And It Will Sound Like . . .

Some friends are starting up an old guys’ R&R band and they need a bass player. They aren’t going to ask me because, “You don’t want to be in this band. It’s gonna be loud and sound like shit.” Of course, they know me too well. I don’t want to be in a band like that and haven’t since I was in my mid-twenties.

I missed the “opportunity” to run FOH for a “bluegrass band” at Hobgoblin this past Saturday because of family obligations. I know one of the band members a little and he’s a fine musician, a terrific songwriter, and a nice guy. The band’s banjo player/sound guy and I had a couple of email conversations and it was obvious (at least to me) that we wouldn’t work well together, so missing the gig wasn’t at all painful for me. Sunday, I was at Hobgoblin for another gig and, as expected, the house sound system was mangled and as far from reasonably “zero’d” as possible. [Who turns powered speaker systems’ volume controls to “off” and messes with the crossover settings?] The questions that cued me into knowing this wouldn’t be a fun gig were all about the number of monitors (4) that would be needed for a 5 piece “bluegrass” band in a 70 person (max) venue. Any is too many, four is a symptom of deaf rockers pretending to be purists.

Somehow, this sequence of conversations reminded me of one of my favorite 60’s albums, Jefferson Airplane’s “Surrealistic Pillow.” There are lots of stories about how “awful” the studio experience was for the Airplane kiddies, but it’s pretty obvious from the quality of the playing that some actual musicians were involved in the making of the record. Post-Pillow, the Airplane’s zombies were big stars and in charge of their own sonic future; which accounts for the godawful sound of every other recording they made in the band’s lifetime. The band had no input as to how their instruments or voices would be recorded by RCA’s actual engineers (guys in white coats) and if they couldn’t play a part, someone else did. The lack of technical input from the kiddies resulted in a historic record of the times.

Those days will never return. Everyone with $500 and an ego can afford a decent recording rig, today. Goldman’s rule, “nobody knows anything,” has been multipled by millions of uninformed, tasteless kids with a cheap microphone, Pro Tools, and an endless collection of loops and plug-ins. I guess the logical extension of the rule would be “nobody knows anything and everybody thinks they do.”

The end result for me has been that when I’m asked if I’d be interested in a recording project and, if so, what would it cost, my reply is, “If I like it, I’ll do it for free. If I don’t, you can’t afford me.” Most of the time, I won’t like it and the conversation doesn’t get that far because I change the subject before the question is asked.

A Backward Look at the Music Industry

Lots of people are selling their insights into “the music industry” these days and, mostly, that’s because making an actual living in what’s left of that so-called industry is next-to-impossible. It always has been, so that shouldn’t surprise anyone familiar with the territory.

A Facebook discussion with a friend today reminded me of one of my many missed “opportunities” to dive into the music business face (and life) first. When I moved to California to work for QSC Audio Products as a Design/Test Engineer, leaving Nebraska required selling off almost all of my recording studio equipment, most of my musical instrument back-line, and the disposal of probably 90% of my family’s personal possessions. We were moving from a 2,200 square foot house with a full basement and double car garage to a 650 square foot apartment in Huntington Beach, California. It was a sacrifice-filled “adventure” that required all of us, including my two adolescent daughters, to give up a lot of stuff.

1983 was a seriously economically depressed time in the Rust Belt and finding technical or manufacturing work of any sort in Lincoln, Omaha, Des Moines, Kansas City, Denver, or any of the smaller Midwestern cities was unlikely. Make that doubly-unlikely in my case, since I was 35 and still going to school nights working on my Electrical Engineering degree. Thanks to an old connection, I got a few job offers from the coasts and QSC seemed like the best of the lot. In fact, for almost a decade, my jobs with QSC were close to a dream come true. I got to work closely with Patrick Quilter, one of the best, most creative engineers I’ve ever known. I was instrumental in turning a small, still mostly start-up after a decade of struggle, manufacturer into one of the first American-made quality-driven manufacturers. California still provided incredibly cheap education and actually catered to non-traditional students, so I was able to continue my pursuit of a degree and hold down a 60-80 hour/wee management job. Most of all, we built the absolute best professional power amplifiers in the world and could prove it with customer testimonials.

