Digital audio carries binary data e.g. “01100100”. The digital data can be clone perfectly in digital copy. This is the no.1 rule in digital theory. When you copy a photo from memory stick to hardisk, they are identical and exactly the same. In professional audio world, we called this “Bit Transparent”.
First digital audio QC procedure – “Bit Transparent”
As a mastering engineer, the first QC tests final CD product is 100% identical data compare to the CD Master. It was shocked that there are manufacturing plants cannot meet this minimum baseline. Legedary mastering engineer Bob Ludwig famous quotation “Never turn your back on digital” is another great example. We reject using those plants which cannot supply data identical product.
Identical data but different sounding
Within audiophile community, it’s a general accepted concept that Compact Disc, which made by different manufacturing plants produce different sounding. This is a confusion against the law of physics. How can the same digital audio data CD produces sonic differences? These researches were rooted around mid 90’s. Julain Dunn wrote a AES paper in 101 AES Convention. (AES Preprint number: 4399 – October 1996). We now understand that the effect of timing error. “Jitter” – the timing error affects real time playback.
In the quest of better audio quality, there are special designed replication plants trying to maintain high standard CD replication. This area is like a myth to the general public, especially to those computer programmers that know so well about the checksum/digital data clone.
Hardware playback solution journey:
In high end audio history, hardware manufacturers developed separated CD Transport & Digital to Analogue Converter (DAC) to avoid the CD mechanism (movement parts & servo) draws the same power sharing with the DAC. Sony invented the SDIF-2 interface with 3 BNC connections that one dedicated cable for wordclock connection. Recent years, it is more popular that a master workclock links multi-boxes for higher precision in timing. More sophisticate PLLs (phase lock loop) are designed to remove timing error, such as asynchronous sample rate conversion, DSP solution and RAM buffering.
“DWSQC DISC” – Better Quality Control in Final Products
It takes a full time engineer to create 100% in house with the superior CD-R material and specific low speed creator. This is different than other companies using high speed CD-R duplicator. Each final CD-R is inspected by our QC engineer. The package included an unique performance printed report. The industry standard is < 220, the “DWSQC” tolrence is extremely tight < 5. This QC method was used only on CD Mastering session before. It cosumes very high cost and long production time. Each DWSQC CD takes average 60mins to produce, measure and report. The benefit however, is exactly the method we have been done on all our CD masters! This is one of the most challenging and transparent QC ever in CD production. It is a tailor made procedure with highest quality expectation. If audiophile would like to focus on the very best details, we certainly would like to offer.