Pat Quilter of QSC: Sound Reinforcement and Solid-State Amp Guru, Part One

Pat Quilter of QSC: Sound Reinforcement and Solid-State Amp Guru, Part One

Written by John Seetoo

Since Quilter Sound Company was founded in 1968 and incorporated as QSC Audio in 1973, QSC has grown to become one of the most recognized global names in sound reinforcement. Founded by engineer Pat Quilter and brothers Barry and John Andrews, QSC equipment has become synonymous with exceptional sound reproduction quality. A very incomplete list of Quilter and QSC artists includes Los Lobos, Train, Foo Fighters, Black Sabbath, Albert Lee, A. J. Ghent, Vernon Reid, Hall and Oates, Devin Townsend, Doyle Bramhall II, Brad Paisley, Dierks Bentley and the Zac Brown Band, among many others.

Pat Quilter in the early 1970s.

Roughly ten years ago, Pat Quilter retired from day-to-day activities at QSC to focus on his first passion: guitar amps. He launched Quilter Amps, premium-grade amplifiers that deliver high power and volume from small sizes.

Taking a break from the latest project, Pat Quilter spoke with me about his philosophies on music and sound reinforcement, the history of QSC and Quilter Amps, the relationship between home and pro audio, amplified vs unamplified sound and why he still considers himself an analog guy in a digital world.

John Seetoo: You started your foray into amplifier design in the 1960s by building a bass amp for a friend and deployed an almost unheard of design at the time involving bridging the solid state transistors to generate 100 watts. Did you realize at the time how unorthodox this was for amp design, and did you foresee how this would be a concept you would use with QSC power amps down the road?

Pat Quilter: Yes, I thought it was unusual because I had just read about this trick in Radio Electronics magazine. Back in those days, transistors didn’t come in very high voltages. I was laboring under the misimpression that it was always necessary to drive an 8-ohm load. So, getting 100 watts into 8 ohms required more voltage swing than what you could regularly get from a normal single-ended transistor design. We made bridged-output amps for the first few years using series-parallel 8-ohm 4 x 12 speaker cabinets, but musicians would add a 2 x 15 cab thinking it was only “a little more,” not realizing adding the 4-ohm box was creating an overload. So we eventually switched to a high current half-bridge design with all speakers wired in parallel which worked like people expected.

Actually, we made little use of bridged outputs in our power amps at QSC. Marketing wanted us to be able to offer a bridged output from a stereo amp, and you can’t really bridge a bridge, if you will. Transistors improved greatly in the 1970s, so we were able to deliver respectable power using a single ended, half-bridged design.

Early Quilter musical instrument amplifiers.

JS: Analog solid state guitar amp technology in the 1960s had a reputation for delivering good cleans but sterile distorted tones. What made you come up with the preamp overdrive concept in your early guitar amps in the late 1960s, which predated other commercial guitar amplifier manufacturers by at least three years?

PQ: We were probably the first to offer preamp overdrive with an adjustable Master Volume control, which we called our “output power control.” I had observed that my younger brother was systematically using [amplifier] overdrive distortion as part of the hard rock sound that emerged in the late 60s. But [musicians] didn’t want to always use the full [volume] of their amplifiers, especially in small places. So, [being able to get deliberate, controllable distortion at any volume from the preamplifier section of a guitar or bass amp] was just one of those, “aha!” moments – possibly one of my few original ideas over the years – that has become a mainstay of the art since then. [We’ve evolved over the years and we can do all of our tone shaping in the preamp, where we have some fairly tricked circuits that [emulate] all the desirable properties of a traditional tube amp. Coming back to guitar amps after all these years lets me bring in Class D power technology that we developed at QSC for highly dynamic powered speakers, which supports a high output voltage swing without the losses and temperature rise you would get with traditional power circuits. Of course, I added some special circuit tweaks to make it sound good for guitar amplification.

JS: In 1968, you co-founded QSC Audio with brothers John and Barry Andrews. Was the changeover from guitar and bass amplifiers to power amps for sound reinforcement a business-driven decision or were there other factors involved?

PQ: I founded Quilter Sound Company in the summer of 1968 but we didn’t actually incorporate as QSC until 1973. In those first few years, we tried to get into the guitar amp business which seemed like a good opportunity at the time. But as fate would have it, we kind of missed the boat.

During this time, John and Barry Andrews joined the company, and we made a conscious business decision.  We needed something that would [provide] a steady business, a product that we knew would sell regardless of any change in musical tastes.

So we took stock of the technology we had developed. We had some preamp technology. Our cabinet-making shop was completely insufficient for any kind of mass production. We realized the one thing that we knew how to do that was difficult and that you couldn’t readily get out of the back of a book was [manufacturing] power amps. And so, we decided to focus on professional power amps.

