If the DAC is the same, how different do CD transports sound?


One interesting topic of discussion here is how audible the differences are between CD players when they are used as transports only — or when they are only transports to begin with.

In other words, in a comparison which keeps the DAC the same, how much difference can be heard between CD transports?

This recent video by Harley Lovegrove of Pearl Acoustics provides one test of this question. It may not be the ultimate test, but he does describe the experimental conditions and informations about the qualifications of the listeners.

He comes to the main conclusion here: https://youtu.be/TAOLGsS27R0?t=1079

The whole video is worth watching, I think.

128x128hilde45

+1 @jasonbourne71 and @2psyop

You are limited by the data stored in a CD regardless of what one do how to extract, decode and play. An audio compact disc consists of one or more stereo tracks stored using 16-bit PCM coding at a sampling rate of 44.1 kHz.

Main problem during extracting this information is "jitter." Jitter is produced either when a digital signal is created from the analog recording or when a digital recording is reconverted into an analog signal for playback.

Jitter occurs when the clock signal drifts slightly and the intervals between samples end up with tiny variations in length, causing distortion of the original sound when played back.

There is not a whole lot one can do about jitter produced when the digital signal is created from the analog signal. Technically, playback jitter is the inaccuracy in the timing of the "ticks" of the clock that transfers the samples of digital data into the D/A converter chip. To move data in a digital system from one point to another, it is usually clocked.

Most modern DACs have good reclocking mechanisms and other methods to reduce playback jitter. Any transport can provide the digital signal with varying degree of jitter. So the issue is, if you have a good DAC, then why would the transport matter? Because DAC should be able to buffer the incoming digital signal from any transport and convert into an analog signal based on its own clock and analog filters. Now one can argue about different DACs and their implementations. However, different CD transports should not impact the digital signal or its quality.

My recommendation is investing in a good DAC. Some of the DACs from the past will include excellent chips such as multi-bit Ultra Analog D20400, Burr Brow PCM63, PCM1704 as well as some outstanding one-bit DACs (Delta-sigma). If you really want to go crazy, try using DACs with tube analog stages. But return on a transport will be a question mark.

If you embrace the influence of expectation bias you can appreciate that the more you spend on anything the better you will think it sounds. That always works.

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I am not aware of any compelling explanations as to why this might be the case, but in my experience, top-loading transports which utilize weighted pucks on top of the CDs sound better than other designs.

No confirmation bias involved in my observations, though I have never A/B tested.