Audio design applications
Audio devices are used in many interesting applications from homes to shops, houses of worship, cruise ships, you name it. Audio devices can be part of a large background music system or simply a little boom box.
Knowing your target application for audio design is always the starting point to understand which design elements are needed. The main setting of the audio device you are developing will be key.
Depending on the sector, people’s perception of good and bad audio changes. More on this later.
Standards and competitors
Audio design suffers from a lack of industry performance standards, from signal to noise ratio, how loud it can go and other considerations. It can often feel like the wild west.
As a result, if you are designing a new audio device, you’ll likely take notes from your nearest competitor to see what features they offer and how you can exceed them and connect with your target audience.
Audio design trends
The trends in audio design change regularly. How many watts you get out of your device used to be the big thing. Original audio amplifiers like guitar amps used to focus on how loud they could be. You also found a lot of people claiming that their product offered more power than it produced or exaggerating other claims.
The rise of Dante technology
Dante is causing a stir in the audio world.
“Dante audio networking provides digital audio distribution over IP networks.” About Dante.
Dante’s advantages include monitoring and controlling software and automatic device discovery. This has resulted in major manufacturers integrating this.
The ability to send audio over IP offers interoperability that is enticing to many product developers.
Therefore, if you are looking at futureproofing an embedded device it is worth considering whether to utilise this emerging technology or another option such as AES67.
Of course, this integration doesn’t come cheap with expensive licencing and modules. With an initial cost to use the card and continued subscription. You need to weigh up the pros and cons of marketability and the longevity of your product against this ongoing cost.
The growing Bluetooth integration
Bluetooth has traditionally been associated with being a great user friendly multi-use tool for consumers. However, the technology is now finding its way more frequently into industrial and business settings. For example, temporary meeting spaces.
As people move back to the office after working from home, they are becoming less tolerant of older systems. For instance, if a business professional is used to being able to connect instantly to their Bluetooth speaker, they are going to be frustrated when they have to use wires and faff about in the office.
As such product developers and manufacturers have had to up their game and adapt to their increasing customer expectations.
Equally it is worth looking at Bluetooth in the product development process, you can read more about the pros, cons and alternatives in our Bluetooth article.
The power of marketing
There are many great products on the market that don’t get a look in because they fail to promote their product enough or through the right channels. Equally many audio products that get a lot of attention are found to be inferior but still make a healthy profit because they push their brand and shout the loudest.
So the key is to produce the best audio design whilst making sure your marketing strategy, with a budget to match, supports that and communicates it effectively to the right audience.
In the B2B audio market it can be tempting to rely on word of mouth or even B2C consumer reviews but in the modern world this means you miss a huge chunk of potential. With the volatile market dealing with everything from the pandemic to chip shortages it’s not enough to rely on repeat business. Existing customer relationships are hugely important but they could go bust or decide to go down another route and if you don’t plug the gap with new business this leads to decline and a threat to your business continuity. And if that happens you could end up letting down your remaining customers as your R&D potential suffers or worse.
There are two main platforms you can utilise for audio electronics.
Either an analogue or embedded digital approach
Advantages of analogue audio design
- Audio Quality – Analogue audio design can often sound better, with some key performance parameters easier/cheaper to achieve in a less complex design (SNR, headroom, bandwidth…)
- Cost – For simple audio products a fully digital system with DSP would be under-utilised and only add unnecessary cost. It can be cheaper to implement an analogue only signal path.
Disadvantages of analogue audio design
- Inflexibility of final design – The features are set in stone once you hit the production stage, you need to undertake a major redesign in order to add features and assets to your product.
- PCB area – For a more complex feature set, an analog platform is likely to take up more board space than digital one. This increases the PCB cost and the final product size.
Advantages of embedded digital design
- Feature updates – The biggest advantage to DSP is the ability to make changes and add new features later down the line through software updates only. No costly board changes.
- Quicker route to market with final design – A product with a complex feature set is likely to hit the market quicker with an embedded platform, as software only features can be developed in parallel to the hardware.
Disadvantages to embedded digital design
- Audio Quality – As you will be relying on ADC & DACs to translate your signals, their quality may become the limiting factor in your design. With performance scaling alongside cost, depending on your budget an analogue approach may perform better.
- Market availability needs major consideration -Although no design is safe from component shortages, you will be very unlikely to find drop-in replacements for DSP chips or ADC/DACs. Unlike transistors and opamps, these semiconductors are generally unique, with different manufacturers employing different PCB footprints.
The above options present a trade-off and it will depend on your specifications and what you are trying to achieve that will determine which route is right for you and your customers.
Amplifier design is super critical in an audio product.
You’ll need to consider if you want to use an analogue amplifier or a digital amplifier.
You can use many different topologies in your product, but the main ones are Class AB (Analogue) & Class D (Digital). Here are the pros and cons.
Class AB advantages
- Audio fidelity – Widely contested across internet forums & discussions, Class AB vs Class D audio quality is a sticking point. However, in most applications a Class AB amplifier will offer sonic advantages.
