John Curl's Blowtorch preamplifier

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#17,103
I will also take into consideration that he is a capacitor engineer, that the measurements were objectively measured this century rather than 30 year old hearsay, and that he specifically developed the test equipment used to make the measurements. He also doesn't lump all ceramics together when talking about them. He found reliability issues with micas, and found low DA in NP0s. Unfortunately, his website is seriously restricted on download volume.
 
#17,104
OFF topic, but still important. This is for SCOTT WURCER, primarily.
SCOTT, we are now using an OPA 569 and thinking about using an OPA 558 for a new project. Our problem is with the INPUT overload range of the 558, and the MAX supply voltage of the 569.
Does Analog Devices have a similar product (range) than might be as good or better than these devices, especially a part that has good input range, BUT higher MAX supply voltage that the 569? We need answers fast, as we must order, today.
 
#17,105
john curl said:
OFF topic, but still important. This is for SCOTT WURCER, primarily.
SCOTT, we are now using an OPA 569 and thinking about using an OPA 558 for a new project. Our problem is with the INPUT overload range of the 558, and the MAX supply voltage of the 569.
Does Analog Devices have a similar product (range) than might be as good or better than these devices, especially a part that has good input range, BUT higher MAX supply voltage that the 569? We need answers fast, as we must order, today.
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a) What do you mean by "input overload range"?
b) OPA558 doesn't exist.

It would be better to state your application; OPA569 look like being an ultra specialized part (5.5V supply, rail-to-rail and 2A output current). Very slow and most likely CMOS or BiCMOS, improper for audio.
 
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#17,116
john curl said:
It sure is pretty! Rode in one back in 1967, from Rome to a small coastal town. Memorable experience.
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Few decades ago, a world renown wine expert visited my country. He was interviewed for a newspaper. The reporter asked him about the best wine he ever tasted. The wine expert replied: "I was in my twenties, with limited means. I dined in a budget restaurant in Venice with a local 18 years old young lady. The wine was whatever they served in that budget restaurant. That was the best wine I ever had".
 
#17,117
Bob Cordell said:


I do not buy the argument that just because low inductance is important for power supply bypassing that it is equally important for compensation circuits, since the impedances involved are quite different.
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I did not say that it was equally important and it depends on the compensation circuit - nested Miller loop compensation is one area where file caps such as polystyrene perform inferior to ceramics for me (where a defined frequency charachteristic out to several tens of MHz is required and well as values >200pF).

Cheers,
Glen
 
#17,118
pooge said:


Cyril Bateman's articles on capacitors showed extensive measurements. NP0/C0G caps were one of the lowest distortion caps. Didn't do any tests on piezo properties, but NG0/C0G caps are not made of the same piezo ceramic as lower class ceramics are made of. His articles are posted on his web site:


capacitor sounds articles
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:nod: :nod:

Along with the superior HF charachteristics I see little valid technical reason for avoiding these capacitors in freq. comp circuits, or spending up big on a w@nky teflon cap instead.

Cheers,
Glen
 
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