Re: 50 vs. 75 ohm
What's the deal with the goretex? I thought it was a fabric used in sporting clothes because it lets perspiration out but not rain in...
As far as the SPDIF connection...I have been skimming through this thread:...is there a definite right or wrong here or what? All our RF electronics at work is 50 ohms, as far as I understand 50 ohm is a choice that was made a priori Xmit, receiver and probe circuit are all 50 ohms.
Is there an equivalent std for spdif? Should we all rip out our rca digital coaxial connector and go for 50 or 75 ohms BNCs? I don't hang out in the hi-end digital circles so I have never seen bnc used in dig. coax line.
I have a load of BNC at work including those very cute and tiny gold plated ones (don't remember the type) that one can solder directly on the board...
Jocko Homo said:
What's the deal with the goretex? I thought it was a fabric used in sporting clothes because it lets perspiration out but not rain in...
As far as the SPDIF connection...I have been skimming through this thread:...is there a definite right or wrong here or what? All our RF electronics at work is 50 ohms, as far as I understand 50 ohm is a choice that was made a priori Xmit, receiver and probe circuit are all 50 ohms.
Is there an equivalent std for spdif? Should we all rip out our rca digital coaxial connector and go for 50 or 75 ohms BNCs? I don't hang out in the hi-end digital circles so I have never seen bnc used in dig. coax line.
I have a load of BNC at work including those very cute and tiny gold plated ones (don't remember the type) that one can solder directly on the board...
Where do I start.........
Oy!
Gore-Tex was originally designed as a low-loss (air filled) Teflon insulating material for microwave cables, not clothes.
The SPDIF standard is 0.5 V p-p into a 75 ohm load. RCAs are what J. A. Pan and the like use. They suck for RF, which is what SPDIF is. They are nowhere near 75 ohms, being in the 30-35 ohm range.
If you want your SPDIF to work to its fullest potential, you have to minimise all reflections. Which means matched impedances at both ends, and the cable matched to them.
BNCs are used by people who like to think that we know what we are doing, but not necessarily does that mean high-end. Most high-end stuff is also wrong.
Phred will point out that he can make a network to offset the impedance mismatch from using RCAs. He can, but I suspect most folks here can not.
I believe that you might be refering to SMA connectors, which are good.
Any other questions? I really do not want to have to 'slpain this again. I'll let Frank do it.............
Jocko
Oy!
Gore-Tex was originally designed as a low-loss (air filled) Teflon insulating material for microwave cables, not clothes.
The SPDIF standard is 0.5 V p-p into a 75 ohm load. RCAs are what J. A. Pan and the like use. They suck for RF, which is what SPDIF is. They are nowhere near 75 ohms, being in the 30-35 ohm range.
If you want your SPDIF to work to its fullest potential, you have to minimise all reflections. Which means matched impedances at both ends, and the cable matched to them.
BNCs are used by people who like to think that we know what we are doing, but not necessarily does that mean high-end. Most high-end stuff is also wrong.
Phred will point out that he can make a network to offset the impedance mismatch from using RCAs. He can, but I suspect most folks here can not.
I believe that you might be refering to SMA connectors, which are good.
Any other questions? I really do not want to have to 'slpain this again. I'll let Frank do it.............
Jocko
Fine, but.......
I have been in the electronics business over 30 years. I have never seen gold-plated BNCs. Anywhere. Any time. Maybe some high-end twits plated their own to impress people who easily impressed. I can not see how it will affect the sound any, but I can think of lots of other factors that will.
I have sources for all manner of BNC connectors, but they are all:
1.) In the USA, and
2.) Do not sell any that are gold-plated.
Is that what you really wanted to hear??
Jocko
I have been in the electronics business over 30 years. I have never seen gold-plated BNCs. Anywhere. Any time. Maybe some high-end twits plated their own to impress people who easily impressed. I can not see how it will affect the sound any, but I can think of lots of other factors that will.
