GedLee Papers and Publications

Title Description
Directivity in Loudspeaker Systems This white paper was written to explain the importance of directivity in a loudspeakers system. The polar map method of showing plar response is described and examples are shown.
Why Multiple Subs? This white paper defeines the low frequency modal problem in smaller rooms and shows how to mitigate these problems by using multiple subs. There is also a PowerPoint of this topic.
The Geddes Loudspeakers Design Philosophy This white paper is a little older but fundamental to the design assumptions used when a Geddes design is done.
What is a Waveguide? This white paper was written to outline the historical evolution of the term "waveguide".
Subjective Testing of Compression Drivers This paper describe a test that was done by GedLee in cooperation with B&C Speakers of Florence Italy. It concludes that the sound quality of a compression driver and horn combination is not strongly affected by the compression driver, it is dominated by the horn. It also concludes that THD is not a significant factor in compression driver sound quality. This is a refereed publication in the JAES.
Audibility of Linear Distortion with Variations in Sound Pressure Level and Group Delay This paper describes a test done at GedLee to show that forms of linear distortion, namely group delay, can be perceieved as non-linear distortion because they, like nonlindistortion rise in audibility with sound level. These results indicate the audibility of Higher Order Modes in waveguides.
Audio Acoustics in Small Rooms This is a PowerPoint review of work done by bDr. Geddes on the acoustics of small rooms. This is an older presentation with older room data, but it is still pertinent.
Comments on “Weighting Up” by Keith Howard This was a published response to Mr. Howards publication on the GedLee dstortion perception work.
Auditory Perception of Nonlinear Distortion - Theory This is part 1 of our two part series on the testing that Dr. Lee and I did on the perception of nonlinear distortion. Its results were revolutionary at the time, although numerous other researchers have duplicated our results since this paper was published.
Auditory Perception of Nonlinear Distortion This paper is the second part of the disrtion perception study containing the subjective test results. Anyone who wants to understand what is perceived as "sound quality" must undertand these results.
The Perception of Distortion This is a Powerpoint review of the above work.
Letter to the Editor AudioXPress This is a leter that I wrote to the editor of Audio-X-Press on Bjorn Kolbrek's paper on horn theory. This information is key to the unederstanding of why Horn theory is wrong and why Geddes wavguides work so much better than devices based on these older concepts.
Rooms and Sources This is a short study that I did mostly to prove a point - that monopoles and dipoles both have about the same effect on the modal aspects of small rooms at low frequencies.
Setting up subwoofers This paper describes what measurements are required for my sub setup program and how to obtain them.
Sound Quality Improvements in Compression Driver Systems This paper describes the work done by Dr. Geddes on improving the sound quality of horn/compression driver subsystems. It outlines his concepts and how they work to achieve his notable sound quality improvments.
Weighting Up This is the original Keith Howard paper that I responded to.
The Perception of Distortion This is a PDF of a paper by Dr. Geddes which reviews all of the GedLee work on distortion perception. There is a lot of the information presented on this webpage all in one presentation.