It’s hard to imagine now, but I was a driven, workaholic for most of my life. While I was engineering and testing products for QSC and going to school nights, I also ran a repair business that serviced much of Roland and Yamaha’s customer returns and provided equipment and studio repair services to Orange and LA counties. That business began through an AES contact, Wes Dooley, who introduced me to several studio owners and maintenance engineers at our local AES meetings. One of the techs was a young man who was the maintenance engineer for Record Plant on Third Street in LA and for a few years in Hollywood. When he was overloaded with clean-up (often vacuuming the coke out of the faders) and repair work, I occasionally filled in to help: for a price, of course.

When he decided it was time for him to crawl out of his repair shack and get a life, he let me know the Record Plant job would be open. I drove up to Hollywood to hear more about the job and, eventually, he told me it paid about $20k/year. Without overtime, that works out to about $9/hour and there would be plenty of unpaid overtime (it was a salary job). I thought he was joking, but he reminded me that he “lived” in the repair shack about 5 days out of a week and his “home” was a rented room. 

My kids were teenagers, my wife didn’t work, and my family depended on my income. Honestly, I couldn’t find any way to consider what my friend had been doing for a decade anything resembling a “career.” Today, I suspect we’d call that sort of wage-slave an “intern.” Back then, in LA, I lost about 90% of the respect I had for my friend’s job and the Record Plant in that one conversation. I have never been able to do much with the “do what you love and the money will follow” philosophy because the cost of my reality always trumped the income my dreams would produce. Getting married at 19 and becoming a father at 23 will do that for you.

As we were winding down the job conversation, my friend offered to show me the resumes from the other applicants. I expected a bunch of right-out-of-tech-school kids with no experience in audio equipment repair or use. What I saw were guys (and a couple of women) with EE degrees from schools like UCLA, Cal Tech, Georgia Tech, and other decent electrical engineering schools along with the applicant pool I had expected. There were also guys I knew from the LA AES chapter who had good jobs with manufacturing companies. Some of those guys were decent engineers, too.

Before that moment, it never occurred to me that working for a recording studio would pay that poorly. While a friend back in Omaha did the maintenance engineering job for the city’s one-and-only professional studio, Sound Recorders, and I knew he still lived with his parents, I hadn’t considered the possibility that he lived like a college kid because that’s the kind of money he was making.

Way back in the 1960’s, I had a 1959 MGA. The MGA was a dream car, until it was my responsibility to maintain it. In less than six months, that awful vehicle wiped out my fairly substantial savings and left me broke and transportation-less. I have never envied a sports car owner since. In fact, I usually pity any sports car goofball, unless he is obviously a trust-fund brat: then I’m happy for his misery and transportation disabilities. Likewise, since my moment-of-zen at the Record Plant, it’s tough for me to consider recording studio work seriously and I can’t generate any level of jealousy when it comes to working for peanuts, regardless of the work. I’ve done a lot of studio work since then, but other than my own studio maintenance business I have never considered the studio business anything but a fun hobby. Not only do I not have a trust fund to fall back on, you could burn up my entire inheritance on a decent New York restaurant in one meal for two.

A couple decades later, I made a connection with an old acquaintance, Skip Cave, from my hometown. He had wandered off to L.A. in the 60's to make his fortune as a musician after graduating high school. His aunt was married to Howard Roberts who took Skip to one of the seedy nightclubs where the jazz guys hung out. The music was amazing, as the band was the core of the famous Wreaking Crew, and the audience was filled with jazz musicians the kid knew about from his record collection. Possibly Skip's strongest memory of that place was the gist of most conversations, "Have you got a couch I can crash on tonight?" Famous jazz musicians who didn't have a place to stay or anything resembling dependable income. Skip went back home determined to look for something else to obsess on, which turned out to be electrical engineering. His obsession was a lot more focused than mine and he did really well for himself. He still plays music at a high level, in retirement, and always has a bed to sleep in.

