John Curl's Blowtorch preamplifier part II

[scott wurcer]

Originally Posted by Esperado

Too, i would like to know if the number of transistors in an IC OPA has a great impact on its manufacturing price.
(thanks for the previous answer)

Die size and process are about all that matters. Big power outputs probably matter in that case,

[SY]

Originally Posted by Triodethom

What equipment was used that can measure above about .2hz aprox. the noise floor at -200db . some old tests showed that a few could hear below a noise floor by 10db when the floor was about -60db .

That was exactly my point- the noise that Ed wants us to worry about is ridiculously lower than anything that could possibly be imagined to be significant.

[simon7000]

Originally Posted by SY

That was exactly my point- the noise that Ed wants us to worry about is ridiculously lower than anything that could possibly be imagined to be significant.

Ah so you admit to limited imagination!

(But why does it show up in measurements?)

[SY]

Because you (maybe deliberately) didn't take care of grounding or layout properly for your test, that would be my first guess. It certainly doesn't show up in any of my gear and doesn't seem to show up in any of Scott's high precision work.

Have you published measurements showing this on the output of a 797 fed by a reasonable raw supply and a regulator, or are you moving the goalposts again?

[john curl]

Yes, as if we would DELIBERATELY screw up on grounding or layout! '-)

[john curl]

What the market will bear, just like hi end audio. '-)

[sofaspud]

Too, i would like to know if the number of transistors in an IC OPA has a great impact on its manufacturing price.

Just to add... The biggest cost difference may be in the reticle used, and it is reusable over the life of the device.

[SY]

Originally Posted by john curl

Yes, as if we would DELIBERATELY screw up on grounding or layout! '-)

Maybe inadvertent, maybe deliberate (to try to make a point), maybe he's switched gears and is talking about a different measurement of something else entirely. Nailing jello to a wall is not easy.

[Esperado]

Originally Posted by simon7000

You asked about other effects. Did you know that from the same manufacturer, the same series of capacitors, even the same values will have different resonant frequencies for axial vs. radial?
Anybody care to explain why?

Because the inductances of the wires differ ?

[john curl]

Everyone, it might be important that we review how moving magnet cartridges actually work and what normally gives the best frequency response. I am looking for some classical articles from 'AUDIO' and others that might give us a better understanding.