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post #211 of 1712
Quote:
Originally Posted by slim.a View Post
Dan Lavry,

Thanks a lot for taking the time to explain to us your view on the relationship between digital cables lengths and jitter. It gives valuable information for anyone using a usb to spdif converter as a transport with an external dac which obviously requires the use of a digital cable and choosing the adequate length (shorter or longer).

If you don't mind, I am going to link your posts in the main review (as well as Steve Nugent's article) so that readers can be aware of both views and make up their minds and choose the right length of digital cables accordingly.
I do not mind if you want to link my post. But please note that I am not "expressing a view". I am stating facts about basic electronics principles, and those facts can not be disputed, any more then Ohms law can be. In fact, it is Ohms law that is the KEY for understanding the reflection issue.
I will be glad to explain why that is.

It was wise of you to point out that cable impedance IS related to the issue (SPDIF to USB conversion and USB to SPDIF). And of course, what I stated would be good information for ALL cables including USB. It is always good to have an idea about the signal rise time, and the delay (cable length), which tells one if they need to terminate or not.

But it seems to me that some people here rather not hear it.

One more time: if anyone has a "different view" of reflections then what I stated, they just do not know what they are saying. The subject is not about wishful thinking, "adopting a view" or about making things up as you go along. As a professional, I have no need, time or desire to argue with non professionals that have no clue. I stated what I did as a "public service". I have no commercial interests in convincing anyone to buy shorter cables, longer cables or any cables. I like to enlighten people because I am for great audio.

The first time I had to focus on the subject of reflections was around 1970. I was working at EH research (California) where my job was to design a state of the art in high speed integrated circuits tester for IBM. The million dollar system had 2 huge chassis, each with 24 large printed circuit boards, and it was all controlled by an IBM 1130 computer. Toshiba also bought a few of that system. Much of the technology I used was ECL (emitter coupled logic), and the main maker of the logic was Motorola. At that time, a 1nsec (MECL III) rise was considered real fast, and 3nsec (MECL 10K) was very fast also. Motorola called the IC's family MECL (M for Motorola). At that time, Motorola supported thier MECL IC's with a handbook called "Designing with MECL integrated circuits".

I mention that old publication because it is a very good material for anyone that wishes to read about reflections and how to deal with the issues. I suspect one can get their hand on that publication - they printed a lot of them over many years. That is how I focused on reflections, so it may help others interested in the subject.

Of course there are very many other newer publications that deal with line and cable terminations. One can look at application information regarding line drivers and receivers. The information is all over the place. This is all basic general engineering stuff, not just digital audio stuff, and no one outside of some fringe group in audio has the "hutspa" to go against it.

I am sorry if I sound short or harsh, but electronics engineering is not a democracy! Folks do get to "vote" on what they like or dislike. But one does not get to vote on Ohms Law, and 1+1=2 and is not a subject for disagreement or opinions.

Regards
Dan Lavry
Lavry Engineering
post #212 of 1712
Quote:
Originally Posted by punk_guy182 View Post
Who are you man?
What does that matter, dude or do you listen to viewpoints only based on their reputation?
post #213 of 1712
Thread Starter 
Quote:
Originally Posted by Dan Lavry View Post
I do not mind if you want to link my post. But please note that I am not "expressing a view". I am stating facts about basic electronics principles, and those facts can not be disputed, any more then Ohms law can be. In fact, it is Ohms law that is the KEY for understanding the reflection issue.
I will be glad to explain why that is.

It was wise of you to point out that cable impedance IS related to the issue (SPDIF to USB conversion and USB to SPDIF). And of course, what I stated would be good information for ALL cables including USB. It is always good to have an idea about the signal rise time, and the delay (cable length), which tells one if they need to terminate or not.

But it seems to me that some people here rather not hear it.

One more time: if anyone has a "different view" of reflections then what I stated, they just do not know what they are saying. The subject is not about wishful thinking, "adopting a view" or about making things up as you go along. As a professional, I have no need, time or desire to argue with non professionals that have no clue. I stated what I did as a "public service". I have no commercial interests in convincing anyone to buy shorter cables, longer cables or any cables. I like to enlighten people because I am for great audio.

The first time I had to focus on the subject of reflections was around 1970. I was working at EH research (California) where my job was to design a state of the art in high speed integrated circuits tester for IBM. The system had 2 huge chassis, each with 24 large printed circuit boards, and it was all controlled by an IBM 1130 computer. Much of the technology I used was ECL (emitter coupled logic), and the main maker of the logic was Motorola. They called the IC's MECL (M for Motorola). At that time, Motorola supported thier MECL IC's with a handbook called "Designing with MECL integrated circuits".

