Is a Digital Coax cables built the same way as a single channel RCA interconnect? I am assuming there is some kind of difference between a Digital RCA cable and a Standard Analog RCA cable.
I have a pretty crappy monster cable Optical Cable for my HT and am feeling the drive to build something better. I have heard that Digital Optical cables are only good at short distances and that Digital Coaxs are better for long distances. Please correct me if I'm wrong. Any help would be great. Thanks
Brian
I have a pretty crappy monster cable Optical Cable for my HT and am feeling the drive to build something better. I have heard that Digital Optical cables are only good at short distances and that Digital Coaxs are better for long distances. Please correct me if I'm wrong. Any help would be great. Thanks
Brian
There has got to be someone that can help with this 
. Maybe I should rephrase my question sence I'm a bit new here.
My goal is to build a Digital Interconnect to run from my DVD player to my DTS 5.1 decoder. I would like to build the cable from the ground up. All the information I have found till this point has said not to use RCA connector and instead us BNC's. My DVD player is a new model but doesn't have the BNC connections on the back. The only digital connections are Digital Coax (RCA) and Digital Optical (fiber).
Should I just live with a store bought RCA or Optical cable?
Any tips or advice would help.
. Maybe I should rephrase my question sence I'm a bit new here. My goal is to build a Digital Interconnect to run from my DVD player to my DTS 5.1 decoder. I would like to build the cable from the ground up. All the information I have found till this point has said not to use RCA connector and instead us BNC's. My DVD player is a new model but doesn't have the BNC connections on the back. The only digital connections are Digital Coax (RCA) and Digital Optical (fiber).
Should I just live with a store bought RCA or Optical cable?
Any tips or advice would help.
For the digital cables, you need to amke sure the cable you use is impedance matched to the drivier and receiver circuits at each end (I think it is 50 ohms for the digital interconects). So, what you would be best doing is to pop down you local electronics store and buy some of their nicest 50 ohm coax a BNC and one RCA plug then just make the cable up with those on the ends (two BNC's would be a tiny bit better, but I don't think it will make too much difference, especialy if your receiver doesn't have one on already).
Actually, the impedance is 75 ohm if I'm not mistaken. You wont really hear a difference in the sound if you use optical or coax transmission--because the same bits get to the decoder, no matter what cable you use. 50 ohm cable will attenuate the signal because it's output is for a 75 ohm load. I'd use any standard 75 ohm coax, because it's probably only a few feet. BNC connectors are overkill too, you really don't need them for short distances. If you hear digital noise, breakup, etc then change your cable, but since it's digital, what ever transmission you use, either optical or coax, you wont hear any difference.
It is foolish to use BNC to RCA adaptors if the equipment already has RCAs on it. The more contact points the worse for the signal. Just get some nice RCAs(I like silver/rhodium) and some high quality 75ohm coax(not radioshack). Belden 1694A is great but hard to get in less than 500' rolls, try anyway. I'm an engineer in the broadcast/production industry and deal with this every day so you can trust me. The reason we use BNCs in broadcast is that the dont loosen or fall off and maintain constant contact, not because they are any better at transfering the signal.
P.S. Gepco VS2001 is okay too.
P.S. Gepco VS2001 is okay too.
If you are stuck with equipment using RCA jacks, you might consider the Canare RCA plugs... they're about as close to 75ohm as you can get for an RCA. Canare also makes good cable... their L-5CFB coax cable is very similar to Belden 1694A. I've heard you can get Belden by the foot from Zack Electronics, and markertek.com will sell you the Canare connectors and cable by the foot. Also try haveinc.com.
Check out this page: http://www.bus.ucf.edu/cwhite/theater/DIYCable.htm
Check out this page: http://www.bus.ucf.edu/cwhite/theater/DIYCable.htm
The Loch Ness monster and other myths
'If you are stuck with equipment using RCA jacks, you might consider the Canare RCA plugs... they're about as close to 75ohm as you can get for an RCA."
