TweekGeek Silver digital coax for only $19.95?

woodsyi · « **on:** 1 May 2006, 05:08 pm »

This looks like a good deal on a digital (SPDIF) cable. Has any body used this before and if so how does it perform?
http://www.tweekgeek.com/product.asp?pf_id=CTSilverAV

JoshK · « **Reply #1 on:** 1 May 2006, 05:21 pm »

I am using them and like them but I have made no pairwise comparisons. I think for $20 you can't go wrong. You can always put fancier connectors on the ends if you want to up it some. These kind of cables are very easy to terminate.

hometheaterdoc · « **Reply #2 on:** 1 May 2006, 07:47 pm »

I've got one here that was given to me to try after CES last year. It's not the best cable I've ever heard, but you won't find better for $20 unless someone is giving something away

Pretty clean sounding cable. I don't like it as much as the Analysis Plus digital cables I normally use, but there is a disparity in price, afterall

Russell Dawkins · « **Reply #3 on:** 1 May 2006, 07:57 pm »

I'd feel still more secure going with Blue Jeans at 13.50 for 3 ft or 14.50 for 6ft.
I don't think the silver aspect has any relevance for digital transmission, although the 75 ohm impedance apparently does, and I trust that Canare knows how to make 75 ohm RCAs.
All this is moot if the cable does not "see" a 75 ohm termination at either end. My (limited) understanding is that reflections from end to end within the cable that occur when there is an impedence mis-match at either end of the cable add jitter to which some D/As are more sensitive than others.

Dan Banquer · « **Reply #4 on:** 1 May 2006, 08:32 pm »

Quote from: Russell Dawkins

I'd feel still more secure going with Blue Jeans at 13.50 for 3 ft or 14.50 for 6ft.
I don't think the silver aspect has any relevance for digital transmission, although the 75 ohm impedance apparently does, and I trust that Canare knows how to make 75 ohm RCAs.
All this is moot if the cable does not "see" a 75 ohm termination at either end. My (limited) understanding is that reflections from end to end within the cable that occur when there is an impedence mis-match at either end of the cable add jitter to which some D/As are more sensitive than others.

As far as the silver aspect of the cable goes, the Belden rep I spoke to doesn't think much of it either. They predominantly sell the silver stuff to the military. You are absolutely correct about reflections & impedance mismatch. The cable is only 1/3 of the sum total of the transmission line. The output driver and the input receiver comprise the other two thirds.
Great post Russ;
d.b.

MaxCast · « **Reply #5 on:** 2 May 2006, 11:33 am »

Are you saying the output driver and the input receiver are or can be different impedances?

Is the tweek geek cable a 75 ohm cable?

What is the difference between a 75ohm connector and a non-75 ohm connector?

Thanks

Dan Banquer · « **Reply #6 on:** 2 May 2006, 11:51 am »

The output driver must have a 75 ohm output impedance and the input receiver must have a 75 ohm output input impedance for SPDIF. The connectors must also have the same impedance. That's the theory for transmission line applications.
Hope this helps;
d.b.

woodsyi · « **Reply #7 on:** 2 May 2006, 02:05 pm »

So, how do I measure the impedance of my source output and my DAC receiver input? Am I right in reading that you are implying that these are not all 75 ohms as they should be?

Dan Banquer · « **Reply #8 on:** 2 May 2006, 04:42 pm »

You really need a network analyzer to do an accurate measurement of this type.
I find that, from what I have seen to date, that most output drivers found in consumer equipment just cannot be a 75 ohm output impedance over the frequency range needed. Given the ready availability of video band op amps with line drive capability I find this hard to understand. Then again there are a number things that happen in consumer audio that puzzle me, so I guess we can add just one more to add to the list.

d.b.

Russell Dawkins · « **Reply #9 on:** 2 May 2006, 05:32 pm »

I'm no EE but my understanding is that impedance matching is important for digital transmission by wire.
I had presumed that, since it was first raised as an issue in the "mainstream press" about 15 years ago, when it was discovered that not many cables, inputs or outputs actually measured very close to 75 ohms at all, manufacturers would have been going to greater lengths to ensure that their SPDIF ins and outs were actually, rather than nominally, 75 ohms. I haven't bothered to check, but, as Dan points out, you need a network analyser.
I notice that some respected cable designers don't agree; here is a clip from the April 2006 newsletter from Virtual Dynamics designer, Rick Schultz ....

quote...

On to the "tip of the month": digital cables. Well, please read outside of "the box" and know this isn’t just about digital cables.

Over the last few years I’ve had several people inquire if we build 75 ohm digital cables. The answer is no. The question that comes to mind every time I’m asked a question like this is, "What is this customer actually looking for?" A good sounding cable? Or 75 Ohm?

What is a digital signal? It is an electrical representation of data. What is confusing is all of the theories behind digital cable builds. It seems as though some are actually trying to convince us that digital data contains the same "1’s" and "0’s" that you see on this page. This is obviously not the case. Sometimes things become so technical we forget how simple it is! For those of you who don’t already know, Virtual Dynamics builds digital cables the same as analog. It is the same cable with a different label, that’s it! Why would we do such a thing?

This presents an opportunity: if you have one of our analog cables, you can try it as a digital. If you remove bias of how it ought to be built, and just listen, you will hear why we’ve had such high praise for our digital designs. You will understand that electrically speaking, there is no such thing as digital data, simply electrons. We believe our cables are the ideal environment for electrons to pass a signal. This brings me back to the start. When shopping for your next audio component, keep an open mind and trust your God-given senses. If it sounds realistic, and it sounds like truth, it probably is.

Lastly, the question often comes up, "What digital cable should I use?" In our experience, the benefit of using RCA, BNC, or XLR simply can’t be beat and we’re exposed to some of the very best types of signal transfer, including glass optical cables costing $4000+. The reason is that the signal does not have to convert from one medium to another. For example, conversion from electricity to light, and then back again must cause degradation to the signal. Our advice is to keep the signal in its original electrical form, and use the best cable you can commit to, often it is one of the most important links in your system.
....unquote
http://www.virtualdynamics.ca/newsletters/february%202006/

I'm guessing a network analyser is not part of his shop.