Loudspeaker Design Philosophy
We believe that measurement is an essential part of successful loudspeaker building.
Simply relying on datasheets, published cabinet and crossover designs, or purely theoretical approaches will not achieve the desired end point. Careful and methodical measurement at each step along the design & construction process provides 'visibility' of what is happening and how the speaker is likely to perform even before you reach the listening stage.
Once you have reached the stage where your ears start playing a major role, there are often so many variables to contend with that unless measurements have been taken at key intermediate stages it will be very difficult, if not impossible, to know where to start to make your adjustment
For the design of enclosures and crossovers, many published 'rule of thumb' methods miss out important elements - for example, crossover designs that assume resistive loads, where in reality each driver's impedance (and therefore the load the crossover is working into) will be varying with frequency. To achieve the required crossover points and slopes, before designing the filters it is necessary to (a) measure the impedance curve of each driver against frequency, and (b) deploy correction circuits at driver resonance and the HF point where impedance begins increasing rapidly with frequency - particularly where these occur within an octave of the crossover required point
The measurements involved in the above are numerous:
- Driver impedance and extracted Thiele-Small parameters (in free air)
- Driver impedance and extraction of Thiele-Small parameters (in the intended cabinet, including damping)
- Anechoic frequency response on axis
- A comprehensive set of directivity curves to ensure the most uniform on-axis/off-axis performance with the driver/cabinet combination
- All passive components
- Electrical performance of driver correction, crossover and equalisation networks
- Acoustic performance of the driver + cabinet + passive network combination
- Final listening-room testing and system ‘voicing’
This methodical approach is the one taken by Loudspeaker Design & Restoration in our own designs and we offer these measurement services to our customers. Please refer to the description of design, construction and measurement service. Further information can be found in the technical section where a number of papers and design tools will be added over time.
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