So *that's* why the old books always called thermal noise in vacuum valves "shot noise". Very very cool.
Thanks much,
Chris
Yes the original notion of "shot noise" was based on the particulate nature of charge carriers, after the electron was discovered, and the idea that they slammed into plates and the way that this represented a noise when they were completely uncorrelated and had a small finite charge per particle. A great IRE review article from the late Bernard Oliver and reprinted elsewhere in at least two books is probably accessible online: Thermal and Quantum Noise.
I don't know the etymology for certain, but I'd heard that the "shot" nomenclature was based on very small number of particles phenomena and not named after the first to produce an account of it, Walter Schottky (at least he gets a type of diode named after him). See the very good wiki: Shot noise - Wikipedia, the free encyclopedia 😀
Please excuse me double checking this point . . .
Are we saying for definite, that even after the signal ( and noise ) has been stepped down by the o/p transformer, that the noise levels of a typical top quality valve amp are greater than a typical top quality SS amp ?
Are we saying for definite, that even after the signal ( and noise ) has been stepped down by the o/p transformer, that the noise levels of a typical top quality valve amp are greater than a typical top quality SS amp ?
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😀😀😀
And this is for people listening to new productions.
As long as everything is delayed by the same amount regardless of frequency, give poor electrons as much time to pass through your audio system as they want. Don’t push them because they get swet.
George
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Especially as they are lazy and only drift along the wires at a few mm per hour.
John, by high end manufacturers you mean Audio ones, and I presume you mead leaded capacitors...
John, by high end manufacturers you mean Audio ones, and I presume you mead leaded capacitors...
Looks to me as if you're projecting your own laziness on to subatomic particles. Given their diameter of roughly 10^-14m, even 1mm per hour would correspond to ~10^11 diameters. For a human, the normalized-to-size velocity would be around 200,000,000kph.
(math error first time around, amended)
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Yeah, I've seen this sub-topic on the forums before, and don't quite understand it. Isn't a coulomb something near 6x10^18/sec? Seems like a lot of charge movement going on. If the charge carrier doesn't make it far along the conductor doesn't seem relevant. Anyhow, I'll retreat back to absorbing the noise physics stuff.
'Schottky' and 'Schrot' were already taken, 'Shot' still somewhat resembles Schott(ky).
=> http://de.wikipedia.org/wiki/Schrotkugel (Schrot<=> Buckshot)
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Voltage stepdown by the OPT is irrelevant, as noise is determined much earlier in the circuit. The stage to concentrate on is the first stage after the volume pot (or for turntables the first few stages in the phono preamp). In some cases the dominant noise here could be thermal noise from the pot resistance.
Valves are typically a bit more noisy than BJTs. For power amps and line stages this makes no practical difference. You can design quiet or noisy amps either way, depending on your skill. For phono preamps valves are fine for MM, but struggle for MC unless aided by a transformer.
Valves are typically a bit more noisy than BJTs. For power amps and line stages this makes no practical difference. You can design quiet or noisy amps either way, depending on your skill. For phono preamps valves are fine for MM, but struggle for MC unless aided by a transformer.
I was referring to electron drift velocity Sofaspud, and with an AC signal they just jig back and forth and never leave the wire, unless JNeutron is around.🙂
The pretty picture of electrons zooming round like carriages on a train is misleading, simplified view of signal flow which conveniently avoids the h and e fields.
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Think what will happen when one puts forth the “electron”probabilistic clouds sweeping around nucleuses. 🙂
In fact, thinking and working using EM fields and it’s effects is much more understandable, intuitive and capable of conveying practical results
George
In fact, thinking and working using EM fields and it’s effects is much more understandable, intuitive and capable of conveying practical results
George
I do a lot of high speed and SMPS layout and we have to think in terms of EM fields, and have to think carefully where the fields are terminating and what is within the field boundaries, especially the magnetic field.
🙂
🙂
Yes, I think DF96 summed it up well, though I'd quibble about classifying input transformers for MC as "aids." They're part of the rational approach to engineering, no different in kind than than bias and loading methods.
I wouldn't call "rational approach to engineering" using a part that may double (at least) the cost of a MC preamp, in particular if there are options to avoid it (as for SS).
Now if the requirements are specifically asking for a very low noise hollow state MC stage, then indeed an input transformer is the only practical option. Since there aren't any other options, that's also not really a "rational approach to engineering".
Double? Really? Yes, you could overspend, but you can get very nice transformers for a small fraction of the price of the rest of the circuit. I paid under $200 for the pair I used, which compares very favorably to the cost of a ready-to-go 20dB gain stage (including power) with equivalent input noise density of <0.1nV/rtHz. That would take a whole ****-ton of low noise FETs...
Remember the context: this is talking about tube MC stages, not MC stages in general.
Remember the context: this is talking about tube MC stages, not MC stages in general.
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