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post #151 of 4052
Quote:
Originally Posted by tim3320070 View Post

........................ And explain to us how 50ohm is worse please.


Can I explain? The SPDIF standard for transmission is 75ohm. That means all devices & cables used for SPDIF should be 75ohm. What happens if 75ohm is not used? Just like any wave when it encounters an obstacle it will generate a back reflection & also cut down the amount of energy in the wave passing beyond the obstacle. The energy issue isn't such a big problem but the reflections are. Just as in a wave machine the reflections superimpose on top of the original wave & we no longer have a clean SPDIF signal (yes high speed signals are treated as waves in cables). This can cause jitter - it's that simple! That's why/how 50 ohm is worse! 

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post #152 of 4052
Quote:
Originally Posted by jkeny View Post




Can I explain? The SPDIF standard for transmission is 75ohm. That means all devices & cables used for SPDIF should be 75ohm. What happens if 75ohm is not used? Just like any wave when it encounters an obstacle it will generate a back reflection & also cut down the amount of energy in the wave passing beyond the obstacle. The energy issue isn't such a big problem but the reflections are. Just as in a wave machine the reflections superimpose on top of the original wave & we no longer have a clean SPDIF signal (yes high speed signals are treated as waves in cables). This can cause jitter - it's that simple! That's why/how 50 ohm is worse! 


Do you have some exact measurements you can show us about how much jitter is caused by this and how exactly it will affect the audio signal?  I'm asking because I see a crap-load of talk about interfaces, cables, jitter, types of USB and other stuff, but so far, no actual measurements from anyone* showing exactly how much this stuff matters, or doesn't.  This would be helpful, as people are picking this kind of chatter up who have no genuine idea what it means and spouting it as if they do know, which they don't.  Actual data would be helpful to everyone, as then this stuff wouldn't be rumour and speculation but hard fact upon which we could make sane decisions about what we buy and what we'll actually get from it.

 

*Kingwa did, a long while back, state that he chose coax and RCA on his high-end DACs as they had the lowest jitter of all the interfaces he measured and he has occasionally post pictures of what his oscilloscope shows with regards to things, but nothing beyond that.

post #153 of 4052

This looks like an isochronous usb with an asynicrous resampler,  similiar to the units audio alchemy used to sell to "clean-up" spdif.   Interesting means of dealing with USB but the jitter will only be as low as the resampler.  As far as the 50 ohm BNC,  just swap it out for a 75 ohm BNC and quit arguing about it,  will cost $5 and 10 minutes.  I imiagine it won't be bitperfect (ie pass HDCD or DTS tests.)


Edited by regal - 7/18/10 at 4:29am
post #154 of 4052
Quote:
Originally Posted by jkeny View Post




Can I explain? The SPDIF standard for transmission is 75ohm. That means all devices & cables used for SPDIF should be 75ohm. What happens if 75ohm is not used? Just like any wave when it encounters an obstacle it will generate a back reflection & also cut down the amount of energy in the wave passing beyond the obstacle. The energy issue isn't such a big problem but the reflections are. Just as in a wave machine the reflections superimpose on top of the original wave & we no longer have a clean SPDIF signal (yes high speed signals are treated as waves in cables). This can cause jitter - it's that simple! That's why/how 50 ohm is worse! 

Okay, point out how it sounds worse. If it's worse, why would Kingwa use it? I doubt he would skimp here for a few dollars.
 

post #155 of 4052

 

 

Because in average most people don't have a trued 75 ohm cable, receptacal, and load is my guess,   or he is just copying what he saw on the hiface.  Don't think that Kingwa is infallable, no one is.  Fact is it should be a 75 ohm jack,  just change it,  $5 and 10 minutes,  not worth three pages of discussion.

 

Quote:
Originally Posted by tim3320070 View Post



Okay, point out how it sounds worse. If it's worse, why would Kingwa use it? I doubt he would skimp here for a few dollars.
 

post #156 of 4052

 

Originally Posted by tim3320070 View Post

 

why would Kingwa use it? I doubt he would skimp here for a few dollars.

