John La Grou, Millennia Media, on Preamps
John La Grou started in computers, escaping Silicon Valley in 1989 to found Millennia Music & Media Systems, where he designs high-end microphone preamplifiers and related gear. His team has come up with everything from the HV-3 family of preamps to a Library of Congress archiving system.
John La Grou
Quick bio: John La Grou started in computers, escaping Silicon Valley in 1989 to found Millennia Music & Media Systems, where he designs high-end microphone preamplifiers and related gear. His team has come up with everything from the HV-3 family of preamps to a Library of Congress archiving system.
Sam: Many people rely on their preamp to help "get their sound." How has this affected design?
La Grou: Just about everything we design is focused on accurate, transparent, linear responding circuits. For this reason, our customers tend to be those looking for a neutral signal path–acoustic music recording, classical music, film scoring. Those looking for a preamp to convey a "sound" would generally be looking at transformer-coupled designs and those that mimic old vintage units. Remember, there is no undo button on the mic preamp. We think it's usually better to keep the signal path flat and neutral at the front-end. You can always add coloration and effects later.
Sam: Is the universal preamp a myth?
La Grou: Right. Just as there is no universal microphone. That said, I've been experimenting for years to develop a design that makes everything sound, for lack of a better work, pretty. I've built and tested countless circuits on the bench, trying to achieve a sense of enhanced musical beauty and richness. It sounds like some kind of holy grail, but I've made a few fascinating discoveries in the process.
Sam: There's a lack of standardization in microphone loads and outputs. Does this make design more difficult or more fun?
La Grou: This is another reason why mic amps have such a wide variation in sonic performance. One has a 1,000-ohm input impedance; another has 20,000 ohms. Rather than a liability, I see this as a healthy market in which engineers have literally hundreds of specifications from which to choose. Product variation is good, to a point. And such variations reflect the goals of each designer.
Sam: Your first digital, remote-controlled preamp, the HV-3R, is now shipping. What was it like putting digital circuitry into a box with such pristine analog circuits?
La Grou: This has been our biggest R&D effort to date. The HV-3R employs Ethernet, MIDI, microprocessors, eight mic amps, eight high-end A/D converters, high-resolution digital metering, two liquid crystal displays, a 24-channel output option module, digital temperature and voltage sensing–all controlled by our Windows user software. It took us nearly three years and six revisions to get it perfect. What doesn't kill you makes you stronger.
Sam: Preamp specs are hard to compare. Which do you feel are the most useful?
La Grou: All mic amps specify good total harmonic distortion, noise, and frequency response, but these are somewhat meaningless in predicting how a circuit actually sounds. Other specs such as headroom, input clip, common mode rejection, drive current, and maximum gain are really important to the sound operation of a mic amp.
Once you confirm that the fundamental specs are sound, then you need to listen to the mic amp with your microphones, with your program material, in your recording environment. That's the only way to truly judge the merits of a mic amp.
Sam Berkow is the founding partner of SIA Acoustics, an acoustical design firm with offices in New York and Hollywood, Calif.