I mention that old publication because it is a very good material for anyone that wishes to read about reflections and how to deal with the issues.

Of course there are many other newer publications that deal with line and cable terminations. This is all basic general engineering stuff, not just digital audio stuff, and no one outside of some fringe group in audio has the "hutspa" to go against it.

I am sorry if I sound short or harsh, but electronics engineering is not a democracy! Folks do get to "vote" on what they like or dislike. But one does not get to vote on Ohms Law, and 1+1=2 and is not a subject for disagreement or opinions.

Regards
Dan Lavry
Lavry Engineering
Thanks for the clarification. Since I am no engineer, I did not fully understand your statement

Anyway, as Lavry Engineering is one of the most respected companies when it comes to professional DACs, I am sure you know your physics/electronics and jitter theory better than most of us.

I will link your posts as being an explanation of jitter theory on digital cables and statement of facts about electronics principles (instead of point of you). I will however also link Steve Nugent's article on digital cable mentioning Empirical Audio also sells digital cables (which obviously affects their objectivity).

Thanks again for taking the time to explain to us about this issue. Recommending shorter cables will probably save a lot of money for many people (including myself).
post #214 of 1712
Dan,
I would be quite happy to trash this out in another thread if you wish but your statements that what you are saying is "fact" is a typical ploy of those who can't use logic to put their point across. I would be delighted to hear your full response to my points above in another thread!

So far you have tried to insult me a number of times now rather than answer the individual points I've raised so I'll await your detailed reply to my last post to you

I'm willing to learn but so far what you have said doesn't make sense to me. It's not that I don't want to hear, I just can't gel it with what I have heard already that does make sense to me!
post #215 of 1712
I wouldn't want to speak for Dan, but I frankly wouldn't give a half a squat about trashing this out with someone whose argument is that something does not gel with what they hear, especially not in a public thread and I'm not a professional circuit designer. I personally say good riddance to those who read his explanation and still decide they wish to travel into the mist. I would rather read about USB to SPDIF converters more.
post #216 of 1712
jkeni

I did not mean to insult you.

You said:
"I believe this is contrary to the accepted understanding of a reflection - as a portion of the signal that bounces back along the transmission line (multiple times) & one of the main causes is when a signal encounters a variation in impedance on the transmission line. Is this not what you understand by a reflection?".

Yes and that is what I said, and in greater detail. You have a reflection coefficient at the load end and a different one at the driver end, and the reflections bounce back and forth. For a single rise or fall, the reflections decay exponentially, and of course the driver may send a new rise or fall way before the previous reflections decayed, which causes a mess. The cure is to terminate the line with a resistor equal to the line impedance (such as 75 Ohms.

"There are multiple return reflections on EVERY line, long or short. Whether there are reflections is not a function of the length of the line - only the time it takes them to travel from one end to another is effected by the length of the line".

That is also correct. In fact the reflections last forever, even for a single transition signal. They decay exponentially. But from a practical stand point, at some point the amplitude is lower then the noise. Say you have a reflection coefficient of .2 at the load and -.9 at the source.
1st: reflection at the load is .2
2nd: .2 X (-.9 X .2)= -.036
3rd: .036 X (-.9 X .2) = +.00648
4th: .00648 X (-.9 X .2) = -.00116
5th: .00116* (-.9 X .2) = +.000209 ....
10th: .... = .000000004
15th: .... = .0000000000075

And indeed, if the line is longer, then it takes more time. As I stated, the travel time is around 1.5nsec per foot. But you seem to miss the point: A reflection only happens if you have something to reflect. When you drive a sudden step into a line, say 10V into 100 Ohm line, You are sending a 10mA current step down the line. But the signal does not appear at the end until later, which is the time delay of the line. When that sudden current wave-front (step) gets to the end, if it sees a 100 Ohm termination, then according to Ohms law, 10mA X 100 Ohm = 10V, and all is fine.

But say the termination is only 80 Ohms. Ohms law still rules. Now when the 10mA wave arrives at 80 Ohms load, you have 10mA X 80 Ohm = 8V. So 2 volts are "missing", and something needs to happen to solve the in-balance. Now you have a line with 10V at the driver side and 8V on the load. That means 2V across a 100 Ohm line, thus 2mA reflection going back to the driver side. You can continue the process back and forth...

