<table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>
<font color='#000000'>Response to Gene:
[ Please refrain from posting links to Jon Rischs cable receipts as we feel that his designs can do more harm than good. ]
This is too much Gene, way over the top, and without any basis in fact.
I would like to know exactly how ANY of my audio cable designs can be said to be bad, or worse than zip cord or OEM freebie interconnects. Specifics and details, not some unfounded and unsubstantiated feelings or bias.
[ IE. his psuedo twin feeder coax cable receipts where he shorts the center conductor to the adjacent ground shield of the other cable may reduce inductance, but at the extreme expense of adding cable capacitance and reducing the benefit of the shielding. In addition, the cable resistance of his recommended cable is almost 2x greater than standard 10AWG zip cord. ]
If this was meant to be such a detail or technical issue, then you are WAY off base. How about some factual numbers, with the data coming mostly from Fred Davis, so that no one can accuse me of doctoring the numbers, or of 'bad' measurements, etc.?
Typical 12 ga. zip cord, the universally recommended speaker cable, has about 0.00342 ohms of resistance per foot (round trip resistance), about 21 pF of capacitance per foot, and about 0.25 uH of inductance per foot. (Fred originally measured one of the best 12 ga. zips out there, one with closer spacing of the two conductors, so his measurements had the C slightly higher, and the L slightly lower. I am using typical 12 ga,. numbers here, which were provided by Fred on the news groups)
This leads to a measured 0.25 dB HF roll-off at 20 kHz, with a 10 foot length, and a 4 ohm load (This is my measurement, which has been double-checked, and verified by another engineer).
A 10 ga. zip cord would have lower resistance, but the inductance would climb as well, rolling off the HF even more.
My DIY Cross-Connected 89259 speaker cable design has 0.00443 ohms of resistance per foot (round trip), and has 49 pF of capacitance per foot, while only having 0.067 uH of inductance per foot. Note that the HF roll-off would be very small with this level of inductance.
For a point of reference that was not chosen to sound impressive, the resistance is only about 30% higher than for 12 ga. It is not exactly a good Resistor by comparison.
Now the capacitance is indeed about 2 1/3 times as much, but this amount of capacitance must be taken in context with what will cause problems with power amps, or in a system. I also note that the inductance is more than 3.7 times as low.
For instance, heavily braided cables, or the flat ribbon type cables that shoot for extremely low inductance, reach figures of 500-700 pF per foot, more than 10X the capacitance of my design. Yes, some of these cables, with unstable amps, and with longer runs, can reach a total level of capacitance that will
cause oscillations, intermittent instability, etc. This can usually be cured, by helping to stabilze the load the amps see, by placing a speaker cable Zobel at the speaker terminals, which consists of a 8 to 10 ohm non-inductive resistor and a 0.1 uF to 0.22 uF film capacitor.
What is in action here, is the total amount of capacitance causes an interaction with the amplifiers feedback loop, and pushes the phase margin in below the unity gain point. What occurs is a classic example of an oscillator circuit. Technically, this is an amplifier problem, and not totally a cable issue, BUT, in the real world, with folks pushing for maximal bandwidth in the electronics, and so-on, there are a fair number of power amplifiers that are not unconditionally stable, and thus will react badly to enough total capacitance on it's outputs.
How much is this amount of capacitance? Well, for some really unstable power amps or receivers, this can be around 3,000 to 5,000 pF into an 8 ohm nominal load. Most of these kinds of amps will not ever have a problem until the total C exceeds 10,000 pF. There are some exceptionally unstable amps, such as the Naim, which lose it at very low levels of capacitance, barely beyond the amount for a moderate length of zip cord. However, the Naim is an exception, and not the rule.
Note that at these levels of capacitance (3,000 - 5,000 pF), only around 10-12 feet of the braided or ribbon cables will be a potential problem
How many feet of my CC89259 speaker cable will it take to cause a typical worst case unstable amp to _maybe_ have problems? At 49 pF per foot, this would amount to more than 60 feet of cable to exceed 3,000 pF. To reach 10,000 pF, would require more than 200 feet of CC89259 speaker cable.
That is an awful long speaker cable run, and not to be recommended for use in a high performance system.
I want to note that I am on record as recommending the use of 12 ga. zip cords for all but SOTA or near SOTA HT system rear channels/speakers. The signal quality of these rear speaker signals just does not usually warrant anything better.
What about the shielding issue? This is a total red herring, as zip cord HAS no shielding. Most speaker cables do not have shielding, and unless you have severe RFI problems, it is best not to use shielded cables that have a non-active signal carrying shield. This would include foil or copper braid, or a combo over a twisted pair, that is grounded at one end only.
