[eric343]

Chill, guys.

I've heard the VD Nites. My opinion is that they are as Ebonyks says, euphonically distorted. That's a fancy way of saying that they sound good, but aren't the most transparent cables on the spool... see my review for more details

Now, from a more techincal (scientific?) standpoint, the cables are rather interesting. They have a lot of frequency dispersion, which is a fancy way of saying that if you send a pulse down them, the reflection will be a wider (but shorter) pulse than the one you sent.
Here's a picture of what I mean [a TDR screenshot of the Nites]
http://www.drsue.net/images/TDR/DSCN3450.JPG.jpg

Notice how the second (reflected) pulse is much wider than the first one.

How does that affect audio? Strictly speaking, it shouldn't. However, strictly speaking, cables should be identical at audio frequencies! The TDR trace, however, suggests to me that the cables are "slow" - they have a measurable risetime (compared to the barely-existant risetime of say, microwave-designed coax) and a VERY slow falloff. If you translate this to the audio bands (which, again, strictly speaking you CAN'T do) then one would think the cables would have a smooth character lacking in the high end.

The problem is, this is High Fidelity audio we're talking about- where things like Mapleshade cones and IEC jacks (see the Pink Chiarra thread in the DIY forum) make a difference, even though they by all accounts should have no audible effect at all. So personally, I'm happy to have finally found an instrument that can do in a limited fashion what our ears have been doing for years- tell the difference between audio cables.

Unfortunately, I don't know of anyone who's tried frequency response sweeps on cables, which "should" tell us everything. I'd try it, but the gear to do a proper sweep is pricey enough that I'll get a Wadia (or dCS stack

) first.

 

[Habib]

While I am a believer of ICs, I think I might have hit a wall with the VD Power 3 I just purchase. There is a barely noticeable difference in the bass region which fleshes out the sound slightly more. I would imagine ppl not familiar with my setup unable to detect the difference. I may have crappy power since it causes anomaly on CRT monitors around the house. However, I am still skeptical about PCs.

 

[Ebonyks]

In my experence, the effects of a PC are limited, but are certaintly worth looking into. I'm a big fan of john risch's explaintion of powercables, avaible here:

http://www.geocities.com/jonrisch/ac-cords.htm

I would think that by getting some 12ga copper wire, and wrapping it thick in shielding foil, you could get pretty close to the results of the power three at a fraction of the price. Cryogenic treating in a powercable, IMHO is just silly

 

[Hirsch]

Quote:

Originally posted by eric343 Unfortunately, I don't know of anyone who's tried frequency response sweeps on cables, which "should" tell us everything. I'd try it, but the gear to do a proper sweep is pricey enough that I'll get a Wadia (or dCS stack ) first.

John Atkinson at Stereophile has been doing measurements of gear for years, trying to objectify what his reviewers report. Results have been imperfect. If he hasn't done a frequency response sweep, he might be willing to try if you can make a good case for it.

 

[markl]

Eric,
IIRC, wasn't the signal you sent through the VD cable and measured well outside the audible band? If so, what does that test really tell us about the behavior of actual audio signals via the Nite cable? Or am I thinking about something else?

 

[eric343]

Quote:

Originally posted by markl Eric, IIRC, wasn't the signal you sent through the VD cable and measured well outside the audible band? If so, what does that test really tell us about the behavior of actual audio signals via the Nite cable? Or am I thinking about something else?

Yes, it was- that's why I'm saying that you strictly speaking can't translate TDR results to the audio band!

Unfortunately, due to basic physics, it would be impossible to do normal pulse-type TDR testing at audio frequencies unless the cable was fantastically long (we're talking miles here). Unfortunately I haven't been able to afford a metallic (step) waveform TDR instrument which in theory could work at audio frequencies since it uses the leading edge of a square pulse as its 'spike'.

 

[Czilla9000]

I think eric, markl, and ebonyks are all correct. But in different ways and reasons.