But for all that to happen, you need to have the current wave step go back and forth on the line. We assumed that the signal rises real fast, and that it will take some time to get to the end of the cable, and be reflected.

But say I have a 10 nsec cable, and instead of sending a sudden step, I take a whole hour to increase the signal from 0 to 10 Volts. You can do it with say a 10V source and a potentiometer (and a lot of patience). Will you have a reflection? Of course not. You do not have a discrepancy between the voltages at both ends, because when the signal is very slow, so the voltage at any point of the line is the same for all practical purposes. Of course one hour is very long but it helps make the point. At the extreme, the slowest signal is DC. As you speed up the rise time, and as you make the cable longer, you get closer to the "sudden rise time” model.

In the real world, one does not have zero rise time, and as I stated, SPDIF is specified to be 5nsec to 30nsec. Say the rise is 5nsc and the cable is 100nsec. Clearly you have a wave front of 5nsec propagating down the line, and it will eventually get there and be reflected. Buy say your line is very short such as 0.1nsec delay. Now you do not have a 10V signal going down the line. The driver barley started increasing the signal from 0 to 10V, and that current wave is already at the end of the line. There is very little difference in voltage between the two ends of the line. This is similar to the "one hour example" above.

Think of the analogy of a water. If you dump a ton of water very suddenly into one end of a long swimming pull you may have some wave action. But if you fill the water slowly, the water level everywhere is the same, no waves.

So digital hardware designers know to pay attention to reflections when the cable delay is around the value of the rise time. If the rise time is much slower then the cable length, then termination is not needed, and reflections amplitude is so small it can be ignored. But when the rise is around (or less than) the magnitude of the cable delay, reflections will take place. So there is no way to argue that a shorter cable will cause more of a reflection problem, and the comment that 2 meter is some minimum is baloney.

I don't think this adds anything to the statement that the main way reflections are caused is by a mismatch/change in line impedance along the transmission line?

I never said that there is a change in impedance along the transmission line. You seem to misunderstand much of what I say. I talked about 2 impedances - one is the termination, the other is the line impedance. I used a 75 Ohms line in my examples. I did not say it starts at 75 Ohms and ends at 80 Ohms or anything other then 75 OHMs it is the TREMINATION RESISTOR that may have a different value, and to eliminate reflections, the termination must equal to the line impedance. If the line has impedance that is not constant, you have to know how to handle it. As rule, it is not wise to have anything other then constant line impedance.
"Is it not true that in all cases you need to consider reflections & proper termination?"

Not true, and it seems to me that you did not read what I said. I stated that you DO NOT NEED to terminate 100 feet of analog audio (20KHz or even 100KHz), I will raise it to 1000 feet! The signals are too slow to worry about reflections. Any cable impedance is always between 50-150 Ohms, and most audio analog destinations (such as line input or pro inputs) are at least 10KOhms. The mismatch between 10Kohm load and 100 Ohm cable is huge. The reflection coefficient is almost 100%, but there is no signal reflected, because the signal changes very slowly with respect to the travel time (cable length.

This logic sounds flawed to me - you are taking a moment in time snapshot & trying to show something at that moment - now move the time forward to say 9nsec (the signal is at 90% of it's value) & the reflection has 1nsec delay - it returns right at the transition step & interferes with it = jitter = what was said in my quotes above, I believe?

I can not help it if you do not understand me. Please try and not put words that I did not say in my mouth. Reflections are a bad thing for jitter. Shorter cable is BETTER, always. One can use a longer cable and with proper termination get good results. But one can NOT argue that 2 meters is better the 1 foot. The shorter, the better! That was very time consuming for me. I hope it helped.

Regards
Dan Lavry
Lavry Engineering
post #217 of 1712
Quote:
Originally Posted by manaox2 View Post
I wouldn't want to speak for Dan, but I frankly wouldn't give a half a squat about trashing this out with someone whose argument is that something does not gel with what they hear, especially not in a public thread and I'm not a professional circuit designer. I personally say good riddance to those who read his explanation and still decide they wish to travel into the mist. I would rather read about USB to SPDIF converters more.
Listen, if you bothered to look into it - the sources I quoted are highly respected industry figures & RF engineers who have been doing digital audio work for over 30 years. I'm sure that Dan knows of them & is aware of their reputations - indeed he would know the products that they have designed.

