crm0922 wrote on Wed, 23 March 2005 01:31 |
danlavry wrote on Tue, 22 March 2005 17:28 | Max,
Yes I know, you cannot argue about “Ultra Low jitter cable”. No one can. You don’t have any measurements to show, just the regular SNAKE OIL blended with personal attacks, followed by claims of hearing it better.
ULTRA LOW JITTER CABLE IS SNAKE OIL. No way around it! Oops, you forgot to answer the other question about the "Temperature Controlled Cable".
Dan Lavry Lavry Engineering, Inc.
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Dan, if I were to use a piece of zip cord to carry word clock signals, would I experience more jitter on the receiving end of my system? I am asking this question honestly, as the thought that a cable could contribute to jitter issues seems at least reasonable.
If the zip cord is bad news, then would proper impedance and capcitance ratings improve the jitter situation? If so, could Apogee's cable be built with exacting standards that help resolve such issues?
I sure have learned a lot from this discussion, and I don't mind the snapping back and forth. This type of discussion will make everyone's products better, since you know there are people there to question it.
Now I'll refrain from posting to this thread 10 times a day for a little while.
Chris
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Chris,
First, let me have some fun:
Let us give Max the opportunity to dig a bigger hole!
Say Apogee is right. Say they discovered that there is another physical law to be added to the 5 Maxwell equations. Maybe not, I will be flexible. Say there is some mechanism that makes cables manufacture jitter. That is what Max said is it not?
So in the good old tradition of cable specs, lets come up with a figure for pico second per foot (cables are specified in pF/foot , Ohms/foot, uH/foot…). Say 1psec /foot jitter sounds like a great spec to me (why not, I can pull things out of the air as well as Apogee). So take a zero jitter clock (assuming it is there) and add 100 feet of cable, and you have 100psec jitter.
So that is one more argument leading us to the conclusion that internal clocking is better, and assuming Big Ben has little jitter, 100 feet of cable will do you in. So go for internal clock.
There is still one more problem left. No one is saying what temperature controlled cable is. I thought about it long and hard, trying to figure out what the hack is temperature controlled cable. I figured if I say the wrong thing, I will be accused of deception, but let me give it a try:
There is a hidden oven built around the copper to make sure the electrons are happy. If they get a cold, they may start shaking very fast and when they enter the low jitter PCB trace they will be very jittery. I wonder if the temperature control is solar or nuclear.
That is the best I can come up with, and the sellers of that will not shed any more light on the issue. Until such time, I have the right to mock it. I think the customers have the right to demand an explanation!
Now, that I had my morning fun… to your question
If I carry your argument forward, then resistors make jitter, capacitors make jitter, everything does. Of course passive components do not generate jitter, least of all a cable, a solid piece of copper.
A cable bandwidth, capacitance, resistance, inductance, the skin effect, the proximity effect and the rest of the specs obey the same principles that ALL OF ELECTRONICS does – the 5 Maxwell equations, the laws of physics that govern all electricity and magnetism (which always go hand in hand).
A resistor generates noise. That noise is and the mechanism which generates it is all in line with Maxwell’s equations. There is a mechanism at play that is explainable. Say I build a comparator circuit for word clock detection. I will use resistors. To set a detection point (threshold). If I use higher value resistors, they will generate more noise, and the outcome can be more jittery.
Does that open the door to salesmen to sell low value resistors as "low jitter resistors"?
Each part, be it a resistor, IC, cable… has specific characteristics that are INDEPENDENT of its application. A 10 Ohm resistor is ALWAYS 10 Ohms resistor, be it for audio, instrumentation or just in the stock room all by itself. A 1/4 watt resistor is always a 1/4 watt resistor. I know a lot of things about that resistor and they GO WITH THE COMPONENT. Of course if I dissipate more power than the rating allows, I will fry it. If I only dissipate 1mW in a 250mW device I have huge margin of safety. It does not mean that I can call it high reliability device. IT IS THE WAY I USED IT that made it high reliability.
It would be appropriate to consider the specs that come with a cable. You may want it to be of certain bandwidth, capacitance, shielded, and so on. That is how you put a system together. But to say that the cable makes jitter?
You can say that a system has low jitter because of a list of factors and cable bandwidth may be one of them. Cable shielding may be another. Much of the outcome is about the interaction of different factors such as cable driver characteristics, load, environment noise, grounding. So you cannot attach attributes to a component characteristics, that varies from case to case, from setup to setup.
I can cut a tree and put it on a high speed jet. Does it become a “high speed tree”?
And again, I really want an explanation regarding the meaning of temperature controlled cable. Apogee will not answer me. They are the “Wal-Mart of converters”. There are a lot of ear people in the industry, that do not know much technical. But almost every one knows that there is a thing called jitter and “it is a bad thing”. So you sell them a flawed concept about an external box fixing a problems in another box, and that is a crock. But they push it anyway. Even after their engineer backs off the claims AND HE DID RIGHT HERE ON THIS FORUM. ANYONE THAT CAN READ CAN SEE IT FOR THEMSELVES. Then you add some BS about ultra low jitter temperature controlled … it is really bad for the industry to have people believe in BS.
You see, ear people get to decide what they want, what they hear, what they like. In a sense, everyone is “king” of their own turf. But this forum is technical, and that “equality” does not exist here. Some people are technical gurus and others are totally uninformed. One can have a lot of awards in the ear side and it does not make them technical. One of the difficult challenges for me is to learn to accept that a lot of visitors here are just “used to a different style” where they get to decide everything. A guy came here yesterday talking about his awards and many years of work as if it is the most importent thing for a cable or clock discussion. What about my many years of dealing with the ELECTRONIC aspects of the cable? I have no cable awards. In fact, it is the end of the era where “fat cat club” ruled audio by ear, ignoring technical realities, with technical awards given by name recognition (thus advertising money). Where is it all leading?
The method of advertising crock in audio has been traditionally to drum up some well known names and have them say nice things for you in exchange to something else.
Technical folks are a lot less willing to “just say anything”. But hearing people don’t look at numbers, and they “bend easier”. You can see the discrepancy between Lucas and Max. Lucas came back to a defensible position. Max will not. Perhaps Lucas wishes that his company would have not said that their cable is low jitter temp controlled.
So naturally, all the snake oil in audio comes back to drumming up folks willing to say things about “how it sounds”. You make them believe you are about substance and they will back you up. Some have so much confidence that they do not even bother with a blind test. They have done so for many years, being respected, even reinforced for such behavior.
And now I am here, calling it BS. Yes Max, the equipment salesman from Sweetwater, now at Apogee, has attacked me and I will respond to it in the next few days. I am still here, at almost 60 years of age, after designing lots of gear for my own and various companies and making a very good living, with very appreciative and happy customers.
I have 3 new products waiting for me to finish them if only I could get away from this forum for a while.
Regards
Dan Lavry
www.lavryengineering.com