NOTE: This article was sent to me by the author, Mark Amundson, several years ago to use in my Audio Engineering classes. The article had been on my website as a link in the original Microsoft Word format for a decade. Unfortunately, Mark’s article seems to have vanished from FOH Magazine’s article history, which is a huge loss for audio engineers who actually care about optimizing distortion and noise characteristics in their signal path. A version of this discussion is included in his book; Live Sound Practice and Theory.

Manuscript: Madness to the Method – Gain Structure
Magazine: FOH
Manuscript Type: Technical Article
Issue Assignment: May 2003
Word Doc No: GainStructureMadness.doc
Figures: -
Photos: One
Editor: Bill Evans
Revision: -
Date: 05/12/03
Word Count: 1516

Madness to the Method – Gain Structure

By Mark Amundson

In this dissertation I am going to do a little Q&A, ala the old Audio Cyclopedias about questions you may have wondered about, but just did what you were told. I am going to throw down a generous helping of electronics history as a way of answering the question, and to remind us all were all this technology came from.

Q: WHY IS 0dBu THE REFERENCE SIGNAL LEVEL?

The question could easy re-phrased why is 0.773 volts RMS (0dBu) the standard and not some other convenient number like 0.1, 1, or 10 volts?

The answer goes way back to Alexander Graham Bell’s era when no such thing as radio or broadcasting was thought of. As the “Bell System” and “American Telephone and Telegraph” (AT&T) became the monopoly in the phone service industry, Western Electric Company was formed as a subsidiary of the Bell System to design and produce telephone gear for the whole country. After much trial and error, a standard two-wire pair transmission line was developed with 600-ohm source and load impedances to maximally send carbon microphone signals down the wires. With the right construction materials, voice signals (about –20dBu) could transit 5 miles with a passable loss of signal amplitude.

When Lee DeForest invented the Vacuum Tube Triode for signal amplification, his “killer app” was re-boosting feeble telephone signals, thus creating long-distance phone service in the second decade of the last century. Western Electric still had a lock on the electronics industry in the 1920’s as broadcast radio was just emerging, so naturally it had the highest technology suitable to fulfill civilian and military requests for standard “Public Address” apparatus. By the early 1930’s Western Electric had the first quality dynamic microphone (requiring no DC power unlike carbon mics) and combined vacuum tube amplification connected to the first efficient “loud-speaking apparatus” that we now know as horn loaded drivers.

As broadcast radio became widespread, and specialized companies like Electro-Voice, MagnaVox, and Shure Brothers came to supply (with Western Electric) the needs of public address and broadcast gear, the 600-ohm line cabling still held as the lowest loss method of distributing and processing audio signals. From that era, a one-milliwatt reference level into 600-ohms became the reference level, or 0dBm (zero deci-Bels referenced to one milliwatt). 0dBm is exactly 0.773 volts RMS, but as technology marched on audio electronics moved from power matching to “bridging” impedance matching, the 0.773 volts without any specified load impedance was now described as 0dBu (zero deci-Bels unreferenced).

To answer the lingering question of what became of Western Electric, government anti-monopoly policies in the 1930’s forced the breakup of AT&T (the first time) into RCA for broadcast, Bell Labs for telephony, and All-Technical Products (Altec) for public address. Altec slowly became Altec-Lansing, then split back to Altec and James B Lansing Inc., then on to JBL.

Q: WHY GAIN (TRIM) TO LINE LEVELS AND THEN MIX AFTERWARDS?

This question is more math than history, but we still thank the early broadcast pioneers of the 1930’s for the first work on defining signal-to-noise and noise source definition. This question could also be formed as what is the best method to minimize hiss in the mixing console?