So all I was doing was quoting what I understood and quoted from these guys. What Dan said contradicts what I quoted so I'm asking questions

If you want to denigrate this go ahead, it only shows your blinkered mind-set!
post #218 of 1712
Dan, I repect your standing in the audio field but I'm not going to continue discussing this here because you continually loose focus on what is being discussed - "the length of DIGITAL cable & it's relationship to reflections". You flip into analog audio cable when all my statements refer to DIGITAL cable so I don't know if you're being deliberately obfuscating or this is a technique of yours? I also believe that this topic is no longer appropriate on this thread!

My simple understanding of it is that it's necessary to avoid reflections arriving back during the SPDIF transition. This may be possible with short cables but I'm not convinced, however, it's perfectly logical that it will work for longer cables. I'll requote what I said originally & nothing you have said has negated this:
Quote:
I was paraphrasing Fred & Jocko from DiyHifi.org who are respected RF engineers - I'm not an RF guy so I'll just quote verbatim:
Quote:
If you look at both the prop delay to the load and the delay for returning reflection from the load end for a 1 meter digital cable you will find sometihng interesting. The relected signal shows up during the logic transistion of the SPDIF waveform. This is kind of a no brainer to try a 1.5 to two meter digital interconnect and listen for the difference. Anybody want to guess along these lines as to why why digital cables are usually audibly directional.........
Edit: And another:
Quote:
just pointing out why digital cables sound better at 1.5 meter and up. I worked this out with SPICE transmission line models, various published cable propagation delays, and different logic family rise times. This was over ten years ago when I was designing digital cables. Jocko was doing something simular but with real life TDR measurements.
And BTW, look carefully - this is based on "measurements done " AND theory - it's not opinion!!
post #219 of 1712
Quote:
Originally Posted by jkeny View Post
What does that matter, dude or do you listen to viewpoints only based on their reputation?
Dan Lavry is a highly respected engineer with decades of experience in a number of areas, whom you are accusing of being wrong, despite that, by your own admission, you are not an engineer nor have (unless you haven't presented it) have any direct experience with the subject at hand. Whose commentary is likely to be more seriously considered?

That being said, some people believed they gained some sonic benefit from a long, 75 Ohm coax on their DAC, though some serious listening or testing might be in order to verify that people weren't just hearing things that weren't there. I think these things, along with a lot of the questions raised by digital converters and interfaces need some serious testing so we can see what is going on and compare it to what we hear.
post #220 of 1712
Quote:
Originally Posted by Currawong View Post
Dan Lavry is a highly respected engineer with decades of experience in a number of areas, whom you are accusing of being wrong, despite that, by your own admission, you are not an engineer nor have (unless you haven't presented it) have any direct experience with the subject at hand. Whose commentary is likely to be more seriously considered?

That being said, some people believed they gained some sonic benefit from a long, 75 Ohm coax on their DAC, though some serious listening or testing might be in order to verify that people weren't just hearing things that weren't there. I think these things, along with a lot of the questions raised by digital converters and interfaces need some serious testing so we can see what is going on and compare it to what we hear.
Thank you, Currawong, I understand Dan is a highly respected member of the audio community - I already recognised this in an earlier post. The two quotes I have referenced are also from respected RF audio designers.

I'm not saying Dan is wrong - he said my statement was wrong & I replied with these quotes. I also found it necessary to defend myself from personal insult which he has since retracted. I will be the first to accept his argument but so far it hasn't made logical sense whereas the quotes about long cables do make logical sense.

I thank you for your open-minded attitude to these posts which we all need to adopt. Unlike some here, I'm glad you haven't suspended your critical analysis faculties & when faced with conflicting viewpoints from two equally qualified people (I'm not referring to myself here ), I believe we have to evaluate them based on logic & understanding. I'm glad to see that there is some empirical evidence to support long cables, however unscientific it might be
post #221 of 1712
I am an engineer as well, how about some real application information on how to "fix" a DAC that has an RCA digital input jack, i.e. how do you convert it properly to a BNC connection and how long and where do you buy a BNC cable? How about how do you convert a transport to BNC output?

Theory is great but what we need are instructions on how to apply the these jitter reduction ideas in our USB to SPDIF quest.
post #222 of 1712
I fail to tell the difference between short canare bnc and 18' tjc bnc cable. I am not an engineer. :-)
post #223 of 1712
Thread Starter 

Follow-up 2 (17/11/2009)

I have just updated the main review with the following.

Follow-up 2 (17/11/2009) : Digital Cables - Which length to choose ?

