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USB to SPDIF converters shoot-out : EMU 0404 USB vs. Musiland Monitor 01 USD vs. Teralink-x vs. M2Tech hiFace - Page 84  

post #1246 of 1712
Quote:
Originally Posted by Dan Lavry View Post
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

i wish everyone on head fi would read this statement thanks dan
post #1247 of 1712
Quote:
Originally Posted by techenvy View Post
i wish everyone on head fi would read this statement thanks dan
Don't blame head-fi, the longer coax is better myth has been floating around for decades.
post #1248 of 1712
Quote:
Originally Posted by regal View Post
Don't blame head-fi, the longer coax is better myth has been floating around for decades.
While Dan Lavry is certainly a very respected and knowledgeable source when it comes to digital audio, he is certainly not infaillible nor the only one.

If such a myth exists on head-fi and other places, it is because other people strongly believe in it:

ART - SPDIF cables

spdif

The "technician" who tapped the DSD stream on my SONY SACD player to ouptut high rez PCM through SPDIF also recommended me to do so (either very short coaxial cable under 2 feet, or longer than 6 feet). Casually, he also happened to give some lectures on such topics in Eastern Europe Universities.

As much as I love Dan Lavry's products (see my sig), I just wasn't convinced by his explanation. As for me, I will stick for now with my Apogee Wyde Eye of 3 meters. Hey, mind you, it is not even expensive
post #1249 of 1712
Quote:
Originally Posted by shamu144 View Post
While Dan Lavry is certainly a very respected and knowledgeable source when it comes to digital audio, he is certainly not infaillible nor the only one.

If such a myth exists on head-fi and other places, it is because other people strongly believe in it:

ART - SPDIF cables

spdif

The "technician" who tapped the DSD stream on my SONY SACD player to ouptut high rez PCM through SPDIF also recommended me to do so (either very short coaxial cable under 2 feet, or longer than 6 feet). Casually, he also happened to give some lectures on such topics in Eastern Europe Universities.

As much as I love Dan Lavry's products (see my sig), I just wasn't convinced by his explanation. As for me, I will stick for now with my Apogee Wyde Eye of 3 meters. Hey, mind you, it is not even expensive
Shamu, the "technician" who said this is absolutely correct, I believe & this is the conclusion I came to after disagreeing with the short cable proponent, Dan Lavry (His quoted reply was a response to me) & Pat diGiacommo(Jocko from DiyhiFi.org) from ART, the long cable proponent.

Here's the long & the short of it - either short < 2 feet or long > 6 feet cables are the recommended lengths. So both Dan & Pat were incorrect in their dogged view that their cable length was "the only" way.

The arguments go like this:
- the short cable works because the inevitable reflections of the signal pulse return fast enough that they don't fall in the signal detection window of the receiving device.
- the long cable works, I think, because the reduced, reflected signal takes a long enough time & has diminished enough in strength that it falls outside & doesn't effect the signal detection window of the receiving device.

I believe, however, that the long cable also needs to be of a good quality so as not to cause too much reflection & of a proper length. Both of these fact play into the hands of cable sellers! You need to work out how long by checking the signal rise time and speed of signal in the cable so that any reflection safely stays outside the trigger window.

So I come down eventually on the side of the short cable as being most appropriate but not for the strange explanation given by Dan above because, as far as I know, how "reflections" occur has nothing to do with cable length but all to do with the cable structure & having the correct termination.

The real problem lies in the fact the the usual digital cable length sold is precisely in the no-go lengths 1M to 2M, go figure
post #1250 of 1712
I am very disappointed to read misrepresentations about our firm. We do not state that long "is the only way to go". It is merely our educated opinion that it is the way we prefer to go. As a result, we only sell long cables.

The person who says "no self respecting radio frequency engineer or any other electrical engineer will come up with such false claim" is bordering on slander. It may be his opinion that long is not best, but to malign our design staff is unacceptable. I do not know that person, and I think it safe to say they do not know our design team. They are all competent engineers. To make such claims goes beyond healthy debate.