There is no such thing as a "75 ohm RCA" since the physical dimensons of a RCA (cinch) connector make it impossible, even with a dielectric constant of 1. The Canare are not the closest either. Using 50 ohm cable and load and source impedance would help reduce the mismatch. I believe Jocko's TDR measurements showed somewhere around 25 to 30 ohms for a typical RCA connector. Don't forget that the female connector is part of this impedance.
About all one can do is minimize the length and capacitance of the connector, unless you know how to design a simple matching network to go in the RCA connector............. I wonder what a pretty good network would be would look like? A book on transmission lines and a Spice program make this a pretty reasonable task.
Transmission Line Design Handbook (Artech House Microwave Library) by Brian C. Wadell 1991
Fred
'If you are stuck with equipment using RCA jacks, you might consider the Canare RCA plugs... they're about as close to 75ohm as you can get for an RCA."
There is no such thing as a "75 ohm RCA" since the physical dimensons of a RCA (cinch) connector make it impossible, even with a dielectric constant of 1. The Canare are not the closest either. Using 50 ohm cable and load and source impedance would help reduce the mismatch. I believe Jocko's TDR measurements showed somewhere around 25 to 30 ohms for a typical RCA connector. Don't forget that the female connector is part of this impedance.
About all one can do is minimize the length and capacitance of the connector, unless you know how to design a simple matching network to go in the RCA connector............. I wonder what a pretty good network would be would look like? A book on transmission lines and a Spice program make this a pretty reasonable task.
Transmission Line Design Handbook (Artech House Microwave Library) by Brian C. Wadell 1991
Fred
Re: The Loch Ness monster and other myths
The point is moot. In 20 plus years of working in the field I have never run accross a problem where impedence mismatch caused enough roll-off to do anything to a digital audio signal. Video, only a handfull of times but audio never. Analog is much more influenced by impedence, in digital if the signal is there it is there.
In short, make the cables, use RCAs, and dont worry.
Fred Dieckmann said:
The point is moot. In 20 plus years of working in the field I have never run accross a problem where impedence mismatch caused enough roll-off to do anything to a digital audio signal. Video, only a handfull of times but audio never. Analog is much more influenced by impedence, in digital if the signal is there it is there.
In short, make the cables, use RCAs, and dont worry.
A farmer outstanding in his field
"The point is moot. In 20 plus years of working in the field"
I don't know what field you have been working in ....... but it is not digital data interfaces. Cables and the interface have great impact on RFI and jitter. Stereophile did measurements that showed changing the cable direction resulted different measured jitter levels. When you have done a few hundred hours of TDR, Spice modeling, and listening test I will take you seriously. BTW I designed digital audio cables and interfaces for about three years and did signal integrity and EMI reduction in digital telephony. I also designed amplifier buffered video cables. But technical details like yours on the subject are hard to refute. I'll return you to spreading fertilizer in your field.
"The point is moot. In 20 plus years of working in the field"
I don't know what field you have been working in ....... but it is not digital data interfaces. Cables and the interface have great impact on RFI and jitter. Stereophile did measurements that showed changing the cable direction resulted different measured jitter levels. When you have done a few hundred hours of TDR, Spice modeling, and listening test I will take you seriously. BTW I designed digital audio cables and interfaces for about three years and did signal integrity and EMI reduction in digital telephony. I also designed amplifier buffered video cables. But technical details like yours on the subject are hard to refute. I'll return you to spreading fertilizer in your field.
WE DON"T STINKING IMPEDANCE MATCH
Mark & Brian,
Ever mismatch add up to a transmission refection problems which effect the how the DAC’s receiver decodes and clock the data. When Fred said you need 75-ohm impedance cable he not kidding. If you know what a TDR is, you be able to see the reflection caused by the impedance mismatch.
In addition, BNC are made in 75ohm and 50-ohm impedance for a reason. In addition, as Fred stated, there no such thing 75-ohm RCA, no matter what Canare states. I have already been down that path myself.