Strictly speaking, if we look at the overall impedance of the CC89259 vs. the zip cords, with respect to how the impedance impacts the amount of inherent noise pickup, the CC89259 has a lower impedance than the zip cords, and so, will have a slightly better situation in this regard. So it is not clear exactly how or why Gene is claiming that there is a shielding problem.
If anything, the CC89259 is better than typical zip cords in terms of external noise pickup.
None of this addresses the OTHER factors in speaker cable performance, and even if one wishes to totaly dismiss the materials involved with the CC89259, the bare copper (it is not uncommon for zip cords to have tinned copper conductors, for at least one of them), the teflon insulation vs. the typical zip cord PVC, and the smaller overall wires involved compared to the 12 ga. which means less skin effect related issues (whether or not you believe that skin effect is an issue for audio cables,or speaker cables, the truth is that the CC89259 will have a lot less than the 12 ga. zip). And of course, that bug-a-boo of AH, the dreaded strand jumping, will be less than for the 12 ga. Again, whether or not you have feelings about strand jumping being a relavant issue or not, there is going to be less of it in the CC89259.
In point of fact, there is absolutely no down side to the use of the CC89259, unless you manage to place yourself in the uneviable position of having a speaker cable run to the front speakers longer than 60 to 200 feet, WITH an unstable amp/receiver, and no parts stores in your universe to construct a simple Zobel network.
Not really any down side, the R L and C are all within acceptable parameters, and the materials and construction COULD offer the potential for superior performance, but certainly NOT worse performance.
One final note, if one actually REQUIRES a 10 ga. speaker cable, then it is a relatively simple matter to create a Star-Quad Cross-Connect 89259 speaker cable, which will then equal a 10 1/2 ga. cable. The capacitance will still remain bearable for most real world lengths of speaker cables of less than 30 to 100 feet, and the inductance wil go down even lower.
[ We have reviewed much of his website and found most of the content therein to be either incorrect, imcomplete, or very misleading. ]
Website. As in the whole website.
My website, at:
http://www.geocities.com/jonrisch/index2.htm
includes DIY information on:
Acoustics treatments of all types, including bass traps, sound absorbing wall panels, room lens, diffusors, all of which have been widely held in high regard.
AC Power Filters, Isolation Transformers, and Balanced Power
Vibration control tweaks and projects
(All of the above acheived at extremely low cost relative to retail products)
Op-Amp upgrades
Sophisticated crossover circuits
A wealth of information on digital audio jitter
and of course, information on DIY audio cables, including an annotated bibliography on cable references.
Perhaps you do not like the cable technical content, and for whatever bizarre reason, do not like the DIY cable designs/projects, but to make such a blanket statement regarding the entire website just shows how personal and biased the comment is, and that it is not really about science, but about your POV vs. my POV, and where audo cables are concerned, you are either the right or the damned. Obviously, AH thinks themselves in the right, and I am damned.
Now I have pointed out errors in the AH cable articles in the past, and when I pointed them out, AH and Gene were very defensive and would not admit to any errors or incorrect content. But then, at the push of a key, the articles are quietly edited, with just a little notice at the very end of the article, that does not detail ALL the changes and corrections.
I note that in one particular article, the one titled:
"Component Video Cables - The Definitive Guide"
I pointed out around 16 errors or inconsistencies in the article, and that as of this date, about 12 of those points have been edited for correction, clarity or content. There are STILL some errors in the article, and some incorrect content, despite it having supposedly been proofed and 'peer-reviewed'. Some of these are the same as my original points, and there are some new ones that have crept in.
In essence, I was right about most (if you do not wish to believe all) of the problems with the article. And yet at the time, I was portrayed as an unscientific cable guru, and other such attempts at denigrating me. Now, the article has been edited along the very lines that I commented on.
I know my cables, my DIY designs are very good, and perform well above typical zip cords or OEM freebie interconnects, yet AH/Gene want to portry me as some sort of evil misleading cable guru that is doing harm to the hobby of audio.
Personally, I think that people who try to discourage folks from trying high performance audio cables for themselves are the ones who are doing harm, and are hurting the hobby.
Finally, let me say that there are some pretty far-out claims made by some audio cable vendors, most of it is marketing excess, some little of it does appear to be incoherent BS.
None of that means that ALL cable vendors are selling snake-oil, or are trying to bilk the consumer, the impression that AH would seem to be trying to make. I believe that most of the smaller audio aftermarket cable companies ae genuinely trying to bring their own honest idea of what is sonically the best to the table, and provide it to the audiophile/music lover.
AH paints with much too broad a brush, including my website, and my cable information. The proof of my DIY designs is in the listening, and so far, not one person has ever regreted building these DIY designs. This is with thousands of folks having built the speaker cables, and thousands more having built the DIY interconnects.
Jon Risch</font>