There are other minor issues I see have been posted, but I do not care to address them. Nor do I intend to be dragged into a "long vs short" debate". Anyone wanting further information is urged to contact us through our site, after they have read its content. We will not address any issues that do not directly concern published content on our site.

Thank you for your attention and cooperation.

MEB,
Owner, AR-T
post #1251 of 1712
Quote:
Originally Posted by meb View Post
I am very disappointed to read misrepresentations about our firm. We do not state that long "is the only way to go". It is merely our educated opinion that it is the way we prefer to go. As a result, we only sell long cables.

The person who says "no self respecting radio frequency engineer or any other electrical engineer will come up with such false claim" is bordering on slander. It may be his opinion that long is not best, but to malign our design staff is unacceptable. I do not know that person, and I think it safe to say they do not know our design team. They are all competent engineers. To make such claims goes beyond healthy debate.

There are other minor issues I see have been posted, but I do not care to address them. Nor do I intend to be dragged into a "long vs short" debate". Anyone wanting further information is urged to contact us through our site, after they have read its content. We will not address any issues that do not directly concern published content on our site.

Thank you for your attention and cooperation.

MEB,
Owner, AR-T
Hello, new member, just joined (Owner) from AR-T I hope you don't mean that I am mis-representing the position? I had a long debate with Jocko Homo (Pat diGiaccomo) about this very topic - can you confirm that he owns AR-T because if not, I have paypaled money to him under the banner of AR-T & you should look into this immediately I will point you to the thread on DiYHiFi.org (Jocko's site) which I started about this & his argument is laid out there DIYHiFi.org &bull; View topic - SPDIF Cable Length but I'm sure you know this thread already

If you need a reminder of Jocko's statement here it is "Shorter cables are worse for reflections, because they will arrive too close to the decision point." I don't know how you interpret this but to me it is a statement that "long is the only way to go" for best performance!
post #1252 of 1712
Quote:
Originally Posted by jkeny View Post
If you need a reminder of Jocko's statement here it is "Shorter cables are worse for reflections, because they will arrive too close to the decision point." I don't know how you interpret this but to me it is a statement that "long is the only way to go" for best performance!
Hmm... I'm puzzled and I don't think this issue is solved. There is going to be more debate about the longer vs shorter cable impact on SQ IMO.
post #1253 of 1712
No need to be confused, Shamu's technician is correct in my opinion - either short or long cables are best - just not the 1-2meter ones.
post #1254 of 1712
Quote:
Originally Posted by jkeny View Post
No need to be confused, Shamu's technician is correct in my opinion - either short or long cables are best - just not the 1-2meter ones.
I'm not an expert at all but I would like to see some empirical evidence that proves whichever theory you are refering to.
We are talking about jitter right? If so, that is a measurable and we can also hear the effects it has on SQ.
post #1255 of 1712
Firstly, look at the explanation above for how both short & long cables work in this regard (it's not that difficult to understand) - then you can try to get a set of measurements that can show short, medium, long cables that are comparable - I wish you luck in that quest
post #1256 of 1712
Quote:
Originally Posted by jkeny View Post
I will point you to the thread on DiYHiFi.org (Jocko's site) which I started about this & his argument is laid out there DIYHiFi.org &bull; View topic - SPDIF Cable Length but I'm sure you know this thread already
OMG !

Thank you Jkeny for pointing us to this thread. I've been quickly reading the 6 pages to realize that this issue is a LOT more complex than I ever could have imagined.

