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John Curl's Blowtorch preamplifier part III
John Curl's Blowtorch preamplifier part III
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Old 26th May 2019, 02:52 PM   #20021
jneutron is offline jneutron  United States
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Quote:
Originally Posted by Tournesol View Post
I thought to this, of course. But the way RJ plugs cut both the isolator and enter IN the wire, when crimped with the pliers, leaves me to think that the contact is made with aluminum. Once the two parts in close contact with high pressure, they must be safe from the air ?
We think exactly alike.
I do worry about how gas tight the contact could be. Imagine a server farm with thousands of aluminum network cables, only to find that 5 years from now they start to have intermittent connections.

Aluminum power connections afaik, do not rely on gas tight anything, but use the paste (some kind of fluorine compound I believe.)

At work, copper quadrupled in cost between estimates and purchase...never, ever, would I have considered going aluminum. It only takes one connection out of tens of thousands to bring the machine down.

Jn

Quote:
Originally Posted by scott wurcer View Post
I remember how long it took to realize the "definition" of non-linear in an R/C circuit was the fact that an exponential is never a straight line. That definition with respect to the concept of linear time invariant conditions for circuit analysis you won't find in any reference.
Scott, I am still totally shocked by your earlier post where the electrician said don't worry it has a 50 amp breaker on a #10...
Any maroon knows the breakers are not there for the protection of the appliance, but to protect the wire...
Good thing you caught it, the average person wouldn't. Hopefully an inspector would. In my town, kitchen upgrades even by the homeowner require permit and inspection.
Jn
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Old 26th May 2019, 03:07 PM   #20022
DF96 is offline DF96  England
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Quote:
Originally Posted by indra1
Change of electrical properties could be related to change in microstructure of the conductor wire over time and usage. I would be astonished if the change is not measurable.
I would be astonished if the change was truly audible, given the physics of trivial potential dividers.

Quote:
A cold drawn copper conductor change its tensile strength and conductivity over time while a properly annealed one will exhibit less of a change. I have seen no study with relevant electrical properties measurement on effect of current flow, EM field, thermal cycling, grain size, fatigue, break in procedure or others in wires.
Such studies may or may not exist, however, we can be sure that these effects, even if real, have no relevance to audio wiring because they are simply too small.

Quote:
Originally Posted by john curl
The same tired arguments.
It must be boring for people designing the latest technology when they have to use the same tired old equations such as Fourier, Maxwell and Schrodinger - all dead men. Much more exciting to just move a few polished stones around and then listen to the universe - this is how LIGO did it, wasn't it?

Quote:
I still don't recommend silver, unless you specifically know what you are doing, because it has a tendency to sound 'bright'. Not necessarily hi freq tip up bright, but maybe 'higher order distortion bright' or something similar.
Nice one, John! Smart of you to suggest that the alleged brightness will not show up in a frequency response test. Can we assume that this alleged higher order distortion also might not show up in a 'conventional' distortion test?
 
Old 26th May 2019, 03:08 PM   #20023
Max Headroom is offline Max Headroom  Australia
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Quote:
Originally Posted by chris719 View Post
This is not the right way to measure noise. Not that it matters, because your theory is crazy and you said it could be heard with a Samsung phone, but I don't have a Bose system. I have Sennheiser HD800s and Dynaudio monitors.
Ok good you have decent gear, you ought to hear fine differences. Try swapping interconnect direction one channel at a time, IME you ought to hear sideways shifting of centre panned sound sources. Swapping the second interconnect IME ought to recenter the image but now the depth imaging will be different. You may need to try this detailed/close listening on a selection of tracks to display the effect, this is sort of subtle stuff but once heard and noted cannot be unheard.

Of course a decent system will sound good with interconnects in both the directions, but it will sound more correct and with more realistic depth imaging in one of the directions. This process is not hard to do but may take a little time, I recommend that you try it properly.

Dan.
 
