Optimize the acoustic performance
Ole Wolff Elektronik A/S, Roedengvej 14, 4180 Soroe
sales@owolff.com, T: +45 5783 3830
sales@owolff.com, T: +45 5783 3830
29-03-2023
Speaker system Design
Integrating speakers into end products and optimizing performance
Integrating a speaker into a product is not as straight forward as it may seem. Even small changes to volumes and openings behind or in front of the driver can alter sound performance dramatically. Very often the design of the product is far from ideal seen from the acoustic engineer's point of view but once the right driver is chosen and integrated properly into the end product, impressive results can be achieved.
Ole Wolff has the tools and experience necessary to help our customers optimize the acoustic performance regardless of the form factor of the end product.
Micro speaker system design
Maximizing performance in minimal space
Ole Wolff is specialized in not only the design and manufacture of high efficient micro loudspeakers with maximum performance relative to the physical size and required form factor. Ole Wolff is also dedicated to the implementation and optimization of our drivers into our customer's products.
Selecting the right driver / custom solutions
Ole Wolff has a very large portfolio of speakers for various applications. In most cases Ole Wolff can recommend a driver from the existing portfolio that will be ideal for the job. Sometimes minor modifications of the driver are necessary in order to achieve the best performance in a given application. But often Ole Wolff join projects where a new driver has to be developed from scratch due to special requirements regarding form factor, electrical termination and so on. In such cases there are of course requirements for a minimum quantity of speakers and for the lifetime of the project, as well as a slightly longer development time compared to when an “off the shelf” product is being used.
A selection of Ole Wolff micro speakers
Virtual prototypes
Saving time using advanced simulation tools
Ole Wolff has been using Comsol Multiphysics™ since 2016 and can do acoustic simulations on both raw drivers and speaker systems. Using simulation a lot of prototyping can be done "in the box" in close cooperation with the customers CAD team. Often customers want to know the effect of different hole dimensions, placement of drivers, different driver types etc. So instead of building an endless set of physical prototypes (which can be tedious and very time consuming!) the customer can have Ole Wolff simulate the various configurations based on the customers CAD files only. This way development time can be drastically reduced and performance targets can be met much faster.
Next stage is to make the prototypes, either as SLA or machined parts, to be used in the following verification stage, where the performance is measured and matched to the simulation results.
Operating temperature
Operating temperature inside the speaker box is measured to ensure that the driver is operating within its safe operating area. The Ole Wolff drivers are using glue that can withstand the high temperatures at maximum operating levels.
Read more about Comsol Simulation
Simulation of a small Ole Wolff speakerbox with 1x Ø52mm speaker + 1x Ø55mm PR.
Getting a good start
Even what may seem as minor adjustments can have tremendous effect on the audio performance. By involving Ole Wolff early in the process the foundation can be laid for great audio performance which can be further optimized later on in the design process.
The speaker placement can seriously affect the frequency response.
Speaker box design
The Ole Wolff mechanical engineers work closely together with the acoustics teamUsing a speaker box can be an advantage in applications with "problematic" rear volumes, in products where sufficient acoustic sealing is difficult to achieve etc.
The Ole Wolff speaker boxes can come in a variety of form factors but are always optimized for maximum performance within the physical limits of the product they are to be installed in. Special features such as front (Helmholtz) resonators and passive radiators can be integrated in the speaker box and special measures can be included to reach certain IPxx ratings, waterproof ratings and more.
A selection of prototypes of speaker boxes desiged by Ole Wolff designed to optimize perfomance in the limited space available
Passive radiators and bass reflex
Sometimes adding passive radiators or bass reflex can improve perfomance
The inclusion of a passive radiator (also known as "slave unit") in a speaker system can sometimes improve the low frequency response (bass). This technique uses the tuning of a resonator to have its resonance just below the resonance frequency of the active driver itself and thereby adding more acoustic sound pressure level in this region. The tuning is controlled by the moving mass, the mechanical compliance, the piston area of the passive radiator and the compliance of the air in the speaker box. The passive radiator interacts with the active speaker and care must be taken to cut off frequencies where the passive radiator and speaker play in opposite phase and to make sure that the active speaker doesn't exceed excursion limits. Obviously designing a well-performing passive radiator system is not straight forward and often enclosures of certain sizes will actually perform worse if a passive radiator is included compared to just having a single driver in a sealed enclosure.
Ported boxes
In smaller enclosures there is rarely any advantage of using bass reflex (ported boxes) since the port/tube itself takes up a lot of volume if port noise is to be avoided. However there are cases and applications where ported boxes can be an advantage.
- Ole Wolff knows the do's and don'ts of passive radiator/bass reflex integration and can help finding the best solution for your application.
Ole Wolff uses a custom designed test rig to test and develop passive radiators
DSP Tuning and speaker protection
Tayloring the frequency response, maximizing bass while protecting the speakers from being overloaded.
Ole Wolff has the reputation of designing very high quality and robust loudspeakers having excellent reliability.
However, feeding our loudspeakers with carefully tailored electrical signal processing can further extend the audio performance without challenging the reliability and lifetime.
However, feeding our loudspeakers with carefully tailored electrical signal processing can further extend the audio performance without challenging the reliability and lifetime.
Knowing all the characteristics of the speakers allows for driving them to the very limit of maximum allowed voice coil temperature as well as maximum allowed stroke of the diaphragm.
There are so-called Smart Amps (amplifiers) on the market, which accept these loudspeaker characteristics to be programmed in, and giving the result of a very high sound reproduction quality at all sound pressure levels and at a very low distortion.
Ole Wolff supports our customers in this optimization process as a natural part of our service.
Verifying the performance
Measured response as well as subjective impressions matter
The acoustic labs at Ole Wolff in Denmark and China are equipped with the most advanced measurement equipment specially developed for performance verification of audio products. This includes artificial ears, Head & Torso simulators, anechoic chambers, Klippel laser equipment for speaker parameter detection through diaphragm movement etc. and are all parts of standardized test methods used and acknowledged all over the World.
This makes us possible to communicate test results in same technical “language” as our customers as well as other independent laboratories are using.
This makes us possible to communicate test results in same technical “language” as our customers as well as other independent laboratories are using.
The Ole Wolff lab in Denmark has invested in Klippel add-on equipment, the SCN NEAR FIELD ADD-ON (SCN-NF), which is a smart alternative to an anechoic chamber and is an-add on to our existing Klippel laser diaphragm scanning hardware.
Klippel laser diaphragm scanning hardware
Some of the functionalities include
- Holographic measurement
- Ideal half-space conditions
- Suitable for transducers and complete systems
- Extrapolate SPL to any point in 3D half-space
- Balloon, contour, polar and sound power plots
- Near and far field information
Do you want to know more about speaker system design?
Involve Ole Wolff early in your design process and you will get the best result.
Send an e-mail or contact your local sales contact to learn what Ole Wolff can do to help developing your products.