CD Player used as transport


Does anyone have experience trying different CDPs as a transport for a DAC? I've tried a few and the results were all over the map in performance from terrible to OK, I suspect problems from the balance of the unit creep into the performance of the transport. Some could be poorly made or the designed is a 2nd thought from a transport perspective. There seem to be a lot of new or used options in the $500 range from manufactures like Oppo, Marantz, Sony, CA etc. but do any of them get the design and integration of the transport right so the unit can stand alone as a quality transport? I'm a vinyl and CD spinner, tried the computer route didn't like it. Looking to improve the transport side of CD playback before I consider upgrading my DAC.
128x128musichead

Showing 6 responses by audioengr

Every transport will have different jitter characteristics, and typically fairly high jitter.  This is the difference you are hearing.  For transports, only output jitter matters, nothing else.  You can lower this a bit by putting various treatments on the disk, but the simple and more effective method is to add a Synchro-Mesh reclocker in the S/PDIF cable.  This has several advantages:

1) lowers the jitter to ~20psec - only the most expensive transports achieve this

2) upsamples the data to 24/96 - this forces the DAC to select a better sounding digital filter internally further improving SQ

3) provides galvanic isolation - breaks the ground-loop between the transport and the DAC which lowers the noise floor

4) it is no longer necessary to treat the disks to lower jitter

Here are measurements showing the effect of the Synchro-Mesh on an Oppo transport:

http://www.audiocircle.com/index.php?topic=154408.0

It is highly recommended that you use the best S/PDIF digital cable you can afford for the output to the DAC from the Synchro-Mesh.  The Empirical Audio Standard BNC cable is $275 and will satisfy this requirement. 

Here are some jitter plots showing how much jitter is added by typical S/PDIF coax cables:

http://www.audiocircle.com/index.php?topic=154425.0

Steve N.

Empirical Audio

Jitter is our expertise.

I have an older Wadia transport since new and connect it to a Jadis dac by the AES connection also have a Shitt Gungnir M/B dac connected to a Cambridge Audio CDX transport by way of the rca. Do you feel your answer would improve either of my dac transport combos especially the latter. Cables used in both instances are Acoustic Zen MC2.

Definitely.  The Synchro-Mesh does not have AES/EBU in or out though.  It has Toslink and coax, BNC and RCA in and out.

I have AES/EBU interfaces in my designs, but I have found them to generally have higher jitter for three reasons:

1) higher voltage is required for AES/EBU than S/PDIF, so more energy is required to get a fast risetime

2) usually and additional buffer is needed to do AES/EBU right, so this adds jitter

3) there are no 110 ohm XLR connectors to my knowledge, so matching the impedance is a challenge.  Cables for AES are also more difficult to build and get uniform impedance.

You could get a good Toslink cable and an excellent coax cable like my Reference BNC for $499 and run both of these from your two transports to the Synchro-Mesh.  Then you can switch between them on the front panel and get the benefits of the Synchro-Mesh for both.  A single excellent coax cable would connect to your DAC.

Here is a good Toslink if you can use it:

https://btpa.com/TOSLINK-XXX.html

Steve N.

Empirical Audio

BTW, 30-day money-back, less shipping cost, no questions asked on the Synchro-Mesh and my coax cables. My BNC cables come with 75 ohm RCA adapters.

There are customer feedback on both on my forum:

http://www.audiocircle.com/index.php?topic=154039.0

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Steve N.

Empirical Audio

All transports are equal and even better than before, provided you reclock with a Synchro-Mesh.

Steve N.

Empirical Audio

so just buy a transport that is reliable and has the functionality you like and the Synchro-Mesh will make it sound no different than the most expensive and highly regarded transports?

You got it.  It's that simple.

what creates jitter?

Anything that causes noise on the power or grounding systems or otherwise affects the timing of the bits.  Slow risetimes in signals can cause jitter because the noise on the power supply changes the point in time that the gates detect the signal changing.  In cables, its the bandwidth and dielectric absorption that can move edges and distort the signal.

dedicated transports seem to work better than CD players used as transports, does the DAC side of the CD player create jitter?

In dedicated transports, the manufacturer probably makes more effort to create a better S/PDIF output signal and reduces the path of the master clock to the output signal.

The D/A part of the CD player is certainly affected by the same jitter, but the jitter is usually less than what you see at the S/PDIF output.  The jitter starts at the master clock in the CD player and is affected by the associated circuits, power supply, ground noise, decoupling caps used and implementation.  By implementation, I mean what comprised the circuit.  There are many ways to do the clock circuits and most are not optimum for minimizing jitter.  The more stages, the more jitter.  The slower the logic family used, the more jitter.  Very few designers understand this.  This is what I do for 42 years.

Also my Rega Dac-R claims to reclock the signal coming in, I never considered a reclock before because of this.

This means that a reclocker is already inside your DAC.  This is fine, depending on the quality of the master clock used and the other ancillary circuits, as well as the implementation as described above.  The problem is that this all goes out the window if they have not selected the best chip for the resampling.  There is literally only one chip on the market that does a good job, and that's the one I use in the Synchro-Mesh.

I would predict that my Synchro-Mesh would even make your DAC sound better, even though it already has a reclocker inside.

If you change sources to your DAC or change coax cables and it changes the sound in any way, then the DAC is not immune to jitter.  This is typical for DACs with reclockers inside.

Any downside to up sampling? there seems to be mixed opinions out there.

There are mixed opinions on practically everything. Ignore them

If a good chip or algorithm is used for upsampling, it is only beneficial.  I used to believe that upsampling colored the sound, but that was because older chips were crap and older software was not great.  With the advent of newer more optimum algorithms and chips, there is no downside.  In fact, with many tracks it is difficult to tell the difference between the original and the upsampled providing the original has low jitter.

The main benefit of upsampling 16/44.1 to 24/96 is that it forces the D/A to select a more optimum digital filter that is well outside the audible range.  This is not possible with 44.1.

BTW, my DAC has no upsampling on the input.  The way I get around the 44.1 filter issue is that I can select the digital filter for 192 when playing a 44.1 track.  Sounds great even without upsampling.

Steve N.

Empirical Audio

Buying an expensive transport is like buying a $5 golf ball and hitting it with a $100 set of clubs.  It's putting the money in the wrong place IMO. Get the good clubs and hit the $1 ball.

Get a cheaper, solid transport with a good read mechanism like the Oppo and add a Synchro-Mesh.

Steve N.

Empirical Audio