CD Transports

I recently purchased an Atoll DR 200 Signature. It’s a fine unit. That may be another unit you may want to check out.

 The Atoll transport can be serviced in the U.S. and uses a Teac 5020 CD drive. I believe that drive is also used in the Tascam 200, and appears to be a decent quality unit (certainly not a $15 computer drive). The Atoll unit is built in France, and most of the subcomponents, are also manufactured there.

 I believe there is more to the transport issue rather than just jitter. Several factors come into play before the data reaches the DAC. The laser must remain in focus and track the disk. The disk must rotate at a constant angular velocity. The HF signal should be as noise free as possible. The transport should be vibration free. Errors with reading the signal and the PCM conversion are corrected on the fly, typically using a Reed-Solomon, or similar correction method. 

I believe the error correction process and method may also affect the signal. As data are transmitted “on-the fly”, no checksums are involved. There is no guarantee the data will be “bit-perfect” as compared to the source. This is true for disc or computer based systems when the data are “streamed” to the DAC. The signal could also be contaminated with noise, or altered, during transmission.

 Regardless of your choice, a CD transport with a good clocking circuit, power supply, and vibration dampening should be a priority in my view. I looked at the Sim Audio, but decided on the Atoll as a replacement CD drive may be easier to source in the future (Teac 5020 is a well-known unit). I ended up purchasing a spare drive from Atoll at a nominal cost. 

In my experience the transport can have almost as much effect DAC on the sound quality as the DAC. However, above a certain level, the transport differences may be smaller.

I couldn't recommend an Oppo 93 as a transport.  It has high jitter.  I had one and it took me some time to figure out it was the cause of my system not sounding as good as it should.  Replaced it with the Atoll and all is good now. 

Yeah, perhaps the DAC has more influence. Say 70% DAC to 30% transport? Hard to quantify, but as bigkidz says the transport can certainly be heard.

Compare the build quality of the $10 Sanyo assembly and the out of production $20 Philips to the $105  current production, audio CD only Teac. That Tascam 200 is probably a good, low cost option. 

When you move up in price you usually will get better, more robust power supplies and filtering, vibration control and dampening, better clocks and regulation circuits, SPDIF isolation, etc.  All things that will provide a more refined sound. Audiolab 6000CDT might be another lower cost option.