Quote:
Originally Posted by jkeny View Post
No need to be confused, Shamu's technician is correct in my opinion - either short or long cables are best - just not the 1-2meter ones.
I'll stick with this one
post #1257 of 1712
Quote:
Originally Posted by jkeny View Post
The arguments go like this:
- the short cable works because the inevitable reflections of the signal pulse return fast enough that they don't fall in the signal detection window of the receiving device.
- the long cable works, I think, because the reduced, reflected signal takes a long enough time & has diminished enough in strength that it falls outside & doesn't effect the signal detection window of the receiving device.
:

Between those two obviously #1 is the better choise as we have no idea what the strength is of the reflected signal and we do know that the reciever can pickup the reflection above a certain threshold. So why not eliminate that possibility?
post #1258 of 1712
Quote:
Originally Posted by regal View Post
Between those two obviously #1 is the better choise as we have no idea what the strength is of the reflected signal and we do know that the reciever can pickup the reflection above a certain threshold. So why not eliminate that possibility?
It's not quite that simple as the length of the cable is selected so as the reflection is timed to fall outside the trigger window of the SPDIF receiver. But, yes that's why I came down on the side of the short cable argument as these calculations are no longer needed but are there other considerations, I don't know about, to also take into account? That's why I started the other thread - to find out from experts what are these considerations - I got a lot of good information from Gmarsh on that particular thread but it all ended in tears, I'm afraid
post #1259 of 1712

This new news that the Musiland Driver can decode HDCD is really surprising. First AudioGD told us recently that he could not afford the licensing fees that M$ required to implement HDCD decoding in his DSP-1.  Now all of a sudden Musiland is claiming HDCD decoding?

 

I offer four possibilities and will try to get to the bottom of it:

 

1. The HDCD light on the software is just an indicator and the customer service rep who said it was actually decoding was wrong.

 

2. They incorporated the HDCD.exe code into their new driver,  not a big deal as this has been available for foobar for a while,  it is an incomplete HDCD decoding only decoding peak extend not the filter/dithering.

 

3. The HDCD licensing patent expired and we have the the true first of its kind HDCD decoding transport.

 

4. They actual paid the licensing fees and we have a true first of its kind HDCD decoding transport.

 

#3 & #4 would really be a revolution for Deadheads and others that listen to a lot of HDCD material as it would mean we would be able to apply DSP and still have true HDCD,  sort of revolutionary for me personally.

 

post #1260 of 1712
Thread Starter 
Quote:
Originally Posted by regal View Post

This new news that the Musiland Driver can decode HDCD is really surprising. First AudioGD told us recently that he could not afford the licensing fees that M$ required to implement HDCD decoding in his DSP-1.  Now all of a sudden Musiland is claiming HDCD decoding?

 

I offer four possibilities and will try to get to the bottom of it:

 

1. The HDCD light on the software is just an indicator and the customer service rep who said it was actually decoding was wrong.

 

2. They incorporated the HDCD.exe code into their new driver,  not a big deal as this has been available for foobar for a while,  it is an incomplete HDCD decoding only decoding peak extend not the filter/dithering.

 

3. The HDCD licensing patent expired and we have the the true first of its kind HDCD decoding transport.

 

4. They actual paid the licensing fees and we have a true first of its kind HDCD decoding transport.

 

#3 & #4 would really be a revolution for Deadheads and others that listen to a lot of HDCD material as it would mean we would be able to apply DSP and still have true HDCD,  sort of revolutionary for me personally.

 


I think that the most likely scenario is #2.

 

I doubt it is possible to make a true HDCD decoder at the transport level. HDCD decoding implies among other thinhs a particular (and multi-step) 8x oversampling (according to the datasheet of the PMD100). The way I see things, the only way to properly implement HDCD decoding at the transport level would be to use a 352khz (8x 44.1) capable transport into a NOS DAC. Any other combination would mean that the HDCD signal will have to go through the filtering/oversampling of the DAC which will probably cause some harm to the data.

This is only speculation from my end and I might be wrong. However, I just don't see how it is possible to replicate the full HDCD decoding (of something like the PMD100) at the transport level when using conventional oversampling DACs.

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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