamps versus S.S. preamps (or mixers, time marches on). I did that. PAS2 poly film cap/metal film resistor (over 100k) versus 1990 op amp design disco mixer. A wash at this point. I'm pushing the disco mixer into the 21st century, see "upgrading a disco mixer to mid fi performance" on analog input line level thread. Next trial: your choice.
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