A Beginners Guide and Other Thoughts on Audio - Chapter 1: Cone Speakers
Roger Modjeski and Anthony Chipelo | Published on 11/27/2023
This month in Roger’s Corner we present Chapter 1 of A Beginners Guide and Other Thoughts on Audio. This chapter is dedicated to Cone Speakers. While Roger was best known for designing amplifiers and preamplifiers, he also possessed a wealth of knowledge on speaker design. I remember seeing his single driver speaker using a Radio Shack 4” driver (a re-branded Fostex) in a beautiful wooden cabinet. He gave those speakers to me with the caveat that they only went down to about 60 Hz, and I would have to figure out how to get the lower octaves. That lead to my initial interactions with Roger on speaker design and it was he who taught me about resonance, how to measure it, and why it was important. In the process he convinced me that the best way to achieve bass in a system was to use an electronic crossover to bypass the unwanted resonance in the bass driver.
Of course, this involved some other lessons in bi-amping and distributed bass arrays, as well as building the appropriate enclosures to get the resonance at the right level and coming up with the right filters so the active crossover could bypass it. These were lessons well worth learning and in this chapter of the book Roger goes into detail on these topics and much more, including some interesting speaker history.
A Beginners Guide and Other Thoughts on Audio
Roger A. Modjeski
Chapter 1: Cone Speakers
I would like to tell you a few things about cone speakers that are not widely known. The cone speaker that we are talking about is a mass loaded device. It was developed by Rice and Kellogg in 1928 while working for General Electric. The purpose of the research was to develop a speaker that did not have the peaks and dips that speakers of this age did. What made this possible is that amplifiers were now available in the 1-watt instead of the milliwatt range. This advance brought us to the modern speaker. I would like to make the distinction that in a speaker we have multiple drivers. In general, we have woofers, mid-ranges, and tweeters. Each of this is a mass loaded device. They all work on the same principles even though they are different sizes, different shapes, and they have different frequency responses.
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