Old 26th May 2019, 03:13 PM   #20024
scottjoplin is offline scottjoplin  Wales
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Originally Posted by Max Headroom View Post
Of course a decent system will sound good with interconnects in both the directions, but it will sound more correct and with more realistic depth imaging in one of the directions.
Presumably it would only be possible to tell this if you'd been at the original recording/mixing session and had a perfectly photographic(?) audio memory?
 
Old 26th May 2019, 03:24 PM   #20025
scott wurcer is offline scott wurcer  United States
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Quote:
Originally Posted by jneutron View Post
In my town, kitchen upgrades even by the homeowner require permit and inspection.
Jn
We sneaked this one by, it's a long story. He was doing work for our managing board and he just fit this one in, it was obvious he was not and electrician or plumber (though the plumbing seemed right).
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Old 26th May 2019, 03:51 PM   #20026
simon7000 is offline simon7000  United States
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Quote:
Originally Posted by scott wurcer View Post
Sorry enough for now you don't answer any of my questions, BTW does the current flow in both leads of the source or not when you close the switch, speaking of one's own interpretation?

I just did the computation for 10m of RG58. Where do you think the 50 Ohms comes from? 100pf/m and a propagation velocity of 2/3 c (close enough) you don't even need to know L/m you can compute it. Gee the characteristic impedance is 50 Ohms, surprise. 10m is about 50ns.

Now take a 1V battery and close the switch 20mA flows. Lets see how much charge we have when everything stops. Q = CV that's easy 1nC, but 20ma flowing for 50ns is also 1nC, surprise again. OK on to the energy stored in the cable, 20mW for 50ns is 1nJ, but L/2 times 20mA squared plus C/2 times 1V squared also equals 1nJ, more surprise.

Why do I use R/L/C, and Vprop because that's all you need.

BTW I don't care about your microphone problem, IIRC you put up pictures from your OWON scope of 10mV dead zones in sine waves claiming something.



No you started it 2 days ago.
As usual we don't communicate. Current is assumed to flow from the positive terminal to the negative one. In actuality as this was determined by looking at sparks they got it backwards.

Now a signal wavefront is symmetrical. Is there something unclear about that?

And how do your comments apply to loudspeaker cable? I have some that is PVC insulated and other that meets fire codes for plenum use and is kynar. Teflon costing more!

Do you really think it takes 50 nS for the signal to propagate in a 10M loudspeaker cable? Where would this matter? What inductance range do you get for loudspeaker cables?

Vaccy,

I do have conversations with some of the loudspeaker manufacturers' technical folks, they tend to blame the marketing folks for the misuse of the word "dispersion." One of the fun bits of jargon is it let's you know who is a member of the club and who isn't. So we will continue to disagree. I will use the word to describe the frequency/speed issue. You are free to use it as you wish. Eventually the definition may adapt.

Last edited by simon7000; 26th May 2019 at 04:07 PM.
 
Old 26th May 2019, 04:00 PM   #20027
Jakob2 is offline Jakob2  Germany
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Originally Posted by mmerrill99 View Post
<snip>

The original genesis of this strand of the discussion arose from a question by RNmarsh
I'm still attempting to answer this question, I guess? I made the point that risetime was not frequency dependent but Scott makes the point (I think) that the more square the wave (faster the rise time), the more HF harmonics are involved (hence the Fourier denial quip, I presume?)
Discussion across several fields are often a bit difficult due to different meaning/usage of the same terms.
For a single tone the slew rate is level dependent, for a complex tone the rise time (for the more "square" that youve mentioned) depends on level and spectral composition.

"Attack" would mean the difference between playing the same notes by "plucking" or by "slamming" the strings.
Assuming the same amplitude any high frequency hearing loss will result imo in a different perception of "pluck vs. slam" due to the reasons ive outlined before.
SaM mentioned already that age related effects were not restricted to only high frequency hearing loss (typically the thresholds are higher across all frequencies for elderly subjects).

Experimental results for age related effects on localization are up to now a bit inconclusive as some found that localization got worse in the horizontal and vertical plane while others only found an impact wrt to localization in the vertical plane.
But it seems to be safe to conclude that age related effects do have an impact on localization of sound sources.

