Proprietary Engineering

Our proprietary engineering methodology is called LDLC which stands for Low Distortion and Low Compression. 

This engineering, design, and build/assembly standard is fully equipped with testing protocols and thus allows us to ensure that our drivers will maximize stroke (movement) without compromising sound quality. Seen in the full ability of our complete subwoofer systems, LDLC consistently delivers reliable results in infrasonic bass requiring massive displacement, all the way up to the upper bass frequencies with mind blowing sound quality together with high levels of SPL. 

How do we do this? By engineering our drivers to get as close to mechanical limits as possible with total reliability, and while retaining sound quality, as a minimum standard. A speaker driver's job is to move back and forth, and if the driver can not do that under full rated power, then its usefulness is debatable. 

Quality Control: LDLC requires that each subwoofer is quality control checked at every single stage of the manufacturing process, which includes the manufacturing of raw materials into parts all the way to the finish lacquer applied to the enclosure. This results in over 500 quality control checks completed on each and every subwoofer, at minimum!​

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LDLC Engineering Standards: The following is the standards set by LDLC that govern compliance of the system and its individual components.

1. ​Inaudible distortion at maximum power handling of the motor geometry.

2. Inaudible compression at maximum power handling of the motor geometry.

3. Both distortion and compression must track to the same inclination of linearity over the system design bandwidth. 

4. Efficiency must improve with each component (Driver, Box, DSP, Amplifier) and therefore can not degrade.

5. Materials, parts, and components must be of a specific grade and quality. Testing and verification of each part is essential. 

These five fundamentals are exercised over the following four principals of sound.

1. Distortion in all forms

2. Compression in all forms

3. Efficiency

4. Output

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Testing Methods: LDLC testing protocols are established by and are the intellectual property of Harbottle Audio Ltd and not available for public distribution. These protocols involve strict control points that verify amplifier, enclosure, DSP, and driver behavior for the duration of the test, and so the LDLC qualification is made through Harbottle Audio Ltd. Control of the system tests verifies each part of the system performance. This makes Harbottle Audio the only source of LDLC compliant subwoofer systems.  

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Audio science references.

Ahonen, Jukka, et al. "Perception and physical behavior of loudspeaker nonlinearities at bass frequencies in closed vs. reflex enclosures." Audio Engineering Society Convention 124. Audio Engineering Society, 2008.

Czerwinski E., Voishvillo A., Alexandrov S., and Terekhov A.: Multitone Testing of Sound Systems - Some Results and Conclusions, Part 1: History and Theory, J. Audio Eng. Soc., vol. 49, No. 11, pp. 10111027, (2001, November).

de Santis, M. E., and Simon Henin. "Perception & thresholds of nonlinear distortion using complex signals." Section of Acoustics, Institute of Electronic Systems, Aalborg University (2007).

Dick Olsher. "The Science of Subwoofing" Stereophile - Oct 29, 2008, First Published: Jan 29, 1989

Fielder, Louis D., and Eric M. Benjamin. "Subwoofer performance for accurate reproduction of music." Journal of the Audio Engineering Society 36.6 (1988): 443-456.

Geddes, Earl R., and Lidia W. Lee. "Audibility of linear distortion with variations in sound pressure level and group delay." Audio Engineering Society Convention 121. Audio Engineering Society, 2006.

Gunnarsson, Viktor. Assessment of nonlinearities in loudspeakers: volume dependent equalization. Chalmers University of Technology.

Harwood, H. D. "Loudspeaker Distortion with Low-Frequency Signals." Journal of the Audio Engineering Society 20.9 (1972): 718-728.

Klippel, Wolfgang, and Robert Werner. "Loudspeaker Distortion–Measurement and Perception."

Klippel, Wolfgang. "Loudspeaker Nonlinearities–Causes, Parameters, Symptoms." Audio Engineering Society Convention 119. Audio Engineering Society, 2005.

Klippel, Wolfgang. "Nonlinear large-signal behavior of electrodynamic loudspeakers at low frequencies." Journal of the Audio Engineering Society 40.6 (1992): 483-496.

Klippel, Wolfgang. "Speaker auralization-Subjective evaluation of nonlinear distortion." PREPRINTS-AUDIO ENGINEERING SOCIETY (2001).

Mitchell, Peter W. "The Measure of Bass Quality" Stereo Review, December 1995, pg 144.

Schmitt, R. Audibility of nonlinear loudspeaker distortion. Journal of the Audio Engineering

Society, 43(11):402, May 1995.

Temme, Steve, et al. "The Correlation between Distortion Audibility and Listener Preference in Headphones." Audio Engineering Society Convention 137. Audio Engineering Society, 2014.

Voishvillo, Alex. "Assessment of Nonlinearity in Transducers and Sound Systems–from THD to Perceptual Models." Audio Engineering Society Convention 121. Audio Engineering Society, 2006.

Voishvillo, Alex. "Measurements and Perception of Nonlinear Distortion—Comparing Numbers and Sound Quality." Audio Engineering Society Convention 123. Audio Engineering Society, 2007.

Voishvillo, Alexander, et al “Measurement of Loudspeaker Large Signal Performance - Comparison of Short-Term Testing Signals” Audio Engineering Society (2002).

Voishvillo, Alexander, et al. "Graphing, interpretation, and comparison of results of loudspeaker nonlinear distortion measurements." Journal of the Audio Engineering Society 52.4 (2004): 332-357.