John Curl's Blowtorch preamplifier part II

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canyoncruz

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Single mode and we uses 1300 and 1500 nm sources which are dispersion limited. Our digital source in fact transmits 32 channels at 20 Gbit. Our analog source one channel at20 GHz. Line width are extremely narrow. For air plan radar and comm, dispersion isn't an issue. It is for long haul systems. My analogue fiber audio device in the 90's was in fact multimodw (50 um) and used a broad band eled. In fact currently, the air force uses (100 um multi mode for 5ghz systems. Again, the length is too short to matter.
 
jneutron

jneutron

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Joined 2004
DF96 said:
You now appear to be admitting that your claim is irrelevant to audio as it involves frequencies well outside the audible band.
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Misdirection now??

Look, we all get it. You're trying anything you can to divert.

Stating that a discussion of 5 uSec inverted is greater than 20 Khz is not "appearing to admit" anything.

Humans are capable of 5 uSec ITD. Nothing you say can change that.

The step response of a system defines the fastest rate the system is capable of. No matter what the stimulus is, the other end of the system cannot get any closer to the step response.
edit: If for example, the system settles in 10 uSec to 50% of final value, any change in the drive will take 10 uSec to settle to 50% of final value. It doesn't matter what the drive is, it doesn't matter what the frequency is. The change will settle in the same time.

This is standard, well understood stuff. I'm surprised you do not understand.

I'm not surprised at the tactics you use to bolster a losing argument.

jn
 
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scott wurcer

scott wurcer

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Joined 2004
canyoncruz said:
Linearity is really depend and on the package. Laser run class A because there is no such thing as negative photons. With out cooling there will be a point were you get thermal roll off ( the high end of the amplitude). I will have to get current numbers but it is very good.

The noise we are interested in is RIN, and that is pushing -180 dB.


My apologies for the phone typing.
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We're not quite talking the same language yet. To me -180dB is 1nV re a 1V line level. I was interested in an end to end link performance in terms of standard audio voltage levels, this includes reciever (PD and TIA). The best Hammamatsu has looks to be 30ppm and are $$ (http://www.atom.fysik.lth.se/QI/las...rticles/photo diode linearity measurement.pdf) but I have not done my own tests. There are other issues like dynamic range, +-10V or more peak output capability, for instance, if you want something that looks like a line stage.

BTW some of the things you mention like cooled lasers don't seem like consumer items. I would think there are far bigger markets for optical analog links than the audiophile cable industry.
 
a.wayne

a.wayne

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Joined 2008
jneutron said:
You owe me 4 quatloos. I take paypal..;)

jn
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Bitcoin ..? :)

hhoyt said:
LOLOLOL..I love her!

I have yet to meet anyone who has made a statement such as "silver sounds different than copper" who has actually done their due diligence and constructed the two cables identically in conductor geometry as well as dielectric composition and geometry. As a result, these statements make a conclusion about the metal used, yet their evaluation involves changing many variables.

This leaves the two cables potentially very different in all of the characteristics people are elucidating here.

Has anyone actually made identical cables varying only by the alloy used in the conductor and yet is still willing to make this claim?

Interested in NC,

Howard Hoyt
CE - WXYC-FM 89.3
UNC Chapel Hill, NC
www.wxyc.org

ps: Scott, did you catch my FZ special in Dec?
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Ohhhh K , So you dont get out much ....... :drink:
 
hhoyt

hhoyt

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?

a.wayne said:
Ohhhh K , So you dont get out much ....... :drink:
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I like the smilie, in fact in reference to it I frequent a brewery I helped start up...if that counts! *hic* On the audio side of things I've also mastered a few thousand recordings, designed and set up radio and recording studios and done live sound for close to thirty years...so according to my wife I'm out too much!

