Digital Audio

The design of the electronics in a piece of digital audio equipment is very much more difficult than one would think at a first glance at the problem. Back in the beginning of the 1990:s it was very much more difficult than it is today and at this time the roots of the present design of the Böhmer Audio electronics begin.

In the beginning of the 1990:s I did the design of the electronics in the hugely successful Forsell CD player. At this point in time most digital audio gear sounded, to put it kindly, not so good. The sound from digital usually exhibited very high levels of digital artifacts such as tinny harsh sound lacking resolution to start with getting worse, more congested and harsh, when the sound played back was more complex like a tutti from a symphony orchestra.

I think that if one compared the output stage DAC in let's say a present day iPad and a piece of high end gear from the time the iPad will win in almost all cases. This was the state of art at the time when the Forsell DC-player was designed and put on the market. It quickly acquired a sizable portion of the ultra-high end market for CD-players and quite a few people stated at the time that the Forsell player was the first piece of digital audio gear that sounded like analog.

So, why was this the case?

Well, it has a lot to do with the problems inherit in the design of digital audio equipment. Digital circuits by their very nature generate a lot of unwanted electronic high frequency noise and interference when they operate. In digital audio this noise is present in close proximity to the extremely important and sensitive clocking circuits and the equally important and sensitive analog circuits. This is a very big issue and the cause of many of the problems with digital sound.

To design state of the art digital audio there is an obvious need to master analog circuit design and digital circuit design but above all one need to master RF-circuit design. A piece of state of the art digital audio electronics is about as elaborate a design when it comes to RF as a piece of high end RF measurement equipment. In the 1990:s this was very much the case and it still is today.

What has happened since the 1990:s is that the digital audio electronic components have improved immensely. Today it is much easier to design digital audio that sounds decent than it was 25 years ago. That is why a relatively modest audio circuit in an iPad today can surpass most 25 year old high end equipment.

The components are much easier to implement and it puts a lot less demand on the designer compared to before. By just reading the application notes and implementing your circuit accordingly you will end up with a decent sound. If you source a high end DAC and associated components from one of the well-known electronic circuit manufacturers and implement it according to application notes, you will have a pretty good sounding DAC system.

If you want to create something really cutting edge this will be far from enough though...

Bernt Böhmer