John Curl's Blowtorch preamplifier part II

[RNMarsh]

Originally Posted by Esperado

Like for cars batteries ? We have the - to the ground, un Europa. I don't know if any difference with corrosion.

Think 3-wire or balanced lines. As in - professional microphones?

[john curl]

Bootstrapping for lower dynamic input capacitance lowers the DISTORTION.

[kgrlee]

Originally Posted by john curl

Well everyone, I hope I have given you enough to make my point. However, I am still missing (they are here somewhere) a complete set of noise measurements taken by B&K where they changed the microphone's R's to higher and higher values. It will come around sooner or later. I'll give you a sample, with 100G resistors.

JC, which B&K instrument is this ?

Is this a 2010? If so, what settings? It's obviously not the 1/3 8ve filter set
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Where did you get your 100G resistors in 1974? This would have been of considerable interest to me around that time.

What physical size roughly ?
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Err.rrh! What IS your point?

[kgrlee]

Originally Posted by fas42

Okay, on first dissection, the 192kHz version has some genuine ultrasonic in it but it falls below 40k frequency. All the material above this frequency is residual, borderline noise, nothing above -60dB down. It is barely possible to hear normal audio at this low level, so I think we can safely ignore it.

Does that mean there is no musical content above 40kHz? Even with DXD & DSD?

From Jurassic attempts to find vinyl with high slew rates and also some mike trials, the only musical signals above 20kHz would be cymbal crashes recorded close up.

Anyone know different and can show examples? IMHO, musical content needs to exhibit the characteristics of music. eg dynamic range; remember loud bits and soft bits ... unlike modern 21st century noise.

PMA, do you know if the vintage Telarc stuff issued shows dynamic range above 20kHz? From what I know about their mikes, it is possible.

Scott, excuse me if I exclude some of your exotic instruments from foreign lands. ... but if you can send a beach bum a recording or two, he might be persuaded that these are music.
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Frank I think you were asking about detailed microphone distortion measurements over a large frequency range. I can say these are quite hard to do from experience circa 1980. The only published stuff I've seen is several Sennheiser AES papers where they show the THD advantage of their symmetrical RF mikes.

However, the 'conventional' evil examples in their paper are not really representative and it is trivial to have better performance. Their mikes are excellent but in fact suffer early overload for other reasons which might be more important to a recording engineer.

[PMA]

Originally Posted by john curl

Bootstrapping for lower dynamic input capacitance lowers the DISTORTION.

Who cares?? SE tubes distort like a hell, and they are considered great sounding by many. Not me, thanks.

[scott wurcer]

Originally Posted by kgrlee

JC, which B&K instrument is this ?

Is this a 2010? If so, what settings? It's obviously not the 1/3 8ve filter set
______________

Where did you get your 100G resistors in 1974? This would have been of considerable interest to me around that time.

What physical size roughly ?
______________

Err.rrh! What IS your point?

Glass resistors up to and maybe over 10^12 Ohms were readily available. They would have easily fit in a mic body.

[SY]

Originally Posted by PMA

Who cares?? SE tubes distort like a hell...

Other than output stages, nonsense.

[bcarso]

Originally Posted by SY

Other than output stages, nonsense.

Agree. Particularly to the extent that a triode follows the ideal Langmuir-Child characteristic, a very-lightly-loaded common-cathode- or common-anode-connected one has extraordinarily low distortion. Of course most triodes are not ideal, but many are very good within the middle range of biasing.

However PMA probably did mean SET power amps with significant plate loading.

[PMA]

Originally Posted by SY

Other than output stages, nonsense.

Especially output stages, but common cathode simple stages as well. It is very audible, but who cares?

[Kindhornman]

kgrlee,
I am not so convinced that there truly isn't any information above the 20Khz range as much as the present multi-microphone recording chain just can't get the phase response correct so that we can reproduce this information in any coherent way. If the phase response and timing was correct then we could talk about it, but that is the problem with most of what we are always talking about in upper frequency reproduction. I in-order to reproduce the sheen of a cymbal or overtones from other instruments we would have to get that correct or it is just smeared in the reproduction and then we just hear it as noise. Just my opinion of what is going on in the reproduction and recording chain.