For a very good reason, actually: http://hifiduino.wordpress.com/2010/03/30/some-audio-wisdom/

post #157 of 4052
Quote:
Originally Posted by leeperry View Post

 

For a very good reason, actually: http://hifiduino.wordpress.com/2010/03/30/some-audio-wisdom/


Did you only read the post & not the comment under it? As that commentator says & I've red it from others that use these connectors in the business - there is NO difference in pin sizes between 50 & 75ohm & there has't been since the 20 or 30 years

post #158 of 4052

 

Originally Posted by jkeny View Post

Did you only read the post & not the comment under it? As that commentator says & I've red it from others that use these connectors in the business - there is NO difference in pin sizes between 50 & 75ohm & there has't been since the 20 or 30 years


Yes, I did read the blog comment, but the guy saying it is Bruno Putzeys: http://en.wikipedia.org/wiki/Bruno_Putzeys

 

I know everyone can self-proclaim himself  as being a first rate expert on the internet, but he seems like he knows what he's talking about...anyway, yes it'll take 5 mins to swap it for a 75Ω so it's essentially a non-issue.

 

He also believes that a 50 or 75Ω connector doesn't really matter as long as the cable is 75Ω...I guess he ran some tests using high grade measurement gear before saying that?

 

Whether the audio industry is right or not is not really the issue here IMHO, what stands true is that they all go 50Ω because they seem to believe that using 75Ω female connectors would drastically increase their RMA rates...and OCD'ed ppl can "fix" this non-issue in a matter of minutes anyway.

 

But I don't think you can solder a 75Ω connector, as solder will add resistance...so swapping it will -most likely- still not yield a true 75Ω connection, hah. The 75Ω RCA connectors from Canara cannot be soldered.


Edited by leeperry - 7/18/10 at 10:38am
post #159 of 4052

From what I understand, the 50 ohm connector was only used for comparison to the hiface. Correct me if I'm wrong.

post #160 of 4052

sadly, Marco says that the BNC on the Hiface is indeed 75Ω: http://www.tycoelectronics.com/commerce/DocumentDelivery/DDEController?Action=showdoc&DocId=Catalog+Section%7F1307191_BNC_Connectors%7F0307%7Fpdf%7FEnglish%7FENG_CS_1307191_BNC_Connectors_0307.pdf

 

I love how S/PDIF is ±30yo: http://www.epanorama.net/documents/audio/spdif.html

 

yet still a bloody mess to implement properly in 2010, and they didn't even pay any attention to the stellar jitter you get over toslink, hah.

post #161 of 4052

Just need a IS2 input/output made for his dacs so no need for spdif, only for other brands, also it seem slim.a is a tester or i may be wrong.


Edited by Omega17TheTrue - 7/18/10 at 11:24am
post #162 of 4052

So lets make sure the testers ask for an ethernet connector for I2S that will work with Kingwa's DACs and he can start adding I2S ethernet connectors to those upon request.  ;)

post #163 of 4052



 

Quote:
Originally Posted by Zorlac View Post

So lets make sure the testers ask for an ethernet connector for I2S that will work with Kingwa's DACs and he can start adding I2S ethernet connectors to those upon request.  ;)


 

Sorry, I don't think it is that simple..

 

Kingwa will not say that I2S is a better connection in practical terms. He does say that I2S presents a host of problems (as has already been discussed elsewhere on this thread).

 

According to Kingwa:

“I2S [is] not a world standard, it [..] has different sockets, different logic level between different manufacturer, and it is limit[ed by] the transmit distance, so I don't think [..] [it is a practical interface].”

 

DSP-3 testers, I think, will need to focus on the connections provided on the unit i.e. coax and USB in / coax out. However, I am curious and will want to give I2S a try. (Indeed, Kingwa is supportive of this.) At this stage, I don't expect I2S to better coax. But if it does I will be delighted and report accordingly.

post #164 of 4052
Quote:
Originally Posted by haloxt View Post

From what I understand, the 50 ohm connector was only used for comparison to the hiface. Correct me if I'm wrong.


You are correct! the BNC socket on the DI is a cheapie from chinese manufacturer that avertizes it as 75ohms but Kingwa thinks it is 50ohms. The Canare sockets on his DACs that are 100% 75ohms do not fit on the DI chassis.

Kingwa has told me that he did many listening tests and he does prefer the sound of a true BNC 75ohms connection. After that came 50ohms BNC and at last RCA. He measured the impedance of RCA and the signal fluctuates a lot. It can be as low as 30ohms and as high as 100ohms so that's no good.


Edited by punk_guy182 - 7/19/10 at 6:03am
post #165 of 4052

Is DI going to have real 75 ohm connector or the cheap one that may be fake 75 ohm?
 

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