Hollow State Audio Explained: An Interview with Richard Honeycutt

Whether you are pro musician or an electronics enthusiast, wouldn’t it be ideal to have the know-how to design your own audio systems? If you want to learn about hollow state audio, North Carolina, USA-based Richard Honeycutt is your man.

A musician, scholar (PhD, Electroacoustics), and acoustical consultant, Honeycutt is a well-respected, go-to resource for anyone interested in learning about vacuum tubes, electroacoustics, and acoustical design. In the new book, The State of Hollow State Audio in the Second Decade of the 21st Century (Elektor 2020), Honeycutt dives deep into the subject of hollow-state audio, especially the topics of whether it produces better sound, how to design hollow-state circuits, and how to intelligently modify hollow-state amplifiers. He recently shared his thoughts with the Elektor team about his interest in hollow state audio, his background, and the future of vacuum tube technology.     

Elektor: Elektor recently published your book, The State of Hollow State Audio in the Second Decade of the 21^st Century. Let’s clarify something for the non-audiophiles in our audience. What does “hollow state” mean?

Honeycutt: From Fleming’s valve, which marked the beginning of the electronic era, until the invention of the transistor, vacuum tubes (“valves,” for those on the east side of the pond) were the only electronic devices. Transistorized equipment was soon dubbed “solid-state,” and then sometime in the 1970s, some wise cracker decided that since vacuum tubes were hollow, it made sense to call them “hollow state.” I enjoyed the name and have used it as the title of my monthly column in audioXpress, and also in this book title.

Elektor: How do you define “tube sound”? Is it real? A myth?

Honeycutt: This is too complex a question to answer in a brief interview. It takes up many pages in the book. Suffice it to say, in the words of the late Ed Dell (founder of Audio Amateur Publications, the grandfather of audioXpress), “Some people say they can hear a difference between solid-state and tube equipment. I’m sure they can, because perception is reality. Whether what they hear can be objectively experienced — by other people — or measured, is another question.”

Elektor: Many people believe tubes simply sound better. Do you agree?

Honeycutt: Tube guitar amplifiers sound better to me, and that’s because of the different distortion signature of tubes, compared to solid-state models. But for electric bass amplifiers and home stereo/theater amplifiers, I prefer well-designed solid-state units. The early solid-state audio power amplifiers did not sound as good as the ones made today, and there are specific technical reasons for that. I think much of the current enthusiasm for tube amps stems from that period (1960s), due to humans’ tendency to not question what “everyone knows.”

Elektor: Who will benefit from reading your book, The State of Hollow State Audio?

Honeycutt: Anyone who wants to understand hollow-state electronics, either as a designer, builder, “modder” (someone who modifies amplifiers), user, student, or historian.

Elektor: While working on this book, did you learn something new or surprising?

Honeycutt: I learned a good bit about tube-based capacitor mics — both old and new, and about avoiding oversimplifications, such as, “all triode circuits produce even-order harmonics, while pentodes produce odd harmonics.”

Elektor: Think ahead 15 to 20 years. What are your thoughts on the future of vacuum tube technology?

Honeycutt: Predicting the future is always a crapshoot! Remember, 15 or 20 years ago, the death knell of vacuum tubes was sounded. Yet I think more tubes are sold today than were sold at that time. We certainly would not have predicted that all the “old standby” tube manufacturers would have ceased production; or that, of the few tube factories still in existence today, only one would be in the USA; or that most of the old tradenames would appear on excellent tubes made in a factory in Russia previously used to make tubes for the Russian military.

My cloudy crystal ball seems to show about the same percentage of hollow-state devices in high-end audio in 15 or 20 years as today, and many musicians still preferring tube guitar amps, despite the ongoing progress in modeling the sound of classic tube amps.  I think the market for classic McIntosh, Altec, and Western Electric amps will still be active, and solid-state electronics will continue to dominate the consumer audio market. I guess we’ll see!

Elektor: Which came first — your love of audio or your passion for electronics?

Honeycutt: I fell in love with electronics the same year I first learned to play guitar, but I had been listening to Dad’s 78-RPM records of Chopin and Sousa pieces for years by that time. The records were played on a late-1940’s Arvin radio-phonograph using a crystal cartridge with a tracking weight of OMG-no!!! grams. (Or ounces?)

Elektor: You earned a BS in Physics. Why did you decide on electroacoustics for your PhD?

Honeycutt: My interest in acoustics developed when I was in the ninth grade. When in high school, I designed and built my first set of home-stereo speakers. Later, I built two microphones that my rock band used, although they sounded awful! I found electroacoustics entrancing. I joined the Audio Engineering Society in 1976, and Paul Klipsch was one of the two engineers who wrote the required recommendations for me. The more I read ARE journals and studied Paul’s work, the more entranced I became. By the time I entered graduate school in 1997, electroacoustics was my passion, and the first core faculty member of my doctoral committee often admonished us to follow our passions!

Elektor: What was your PhD dissertation about?

Honeycutt: The dissertation detailed research that I did on a way to allow horn loudspeakers to be built somewhat smaller than they usually are, while preserving good bass response. The first folded-horn subwoofer I built using the principle I investigated is still in use in my living room and is essentially flat down to 30 Hz. Since completing the dissertation, I have further refined my understanding of the operation of the novel design, but I have not published a revised edition.

Elektor: What is your workday like? Are you consulting, teaching, writing, or something else?

Honeycutt: I work full-time as an acoustical consultant and writer, although “full-time” is not as many hours a day as it was 20 years ago!

Elektor: What are you working on these days? Can you share some details?

Honeycutt: The nearby photo shows a church fellowship hall for which I designed the acoustics and the sound and video systems. I also do acoustical design for auditoria, school gyms and cafeterias, music rehearsal rooms, and cinemas. 

Elektor: We live at a time when you can buy a set of earbuds at a gas station and millions of people listen to streaming music via their phones. Do good acoustics still matter?

Honeycutt: Good acoustics absolutely do matter! Ask anyone who is hearing challenged. They will gladly tell you of their difficulty in understanding speech or enjoying music in overly reverberant halls or noisy restaurants. And even the best earbuds cannot compete with the full-body experience of a live concert (any kind of music) in a well-designed venue. Although smart-phone speakers are amazing for their size, their sound is still pathetic compared to a live concert, or even a recording played through a set of excellent speakers in a listening room that has good acoustics. I challenge anyone who thinks otherwise to attend a concert by a first-rate symphony orchestra or a band such as our Air Force and other military branches support.