Reccomend a budget digital coaxial ic!

Right, just for you lot I thought I 'Show you' what a digital out put signal looks from a Transport It should be a Square wave form.
Sorry the Photos are big, but I aint got time for cutting em down at the moment.
Ok, the first photo shows an output signal from a Stock Rotel RCD965BX (16 bit 44.1), using a Quality cable and straight to a 75 ohm dummy load, the second is the same player going through a recloacking latch and src (Pet Tec P1-A as a 24 bit/44.1 signal)
Notice the digital 'reflections on the first piccky' and how after going through the P1-a they are all but gone, it's not the best photo, but you can get the jist. Wm

Stock Rotel into Dummy Load



Now using the P1-a

 

Out of interest does anyone have any experience of how the Apogee Wyde-eye compares with Chords Prodac Silver Plus? I've been thinking of giving the latter a try (I need a BNC-BNC cable which narrows the options somewhat).

Cheers,

Martin

 

Martain, the Apogee is good, I would certainly have it over the Chord effort My view. Wm

 

Well, if you're even slightly handy with a soldering iron you can get an RCA/RCA cable and just put new BNC plugs on it.

I'd recommend the Apogee (and as it's a pro cable I'm sure it's available in a BNC/BNC version).

As people have found with the M-Audio SuperDAC, "pro" products like it and the Apogee cable can give outstanding results for very little outlay.

Mike.

 

Thanks Tony, but so what? With digital signals it doesn't matter if the square wave isn't a square wave. That's the whole point of digital signals, they can degrade substantially and still be reproducable. As long as a 1 can be interpreted as 1 and likewise for 0s, there's no issue at all.

I understand that with critical hearing we (well some of us) can hear the diffrences in sound quality caused by jitter (why has no one produced a DAC with sufficient buffer to eliminate any transport problems such as jitter?) but are these going to be significantly affected by cable quality? and will the differences be that great? I was merely asking someone with a good enough system to demo this because I can't hear any differences between digital I/Cs. As I've often said, this could be due to my age and fucked up (getting technical now) hearing.

 

You get the same zeros and ones, but the timming can be off...

 

Wouldn't that reflection be more due to the termination than anything clever done by the P1-a?

If you look at the waveform using a dummy 75ohm load using a couple of different cables, can you see clear differences in the waveform?

True, provided the cable isn't too large. I was partly thinking from the point of view of being able to demo the cable, although I don't reckon there's much chance of getting a Wyde Eye to demo actually. I've e-mailed the UK apogee site to see if there is anywhere in the UK selling it.

 

Dev, It makes a lot of difference (If you took the output wave form of a transport 'a' and potted it over transport 'b', they would be very different, which one would sound better?, down to the indivdual, does less jitter mean better sound? again I down to the indivdual), even the much vaulted dac 64, is STILL suseptable to Transport/cable changes , best off the shelf jitter eliminator is the tac d70/p70 combo that has a full PLL section, a fifo ram buffer 10 times the size of the 64's and a word clock/sync generator, fuly isolated psu's etc,
Just one point Dev, you can have 3 or more cables all read/measure the same, yet sound different, so I'm open to ideas as well mate
We can demo this with a sub £1200 system no probs at all, some of the cables are more than critical differences.
I could sit here all afternoon telling x & y, however would be better if you used your own ears, to decide Dev.
Maybe Timpy & myself should have a myth busting day, were you guys bring your kit along, and set it up and you guys can do the swopping, maybe that would be bury it one way or the other?

 

Exactly. This is the only way to prove it one way or the other. Perhaps that other infamous cable sceptic Paul can come along as well?

Why do you have to live so far away?

 

Agreed, but shouldn't a DAC be able to cope if it had a big enough buffer?

 

Well Dev, give you a chance to take the BMW for a bimble, good enough excuse I think.

 

Hi Sauerkraut

Just out of interest, exactly what method did you use to measure the impedence of your cable ?
I have been doing a little bit of cable swapping myself over the last few days, including a DIY effort. My DIY effort was made using 75ohm cable , but i found it difficult sourcing 75 ohm connectors ( and so didn't bother inthe end ). I can't say i actually noticed any difference between the cables that i tried so i put my yellow Ecosse digital back in place as it seemed as good as any of the others.

WM,
I haven't got an osciloscope and haven't done any component testing.
I know it is said that you can't believe anything that is said in a Hi-Fi mag , but Hi-Fi World always have a little box in their equipment reviews where Noel Keywood analyses the equipment using his Test paraphinalia and gives his views. I often get the impression that he gives an opinion on what the erquipment should sound like , given his test results, without him actually hearing the stuff in a dedicated listening test/demo/review.
It is quite often the case that the peice of equipment that measures the best , doesn't always sound the best...
ie; a little bit of waveform distortion doesn't always have to be a bad thing in a real life situation.

 

Martin, you have a valid point, reflection are generaly caused by cables and impedence mismatches for sure, however if the output signal is not reaching it's thresholed point (or bearly), this will cause problems as well. Poor clock signal and noisy psu won't help matters either

Some further pictures, here I used a 75ohm adapter to go straight into the scope, from the Rotel (same cable as before), straight out the rotel, next the same cables using the P1-a, notice the great reduction in reflections and tidying up of the wave form, plus some photo's of the cdfix stock output same cable, notice the serious drop in reflections , then with the P1-a in the curcuit, so what can do you deduce from this, I can repeat this and use the true balance output 110Ohms, and the results are slightly better (the xlr has a seperate sync signal extracted, and use to sync the clock).
We have tried over 100+ cables, many of them produce virtualy indentical wave forms (using the same equipment), yet they do sound different, (My personal view, & shared by more than one or 2 other people).

Stock rotel same cables as before, into scope







Now through the P1-a




Stock cdfix into scope same cable




And again through P1-a



They're are many reasons why digital signals degrade & soil the sound, cables/outside ref/efi/noisy psu's/shared psu's/ poor clocks, digital tranmission paths etc, just a case of remove them and letting the full potential show through. Wm

 

Sid, your right, we use our ears, however by looking at the equipment that sounds right to us, we can form an opinion based on other equipment we test, however the ears are the best judge by far.

 

Fun with S/PDIF outputs....



The image is of the waveforms from three digital sources I had kicking about the house. All through the same nominally 75Ohm 1m cable and terminated in 75 Ohms at the scope.

The top is my Linn Karik, the centre a MidiMan Flying Calf ADC, the lower an old Arcam Alpha Plus. The Linn has the fastest leading edges (no surprise there....) and the ringing I think isn't relevant to a digital receiver. The Midiman is a bit slower yet more controlled. The Arcam is naff. I only have a 20MHz scope, these waveforms are pushing it to its limits.

Sorry for the camera shake.

Paul

 

the midiman looks pretty good, I nearly bought the dac once.

Is it any relation to the superdac? or totally different?

I like reading hifi world reviews, but have learned to tread warilly with some reviewers, as their tastes differ to mine.

I enjoy keywoods tech reports, I wish they were longer, I think the comments he makes is where there are KNOWN factors in his listening exp. that affect sound quality...eg with a prominent treble in a speaker being prone to excitement, or extended distortion patterns on an amp causing a little harshness. To be fair, he does qualify and say listening is the final test.