Which budget digital cable ?

I was running a Blue Jeans Cable Belden 1694A which I think is a pretty good budget cable. I use the dac in my Mac MA5300. I jjust bought an Apogee Wyde Eye (1.5 mtr). The Apogee to my ears is a smooth, airy, detailed cable with much better bass impact, and definition. No fatigue here. I was lucky enough to find an Ifi Zen Streamer. Should arrive in a few days. I think it will be an awesome combo. Anyone else with the Mac MA5300? Do you use the onboard dac, or an external? Thanks!

If you want to hear absolutely everything the Stereovox is a great choice. If, however, you'd prefer something a little smoother and fuller sounding the Apogee Wyde Eye is also an outstanding bargain.

Greeni, did you try Valab's digital cable? It is really good.

Certainly, most of what I have read stresses the
importance of jitter rejection/immunity at the DAC end, presumably becuase
changing interconnect cable lengths might work on some equipment but not
other

In S/PDIF, timing is set by the transport's clock, as you know. That means that
timing gets screwed up (i.e. jitter gets worse) if the timing information is not
received correctly by the DAC; errors are maintained through to conversion.
One way for the DAC to deal with this is to maintain a constant 75 ohms
impedance from its input. Read Steve Nugent's paper to find out at least one
reason why this doesn't always happen, though.

Furthermore, whether or not the DAC handles impedance in its own signal
path correctly, the RCA connector, when used, invariably offers a mismatch;
there is no such thing as a 75-ohm RCA connector.

These are two causes of jitter in setups with an external DAC and digital
interconnect. The timing adjustment offered by a 1.5m cable length
diminishes jitter from these causes. Almarg's limpid post makes it easy to
understand why.

Shadorne, you may have heard a lot about jitter rejection/immunity at the
DAC because of the weakness of the S/PDIF clocking system, which uses the
transport's clock, not the DAC's, to establish system timing. ( You can read
more about this weakness at the LessLoss site. ) Double-clocking DACS like
the Apogee Mini-DAC are one approach (in my view, quite successful) to
solving this problem. Another is slaving the transport to the DAC's clock, as
done by Linn (Karik/Numerik), Cambridge (DiscMagic/DACmagic) and
LessLoss. Also, do read Steve Nugent's paper for yet more.

No matter what the DAC's internal design, though, the presence of an RCA
connector suggests that a 1.5m cable may be optimal with that unit.

Would it be the same issue for Toslink?

I'm not particularly knowledgeable about electro-optics, but I don't think so. What underlies the phenomenon Tobias referred to is that for electrical signals with spectral components at rf frequencies, such as the electrical digital outputs of cd transports, a mismatch between cable impedance and load impedance results in a fraction of the incident energy being reflected back towards the source (instead of being absorbed by the load). As you may realize this is referred to as a "vswr" effect ("voltage standing wave ratio"). I wouldn't think that is applicable to light waves being detected by a sensor, and even if it were the quantitative parameters (risetimes, etc.) would be different.

Also, multi-mode fiberoptic cable (which I believe is what Toslink and most inexpensive fiberoptic links are) is subject to other sorts of effects, such as light repeatedly reflecting off of the walls of the conductor, resulting in some of the energy arriving at the destination later than that part of the energy which has taken a direct path. Not sure if that is a significant effect over the short cable lengths and the data rates that characterize audio systems (it may very well not be), but it's another indication that transmission of optical signals and transmission of electrical digital signals are just different animals.

Regards,
-- Al

Regards,
-- Al

Tobias & Al,

Thanks for pointing this out. Everyone seems to agree that jitter on digital interfaces are a problem sometimes a badly audible one - several AES papers refer to this. I'll have a look at the paper you mention from Steve. I have always used 2 meter or longer digital interconnect cables (Toslink) but only for convenience. Would it be the same issue for Toslink?

Certainly, most of what I have read stresses the importance of jitter rejection/immunity at the DAC end, presumably becuase changing interconnect cable lengths might work on some equipment but not others...

Almarg, I have posted on this simple measure a few times now because its benefits are great compared to the cost involved. Yours is the most useful and enlightened response I have yet read. Thanks in turn for it.

I first heard about the phenomenon in a post here by Empirical Audio's Steve Nugent (audioengr). On his Web site's first page he has a link to a technical paper of his which explains in detail ("Paper on S/PDIF cable length in PSOnline"). I had to try it myself, of course, so I made up two otherwise identical lengths of Apogee Wyde Eye. The listening tests I did with a friend were perfectly conclusive: the longer cable was better (with our gear) by a wide margin.

Thanks for the suggestions, I will look into the options. The dac for my headphone set up is the Valab NOS dac, a budget priced but musical piece. There is a review here in audiogon. Looking for a digital cable commensurate in price point and performance. The above suggestions are really helpful.

Unless you are absolutely sure that your DAC maintains internal impedance at 75 ohms, get a cable that is 1.5m long. Often the difference in price over 1m is minimal. The extra length makes a huge difference in cleanness and coherence in most setups. This is because the extra half meter delays internal reflections just enough that they don't arrive at the DAC in time to cause jitter.

Gee, that's a very interesting point that I haven't seen stated before, and which does seem very conceivable technically.

If the input impedance of the dac and the impedance of the cable don't match precisely, a portion of the incident signal would be reflected back to the transport. A portion of that reflection would then re-reflect from the transport to the dac. The two-way reflection path, assuming propagation time of roughly 2 nanoseconds per foot, would be 12ns for the 1m cable, and 18ns for the 1.5m cable.

I don't know what the typical risetimes/edge rates are for transport outputs, but it does seem very conceivable that the extra 6ns could move the arrival time of the re-reflection sufficiently away from the middle area of the edge of the original incident waveform so that it would not be responded to by the digital receiver at the dac input.

Thanks for pointing that out!

Regards,
-- Al

monoprice

Haven't heard Joemazzaglia's digital cables but his analog ones certainly are, as Listener57 says, budget in price and elevated in performance.

I'm very happy with my expensive Atlas Opus and I would think the cheaper Atlas Compass worth a try. I have owned a VH Audio cryo Pulsar and thought that one very good indeed, with an amazing long breakin period.

Unless you are absolutely sure that your DAC maintains internal impedance at 75 ohms, get a cable that is 1.5m long. Often the difference in price over 1m is minimal. The extra length makes a huge difference in cleanness and coherence in most setups. This is because the extra half meter delays internal reflections just enough that they don't arrive at the DAC in time to cause jitter.

The Stereovox cables are one of the best values around.I have the hdxv and with performance as good as it provides I have not been tempted to upgrade to their new digital cable.They are also quite flexible!That said if I were buying used on Audiogon I would certainly go for their newer version the XV2.

Analysis Plus Digital is a great value buy.

I'd give Drew a call at Moon Audio.

Auricle Audio Design Signature digital IC
hand crafted by Audiogon member
Joemazzaglia
Never ceases to impress, and flexible, too. Budget in price, elevated in performance.
You didn't mention details of your set up. Every subtlety of the signal will be transmitted by a great digital IC.