I have sources for all manner of BNC connectors, but they are all:
1.) In the USA, and
2.) Do not sell any that are gold-plated.
Is that what you really wanted to hear??
Jocko
Re: I have no problem with 50 ohms....
Hello Jocko,
Assumed that proper screening (read low transfer impedance) is used, and proper RF termination takes place at sending an dreceiving end, my experience says EMI problems would not occur using higher voltage levels.
What actually counts is the required slope and a well defined threshold level. I find 0,5V gives little margin.
all the best
Guido
Jocko Homo said:
Hello Jocko,
Assumed that proper screening (read low transfer impedance) is used, and proper RF termination takes place at sending an dreceiving end, my experience says EMI problems would not occur using higher voltage levels.
What actually counts is the required slope and a well defined threshold level. I find 0,5V gives little margin.
all the best
Guido
Jocko, actually I've seen some gold-plated
stuff on HP/Agilent equipment/cables, but it's been
many years and I don't remember what it was. But
definitely not very common.
Speaking of "hearing", have you noticed how
the descriptions of cable/connector related
"sonics" always seem to reflect the appearance
of the material? Nickel is generally
characterized as "bright", "harsh", "hard",
"metallic", whereas gold is "warm", "pristine",
"well rounded", etc. Copper the same.
stuff on HP/Agilent equipment/cables, but it's been
many years and I don't remember what it was. But
definitely not very common.
Speaking of "hearing", have you noticed how
the descriptions of cable/connector related
"sonics" always seem to reflect the appearance
of the material? Nickel is generally
characterized as "bright", "harsh", "hard",
"metallic", whereas gold is "warm", "pristine",
"well rounded", etc. Copper the same.
FUNNY, UH?
Hi,
Odd as it may seem I tend to agree, every material has a sonic fingerprint.
So if the 75 Ohm BNCs don't have to be gold plated (and why should they?) than here's a source:
HD
Once you have those a well designed 75 Ohm cable may be a good idea too, right?
They'll really have to twist my arm very, very hard for that to happen.
Cheers,
\ A good TL was all it took.
Hi,
Odd as it may seem I tend to agree, every material has a sonic fingerprint.
So if the 75 Ohm BNCs don't have to be gold plated (and why should they?) than here's a source:
HD
Once you have those a well designed 75 Ohm cable may be a good idea too, right?
They'll really have to twist my arm very, very hard for that to happen.
Cheers,
\ A good TL was all it took.
Hey Frank..................
I suggest that you look more closely at that supplier's chart. I see gold, but it does not seem to indicate that the overall body is gold. I suspect that they are refering to the center pin. At $2 each, how much gold can it have????
Maybe my eyes are worse than yours. No wait...we know that they are.
Gold-plated in H-P? Yeah they charge enough. Although if they did it, it had to be for a real good reason. They use lots of SMAs in the stuff we see.
Anyway, like I said, custom plated by people who try to impress people who are easily impressed. None of the brands that you mentioned are ones that impress me either as an engineer, or someone who does listen.
Jocko
I suggest that you look more closely at that supplier's chart. I see gold, but it does not seem to indicate that the overall body is gold. I suspect that they are refering to the center pin. At $2 each, how much gold can it have????
Maybe my eyes are worse than yours. No wait...we know that they are.
Gold-plated in H-P? Yeah they charge enough. Although if they did it, it had to be for a real good reason. They use lots of SMAs in the stuff we see.
Anyway, like I said, custom plated by people who try to impress people who are easily impressed. None of the brands that you mentioned are ones that impress me either as an engineer, or someone who does listen.
Jocko
LOOKING FOR MY GLASSES.
Hi Jocko,
You probably don't need glasses yet...but I wonder what this obsession with gold is anyway??
I mean, if the center conductor is gold plated than that should be good enough even for the biggest purist surely?
