Digital Playback Comparison


Which sounds better: Original CD, CD burned from harddrive, playback from computer HD through USB, or optic cable, or Airport Express? I cleaned my contacts, installed NOS Amperex tubes in my preamp, had new tubes installed in my Trivista SACD/CD player, and had a go at a comparison test for these playback methods. The HD used was from my MacBook Pro. The piece of music used for a comparison was the Hallelujah chorus from Handel's Messiah, Solti and the Chicago Symphony Orchestra and Chorus (Decca 1985). See my system for equipment used. The USB playback was via a HagUSB via S/PDIF into the Trivista coax input. Here are the conclusions, going from best to least good sound quality:

1. (Tie): HagUSB and Burned CD (CD was burned from HD at 4x, from Apple Lossless file). I couldn't tell a difference between these two after extended listening including other music besides the test music. Great dynamic range, wide and deep soundstage, a "rightness" to the sound (at least within the limitations of digital) that made you want to quit analyzing and just listen.
2. Original CD. I read somewhere recently (some of you might know the source) that there is an explaination for why burned CD's sound better than original, but until I made the comparison, I was skeptical. The original had a slight loss of "presence", and seemed slightly compressed compared to the #1 playback methods.
3. HD through toslink. 1 & 2 are closer in sound than 2 & 3. There is a noticable shrinking of the soundstage and air with the optic cable. The cable is a good one--Van den Hull glass cable with mini-plug out from Mac. I was disappointed in the sound from this method.
4. Airport Express and optic. A significant drop in sound quality here. If you have been using this method I suggest doing what I will now do which is run USB out of computer to HagUSB ($119) via long run of coax (Canare for me) to your DAC. The Airport Express is OK for "working around the house on the weekend" listening, but is a serious compromise from what you can get with only a minimal incremental investment.

Notably absent from this comparison are music servers, or a good quality USB DAC, or good reclocker/converters that could be used with a computer HD and conventional DAC. Hopefully someone else can do comparisons of the burned CD with some of these methods to see what is the best sound for, let's say, a $2000 or less investment (obviously not including the cost of a computer). That is a level that many of us might be willing to make if there is a significant improvement over the #1 methods above.
bruce_1

Showing 3 responses by shadorne

CD's can't have jitter....there is no timing information on a CD...just data samples....in order to get jitter you need some kind of clock or a clock signal.

The is No clock on a CD...

....these audio urban legends go against all logic. The jitter must come downstream of the CD.

So what explains the source of urban legends like thiis? Read on if you care...

Imagine a wobbly surface CD or one where the tracks wobble a lot - this is clealry more difficult to read for a lazer/mechanical system, as the CD rotates the mechanism performs more cyclical corrections per revolution of the disc (in fact the focus corrections will be periodic as each woble repeats on each revolution).

Now the lazer will require more focus adjustments per block of data than a well constructed CD (perfect center and perfect flat surface)....now if you postulate that the rapid oscillations of the focus system for the lazer and the transport mechanism require periodic power and this causes oscillations in the power rails that in turn affect the power to the clock in the D to A......then this may induce jittter in the clock signal.....worse if the jitter is periodic (due to periodicity of the power rail fluctuations) then it will have a much higher chance to be audible than if it where random.

However the problem is the CLOCK timing accuracy! The result may be that one CD perceptively has more jitter than another....but the CD isn't actually the cause. It is the BAD system design that does not properly isolate the lazer tracking mechanism from the clock used to time the D to A.

I hope this helps to explaiin how a CD might "appear" to have more jitter.....what it means is that it may or may not have more jitter depending on the robustness of the CDP player!

Which CD will sound better in a badly designed CDP player? CDR-R? Commercial stamped CD's? The reality is that it will vary....a kind of crap shoot. Genesis found something that worked for them but it may not be the same answer with a different batch of CD-Rs....even from the same manufacturer.

What can you do about it other than playing wiith marker pens and various CD-R manufacturers in an unscientific fashion? ( A hit and miss approach)

A more robust transport, copying either CD to a hard drive and using a computer to play the file back, or a system with an external clock, such as EMM labs use, will generally guarantee that they sound the same. YMMV
Just a note - some early Decca CD's made in the UK have CD rot/CD bronzing issues. This might explain something you observed.

I have a Rossini Decca that bronzed so badly it no longer plays at all. I have several others that are still playable but may be degraded (nearly impossible to tell) I also have several PDO manufactured discs that have an increased noise floor and these are definitely degraded and sound bad.
BTW - that you had issues with airport express is not surprising if you think about it ... a tiny little box with SMPS power supply sandwiched close to the rest of the circuitry. However it is the analog that stereophile took exception to and not the optical out.

Perhaps the PLL design in your Tivista did not like what Airport express was doing jitter wise?

How close was the Airport express to the other gear....as I mentioned the packaging of this thing means it is more likely to raidate EM/RF noise....

Thanks for sharing - interesting