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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
johnnyb53
3,510 posts
 

11-30-07: Vcoheda
i don't see how a burned CD could sound better than the original...
Back when Genesis made the Digital Time Lens, they used to make CDR copies through the time lens, and use the CDRs to demo their speakers. They explained that the recorded disks sounded better than the source CDs because the Digital Time Lens removed a lot of jitter from the source disk before burning the CDR.

These days we often burn CDRs on a computer, which--like the Digital Time Lens--buffers the data stream and burns the CDR with a rather short signal path. Also, it's my understanding that burning a CDR over a USB link could perform the same function because it is bi-directional and solidly locks in the word clock.
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shadorne
7,467 posts
 
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
winstonsmith
25 posts
 
Apparently, the CD burners burn the CDR disc more effectively (i.e., more easily read by the CDP) than the CD original was burned, and that allegedly accounts for the better sound. I'm not convinced. My feeling is that, like with everything Hi-End, each burner will have its own sound and sonic character, a frequency response that works very well in some systems, not so well in others, and that these differences will be the bases for the claims of superiority. I agree with those who say that a well made player with a well designed and built transport, laser, power supply, etc., are what we need to focus on for better sound. But if a burned disc sounds better to your ears in your system, and you've got the cash to invest in a full-blown audiophile-approved CDR burning system, then I say: go for it!
mrtennis
3,295 posts
 
again, we are faced with the eternal question: what does better mean ? if it means i prefer a to b, then a is better, there is no definitive answer as to whether an original sounds better than a copy.

if better has a specific sonic denotation, then i would say the answer is that it is cd dependent.
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drubin
3,267 posts
 
Bruce_1, thanks for your thorough write-up of a comparison that is of great interest to me. I have a HagUSB unit on its way to me and I also have a MacBook Pro and an Airport Express. I will attempt to replicate your experiment with two additions: going through a Squeezebox3 and burning a CDR from an Alesis Masterlink 9600, which is a hard-drive CD burner, among other things.

For what it's worth, I have always been disappointed with CDs burned off my MacBook (ripping via Apple Lossless), which is why I bought the Alesis.
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