So WWW.Beldon.com makes a number of 75ohm cables, I am using RG187 which is a Teflon/Silver which connects the connector to the PCB of the DAC and the Transport DAC. However, the main cable I've been using between the DAC and the Transport is one that made a major difference my converter performance. This cable is one designed by Fred Dieckmann designed and it sure sounds better that the Tara Lab cable I have.
Hat off to you Fred.
Mark & Brian,
Ever mismatch add up to a transmission refection problems which effect the how the DAC’s receiver decodes and clock the data. When Fred said you need 75-ohm impedance cable he not kidding. If you know what a TDR is, you be able to see the reflection caused by the impedance mismatch.
In addition, BNC are made in 75ohm and 50-ohm impedance for a reason. In addition, as Fred stated, there no such thing 75-ohm RCA, no matter what Canare states. I have already been down that path myself.
So WWW.Beldon.com makes a number of 75ohm cables, I am using RG187 which is a Teflon/Silver which connects the connector to the PCB of the DAC and the Transport DAC. However, the main cable I've been using between the DAC and the Transport is one that made a major difference my converter performance. This cable is one designed by Fred Dieckmann designed and it sure sounds better that the Tara Lab cable I have.
Hat off to you Fred.
Re: A farmer outstanding in his field
Not once has a 6 foot piece of coax caused any problems in the transmission of digital audio. The only fertilizer is the stuff you smoke to think you can hear any difference between any two digital cables 6 feet long. Even in the HDTV range I have never had a problem with jitter, reflections, EMI, or any other cable induced distortion and I deal with it every day as I am a post-production engineer for a major studio. Those who claim to know everything because they 'design' don't have the everyday practical experience that is reality. Who do you trust to work on you, a research scientist or a actual doctor with 20 years of working on patients? All your jitter measurements get to the point of academia, after a certain point the sound gets no better with less and less jitter. Your work on digital telephony is commendable, but what does a digital tel line have to do with a piece of coax and EMI? Keep on dreamin'Fred Dieckmann said:
I've always had good results with the Canare LV-77 cable terminated with the Canare RCAP-C77A RCA connectors. I understand that the RCA connectors are not "true 75 ohm", but I've never had any jitter problems. Another good place to get connectors and cable by the foot is Performance Audio .
Cheers,
Zach
Cheers,
Zach
I don't want to be a smart***, butt...
Killjoy99,
If you don't need a new roof, the link to Belden Cables website is:
Belden Inc.
Also, there has been a good bit of discussion "around" this topic before. Around meaning no specifics concerning particular brands of connectors, etc., but much discussion has been presented concerning why some of these digital interfaces can be so poor. A quick search on this site turned up many different threads that have dealt with this more than trivial task of proper interfacing. Here is a link to get you started:
TOSLink Cables All the same? Any degradation over Length?
There are many others. Some of the most knowledgeable posters to look for seem to be Alavius, Fred, Jocko, and Guido Tent. I list these, because they were present in the search response threads. I am sure that there are many other EE that have experience in this area, so please don't take offence to my suggestions.
Also, as you will find in your search, there is alot to be learned in this area for the neophyte. I learn something new everyday concerning electonics. And alot of the material I have learned has been prompted by discussion here.
Thanks,
Killjoy99,
If you don't need a new roof,
the link to Belden Cables website is:Belden Inc.
Also, there has been a good bit of discussion "around" this topic before. Around meaning no specifics concerning particular brands of connectors, etc., but much discussion has been presented concerning why some of these digital interfaces can be so poor. A quick search on this site turned up many different threads that have dealt with this more than trivial task of proper interfacing. Here is a link to get you started:
TOSLink Cables All the same? Any degradation over Length?
There are many others. Some of the most knowledgeable posters to look for seem to be Alavius, Fred, Jocko, and Guido Tent. I list these, because they were present in the search response threads. I am sure that there are many other EE that have experience in this area, so please don't take offence to my suggestions.
Also, as you will find in your search, there is alot to be learned in this area for the neophyte. I learn something new everyday concerning electonics. And alot of the material I have learned has been prompted by discussion here.