- Bigger, heavier, hotter, less efficient – The inverse to Class D, Class AB generates more heat, requiring a larger heatsink and therefore takes up much more room.
Class D advantages
- Smaller, lighter, cooler, more efficient – For a given wattage, a Class D amplifier will be more efficient requiring a much smaller heatsink. This takes up less space inside enclosures and allows designers to achieve more compact product.
- Green credentials – A class D amplifier coupled with an efficient SMPS allows designers to add green energy standards to their products. Energy Star has specific standards for measuring the efficiency of audio products, compliance with may benefit your product.
- EMI/EMC considerations cannot be overlooked – Much like a SMPS, Class D amplifiers contain switching frequency into the MHz range with harmonics higher still. Good practices and effective reduction of EMI is necessary for compliance.
Which is best?
Class D is the future, there are too many benefits to ignore. Also some audio manufacturers offer power-supply and amplifier modules that simply drop into enclosures and interface quite easily with bespoke pre-amplifier circuits.
This is particularly popular in Denmark where many people are taking up power electronics courses at university. This is creating a technology hub in surrounding areas.
Using off-the-shelf parts
The benefit of off-the-shelf parts means there is a quicker time to market and these are usually pre-certified. The downsides are that it the modules are designed to meet a wide range of device specifications. This may be a problem for a complex audio design with specific requirements.
90% of applications can achieve a fine or great result from using off the shelf modules.
What do people want from audio design?
There are two extremes in the audiences for audio design.
Group one: Where aesthetics is key
There is a huge consumer audience of people who care very little about specification. When was the last time you bought a speaker and found yourself bombarded with spec detail on the packaging? Information is less important here.
This group care about how the audio device will look in their home. If the quality is good enough their focus will be on whether it looks nice whilst they entertain their guests or listen to music in their kitchen.
Group two: The spec hunters
Those in a more industrial setting are far more interested in the specifications. The product itself will often be tucked out of sight, what they care about is performance, reliability and how easily the products advanced features can be used.
Just as Raspberry Pi is used for hobbyists and serious product developers there is also a small niche of 10,000s of people who are enthusiasts of audio devices. People are into really exotic components and innovative ways to use audio design such as bees wax. They will really get stuck into the detail.
Those working in the live sound & Instrument sector must design for the best of both worlds. They need it to look right and sound right. Sometimes they need a product to emulate the sound of vintage equipment using the latest modern components.
Stay down to earth: Design for the application
It’s easy to get caught up in all the latest trends but stay true to what’s appropriate for the application. For example, general purpose capacitors might be fine, you don’t need to go crazy with bespoke components (especially in the current chip shortage climate).
Generally, a poor part will generate a poor performance for any kind of electronics design performance so consider the components you use and whether they are appropriate for your market yard.
Testing in audio design
Testing is key for a quality product and many performance figures are benchmarked across the industry between competing manufacturers. Depending on your products application, you may want to test for:
- System Efficiency
- In ‘always on’ applications, minimising power consumption at idle and maximising efficiency when in use is critical for green standard compliance.
- Frequency response & Distortion
- How accurately an amplifier reproduces music can be quantified through testing such as Frequency response sweeps, Total Harmonic Distortion (THD), Inter-modulation Distortion (IMD) tests and others. Performance goals here will depend on your application.
- Signal to Noise Ratio (SNR) & Crosstalk
- Perhaps the most noticeable merit of an amplifier is how much background noise is present when no music is playing. SNRs of beyond 100dB are easily achieved with careful design and investigative testing.
- Low crosstalk between amplifier channels is essential in applications where two separate areas of a building need different music. Nobody wants to hear a mix of two songs!
- Environmental effects
- Component choice for audio amplifiers is done with budget and application in mind. Capacitors are well known for changing specification at different temperatures, but how much an amplifiers performance deteriorates in harsh environments can be evaluated during testing using our environmental chambers.
Don’t forget to listen
Listen to the device, don’t just rely on the data. Some things are difficult to visualise in data and quantitative testing should always be followed up with planned listening tests that aim to answer the following questions and more:
- How effective are EQ controls at compensating the effects rooms and speakers have on perceived frequency response?
- What noise does the amplifier make when it is switched on/off? Any clicks or pops?
- Has something been missed? For example, does use of a network input or digital interface result in noise being heard from the speakers?
The bottom line is hard data is important to check the functionality of the device and to check everything is fine, but this needs to be backed up with extended listening tests.
Watch out for edges cases
These often occur products with complicated mixers with many inputs/outputs and extended feature sets. If you test each feature individually it’s possible that in the field someone could connect inputs, outputs and set features in a way you haven’t dreamt up that could cause a major issue.
Proper testing should pick up these edge cases before the product hits the shelves.
Audio design and service
Ignys can help meet your audio design requirements with engineers who understand the audio industry and have a wide range of electronics design expertise.
Joshua Green has over 6 years experience as an R&D engineer specialising in the Audio/Visual industry.