John Curl's Blowtorch preamplifier part II

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#37,121
What we could do with IC's in 1970.
 

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#37,123
Waly, it would be interesting for someone with up-to-date experience with IC design to tell us about the state of resistor non-linearity in modern IC's both for industrial and consumer applications. For example, what sort of linearity would we expect of the resistors in a device like the 4558, perhaps compared with the resistor linearity of a single resistor if it were measured separately, from an AD797?
 
#37,124
john curl said:
Max Headroom, you asked me a question. I thought that you deserved an answer. I gave you a short answer, based on my history and experience with IC's.
Click to expand...
The rest of that post, interesting though it may be, did not give an answer.

Now we have resistor non-linearity. Is this the answer? One answer (mentioned by someone other than JC), among 'lots of reasons'. Could someone in the know (Scott?) tell us about linearity (or otherwise) of silicon resistors?

JC has N reasons not to use opamps. He still has N-1 of them to tell us about.
 
#37,125
Of course, unless you're going to somehow isolate those resistors, it's irrelevant. The issue is performance of the gain block, which is set by external resistors. I'm not sure we've even gotten to N-1, the only thing that's been revealed is that he had some problems in 1968, which isn't exactly a valid technical argument.
 
#37,128
DF96 said:
The rest of that post, interesting though it may be, did not give an answer.

Now we have resistor non-linearity. Is this the answer? One answer (mentioned by someone other than JC), among 'lots of reasons'. Could someone in the know (Scott?) tell us about linearity (or otherwise) of silicon resistors?

JC has N reasons not to use opamps. He still has N-1 of them to tell us about.
Click to expand...

Thin film resistors would be the most relevant the non-linearity is hard to measure. Check the AD621 G = 100 with two on-chip resistors and a huge difference in power density. There is plenty of secret sauce involved, the thin film sputtering targets are very carefully made to an exact very pure formulation and the contact metallurgy is more complicated than you might think.
 
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#37,130
About on chip evil resistors, makes-me remember a word of Karl Lagerfeld about fluos armbands at the time they wanted to make them mandatory in every cars: "It's ugly, it fits with anything, but it can saves lives !".
DF96 said:
But of course we know that it is easy to 'hear', thus 'proving' that we can hear things that we can't measure.
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Are-you so sure ?
On the contrary, i thing we can measure things that we cannot hear.
 
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#37,131
it really is amazing how hard it is to transmit sarcasm/irony/facetiousness with text on the interwebs sometimes. its unfortunate, as adding a smiley or other emoticon takes all the fun out of it.

there is even the possibility that ive missed some here 😉
 
#37,134
Can't we just compare real world up to date IC's to currently available and in production, not save surplus discrete devices to make comparisons here? Going back to 1969 or even 2000 would seem disingenuous to an argument about the current state of the art. Discrete components seem to be dropping off the radar as fast as the companies can stop producing them, and we have no real ic's that are directed at audio circuits. So who can compare an up to date IC design to the best discrete designs with currently produced devices?
 
#37,135
Bentleys Are Irrelevant, FFS !...

john curl said:
.....Now, don't get me wrong, I use IC's in analog designs, just not my BEST DESIGNS. They are always jfet and mosfet based, and that will probably continue for the rest of my years, to be sure.
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Ok thanks for going to the trouble to post such long reply....interesting history.
What is your current reasoning for using Jfet and Mosfet based op-amps, and which applications ?.

Thanks, Dan.
 
#37,137
I started with a history of being enthusiastic about IC's even 45 years ago. However, they never quite did what I needed from them, SO I went back to using discrete component design with great success.
Now, what about more modern IC's? Some are pretty darn good, so long as you don't use them at their limits, however I can still get better subjective performance from discrete components, typically jfets, so I design almost exclusively with them.
If you, Max, do not know the intrinsic linearity of jfets compared to bipolars, then I just can't answer your question.
What it essentially comes down to, is the OPEN LOOP LINEARITY of an individual design. Negative feedback, while reducing steady state harmonic distortion, appears to convert the open loop nonlinearity into another form of distortion not picked up by THD or IM testers. In any case, the human ear tends to notice it.
 
#37,139
Happy

john curl said:
I started with a history of being enthusiastic about IC's even 45 years ago. However, they never quite did what I needed from them, SO I went back to using discrete component design with great success.
Now, what about more modern IC's? Some are pretty darn good, so long as you don't use them at their limits, however I can still get better subjective performance from discrete components, typically jfets, so I design almost exclusively with them.
If you, Max, do not know the intrinsic linearity of jfets compared to bipolars, then I just can't answer your question.
What it essentially comes down to, is the OPEN LOOP LINEARITY of an individual design. Negative feedback, while reducing steady state harmonic distortion, appears to convert the open loop nonlinearity into another form of distortion not picked up by THD or IM testers. In any case, the human ear tends to notice it.
Click to expand...

My ears are happy with SSM2135......
😀

:joker:

:tongue:

:clown:
 
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