Thanks,
Some years ago I stumbeled over a coax that just outpreformed everything I`ve ever heard, used in pairs as interconnects.
Later I was building a set of my famous speakers for a friend who runs a Jadis-set, incuded the Jadis CD-comb. Until then he hadn`t heard any coax coming close to the optical AT&T-cable, and he didn`t waist his time on cheap cables.
But my intercinnect-reference-coax; Vivanco SX-710 did just that; cleaner in both ends.
Plugs? I just uses some cheap WBT-clones, can`t hear any difference even on my equipment
Later I was building a set of my famous speakers for a friend who runs a Jadis-set, incuded the Jadis CD-comb. Until then he hadn`t heard any coax coming close to the optical AT&T-cable, and he didn`t waist his time on cheap cables.
But my intercinnect-reference-coax; Vivanco SX-710 did just that; cleaner in both ends.
Plugs? I just uses some cheap WBT-clones, can`t hear any difference even on my equipment
Re: Re: A farmer outstanding in his field
Wake up yourself!
I work in telecoms. We are changing now to digital distribution frames, but the old ones are just coax cabling. Two coax cables are needed for one 2Mb connection and yes it is a 'digital telephone line' (31 times 64k speech/data channels, one channel for synchronisation, at least in europe it's 32 channels).
Actually the coax we are using for measurement equipement makes a nice interlink cable for audio
If you ever saw such a distribution frame (spaghetti) you could imagine EMI matters for the cabling and the connectors.
Loosing one connection for even a short moment means 30 dropped calls.
Regards,
markp said:
Wake up yourself!
I work in telecoms. We are changing now to digital distribution frames, but the old ones are just coax cabling. Two coax cables are needed for one 2Mb connection and yes it is a 'digital telephone line' (31 times 64k speech/data channels, one channel for synchronisation, at least in europe it's 32 channels).
Actually the coax we are using for measurement equipement makes a nice interlink cable for audio
If you ever saw such a distribution frame (spaghetti) you could imagine EMI matters for the cabling and the connectors.
Loosing one connection for even a short moment means 30 dropped calls.
Regards,
Cheap digital cable: Belden 1605A; solid bare copper, foamed teflon, foil&braid. Several sites sell it by the foot. Terminate with BNC if your equipment has the jacks (or you don't mind replacing RCA jacks with BNC), or else the Canare faux '75 ohm' RCAs. Thin enough, so I added a second, external braid ungrounded at recieving end (bypassed by 0.01uF to prevent antenna), so the outer shield doesn't carry signal.
If there's still interference, AES/EBU (AES3) may be better (for short distances anyway), and even if your recieving equipment doesn't support it you can make a converter. For example if transformer at either end, you can simply use impedance and level matching resistor network:
http://www.rane.com/note149.html (Fig.1, values in brackets for S/PDIF output)
Someone mentioned AT&T optical. I'm curious about the effect on jitter of the optical recievers. Are they really better than a good electrical connection?
If there's still interference, AES/EBU (AES3) may be better (for short distances anyway), and even if your recieving equipment doesn't support it you can make a converter. For example if transformer at either end, you can simply use impedance and level matching resistor network:
http://www.rane.com/note149.html (Fig.1, values in brackets for S/PDIF output)
Someone mentioned AT&T optical. I'm curious about the effect on jitter of the optical recievers. Are they really better than a good electrical connection?
Okey ...
I agree with markp ..
Creating distortion in digital cables is unmistakably possible,
but a good decoder will however look at the signal as either ONE or ZERO.
And about audiocables having a "direction" that would make a detectable differance in sound quality is absurd. This must be just another marketing skeem by retailers.
/Nysan
I agree with markp ..
Creating distortion in digital cables is unmistakably possible,
but a good decoder will however look at the signal as either ONE or ZERO.
And about audiocables having a "direction" that would make a detectable differance in sound quality is absurd. This must be just another marketing skeem by retailers.
/Nysan
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