Choosing Blu ray player

[Smokey]

No need to take my word for it. Grab yourself a length of coax and measure the resistance with you handy dandy multimeter. I just now took a 6' length and measured: signal (core) = 0.3 ohms; ground (shield) = 0.7 ohms.

What you are measuring is "DC" resistance of cable as cable impedance can not be measured with a multimeter. Special instrument is needed to measure cable impedance since we will be dealing with AC signal, cables inductance and capacitance. AC signal will see the cable impedance, but DC willl not

[Feanor]

What you are measuring is "DC" resistance of cable as cable impedance can not be measured with a multimeter. Special instrument is needed to measure cable impedance since we will be dealing with AC signal, cables inductance and capacitance. AC signal will see the cable impedance, but DC willl not

I stand corrected in as much as there is a difference between AC impedance and DC resistance. However as between one purpose-made coax cable and another versus other components in the source/cable/receiver system, I suggest differences are slight. I note that specified DCR's vary and are specified by unit of length, where as nominal impedance is simply specified as 75 ohms regardless of the length.

HERE is an article by Steve Nugent wherein he argues the coax S/PDIF ought to be at least 1.5 meters (5 feet) in order to minimized jitter resulting from signal echos caused by source/receiver impedance mismatches.

Excerpt ...

When a transition is launched into the transmission line, it takes a period of time to propagate or transit to the other end. This propagation time is somewhat slower than the speed of light, usually around 2 nanoseconds per foot, but can be longer depending on the dielectrics used in the digital cable. When the transition reaches the end of the transmission line (in the DAC), a reflection can occur that propagates back to the driver in the Transport. Small reflections can occur in even well matched systems. When the reflection reaches the driver, it can again be reflected back towards the DAC. This ping-pong effect can sustain itself for several bounces depending on the losses in the cable. It is not unusual to see 3-5 of these reflections before they finally decay away, particularly when using the best digital cables, which are usually low-loss.

So, how does this affect the jitter? 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. Let’s look at a numerical example: ...

Elsewhere Nugent suggest a 10 foot maximum, although I've hear others argue for 30 feet of more. Personally I'm using Blue Jeans Cable coax, Belden 1694A cable with Canare RCAP compression-fit connectors, HERE, with excellent results. (In my case the longer length is partly because of my own computer and DAC placement requirements.)

[Smokey]

[I]HERE is an article by Steve Nugent wherein he argues the coax S/PDIF ought to be at least 1.5 meters (5 feet) in order to minimized jitter resulting from signal echos caused by source/receiver impedance mismatches.

I read his article and he does make sense. I agree with him that RCA connectors and its wiring may cause reflection due to not being 75 ohm. That is something we don't have control over unless doind some serious DYI wiring

But there might be a flaw in his assumption of timing reflection. He assume that that space timing of digital signal is constant as for rising and falling time. But if one look at the coaxial signal itself, we can see that timing between rising and falling signal is not constant:



The signal is encoded in Manchester coding and and as you can see the timing vary between when signal fall and rises. So when we do have a reflection as Steve Nugent mentioned, one will never know whether the reflected signal will arrive at rise/fall time of source signal, or when the souce signal is at steady state.

Also he mentioned that we may have reflection at these point along transmission-line components:

The traces on the Transport circuit board that connect to the driver chip
The wiring to the output connector
The output connector jack and plug (BNC or RCA)
The digital cable
The input connector jack and plug at the DAC input (BNC or RCA)
The wiring to the circuit board
The traces on the DAC circuit board that connect to the receiver chip

So how do we accont for the timing of all these reflected signal?

[Mr Peabody]

I wonder if K-high ever got the Sony

[K-High-Fi]

Well Mr Peabody i was just about to purchase S790 until friend recommend Marantz 7007, which has balance output. So I'm thinking over.

However, i just compare the digital Coaxial output between Sony DVD player DVP-S900 (which was popular in 2003 and around $900) and Arcam 137 and i found Arcam sound a lot better, its more realistic and warm. I'm using high end power cord with Arcam, which is Furutech AC plugs and DH lab power cord, both they enhance Arcam performance. After this comparison I'm hesitating for S790 or similar level player.

Its really hard for me now to leave Arcam

Anyway, may i ask Is it big different in picture quality between blu ray and DVD?
From what I see the picture quality from DVD player is good enough in my Sony HX750 LED 40 inch, also I heard some people found little improvement from blu ray over DVD movies.

[Mr Peabody]

With Blu-ray you are talking 1080p resolution compared to 480p, yes that makes a difference. On a 40" screen I still would think the benefit is there but maybe not as much as a larger screen.

I looked at the UD7007 and it seems much more comparable to an Arcam in build. The XLR outputs are only stereo, you still could use the coaxial digital though. You are wanting performance so the 7007 may be a better choice, however, the Sony has Wyfi, depends on how important internet streaming is and how close you are to your modem. On the other hand the Sony would look like a toy beside the 7007. I have an old 7003 and love it even though it's a bit slow. Good picture quality and I just like the feel of a better built unit with a full remote.

[BadAssJazz]

Anyway, may i ask Is it big different in picture quality between blu ray and DVD?

I strongly recommend picking up a blu ray player and comparing it for yourself. In my humble opinion the differences between a standard DVD and a blu ray DVD are quite distinct, even on my 42" plasma, which I use in the bedroom. I wear contacts. The difference between standard DVD and blu ray is akin to looking through a pair of cloudy contacts that you forgot to take out the night before, versus wearing a fresh, new pair of lenses.

[K-High-Fi]

Thank you all very much for reply, & understood. I think i will choose Marantz or probably Cambridge if later is better.
By the way i noticed Blu ray players are cheaper than previous mediums. For example i remember in 1996 i purchased Pioner Elite laser disk for $1500, and yet its mid level player, also many DVD players called reference and very expensive, i dont see same thing with blu ray players except few brands, I wonder why?

[Feanor]

I read his article and he does make sense. I agree with him that RCA connectors and its wiring may cause reflection due to not being 75 ohm. That is something we don't have control over unless doind some serious DYI wiring

But there might be a flaw in his assumption of timing reflection. He assume that that space timing of digital signal is constant as for rising and falling time. But if one look at the coaxial signal itself, we can see that timing between rising and falling signal is not constant:



The signal is encoded in Manchester coding and and as you can see the timing vary between when signal fall and rises. So when we do have a reflection as Steve Nugent mentioned, one will never know whether the reflected signal will arrive at rise/fall time of source signal, or when the souce signal is at steady state.

Also he mentioned that we may have reflection at these point along transmission-line components:

The traces on the Transport circuit board that connect to the driver chip
The wiring to the output connector
The output connector jack and plug (BNC or RCA)
The digital cable
The input connector jack and plug at the DAC input (BNC or RCA)
The wiring to the circuit board
The traces on the DAC circuit board that connect to the receiver chip

So how do we accont for the timing of all these reflected signal?

Well I don't understand Manchester encoding and I suppose we do have to account for all those reflection points.

Do you suppose the Nugent might say that any reflections would be significant only if they affect the trailing edges of their related square waves, Manchester encoding notwithstanding? All the earliest & strongest reflections would, I presume, arrive within a few nanoseconds.