Anyway I googled myself blind on this and short of opening every single link I couldn't find much useful.
Surely when the TL demands are respected at both ends and properly terminated the only thing that could still matter to the audionut is the quality of the cable inbetween?
Especially the shielding that is, not that I expect anyone to understand why...
Cheers,
Hi Jocko,
You probably don't need glasses yet...but I wonder what this obsession with gold is anyway??
I mean, if the center conductor is gold plated than that should be good enough even for the biggest purist surely?
Anyway I googled myself blind on this and short of opening every single link I couldn't find much useful.
Surely when the TL demands are respected at both ends and properly terminated the only thing that could still matter to the audionut is the quality of the cable inbetween?
Especially the shielding that is, not that I expect anyone to understand why...
Cheers,
Re: Where do I start.........
Thanks Joko, very informative. The impedance should definitely be matched. I can relate this to work in a very scary way.
I can't believe that they would be using 30 ohms RCA when the output impedance is 75 ohms, even 50 is not much better as the reflection is probably just as bad as a 30 ohm.
What was the reason for them to pick 75ohms instead of 50 ohms for spdif?
Jocko Homo said:
Thanks Joko, very informative. The impedance should definitely be matched. I can relate this to work in a very scary way.
I can't believe that they would be using 30 ohms RCA when the output impedance is 75 ohms, even 50 is not much better as the reflection is probably just as bad as a 30 ohm.
What was the reason for them to pick 75ohms instead of 50 ohms for spdif?
Maybe we should start a new thread: "Why Jocko is always in such a crappy mood when anyone mentions SPDIF". This way we can get out of the way of the original question. We have strayed a great deal, although I think that most of us don't see the need for gold-plating.
Hope the guy who started this thread did get some useful info, even though he didn't get the answer he hoped for.
So....I'll hold back my comments in hopes that this moves elsewhere.
Jocko
Hope the guy who started this thread did get some useful info, even though he didn't get the answer he hoped for.
So....I'll hold back my comments in hopes that this moves elsewhere.
Jocko
Re: THING IS YOU SEE...
Hi Frank,
These RCA's are used because it is the AES/EBU norm. These guys chose the wrong standard and now there is no way back....
This is what the CS8412 datasheet mentions: "The connector for the consumer interface is a RCA phono plug (fixed socket described in Table IV of IEC 268-11)"
fdegrove said:Hi,
Thing is even the silliest, priciest high-end incarnations of DACs sport these ubiquitous RCAs.
All that because most end users don't know anything else I presume?
No wonder Jocko gets Pi***d off.
And so should the rest of us for that matter.
Hi Frank,
These RCA's are used because it is the AES/EBU norm. These guys chose the wrong standard and now there is no way back....
This is what the CS8412 datasheet mentions: "The connector for the consumer interface is a RCA phono plug (fixed socket described in Table IV of IEC 268-11)"
RE:STANDARDS.
Hi,
Yeah....I remember how amazed we were when they announced this.
One more good reason to stick with vinyl a while longer I thought back than...
BTW, while doing a google on 75 Ohm RCA connectors I found quite a few, much to my surprise.
Has anyone measured these?
EXAMPLE.
FWIW, I suppose companies such as Linn,Wadia and who have you, buy in large quantities of the gold-plated BNC jobs from Taiwanese or Chinese factories.
Some day these should turn up on the market though.
Hey, why not?
May be fun after all...
Ciao,
Hi,
Yeah....I remember how amazed we were when they announced this.
One more good reason to stick with vinyl a while longer I thought back than...
BTW, while doing a google on 75 Ohm RCA connectors I found quite a few, much to my surprise.
Has anyone measured these?
EXAMPLE.
FWIW, I suppose companies such as Linn,Wadia and who have you, buy in large quantities of the gold-plated BNC jobs from Taiwanese or Chinese factories.
Some day these should turn up on the market though.
Hey, why not?
May be fun after all...
Ciao,
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