QSC GX7 power amplifier.

It was a good decision that led to decades of steady growth and put the company in a position to invest in digital technology and eventually back into loudspeakers.

JS: With John and Barry on board, with John handing the financial aspects and Barry the sales and marketing, it allowed you to focus on design and engineering.

PQ: I was struggling to simultaneously run the company, design new guitar amps, manage inventory, and all that…I have my moments as a designer, but I’m not particularly good at maintaining everyday things like inventory or finances. “What do you mean our checks are bouncing? I just put money in the account two weeks ago!” (laughs)

So, Barry took over the customer [relations] side of the company and his brother John, who was finishing his business degree, joined us with some actual business knowledge. And it turned out that the three of us had complementary skills and temperaments, so we worked well as a team.

JS: As someone with a foot in both the musician and engineering camps, one of the more fascinating perspectives you have from being in sound reinforcement is the challenge of letting an audience hear what each musician is playing, as opposed to just presenting an overall ensemble “sound” to a large audience.

Given that most live music using acoustic (that is, non-electric) instruments, even full orchestras sometimes, are now projected through PA systems, do you think that calling them “acoustic” performances is now a misnomer?

QSC KW153 1000-watt powered 3-way sound reinforcement speakers.

PQ: OK, a complicated question. Let’s go all the way back to the 1920s. I have an extensive collection of vintage 78 RPM records, [and] I’m an amateur student of popular music history. The main purpose of what today we would call a “bar band,” was to be a dance band.  People wanted to go out to a dance hall, and there needed to be a good loud band to get the feet moving. Back in the day, that required what we now call a “big band.” Trumpets, trombones, saxes, drums, bass and so on, all playing acoustically. And if you’ve ever had the experience of listening to a live big band, they’re plenty loud. You have to yell to be heard over [them], just like with an amplified band.

The onset of PA systems in the 1930s allowed singers with comparatively soft voices to croon into the microphone and fill a hall. That technology carried into the era of popular singers like Frank Sinatra or Bing Crosby, who were then backed up by a smaller band. And then in the 1950s you had the onset of amplified guitar and bass [playing] along with amplified [singers] like Chuck Berry and people like that. And in the late 1960s we kind of turned everything up to 11.

But all through that time, you were principally hearing the live acoustic sound of each instrument, even if it was an amplified guitar. It was expected that the guitar amp was going to do the job of filling the hall. The PA system was only intended for a voice, or possibly an acoustic guitar or something that could not fill a hall on its own.

When I was getting into the music business, that was the model I had in mind. I didn’t really want everything to come through one big PA, because, heck, if that’s what you wanted, why not just play the studio album at high volume? It would be a cleaner recording.

QSC Wideline 10 WL 2102-w line array.

I wanted the experience of hearing live music and being able to focus my ears on whichever performer I was most interested in. But there’s a limit, of course, when you get to stadium-sized concerts, as to just how loud you can be on stage and still have a hope of covering the audience. So inevitably, PA systems became the way to do it. Even though there were those fascinating experiments that the Grateful Dead tried, where each of them had a giant slice of PA for their own use…I have to say, I went out of my way to hear that rig at one time and…it wasn’t really any better sounding than a well done PA of similar size.

So now we’re in an era where everything does come through the PA. Fortunately, the sound quality is much better than it was in the 1960s, so we can get much more headroom, more clarity; there’s a lot more science [involved in live sound reinforcement].

Nowadays, “acoustic” is basically the word for “unamplified.” An acoustic guitar or acoustic piano produces a usable amount of sound by themselves – not enough to fill a stadium, but [enough] to fill a living room – and I’ve even heard four South American guitar players fill the  Irvine Barclay Theatre, a 750-seat concert hall, with four unamplified Spanish guitars. Yes, you had to be respectful and listen quietly, but they produced a perfectly adequate amount of sound.

But today we’re in an era where you have an electric guitar plugged into an amplifier that produces a good sound, that is then miked or connected somehow to a PA which produces even more sound, and then points [the sound] in a number of different directions, including back at the performer.

JS: Taking the subject a step further – in what ways do you think that “pure” acoustic concert venues, such as Carnegie Hall or the Ryman Auditorium (home of the Grand Ole Opry from 1943 to 1974), and the construction of acoustically-proper musical performance spaces are no longer relevant because of the sophistication of today’s sound reinforcement systems and the demands and expectations of the concert-going public?

PQ: There are traditional forms of acoustic music – opera, symphony orchestras, chamber orchestras — and part of the deal is that you’re [going] there to hear the pure, unamplified sound. That’s just part of the art form. We will always have those performances and they will need to be done in acoustically well-designed halls to provide a nice listening experience for an economically viable audience size.

