Okay, someone switches on his audio system, and winds up the volume - especially the subwoofer. The air is certainly vibrating, and various surfaces in the room start to subtlely vibrate, like the floor some cables may be resting on, and the stands that audio equipment is sitting upon, and cables are resting upon to some degree.
What's the magic level that means that none of this behaviour is having an audible effect - maybe the people who buy "silly" supports can hear something ...
What's the magic level that means that none of this behaviour is having an audible effect - maybe the people who buy "silly" supports can hear something ...
One more reason to avoid the audiophile-standard silver and PTFE, which is just about your worst case. Cheap vinyl wire with copper does better in this respect, but lacks audiophile cred.
wouldn't EMI pickup induce a larger voltage than that?
Ground wave AM field strength at my house amounts to 22mV/M according to the FCC. I'm not sure if HF, VHF and UHF have similar effects, or if it only applies to frequencies below a couple of MHz.
IME, it all matters - I've worried about both EMI pickup, and static effects - and hear improvements when I do things in both areas ... makes the difference between really good, and just OK sound ...
Teflon covered silver wire works for me! I have never found a problem with it in my preamps or pre-preamps. Perhaps it is that the working impedances, are fairly low.
The "cables do not have a sound of their own" motif is all about pontification and semantics. Strictly speaking neither an amplifier nor a cable has a “sound”. (Except perhaps a faint hum or 'ommmm' sound.) 🙂
The rub is this: if one gets accustomed to thinking in terms of the perfection of single parts/components of a system, one loses track of the possibilities offered by evaluating systems as systems of (perhaps) “less than perfect” components, and that these types of systems might produce better (subjectively experienced or measured) results than systems composed of “more perfect” components.
Thinking in terms of perfection is a conceptual trap. Which is not to say it isn't handy.. It offers one the yet untested security of unassailability in exchange for saving one the trouble of actually evaluating complex systems.
There was some discussion about adding a resistor to the amp output on the blowtorch thread:
http://www.diyaudio.com/forums/anal...rch-preamplifier-part-ii-388.html#post2824959
http://www.diyaudio.com/forums/anal...rch-preamplifier-part-ii-388.html#post2824959
Very much so. I've just had a good, fun day with my UULE, an extremely basic, cheap Aldi combo which works very well when you get all interference effects out of the way. I surprised myself by doing some subtle fine tweaking of the environment, and getting a substantial improvement - essentially being able to go higher volumes cleanly with difficult material.
Subjectively, this ridiculously low-cost, 'primitive' system is able to deliver amazingly powerful, overwhelming sound when the right things are done - the 'perfection' level of any aspect of it is pretty dreadful, but the sum is so much, much more than the ...
You need more practice at estimating values, based on correct circuit theory. The relevant issue is not the load impedance but the source impedance. Assume a source of 200R, and 10nA of tribo current. This gives 2uV i.e, -120dB. I don't think we will hear it.fas42 said:
Of course, an 'audiophile' source with 2k output impedance will be 20dB worse so perhaps then cables might matter.
Or perhaps the performance shortcomings were acceptable in exchange for being able to claim expensive materials. Indeed, it's not like to make an audible difference at low impedances, but run a foot of shielded PTFE/Ag between a volume pot and the input of a circuit and you may be surprised- I sure was.
Well, last time I looked at current it tended to flow in a complete path, a full 360 deg. circuit. I can appreciate the current 'thinking' that the source would be 'nicer', being low resistance, does it 'know' that that is a better place to go ...?
Or is triboelectric a 'special' type of current?
Or is triboelectric a 'special' type of current?
I think we have some confusion here - we're talking about current noise, not voltage noise - which is the chicken, which is the egg ...
Triboelectric current generated in a cable has two paths to choose between: load and source. Given typical impedance values, which one will it mainly choose? If this is too hard a problem, try some Ohm's Law revision.fas42 said:
Okay, so you're saying that the triboelectric action is forming a current source between the forward and return paths of the cable, which sees the source and load impedances in parallel?
You have three things in parallel: triboelectric current source, source impedance, load impedance. The voltage developed is given by the current times net resistance. As the source impedance is usually much smaller than the load impedance we can approximate the total impedance by just using the source impedance.
If you want ask how the current 'knows' which way to flow then you could add the cable capacitance so the voltage has a finite risetime, and so the current has 'time' to choose the path of least resistance. Applying circuit theory is simpler!
If you want ask how the current 'knows' which way to flow then you could add the cable capacitance so the voltage has a finite risetime, and so the current has 'time' to choose the path of least resistance. Applying circuit theory is simpler!
I was actually going to test this last night - until I realized that SY had used shielded teflon over silver. That I don't have, just the simple single strand wire. 🙁 If I can get my hands on the coax type, I'll test it and post the results.
No that analogy is incorrect to an extent, the return current flows at the same time, it is not a train of electrons running round a track...
http://www.x2y.com/filters/TechDay0...log_Designs_Demand_GoodPCBLayouts _JohnWu.pdf
Or you could engineer a solution, where surprisingly these things are looked at and sorted out.
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