The answer comes from the invention of the radio, and techniques used to maximize signal-to-noise ratio; and thus transmission distance. As a signal is created, processed, and sent to its final destination; there is a signal-to-noise ratio (SNR) degradation. As each stage, or processing block passes on the signal, the noise eventually encroaches on the signal level. The number of dB drop of SNR per stage is defined as its noise figure (or noise factor for you dB challenged). A noise factor of 6dB or less per amplification (gain) stage is considered a low-noise design for a preamp.

To better visualize this idea, lets put some example numbers to work. If a typical dynamic mic and voice put out –50dBu signal peaks, and the console’s referred input noise is –128dBu, you have a 78dB SNR which is respectable in live sound applications. As the signal proceeds through the channel mic preamp, eq section, channel fader or VCA, summing amps, master fader, and balanced line driver, there is a noise figure penalty to be paid. The good news is if two gain stages are cascaded together, the noise figure of the first stage dominates with the second gain stage noise figure effectively divided by the gain of the first. What this means is that cheaper electronics can be used after the mic preamp, with a high gain preamp covering for the sins of the rest the console’s electronics.

On other item to be shared is that attenuation circuits (eq filters, faders, pots, VCA’s, etc.) can generally be assumed to be direct losses in SNR, with every dB in attenuation a corresponding dB increase in noise figure. So the theoretical perfect (low noise) mixing console setup would be faders maxed, eq flat, and amplifier gains a perfect match between mic level and power amp full power sensitivity.

But no realistic scenario exists on a mixer without faders to “mix” with. So the next best answer is take your desired loudest channel in the mix, set its preamp gain control (gain, trim, etc.) for about 0dBu average level, and keep the channel, group, master faders reasonably high, but preserve some headroom for the occasional “louder” demand. This minor compromise yields the best SNR while still giving mix flexibility. This practice also applies to the gain of all the other signal source channels, but with the obvious idea that their faders would be more attenuated.

Q: WHY IS +22dBu THE COMMON MAXIMUM LEVEL

This answer also comes from electronics history, but only a half-century back. The dawn of the first mass-produced transistors had a typical maximum voltage level of 30 to 40 volts. Of these early transistors, many were targeted for industrial controls and “analog” computers for military and aerospace usage. The most common analog computer section was the “operational amplifier” or “op-amp”. Because these op-amp sections were designed to be near perfect mathematical gain stages with both positive and negative voltage swing capabilities. By taking the limitations of the transistors plus the need for a bi-polar (plus and minus) power supply, the standard of +/-15 volt supply levels was instituted, and is still used today.

As transistors got grouped on one silicon die, integrated circuits (ICs) were born with the first standard products becoming IC op-amps. As IC prices dropped in the late 1960’s and early 1970’s, more IC op-amps started finding there way into audio equipment, still requiring their +/-15 volt power supplies. Today’s pro-audio signal processing and mixing gear is largely composed of IC op-amps and a few application-specific ICs plus just a few necessary un-integrated transistors. The common legacy of supplying them with +/-15 volt levels still exists, with op-amps capable of near +/-14 volt audio signal swings. This level translates to about 10 volts RMS, or +22dBu at which the circuits would exhibit clipping of the signals. Some math trickery maybe also in maximum output specifications as you can gain another 6dB in level by stating the output as balanced; in which each balanced output contact swings in opposite polarity to double the levels.

With the above explanations that we should set our levels close to 0dBu and keep away from the clip levels around +22dBu, there leaves plenty of headroom for classifying what peak signals can be and what is required to get the drive channels (eqs, crossovers, and power amps) to full output. Most power amp manufacturers set their sensitivity values to around 0 to +9dBu for full unclipped speaker drive. By keeping the post pre-amp levels at or below the power amp sensitivity values, mostly assures a clipping free production. Of course that relies on your keeping the power amp input attenuator controls full up. You do not want to be “low-noise” all the way to the amp, and then throw away all that SNR at the last attenuator do you?