(BTW, sorry if I came off mean earlier)

My opinion on cables is closely related to Audioholics.com's opinion of cables. They believe cables make a difference BUT they CAN also be measured. They believe that capitance and inductance and shielding/EMI/RF are the sole factors involved in cable design - primarily because they can be measured. (The people at Audioholics are EE's BTW)

Because of this, they believe many cables, like Ebonyks and eric do, are distorted. For instance, I read somewhere that the RatShack Golds have 15 pF of capitance - which is extremely good (close to the 12 pF that some $500 Cardas have) .

Because of this, Audioholic's believe that many of the expensive aftermarket cables are really just "long capacitors" and perform worse than many cheaper cables. Because of this, they believe that many cable makers are selling snake oil.

We can observe this is the real world. If you go to Zu Cables website, you will notice that the more expensive the cable they sell the higher the capitance (exception: the Oxyfuel)!

Zu Cable has stopped posting capitance measurements on many of their cables now (for obvious reasons). For instance, Zu's cheapest cable - the $24 Pil - has 70 pF of capitance. In comparison, Zu has stopped posting the capitence measurements of the $499 Varial. The Varial is their flagship cable, and if I remember correctly it had (back when they posted it) 174 pF of capitance. The $24 cable has 70 pF of capitance, while the $499 cable has around 174 pF of capitance! (NOTE: I should commend Zu for being honest in their measurements, though it is fishy that they have removed some of them).

Their is only one cable in Zu's lineup that beats the $24 Pil, which is the $74 dollar Oxyfuel. The Oxyfuel gets 58 pF. However, the $24 Pil beats every other cable in their line up besides the Oxyfuel.

You will notice that the Oxyfuel and the Pil use the least exotic features. I will comment on this later.

(However, by any audiophiles account, the Varial sounds better than the Oxyfuel. Make of this as you will.)

Now about MarkL's opinion. For some reason I have a hunch that, unlike the Zu Cables, the VD cables are not euphonically distorting (or at least as much). Why? Because besides the ferrite, the Vd cables really aren't that exotic. Where as Zu uses odd B3 geometry and funky conductive materials, such as AuTi (gold and titanium are conductive) as a dielectric, and "silver alloy" as a conductor - the VD cables use simple large gauge copper and a standard dielectric. I cannot see where a large capitance would come from.

NOTE: This does not mean that cable manufactuers should not experiment with different cuting edge designs - they should - but some of these designs don't work as well as normal ones.

To eric, I think it is great you are TDRing cables. The FR idea is also good. However, ideally, a cable should perform BAD with the TDR test. This is because, ideally, a cable should be able to transmit 20-20,000 signal perfectly, while rejecting the higher MHz/GHz frequencies.


Thank you for your time.

(PS- I actually have a more exotic theory about cables and capitance.............but I am keeping it for later)

 

[Wodgy]

Quote:

Originally posted by Czilla9000 However, ideally, a cable should perform BAD with the TDR test. This is because, ideally, a cable should be able to transmit 20-20,000 signal perfectly, while rejecting the higher MHz/GHz frequencies.

That's basically what Eric's measurements are saying about the VD cables, intuitively.

Capacitance isn't the only issue. Like everything, it's a tradeoff. More elaborate shielding schemes increase the cable's capacitance, but also increase its resistance to interference. Radio Shack Gold cable plugs also tend to suffer badly from oxidization over time (at least mine do), increasing the overall capacitance.

 

[eric343]

Quote:

Originally posted by Czilla9000 My opinion on cables is closely related to Audioholics.com's opinion of cables. They believe cables make a difference BUT they CAN also be measured. They believe that capitance and inductance and shielding/EMI/RF are the sole factors involved in cable design - primarily because they can be measured.

I agree- sort of. Quote:

We can observe this is the real world. If you go to Zu Cables website, you will notice that the more expensive the cable they sell the higher the capitance (exception: the Oxyfuel)!

In my opinion, capacitance is not the only factor affecting fidelity, nor is it a simple metric by which you can say, "this cable is better than that one because it has lower capacitance." In cables, capacitance, inductance, and resistance are linked in a complex model that results in something called impedance.

http://www.epanorama.net/documents/w...impedance.html
Quote:

Their is only one cable in Zu's lineup that beats the $24 Pil, which is the $74 dollar Oxyfuel. The Oxyfuel gets 58 pF. However, the $24 Pil beats every other cable in their line up besides the Oxyfuel. (However, by any audiophiles account, the Varial sounds better than the Oxyfuel. Make of this as you will.)