:cheers:
Howie

Howard Hoyt
CE - WXYC-FM 89.3
UNC Chapel Hill, NC
www.wxyc.org
 
a.wayne

a.wayne

Member
Joined 2008
scott wurcer said:
I guess we're all just a bunch of homebodies, it's been how many years and no takers on any group large or small getting together to demonstrate and observe these powers of perception. It's like Freemasonry.
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Better than ......... fact we still waiting for you to connect your speakers, imagine testing cables ...:)

:snail:

hhoyt said:
I like the smilie, in fact in reference to it I frequent a brewery I helped start up...if that counts! *hic* On the audio side of things I've also mastered a few thousand recordings, designed and set up radio and recording studios and done live sound for close to thirty years...so according to my wife I'm out too much!

:cheers:
Howie

Howard Hoyt
CE - WXYC-FM 89.3
UNC Chapel Hill, NC
www.wxyc.org
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Congrats and with all that traveling not one person who did an A/B test of the same cable makeup..:)

Academic in my books, if one does a comparison, the cables are made up identically with the exception of conductor material. Two cables made the same identical way , one with silver the other with copper will sound different ...

Everytime ... ;)
 
fas42

fas42

Banned
Joined 2012
marce said:
I have heard differences (or thought I have heard differences) with changes to my system (things have also sounded different though due to my mood and other factors), so I am rather cynical and do not trust my ears as much as others do, and like some empirical back up, and a solid explanation of what is going on.
:)
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I suspect this is where the dilemma is ... I am as frustrated as anyone else in trying to truly understand why these influences, well, influence so much, audibly. However, expertise in controlling the situation holds a higher priority than comprehensive understanding, at the moment as least.
 
jneutron

jneutron

Member
Joined 2004
PMA said:
Correct re ITD, some sources would say 2us. But, cables in audio band?
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2 uSec yes, I was being polite.

Actually, nordmark measured 1.2 uSec, but that was a dithered stimulus, and he had results out to 12 Khz.

Undithered, I believe it was 5 uSec and ran 500 to 5K.

Cables in audio band...that's been the discussion.

As Scott aptly simmed, a 14 ohm cable driving a 1 ohm load has a specific step response.

If he had run a 150 ohm cable, that step response would have been slower. If he ran a 14 ohm load, it should have risen to full value at 35 nSec.

edit: If you examine my graph, a 100 ohm cable, EDC of 10, with a 2 ohm load takes 10 uSec to hit 80%. Drop EDC to 5 and use 1 ohm, comparable results.

The step response of an audio speaker cable/load system we are talking about is dependent on the line to load ratio. The fact that a speaker can have a widely varying line to load ratio based on frequency means that it will have a widely varying step response.

The basic problem we face is trying to measure that step response at different frequencies, issues I pointed out earlier.

That is why I recommended the test setup with the CVR. While it's not easy to measure reflections and such in the audio band, it is easier to measure the current and it's relationship to the drive voltage at the source, trying to keep out the confounder of cvr inductance.

That's why my test uses some arbitrary zip cable, a good cvr, and varies the load from a low of 1 or 2 ohms out to 100 or so. That provides a measure of how much the cable/load mismatch alters the delay of the current at the load.

And as I stated in the past, that only shows that the line/load mismatch causes a delay which rises above the human capability threshold. It does not prove audibility.

jn
 
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canyoncruz

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Joined 2010
Maybe non linear cities are a problem with the Czech s. But the us radar systems seem to work. And yes you are right about the dynamic range. You would have to scale your input to an amplitude range from 1uW to 50 mW . The coolers needed for a vomercial device would be quite inexpensive. For home use a cooler might be omitted at a cost of optical dynamic range. If you do a cable shoot out I would like to include my old 90's links
 
fas42

fas42

Banned
Joined 2012
hhoyt said:
As a result, these statements make a conclusion about the metal used, yet their evaluation involves changing many variables.
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This is at the heart of sorting out what's going on in most situations - it is often very difficult to alter precisely just one variable, and unbelievably tedious to do it rigorously for all the elements that may impact.

The best solution I've come up with so far is to go with the overkill approach: make everything so 'superior' that the end result desired is well and truly achieved, then pull back on one factor at a time until an audible change is noted - the 'optimum', or solution has been found for at least that configuration. Obviously, still a weak approach, because interactions can be very complex - but at least some progress is being made ...
 
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