Audio electronics is one of the most controversial fields of electronics. High quality audio and hifi contain lots of strong beliefs and opinions and excess marketing jargon. Perception of sound and its quality is something we cannot express in numbers but is instead highly subjective matter, making it prone to strong arguments and debates.
In DIY-audio we also face all the extremes of different philosophies and approaches to good sound, and forum threads of hundreds of pages of strong opinions and contradictory statements. While anyone can have their own design philosophy, here I address mine.
- Highly technical and engineered approach
- Technically solid and well measuring circuit is the basis of everything
- Even if the plan is to experiment, this should be the starting point.
- Nevertheless, sometimes deliberately making the signal technically worse, e.g. tube amp distortion or non-oversampling DAC, may lead to more pleasing sound. To some. And it is a matter of taste and debate again.
- Understand the circuit
- If using part of a design from datasheet, application note, or someone else, fully understand the operation before changing anything.
- Experimenting can be rewarding but understand the technical consequences of modifying something.
- This is also the only approach to reasonably show the quality of my designs online with only text, graphs, and photos. If I just told you how great my devices sound it would only be an opinion of one person. Measurement results are not a matter of opinion or personal taste.
- Technically solid and well measuring circuit is the basis of everything
- My main goal is high performance and this leads to some solutions not all makers appreciate
- SMD components
- I try to avoid the smallest packages but I will continue using mainly SMD components.
- SMD components have superior technical performance benefits such as lower inductance and smaller size leading to more compact designs with shorter traces, again lowering parasitic effects.
- Compact design is also cheaper as small packages are cheaper and smaller board area means lower-cost PCBs which may be the most expensive components for a hobbyist, especially if using more than two layers – although prototype multilayer PCBs have seen a huge price drop in recent years.
- Most of the modern parts are simply not available in larger packages.
- I encourage all makers to learn to work with SMD components: get a decent soldering iron, watch some Youtube tutorials, and get hands-on experience. Sometimes you cannot avoid tricky tiny packages but you can solder almost anything with care and patience. Just do not fry the part or PCB traces and always check the results with magnifying class or camera before powering up the board – although this may not help with BGA packages.
- Importance of PCB
- Often understated in DIY community, PCB is certainly one of the most important parts of almost any electronic device, especially digital or mixed-signal.
- 4-layer boards have become affordable to makers as well; they offer better performance especially in higher-speed designs and PCB routing is easier, although requires some extra care as well. Cost is still significantly higher than 2-layer boards which are enough for most simple and low-bandwidth analog designs. Luckily we are seeing 6-layer boards becoming more affordable as well.
- I tend not to use exotic “hifi” components because I think they are mostly rip-off and marketing
- It still does not mean that the cheapest components should be used; in signal paths I use thin film SMD resistors and where capacitors are necessary I use SMD film capacitors, good quality ceramics, or larger through-hole plastic capacitors.
- Sometimes it is also worth paying some extra for nice looking solid components, for example connectors. Overall, for mechanical components paying extra may be worth it.
- I admit I do not know too much about passives yet so I will learn, experiment, and my opinion may change.
- Cost is not the highest priority in a DIY project (while I still do not want to pay for snake-oil components)
- Considering the time invested, BOM (Bill Of Materials) cost does not matter that much anymore.
- It is often not sensible to do extreme BOM optimisations; to perform extensive measurements and tests to figure out if some components can be removed or changed to cheaper ones without sacrificing performance. It is always worth reducing BOM line items though and try to re-use existing components in the BOM. This becomes valuable also when deciding to get boards assembled.
- SMD components
- Modularity is nice in DIY where things tend to change often or are never completely finished
- No need to design and build everything all over again every time – power supply is a good example
- DIY does not mean it must be ugly
- It is difficult or very expensive to get professional looking enclosures but with some extra investment and effort it is possible to create devices that do not need to be hidden behind cabinet doors.
- Despite the engineering approach, I try to stay open-minded
- I accept there are things in audio we cannot measure or quantify.
- I do not have golden ears – if I cannot hear the difference it does not mean that someone else could not. Nevertheless, in that case it is meaningless to me.
- My opinions may (and will) change if someone (or myself) proves me wrong! We must always accept that in science and technology.