As I've said before, I don't think that it is safe to assume that capacitance is inversely proportional to sound quality-- which is why, as you say, that the Varial sounds better than the Oxyfuel. Quote:

Now about MarkL's opinion. For some reason I have a hunch that, unlike the Zu Cables, the VD cables are not euphonically distorting (or at least as much). Why? Because besides the ferrite, the Vd cables really aren't that exotic. Where as Zu uses odd B3 geometry and funky conductive materials, such as AuTi (gold and titanium are conductive) as a dielectric, and "silver alloy" as a conductor - the VD cables use simple large gauge copper and a standard dielectric. I cannot see where a large capitance would come from.

Czilla, there are a number of factors that affect the capacitance of a cable, and internal conductor geometry / conductor materials have fairly little to do with it. Capacitance of a certain cable is related to the dielectric (specifically, the dielectric's dielectric constant), the spacing between conductors (signal and shield, usually), and the length of the cable. We do not know very much about the dielectric used in the VD Nites, however we can determine the length of the cable easily and make a guess at the spacing between shield and conductor based on the CT scan images of the Nites that I posted here: http://www.drsue.net/images/nite/

The only way to accurately determine the capacitance of the cable as seen by the source would be to hook it up to a capacitance meter. Although I have two, when I was borrowing the Nites the idea of measuring their capacitance did not occur to me.

Quote:

To eric, I think it is great you are TDRing cables. The FR idea is also good. However, ideally, a cable should perform BAD with the TDR test. This is because, ideally, a cable should be able to transmit 20-20,000 signal perfectly, while rejecting the higher MHz/GHz frequencies.

Why?

In my opinion, a broader frequency response will usually provide greater fidelity as it will better reproduce harmonics and detail, among other things. Especially in cables, I believe that one should maximise the frequency response so that the components become the controlling factor. It does not do to put a fancy filter into a system that doesn't need it.

The argument for a restricted frequency response, as propounded by Transparent Cable & Co., largely centers on the idea that limiting frequency response will reduce the noise injected into the system by the cable. I feel that noise as generated by a cable is a moot point provided the cable uses high quality 100% coverage shielding.

 

[Czilla9000]

Eric....you are right that inductance and resistance do also make a difference. However, capacitance is said to make the largest difference in interconnects of the three factors.

I could be wrong, but capacitors role off higher frequencies, right?

 

[Ebonyks]

Yes czilla, however, the capacitence in cables is reltively low to a point of where rolloff will not occur in any quanity in the audible range.

 

[00940]

czilla : when I finished my CAT5 speakers cables, i tried them against other cables, with friends, some being very confident in the superiority of low capacitance. It was in a shop where repairs on hifi is done, so we had accurate measures of capacitance.

The capacitance of 12 feet of a cat5 braid, made out of 30 24awg conductors (a braid of 5 braids of 3 twisted pairs), was "awful". I mean, around 8 times superior to some of the good wires in the room. Too much for the good of some amps.

We didn't not all agree on which wire was best. It'd be too easy

However, the cat5 (that was among the cheapest wires, not including my labor

) was perceived as "good" and certainly better than some other wires with low capacitance and (far) higher prices (mainly QED and Oelbach wires in the room). More interestingly, everyone agreed on one thing : the cat5 was among the most extended in the highs, perhaps even slightly bright, with a bass a bit light. It was still the cable with the highest capacitance.

 

[eric343]

If I remember correctly, due to the currents involved in speaker wire, inductance can be an important factor, certainly a more important one than capacitance.

I haven't done any research or development of speaker cable, however.

 

[Czilla9000]

Hehe.....this discussion on capacitience is helping me formulate my design....Thanks guys!

 

[eric343]

Quote:

Originally posted by Czilla9000 Hehe.....this discussion on capacitience is helping me formulate my design....Thanks guys!

Oh no, we're all doomed!

I look forward to seeing what you can produce.