You are here

Log in or register to post comments
Reptiles00
Reptiles00's picture
Offline
Last seen: Never ago
Joined: Mar 16 2006 - 6:28pm
Analog/Digital Cables

Hi, I'm new to these forums and just getting back into having a 2 channel highend system. Can anyone tell me what the physical differences are between analog and digital interconnects.

Also, are there interconnects that are specific to turntables due to their physical construction?

Thanks,
Don

Jeff Wong
Jeff Wong's picture
Offline
Last seen: 3 years 3 months ago
Joined: Sep 6 2005 - 3:28am
Re: Analog/Digital Cables

Hi Don - Welcome to the forums. I can try to answer some of your questions. In the most general ways, materials for example, there's not a lot of difference. The main difference between digital cables and analogue ones has to do with the impedance, and then might differ in construction in order to maintain that impedance. An AES/EBU digital cable should fall into the range of 110 ohms and is a balanced digital cable, using XLR connectors. An S/PDIF cable is single ended and should be 75 ohms. There are + and - % allowances for both. Some of the confusion that may arise probably comes from the outward appearance of analogue cables with RCA connectors and S/PDIF digital cable using RCA connectors. An RCA connector is not really designed for the specifications of S/PDIF. The thing to remember about S/PDIF 75 ohm digital cables is that the ratio of inner to outer conductor diameter in the coax (or connectors) determines their impedance (in this case, 2:1) as long as the dielectric constant of the insulator stays the same. A BNC connector, because of its construction is able to maintain this ratio. With an RCA connector, it's virtually impossible to do this. Unfortunately, there are few companies that use the superior BNC connector.

This is a clear explanation of the above:

http://www.bluejeanscable.com/articles/75ohmrca.htm

The design for digital cables has to be more stringent to maintain these impedances. Analogue cables can vary far more in terms of construction. Goertz ribbon cables have very low inductance, but extremely high capacitance, which makes them poor candidates for hooking up to a turntable (I've tried and the squealing is unbearable.)

Because of the delicate signals involved in the phono stage, I'd think a nice shielded cable would be preferable. But, I know my friend Wes likes Kimber KCAG for phono, and that's a tri-braid construction that relies on its braiding for shielding as opposed to having typical shield. Knowing his preference, I tried a similarly constructed silver cable for my own setup, which I now currently use. The are endless possibilities and solutions... no one construction is going to be right. You need to try out different cables and find what works in your system.

Reptiles00
Reptiles00's picture
Offline
Last seen: Never ago
Joined: Mar 16 2006 - 6:28pm
Re: Analog/Digital Cables

Hi Jeff,
Thanks for the great reply.

I do have some Audioquest Rubys or Emeralds somewhere in my storage unit so I'll have to try them first. I think I bought these cables back in the mid 90s when I was running a Denon DP59L and Audio Technica AT-F3 and AT160ML Cartridges.
Once I have a reference to compare to (with the Audioquests) I can then try something from local dealers and maybe the Kimbers which I think Needle Doctor carries.

Thanks Again,
Don

Jeff Wong
Jeff Wong's picture
Offline
Last seen: 3 years 3 months ago
Joined: Sep 6 2005 - 3:28am
Re: Analog/Digital Cables

Don, you're welcome. As I recall, some of the cables in Audioquest's line use PVC sheathing, which is a less than ideal insulation. If you still have product literature on your cables, check to see what dielectrics are used on yours. If you have PVC, it's definitely worth giving a listen to cables using Teflon insulation.

Monty
Monty's picture
Offline
Last seen: Never ago
Joined: Sep 16 2005 - 6:55pm
Re: Analog/Digital Cables

Hey Don, when you do reintroduce the Audioquest cables into your system, they will have been in storage long enough to need another 100+ hours of current to sound right again. They will sound just awful in comparison to fully settled cables and you might be tempted to yank 'em out too early.

Reptiles00
Reptiles00's picture
Offline
Last seen: Never ago
Joined: Mar 16 2006 - 6:28pm
Re: Analog/Digital Cables

Thanks Jeff and Monty.

Yes, the cables have PVC as their insulation, I thnk all the AQ cables on my system are PVC.

As to break in..... hmmmm..... maybe thats why I'm not too thrilled with the boominess I have now that I connected the old AQs. I was thinking I just needed some sound dampening behind the speakers or tune the speaker ports with the foam inserts that came with the KEFs.

Looks like some breakin and room changes may be a great days project

Don

Oh, I did post some Qs on the Analogue Resources forum as to cartridge setup. I did change my cartridge and realigned it square on my headshell and the soundstage issues seem corrected.

Jeff Wong
Jeff Wong's picture
Offline
Last seen: 3 years 3 months ago
Joined: Sep 6 2005 - 3:28am
Re: Analog/Digital Cables

Don - Hopefully your sound will improve after running signal through the cables for a hundred or two hours. I usually try to stay away from analogue and digital cables using PVC... they often sound smeared and unfocused to me. It's possible the boominess you're hearing might partially be caused by the PVC insulation.

I posted some related thoughts/info here:

http://www4.head-fi.org/forums/showthread.php?p=1984354#post1984354

  • X
    Enter your Stereophile.com username.
    Enter the password that accompanies your username.
    Loading