For those who are interested in any usb to spdif converter they are likely to use a spdif cable and wonder about the optimal length. There are many people claiming that longer cables are better. There is even an article written by Steve Nugent on digital cables (here) which suggests that longer cables are better because they avoid reflections. While I have nothing against Steve Nugent, you have to be keep in mind that Empirical Audio also happens to be selling digital cables.
Below are the prices of the Bitmeister digital cable.
$499 1.0m RCA
$630 1.5m RCA
$760 2.0m RCA


Dan Lavry, from Lavry Engineering, corrected some misconceptions about longer digital cables being better and explains why a shorter cable is better than a longer cable.
While I am no engineer, I believe that the facts stated by Dan Lavry are accurate for two reasons : Lavry has a high reputation in the pro audio world and since Lavry Enginnering doesn't sell digital cables, Dan Lavry has (in my opinion) no agenda or no interest in stating that a shorter cable is better than a longer one.


I copied below extracts from the conversation and if you want to read the whole conversation, it starts here as a response to a post from jkeny :


Quote:
Originally Posted by Dan Lavry View Post

Quote:
Originally Posted by jkeny View Post
It is reported by Radio frequency Engineers that SPDIF cables needs to be 2 meters or longer on a properly terminated 75 ohm line, shorter than this leads to all sorts of cable reflection problems. These reflections will be heard! This could account for some of the perceived differences between cables.

Edit: this is not a recommendation for buying expensive cables - just simple engineering & no magic ingredients!!

Edit Again: I should have also said that making the cable as short as possible will also work with non-ideal SPDIF (RCA connections etc.) - 12" is possible short enough

That is not so, and no self respecting radio frequency engineer or any other electrical engineer will come up with such false claim. In fact, the shorter the cable, the better you are. I am not suggesting to use 3 inches cables, but a 3 foot is better then 10 foot, and at over 30 feet you are certainly asking for trouble.

You said the reason for keeping the length at least 2 feet had to do with reflections. Reflections have to do with MORE LENGTH, not with less length! Reflection becomes an issue when the cable becomes LONG, making the signal propagation delay longer (the signal travel time from the “driver” end of the cable to the destination “end”). What does longer time mean? Longer with respect to the digital signal rise (and fall) time.

A typical cable delay is around 1.5 nano second (nsec) per foot. The velocity is slower then the speed of light, in the range of 1/3 to 2/3 of the speed of light, and it depends almost entirely on one factor - the cable inner material isolation (the dielectric).

The rise time for the digital signal is between 5nsec and 30 nsec. 30nsec is slow but still within the specifications. 5-15 nsec is nice, and the reason that faster is not allowed has to do with setting a limit on the electromagnetic radiation (transmission of interference).

At say 10 feet, the cable delay is around 15 nsec, and a 5nsec rise time is 3 times faster then the delay, so one DOES NEED to terminate the cable and do so properly.

But at say 8 inches length, the delay is around 1nsec and even a fast 5nsec rise is 5 times slower then the cable delay, and the signal will have virtually no reflections at all. The shorter the cable, the better it is from reflections stand point as well as from many other standpoints.

I am not suggesting 8 inch cables. I am not suggesting not terminating. In fact, as a rule the termination is built into the receiver side. The issue here is cable length, and the notion that there is a minimal cable length one should keep is just plain wrong.

Regards
Dan Lavry
Lavry Engineering
Quote:
Originally Posted by Dan Lavry View Post

"But a quote from it is interesting
Quote:
When the first reflection comes back to the DAC, if the transition already in process at the receiver has not completed, the reflection voltage will superimpose itself on the transition voltage, causing the transition to shift in time. The DAC will sample the transition in this time-shifted state and there you have jitter."



This quote is the OPPOSITE of what should be stated!

A reflection IS when a signal super imposes itself on a transition. In fact, when the cable is long and the rise time is short, you are likely to have a lot of reflections. The first reflection is a signal traveling back from the load to the source. The second reflection is from the source to the load. The third reflection is back from the load to the source…. And so on.

For a single rise (or fall), the reflections amplitude a sequence where each “next one” gets smaller and smaller exponentially. Also, if the termination is HIGHER IMPEDANCE than the cable, the reflection is positive. If the termination is lower impedance than the cable the reflection is negative.
Call the reflection “Ref”, and it represents the portion of the original signal that will travel back from the cable “edge”. There are 2 factors for figuring the reflection coefficient:

RL = load resistance and Z = cable impedance.

REF = (RL-Z)/(RL+Z). That is the reflection coefficient.

Let’s look at examples for first reflection:

Example 1: 75 Ohm cable and 75 Ohm termination REF=(75-75)/(75+75) = 0/150 = 0 thus no reflection.

