Rob Roy M. Campbell at his highly specialized workbench in the Electronaut lab and manufacturing facility
CHICAGO, IL—Few audio equipment manufacturers are true “one-man bands” these days, but with the exception of two interns who help him assemble his company’s M63 dualchannel, tube-based mic preamps, American musician, vacuum-tube enthusiast and engineer Rob Roy M. Campbell of Electronaut Company designs, manufactures, QCs and ships all of his products himself.
While embarking on a career in IT, Campbell’s weekend hobby as a touring musician led him into guitar amp repair and construction using his own designs. His refinement of his M63 mic preamp design has allowed him to move into design and manufacturing full-time, last year converting a boiler room/former furniture factory at the base of his apartment building into his lab and production facility. As part of this refit, Campbell purchased an Audio Precision APx515 audio analyzer. “Pretty much every performance graph I’ve ever seen has the AP logo in the corner, and I wanted that gold standard, so that when I made performance claims about my designs, people would believe them.”
Campbell cites the APx515 as an effective tool, providing his operation a high level of logistical efficiency. “The signal-to-noise ratio and distortion is so much lower than I can achieve with tube test equipment,” he elaborates.
“But in truth, the cumbersome nature of carrying out test and measurement routines on circuits with signal generators and scopes also meant that I wasn’t doing it as often as I should have.” Campbell says that, as well as using his AP gear for QC, he now makes measurements continually during design and prototyping. “Given that this is audio equipment that I’m making,” he says, “the final arbiters in both these processes have to be my ears, in a proper listening test, but if I’m testing by ear for eight hours straight, I get tired, and that makes the final selection difficult. If you can get any obvious problems out of the way as soon as possible, and do the listening test at the end of the process, on a smaller group of circuits that you already know are fundamentally OK, you’re more likely to pass the best.”
Campbell also gives kudos to AP’s post-sales support, the staff helping him refine his application, most specifically when he faced an issue evaluating high frequencies through highimpedance output transformer stages. He says the support team “didn’t just explain how to get around the problem, it explained why it was a problem, and gave me a couple of solutions.”
Using the APx at Electronaut hasn’t just been about quality control and design—recently, it has been used on a work of art. In 2011 an artist friend of Campbell’s, Conrad Freiburg, constructed a chipboard form entitled, “the Pod of Absence,” for a performance-art installation. The pod is a heptagonal, tapered, plywood cone designed as a performance space, large enough for musicians to stand in with their instruments. Campbell was sure the structure would have its own resonant frequency, and after calibrating for a particular mic/speaker combination in free space, used his APx515 to confirm that “the pod had a resonance at exactly G natural, and also another at A. Conrad now has plans to incorporate audio analysis into future installations, and is excited about the idea of building similar pods tuned to different resonant frequencies.”
Rob Roy M. Campbell feels that he’s only just begin exploring the creative possibilities afforded by combining tube technology with modern testing capabilities. “I would love to make an automated tube tester for an AP analyzer, because it’s the perfect programmable instrument. I have ideas for a programmable power supply that I would build that would be triggered by an APx, so that I could do sweeps under all sorts of operating conditions, and test for consistency between tubes, and even between triode sections within individual tubes…That would help me a lot.”
For future Electronaut products, Campbell suggests that he’s keen to combine the best of the past with the cream of modern technology. “The general trend at the moment is to reissue classic processor designs—but as a music lover and designer, it’s not very interesting to me…The resurgence of tube gear is largely due to the fact that all of the other components that you need to make a tube circuit have gotten so much better over the past few years. Capacitors and resistors are so much quieter today, and we now have precision manufacturing techniques that the original tube designers could never have imagined. So I’m interested in new circuit topologies, and new ways of interpreting existing designs…There’s plenty to be inspired by in the world of vacuum tubes, and I’m going to see if I can push the envelope further.”
This article is condensed from its original form, written for an Audio Precision company newsletter by Matt Bell.