In Duntech's testing area we subject our loudspeakers to a range of measurements. In addition to routine impedance and frequency response sweeps, we perform "pulse coherence" measurements. These involve using a maximum length sequence source as an input to the amplifier. The sound pressure levels at the microphone, which is placed at the normal listening position of 3.5 metres (11'6") from the loudspeaker, is then displayed on a computer which displays the step response of the speaker.
If a clean step is produced then QC are allowed to pass the speakers. Virtually no other competitive loudspeakers can produce a step response, because to achieve this, the sound from all the drivers must arrive at the same instant in time at the listener's ears. Also, the crossover has to be designed so that all the drivers are in step. The tweeter initially pushes out at the same time as the woofers push out. In most speakers the tweeter can be pushing out, pulling or somewhere in between when the woofer is pushing out. Once you have "pulse coherence", the speaker can go very loud in an instant and can stop making sound and die away in an equally small instant. That's why you can hear music and not the speaker when you listen to a DUNTECH Pulse Coherent Loudspeaker.
At Duntech, quality is the single most important goal in both performance and construction. Duntech operates a Quality Assurance Programme that is the most thorough in the industry.
For example, every driver and crossover component is individually measured before it is used, to determine whether its performance meets very rigid specifications.
After a carefully matched pair of loudspeakers have been assembled, very detailed measurements are made in the Duntech audio laboratory to determine if the performance of each loudspeaker is within specification limits.
These tests include a measurement of amplitude variations versus frequency, using Time Domain Spectrometry; a measurement of distortion and vibration levels throughout the system; and, finally, a measurement of amplitude variation versus frequency and impedance, using a chart-recorder. These graphs are kept on file at Duntech for future reference.