Interesting side effects is the morphology of the pinna as one experiment found that larger pinnae (growing with age) compensated partly for the impact of high frequency loss.

Using complex musical stimuli might in such experiments might lead to different results id assume as experience growing with age could help to compensate for aging effects.
 
Old 26th May 2019, 04:24 PM   #20028
hhoyt is offline hhoyt  United States
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John Curl's Blowtorch preamplifier part III
Quote:
Originally Posted by indra1 View Post
Maybe Mr. Colburn or Mr. Hoyt can help a bit more?
Although I appreciate the opportunity to comment, I already besmirched my boots once wading into this mess.

Wire (not a cable assy) cannot show directionality without causing distortion. Period. Its very definition as well as simple logic both show this must be so if you assume audio to be a signal of alternating polarity of electron pressure.

1) As indra quoted, think about the possibility for contact issues at the connector which inevitably has oxidation, dissimilar metals, entrained moisture (anyone with high vacuum experience knows H2O is very sticky!) and contaminants. Now compare this to the magnitude of any possible issues with the internal structure of the Cu/Al/Ag/Au/Ei/EiO conductor itself. Add to these variables the differing ways of terminating a cable to establish proper shielding and grounding which by design cause desired directionality. I will state unequivocally: ANY WIRE TEST MUST BE DONE WITHOUT CONNECTORS. To think a wire test is valid including connectors is delusional, like checking the brightness of the moon with a photometer in broad daylight.

2) Any directionality would be either in the amplitude or time domain, and amplitude directionality (i.e. micro-diodes or the imagined non-linear zones of conduction) would cause measurable distortion. If the distortion is caused by propagation issues (time) the distortion would be due to IMD between the direct and time shifted signal. As both a broadcast engineer and radio amateur I work with transmission lines which have both a characteristic impedance Zo and velocity factor Vf which describe how a signal propagates on these lines. However we are talking about audio with much longer wavelengths, even 20 KHz in a piece of RG-58 with a Vf of 0.66 has a wavelength of ~10 km. The phase difference between the direct and reflected 20 KHz signal in that 1m cable would be 360 micro-degrees. I won't bother calculating the amplitude loss due to cancellation or resulting IM...

Can we PLEASE talk about something else real? When not distracted JC, Scott, PMA and many others have some really solid ideas on circuit design which I value, like with FET buffers and PS buffering, not to mention the excellent DAC discussions ...have we exhausted the topics?

My conclusion is the best engineers have the best imaginations. The difference between those who merely hypothesize and those who actually create is the ability to analyze and winnow down the possibilities from impossibilities using scientific principles and analyses. John, your designs weren't hypothesized into existence...

Best regards,
Howie
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Old 26th May 2019, 04:35 PM   #20029
Max Headroom is offline Max Headroom  Australia
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Quote:
Originally Posted by scottjoplin View Post
Presumably it would only be possible to tell this if you'd been at the original recording/mixing session and had a perfectly photographic(?) audio memory?
Recordings with decent depth information including spoken word and nature sound recordings are best for showing audible differences according to interconnect direction.
The effect is 'somewhat' like the audible changes that occur when swapping polarity of loudspeaker connections at the speakers.


Dan.
 
Old 26th May 2019, 05:06 PM   #20030
indra1 is offline indra1  Indonesia
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Originally Posted by DF96 View Post
I would be astonished if the change was truly audible, given the physics of trivial potential dividers.
Such studies may or may not exist, however, we can be sure that these effects, even if real, have no relevance to audio wiring because they are simply too small...
Good for you. And yes it is not an important issue for me, but I'm not giving up my curiosity yet.
Quote:
Originally Posted by hhoyt View Post
... Wire (not a cable assy) cannot show directionality without causing distortion. Period. Its very definition as well as simple logic both show this must be so if you assume audio to be a signal of alternating polarity of electron pressure. ...
Thank you Howie, Klaus was also asking about how to reliably make a directional cable, I think you got it covered.
 

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