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John Curl's Blowtorch preamplifier part III
John Curl's Blowtorch preamplifier part III
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Old 15th October 2018, 09:55 PM   #8571
1audio is offline 1audio  United States
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John Curl's Blowtorch preamplifier part III
Yes, that was my understanding. Of course after 25 years it may all be apocryphal.

The goal of reusing existing cables is irritable. Same for cat 3 through cat 7 which started as an effort to reuse existing phone lines for networking. And it never really worked but still made sell in easier.
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Old 16th October 2018, 12:12 AM   #8572
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Yes, that was my understanding. Of course after 25 years it may all be apocryphal.

The goal of reusing existing cables is irritable. Same for cat 3 through cat 7 which started as an effort to reuse existing phone lines for networking. And it never really worked but still made sell in easier.
The AES standard started as BBC project to run digital audio over the existing cable plant. It has been modified as the use expanded. Most importantly it was designed to work over normal audio twisted pair which is still the most common use. I have used it in stadium projects to distribute signals in a digital format for digital sources through the console to the amplifier rooms distributed throughout the venue.
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Old 16th October 2018, 01:40 AM   #8573
RNMarsh is offline RNMarsh  United States
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How does that work? If you have a match terminated drive there is no problem. Do you mean shorted at the source and open at the end, and real engineers passed on this?
Real AES members... authorities.... experts.


-RNM
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Old 16th October 2018, 01:50 AM   #8574
billshurv is offline billshurv  United Kingdom
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John Curl's Blowtorch preamplifier part III
I know to some of you merkins we right pondians don't matter but there is a reason it's called AES/EBU you know!


https://tech.ebu.ch/docs/other/aes-ebu-eg.pdf some history here.
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Old 16th October 2018, 01:59 AM   #8575
scott wurcer is offline scott wurcer  United States
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Real AES members... authorities.... experts.
Those things don't necessarily follow.
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Old 16th October 2018, 02:24 AM   #8576
simon7000 is offline simon7000  United States
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Originally Posted by billshurv View Post
I know to some of you merkins we right pondians don't matter but there is a reason it's called AES/EBU you know!


https://tech.ebu.ch/docs/other/aes-ebu-eg.pdf some history here.
Actually you pondians tend to be the driving force behind most of the digital audio transmission standards.
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Old 16th October 2018, 04:02 AM   #8577
1audio is offline 1audio  United States
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John Curl's Blowtorch preamplifier part III
I guess the story isn't completely apocryphal:

"In fact the original 1983 specification allowed up to a 2:1 mis-match of the line characteristics and this gave a
certain flexibility to "loop through" receivers, or use multiple links radiating from transmitters. This concept
was based on the theory that lossy PVC analogue audio cables would be used and it was predicted that:
reflections in short cables were unlikely to interfere with the edges of the signal, due to the short delays
involved,
reflections in longer cables were likely to be attenuated so much that they would not significantly interfere
with the amplitude and shape of the signal at a receiver.
In practice, however it was soon found that problems occurred with an open ended spur which happened to
have an effective length of half a wavelength at the frequency of the "one" symbol. This length is also a
quarter wavelength for the frequency of the "zero" symbol. This condition causes the maximum trouble for the
signal characteristics on any connection in parallel with the spur."

So even engineers who are supposed to understand this stuff guessed too loosely. I have been burned for taking a few shortcuts but not this bad.
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Old 16th October 2018, 04:07 AM   #8578
anatech is online now anatech  Canada
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John Curl's Blowtorch preamplifier part III
Hi Demian,
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I have been burned for taking a few shortcuts but not this bad.
Haven't we all? That's called learning in some circles.

-Chris
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Old 16th October 2018, 10:36 AM   #8579
scott wurcer is offline scott wurcer  United States
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In fact the original 1983 specification allowed up to a 2:1 mis-match of the line characteristics and this gave a
certain flexibility to "loop through" receivers, or use multiple links radiating from transmitters.
This whole thought process is amazing, even the worst 50 cent "yellow" video cable included with every VCR could give horrifying images if attention to termination was totally ignored, the losses per se are not particularly relevant at a meter or two.
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Old 16th October 2018, 12:05 PM   #8580
simon7000 is offline simon7000  United States
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The thinking was at a 2:1 mismatch the reflection would drop below the digital threshold. Pretty sure Heaviside (sp) would have disagreed.

I am at the railroad train station about to board the Pennslyvanian train to go to the AES in New York.
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