A History of Digital Audio: Have we made progress?

ModBlog – History of Digital Audio: Have we made progress?

“You Spin me right round bayby, like a record baby, right round right round”, Dead or Alive (1985)

Born in 1970, I have experienced LP’s, 8-track, Cassettes, CD’s, streaming and now at age 55 I listen to LP’s. Digital Audio was born in my lifetime and I have seen it chart a course that is interesting, if fraught with problems. We began with analog, discovered digital and have worked hard to prove digital playback that betters analog. The question is, have we succeeded? Is progress truly progress?

In Middle School, I had a Sony Walkman and listened to mix tapes and new cassettes. My sister who is six years older than me, had records, but they were on the way in this point of my life. My father had 8-tracks and we listened to them in his truck on fishing trips. Vinyl was difficult, records scratched easily and took up a lot of space. 8-track was OK, but cumbersome. Cassettes were the popular choice at this age and mix tapes were a thing.

At age 18, in 1988, as an exchange student in Australia, I heard my first CD’s. A kid in the neighborhood had a Sony CD player and each week we all gathered to listen to a new CD that he purchased for $30(!). It was new, cool and much better than cassettes because you could switch between tracks, which you couldn’t as easily with cassette.

In College in the early 90’s, I had a boom box with CD and all I had were compact discs. The audiophile bug bit me here when a roommate in student apartments brought in Carver separates. We listened to Dead Can Dance on his system and I was blown away!

Following college, with engineering degree in hand and some disposable income, I built my first real system. Tube and SS, integrated amps and separates, Sim Audio, Jolia, Sony, Adcom, it was all still anchored to CD playback.

ModWright was formed in 2000 and at CES and all of the audio shows, it was primarily CD playback, some with DACs and others with high end CD players. Instead of mix tapes, we had ‘demo discs’ and we used them religiously at shows. Its tedious now to think at how many times we played the ‘Chinese Drum Solo’ or how many versions of Diana Krall or Patricia Barber songs we played. Admission of guilt here, I still enjoy both Diana and Patricia, but we did overplay them in the day…

Vinyl playback was a thing, but it was not as prominent then, as it is now, for high end demos.

Separate DACs were the next big thing in the early 2000’s and with them came the need to address drawbacks associated with the technology…. Here is where things get interesting in my opinion.

We had DACs built into the CD players, but outboard DACs, like the Perpetual Technologies P-3A DAC were ‘better’. The separation of duties meant a dedicated transport could do its job better and the separate DAC could focus on its sole job of decoding the 1’s and 0’s to audio. But, we found that jitter was introduced between transport and DAC. This was caused in part by the cable and transmission of the spdif or AES/EBU data from transport to DAC and impedance as well as other variables therein.

We learned quickly that internal clocks, cable impedance and connector interface as well as vibration, power quality and other variables all introduced ‘jitter’ or timing errors that affected the sound quality of digital playback.

Fast-forward into the future, we introduced ‘computer audio’, which was very cool! Now we could store thousands of albums on a hard drive that fit in the palm of our hand! This also meant adding a computer, acting as transport to our DAC. Once again, convenience had a cost, yet more jitter and problems to address in digital audio sound quality.

At that time we were using USB cables instead of AES/EBU, Toslink or SPDIF cables. “Well, aren’t they just carrying computer data? It shouldn’t matter what cable we use?” I quickly found out that this was not the case. Without getting too technical, the USB Digital cable for audio, carried binary data, power and ground. Data was carried via twisted pair of ‘+’ and ‘-‘ conductors for signal transmission.  The data was sent in packets, requiring timing error correction. This was also achieved via synchronous or asynchronous mode, allowing for data buffering and re-clocking. So yeah, it got complicated.

Today we use computer servers and streaming, rather than stored digital audio files. We now have computer servers, streamers, DACs, DAC/streamers, ethernet switches and routers, all designed specifically for audio.

So, backing up a bit and recounting where we came from:

1. Vinyl playback involves a needle on a record transmitting analog signal to a phono preamp for RIAA correction and amplification. We have music at this point.
2. Tape playback, reel to reel, 8-track or cassette, we have tape head to magnetic tape to analog filter and amplification. We have music at this point.
3. CD Playback involves a laser head reading from the disc which ‘slices’ up the analog signal into a BUNCH of samples, synched to a master clock. These are then transmitted to a DAC via I2S data format, where it is reconstructed into music again with another synchronized clock. We have music at this point.
4. Adding an outboard DAC then, takes the data from the laser in I2S format, converts it to SPIF, AES/EBU or sometimes keeping it in I2S format, where it is transmitted via pulse transformer or similar, via spdif, toslink or AES/EBU cable. This cable connects to the input of the outboard DAC component. It is then received by an impedance matching circuit, fed into a digital receiver, where it is converted back into I2S format and re-clocked. It is then decoded by the D/A converter (DAC chip), followed by post conversion analog filtering to get rid of extraneous out-of-bandwidth noise artifacts. From here we have music.
5. Adding computer audio, we have music either fed as stored computer files, via USB computer cable, to outboard DAC where data from the USB cable is then converted to SPDIF or I2S where the data is handled per the previous step above.
6. Adding streaming to this, we have now have data streamed via internet to computer router, possibly via computer switch to computer server. From here it is transmitted either via Wifi or ethernet cable as data to computer streamer where it is converted to a format that can be transmitted to a DAC. Again, from streamer to DAC follows a path similar to (4) and (5) above.

At this point I need to take a step back and ask myself, is this progress? Arguably, modern digital playback is very good! The advent of streaming and computer audio has changed how we listen to music, and we all use and enjoy it.

The trouble that I have with the trajectory of technological advancement here is that with each improvement in tech, there are more problems to be addressed. More areas where error is introduced and needing resolution.

Jitter was introduced with digital, acknowledging that ‘perfect sound forever’ was maybe not quite so perfect… These timing errors were exacerbated with each ‘advancement’ in digital technology. Outboard DACs introduced digital audio cables which gave birth to ‘jitter reduction boxes’, re-clockers, etc. Computer audio added a whole other dimension of computer data transmission with its own noise, timing and other issues. Then streaming computer audio added a multitude of other dimensions of issues involving the internet, environmental noise, data transmission, equipment induced noise and even more audio cables and transmission related sources of error.

Consider two parallel paths of high end audio technology: Analog and Digital.

Analog playback has seen advancements in materials, cartridge technology and design, as well as improvements in turntable and tonearm design. We have made improvements in sound when taking analog signal from the needle of the cartridge to the playback of music.

Digital audio, born in 1986, has seen over forty years of improvement and advancement in a field of expanding complexity and refined technology. This path, in my opinion, however, has been one of two-steps-forward and three-steps-back. That’s not entirely fair, lets say two-steps forward, one-and-a-half steps-back. Progress has been made, but at the cost of greatly increased complexity.

I don’t prefer complexity, but I do acknowledge its necessity in today’s modern world. Since I was in middle school, we have all seen huge changes in technology and technological advancement. Much of it good, and some comes with a price. I look at digital audio in the same way.

Do I listen to digital audio? Of course I do! I also prefer vinyl for my most satisfying and soul-fulfilling enjoyment of music. Is progress truly progress or is it just change. At nearly 56 years of age, I primarily have records and turntables. I’m good with that….