Europe has some really wonderful concert halls, but they don’t hold enough people to “pay the freight” if you will, unless you make the ticket prices unaffordable. [That said], I think [one of the most] interesting things these days is that there are some serious attempts to improve [or augment] the acoustics (of a space) electronically. So you can have a hall that can be relatively “dead” for plays or speaking events, but also be [made] “live” for [performances] like a symphony orchestra.

JS: Is any of the work that QSC is doing involved with that technology?

PQ: We have our Q-SYS platform. (JS: Q-SYS is a software-based networking platform that offers audio processing, control and many other functions.) I know Meyer Sound has explored [the process of transforming] an acoustic environment [with their Constellation acoustics-enhancement system]. It’s a very expensive way to go, but interestingly, it’s less expensive than building alternative spaces for different performances – let’s say you wanted a good hall for plays and a good hall for concerts. You might have to build two separate buildings, or [else] settle for compromises. [On the other hand] if the room is electronically adjustable you could have one hall serve both [functions] at a lower cost.

QSC Q-SYS components.

JS: So, the use of a PA in “purist” applications may not necessarily be a bad thing. And it kind of goes back to your original explanation about PAs used for sound reinforcement, as opposed to sound reproduction.

PQ: Yes. [On another note], history will someday look back this COVID-19 era being a period of not being able to go to large gatherings, and it may or may not leave a permanent impression on how we choose to entertain ourselves in the future. That will be a wait and see.

JS: That raises another point: the ubiquity of pre-recorded tracks, outboard effects and the use of Auto-Tune on vocals have increasingly blurred the criteria for audiences as to what constitutes a “live” music performance in a concert setting. Has the PA system transformed from being a sound reinforcement system designed to amplify the actual voices and instruments in a performance, into an extension of the recording studio? And what about the role of the front of house mixing engineer?

PQ: Well obviously, the musicians have to make the music, but the [mixing engineer] is going to determine the overall balance and the relative mix. So yes, they’re going to have to work together, and the mix engineer needs to have a clear idea of what the band is supposed to sound like. He or she is an absolutely critical part of any musical performance larger than a typical club band.


Making life easier on a gig: the QSC TouchMix 16 mixer.

The clarity and the articulation of the PA gear is crucial, and that is an area that has steadily improved over the years. It wasn’t until the late 1970s when I personally heard a PA system that succeeded in being both loud and reasonably clear, where you could actually hear the lyrics without straining. But even then, it was still not what I would call “hi-fI,” but rather a loud, clean blare, if you will. The modern live sound system has approached true fidelity to the point where the only real barrier is that sound can become warped by traveling long distances through the air. Things just don’t sound the same at 500 yards away, even if it’s loud enough.

JS: Do you think that because of COVID-19 and so many musicians now streaming live concerts from their homes, it will create a return to audience demand for more pure performance authenticity and less use of Auto-Tune and effects in these live concerts?

The Interblock 45, a guitar amp you can hold in your hand.

PQ: In the entire history of recorded music going back to the acoustic recording era of the early 20th century, you’ve had audio-quality critics. Initially, they would comment on whether or not you could [simply] hear a performer on an acoustic record sufficiently well to appreciate what they were doing. When electric recording set in, they started complaining about “unnatural effects” such as a crooner singing right up against the microphone while the band is at a natural distance. It’s allowing his weak voice to become a dominant part of the mix! That’s just totally wrong! If a singer can’t belt out to be heard with the band, he has no business being on stage!

Well, I’m sorry. In acoustic recordings, the [performers] had to crowd around the horn in an unnatural way. Caruso would get closer when he was singing softly and back away when he gave one of his famous crescendos. (Laughs) Recorded performances were unnatural from the beginning!

Pat Quilter today.

So technology gives us tools to enhance your sound, whatever it may be. Auto-Tune is [just another] way to get an interesting sound. Electric guitars got a lot of criticism when they emerged in the 1930s. They didn’t “sound right.” They weren’t just louder, they were different-sounding. But brilliant performers made them work and developed a whole new range for the instrument. [On the other hand] if you’re a bad guitar player and you get an electric guitar, you’re just going to be a louder bad guitar player. Some people use Auto-Tune as a crutch for not being able to hit a note. But I’ve heard strongly Auto-Tuned performances from artists where they’re kind of playing with [the] effect. It doesn’t diminish the value of someone who can really hit the notes. There’s room for [artistic] variety, in my opinion.

In the next installment Pat Quilter will discuss the differences between home and pro audio, loudspeaker driver design, advances in audio electronics and a whole lot more.

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