FINAL WORDS

Our latest generation of audio production personnel deserve to be educated on how we use our gain structure procedures, and why these methods came about. Some may argue about exact levels and forming up mixes, but I am coming at this from an electrical engineering view and attempting to shine light on what the design engineers consider optimum use, rather than operator tactics “that seem to work for me”. We need to appreciate that live sound borrowed heavily from the telephone and radio broadcast pioneering work, plus how electronics achievements impacted our practices. The twentieth century could be termed the “electronics” century, and it looks like the twenty-first century will be the “photonics” century; with fiber-optics promising near unlimited bandwidth for passing analog or digital signals from baseband to radio-frequency to optical-frequency signals.

MDA

A Friend, Indeed

I've been putting this off for an unreasonable time. A friend, Mark Amundson, died in early September, 2009. He was 49. It's still hard to imagine that he's not on the other end of the phone or email, waiting to explain some complicate problem in simple terms that even I can understand. 

I'm getting used to people older than me dying, but I will never get used the deaths of people I once considered to be "kids." Mark was a dozen years younger than me and while he was infinitely wiser, kinder, more educated, and smarter than me, I still think of him as a kid. Mark and I met while we both worked for Guidant, a medical device company. We hit it off immediately, in spite of disagreeing about almost everything outside of musical equipment design. We ate lunch often and he gave me an incredible collection of insights into the audio equipment industry and big time pro live sound. 

Bill Evans did a much better job of writing about Mark Amundson's life, personality, and contributions than I can hope to accomplish. Bill's obituary, Music and Order, described Mark as "both liked and respected by both the industry and the [FOH] readers." I can vouch for that. Mark was an extraordinary engineer and technician. He was a generous, insightful friend. He loved music, musicians, and was practically compulsive in his desire to share what he knew (or wanted to know) about music, audio equipment design, and live music reinforcement. He sometimes introduced me to his friends as "the guy I hire to run sound when I'm on stage," which was an incredible compliment and an overwhelming endorsement considering that I ran sound one time for a band he was in and my end of the show was unremarkable. He was being typically generous and I will always appreciate his generosity. 

Once, when I was beating him up for reviews in FOH that were uniformly positive and uninformative, he told me I needed to "read between the lines" for his real opinion of those products he was less than impressed with. I replied, "what's between the lines is white space." His answer was a long explanation of how modern publishing works. He explained that readers provide absolutely none of the money required to publish a magazine and that manufacturers and, worse, publicity agents have long, long memories and are particularly brutal on writers who tell the truth. Not long after that discussion, Mark tailed back his product reviews. He told me, about a year later, that he'd lost his ability to believe in readers' capacity to read "between the lines." In person, 

Mark didn't talk between the lines. He was opinionated and exceptionally well-informed, but he was always hopeful that even the worst companies would do better if he just tried to help them see the error in their ways. He exhibited that patience with me, too; for the same reasons. I abused our friendship several times when I asked him to talk to my live sound classes at the school where I work. He not only put together a terrific presentation, every time, but he gave me PowerPoint slides of his presentation so that I could use that data in future classes. He never wanted to repeat himself, so he expected not just my students to "get" what he talked about, he expected me to take advantage of his gratis work and to benefit from it. 

His ability to explain complicated, often mathematical, audio problems was beyond anything I've experienced in my formal education. I use his work, his explanations, every semester in my classes and it always provides breakthrough insights in my students' understanding of our subjects. It will be impossible to replace Mark as a resource for questions I will always have about audio design, component design, and music reinforcement. More important, it will be impossible to replace Mark's friendship. I've never known anyone like him. Here are a few of his articles and insights: Live Sound: Theory & Practice, Poor Man's Power Distribution, Speaker Cables — You Get What You Pay For, Turn It Up! No, Down! No, Up! No. . ., Mic Selection and Placement.