Example 2: 75 Ohm cable and 100 Ohm termination REF=(100-75)/(100+75)=0.142 so about 14% of the signal is reflected

Example 3: 75 Ohms cable and 50 Ohm termination REF=(50-75)/(50+75)=-0.2 so 20% of the signal is INVERTED and reflected.

But for a signal to be reflected, it must first happen. Nothing will be reflected if there is no signal to reflect. We do not terminate our DC power supply lines, because the “signal” is DC. It does not move, so the reflection coefficient means nothing.

We also do not terminate audio lines, trying to match the line characteristic impedance with an equal termination resistor. Why is that? Because audio signals are very slow in relationship to the speed of the signal which is at least 1/3 the speed of light. We can be safe to assume that a 100 foot cable conducting analog audio (say 20KHz or even 100KHz) has the SAME voltage at all cable locations at any given time.

We are “lucky” that we do not need to terminate lines when the signal speed is slow with respect to the line delay time. Why? ALL cables and wires have an impedance lower then 200 OHMs. You would need to separate 2 wire by the distance of earth to the moon to end up with 300 OHMs. I mean it literarily!

Most lines and cables are in the 50-130 Ohms impedance. Imagine having to terminate each line with around 100 Ohms. If so, the each time you have a 10V signal, you would need to supply .1A current and dissipate 1 watt!.

Say the rise time “step” is say 1nsec, and it takes the signal 10nsec to get from one end to the other, you can have different voltages at both ends of the cable. The driver puts fast 1V step at the input of the cable, and you will not know about it at the end until 10nsec later… In this case you need to consider reflections and proper termination.

But say the rise time is 10nsec, and the cable is say 8 inches (thus 1nsec delay), the signal at the input side has barely began, (it only got to be 10% of it’s value) and you already see it at the cable end. So you can not reflect the whole transition amplitude, because it has not yet happened. It will no be finished for another 9nsec… Clearly, the shorter the cable and the slower the rise time, the less one needs to be concerned about reflections. Take it to extreme - the slowest signal is DC, and the shortest cable is zero length... You really need no termination for reflections of slow signals and short cables.

Reflection is a good view to adopt for the cases where the cable is long enough, and the signal rise time is fast enough to have the complete transition happen at one cable end BEFORE it ever got to the other end. Another way to view it all is from the point of view of “Standing Waves”, which is more oriented to what radio frequency engineers do (certainly so for antenna designers).

I hope that helps clarify things. I wrote it to be helpful and set things straight. I am not going to twist arms to convince people that Ohms law is right, or that 1+1= 2. I did not express an opinion, I stated technical facts. While I will be glad to clarify and answer questions, there is tons of basic engineering materials covering the subject.

Again, this is not about who you like and who you want to respect. It is about physics of how electrical signals behave in conductors.

Regards
Dan Lavry
Lavry Engineering

The intent of this follow-up is not to start up the debate about jitter and cable lengths, however, I felt that it was necessary for any reader to learn what Dan Lavry had to say on the subject.

However, there is something that everybody seems to agree with. To get the best performing digital transmission, it is best to respect the 75 ohms characteristic impedance throughout the digital chain from the transport, the connectors, the digital cable to the digital receiver.

One more thing, Dan Lavry said the discussed issue is similar with usb : "what I stated would be good information for ALL cables including USB".
As a result the usb cable should be kept as short as short as possible (no surprise here).
This is good news for our wallets
post #224 of 1712
Can I respectfully ask someone to explain Dan's short cable operation in simple terms (as was given in the two quotes I gave about long cables - that the reflection arrives back after the SPDIF transition has taken place & thus doesn't causing distortion at the point of transition)? I really want to understand what a lot of others seem to accept as correct but I fail to grasp it. Please help me in my quest for clarity!
post #225 of 1712
Quote:
Originally Posted by jkeny View Post
Can I respectfully ask someone to explain Dan's short cable operation in simple terms (as was given in the two quotes I gave about long cables - that the reflection arrives back after the SPDIF transition has taken place & thus doesn't causing distortion at the point of transition)? I really want to understand what a lot of others seem to accept as correct but I fail to grasp it. Please help me in my quest for clarity!
Can this be taken out into its own thread, please?
Thanks in advance.
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Head-Fi.org › Forums › Equipment Forums › Dedicated Source Components › USB to SPDIF converters shoot-out : EMU 0404 USB vs. Musiland Monitor 01 USD vs. Teralink-x vs. M2Tech hiFace