Mark Waldrep, aka Dr. AIX, has been producing and engineering music for over 40 years. He learned electronics as a teenager from his HAM radio father while learning to play the guitar. Mark received the first doctorate in music composition from UCLA in 1986 for a "binaural" electronic music composition. Other advanced degrees include an MS in computer science, an MFA/MA in music, BM in music and a BA in art. As an engineer and producer, Mark has worked on projects for the Rolling Stones, 311, Tool, KISS, Blink 182, Blues Traveler, Britney Spears, the San Francisco Symphony, The Dover Quartet, Willie Nelson, Paul Williams, The Allman Brothers, Bad Company and many more. Dr. Waldrep has been an innovator when it comes to multimedia and music. He created the first enhanced CDs in the 90s, the first DVD-Videos released in the U.S., the first web-connected DVD, the first DVD-Audio title, the first music Blu-ray disc and the first 3D Music Album. Additionally, he launched the first High Definition Music Download site in 2007 called iTrax.com. A frequency speaker at audio events, author of numerous articles, Dr. Waldrep is currently writing a book on the production and reproduction of high-end music called, "High-End Audio: A Practical Guide to Production and Playback". The book should be completed in the fall of 2013.

28 thoughts on “A Survey of Mixes…at 37,000 Feet

  • Reading your above comments about traditional stereo, I’m reminded of your latest Blu-Ray sampler. While the sound is unabashedly spectacular, I found that your approach to microphone use and placement to be simply wrongheaded. Assuming that all the microphones in the videos were being used (and that is an assumption on my part), I was appalled to see THREE microphones on the piano! and the three microphones were INSIDE the piano, inches from the strings, no less. I don’t know of anyone who listens to a piano with their heads inside the piano, under the lid. The result, in a stereo recording, is a piano as wide as the listening room and with a metallic quality that a real piano, playing in real space, just doesn’t have. Also, none of the recordings on that sampler have any image at all. This is caused by your microphone per instrument approach to recording. You asked about traditional stereo, I’ll give you one rule of thumb that I learned from the likes of C.R. Fine, Lewis Leyton, and Rudy Van Gelder: “Mike the space the instruments (ensemble) occupies, not the instruments.”

    Also on one recording, you have a solo flute which seems to have been “frapped”. One should never use contact microphones on what are advertised as “audiophile grade” recordings. The contact mike on the flute picks up none of the “chiff” of the flautist’s breath across the fipple of the flute, and this is as much a part of the flute sound as are the notes themselves.

    Don’t take these criticisms too harshly. I believe that you want to make and market the best recording there are, your lecture at the S.F. Hi-Fi show convinced me of that. To do that use minimalist real stereo miking techniques and people will praise you to the reverberant hills for making that decision.

    George M. Graves

    • George, I’m not sure where to start. It’s not everyday that I get a comment that has “unabashedly spectacular” and “wrongheaded” in the same sentence. I’ve written extensively on the miking technique that I use for pianos (you can read one of the posts here) and am thrilled at the response I’ve received from reviewers, pianists, and listeners…if it’s working, I’m not inclined to change things. You said, “I don’t know of anyone who listens to a piano with their heads inside the piano, under the lid.” To which I would simply say, I don’t of anyone who listens to their stereo system with their heads right up next to the speakers, either.

      My basic idea is that by recording the intimate sound of the instrument with two stereo pairs of microphones (not THREE) close to the strings and sound board and then reproducing it from a set of speakers, the ultimate instrument to listener distance approximates the real life distance in a chamber music hall. That’s the sound that I personally prefer. If I was to use the traditional technique of placing microphones 15 feet back from the instrument, the final distance would be 15 feet plus the distance from the speakers to the listening position…which loses the detail that my recording have.

      Stereophile magazine reviewed some solo piano recordings years ago and made special mention of how the sound of my piano recording of Anita Chang was superior to a recording of Maurizio Pollini on DG…I was obviously very pleased. And my recent 3D recording of Byran Pezzone performing on the 9-foot Steinway at Zipper Hall prompted him to state, “I’ve never heard a piano recording that actually sounded like what I hear when I play…until now.” Using stereo pairs maintains a sense of depth and imagery that others are hearing in these tracks.

      There are obviously lots of ways to record individual instruments and ensembles. While I appreciate the “Mike the space the instruments occupy, not the instruments” comment, it’s an expression of a particular style of recording and thus only one among many. I have developed another approach.

      As for the contact microphone that is present on James Walker’s flute, he insisted on using it during the recording. However, the sound recorded from it was not used during the mix for the reasons that you stated. I would never use a microphone of that quality on my recordings. I left it there to keep the artist happy. He uses it during his concerts and wasn’t sure about the stereo pair that was floating over his head. When I played the final mixes for him in the studio, he was thrilled at the quality of the sound and the overall blend of the instruments. He was very happy again.

      I’ve adopted a hybrid approach to making my recordings and the feedback that I get from virtually everyone that hears them is extremely positive…more on the “unabashedly spectacular” side of the scale than wrongheaded. If my methods are “wrongheaded” and we continue to receive kudos and awards, then perhaps more engineers and producers should try this approach. My favorite listener comments usually include “blown away”, which I particularly enjoy. George, I’ve been at this for a very long time and do recognize that others may prefer a different sound or mixing style…and I appreciate you taking the time to post your comments. But there’s not such thing as a right or wrong way to record a performer or ensemble…whatever delivers the intent of the producer, artist, and engineer should be embraced.

  • Andre le

    Hey Mark – he plays alto sax on Take Five 🙂

    • I apologize for the error…I was going to confirm whether it was a soprano or alto but was late with the post and let it go. My bad.

  • Mark….. Paul played Alto, goodness. Yes the 2 mic staged low bandwidth tape of that error still thrills and sometimes knowing the groups stage placement adds to the memory, I love that actually. Really hate the one sided panning going on today not to mention narrow stage playback. This Brubeck tone, perhaps to Dave’s credit, is some of the better relaxed analog musicality to which I still judge all else. When the instruments sound correct, the music follows.

    • My mistake…I should have checked it. As for the overall fidelity of Dave’s piano and the band in general…all I can say is that I would love to have a time machine and be able to capture the quartet using my techniques and equipment. “Take Five” in 5.1 surround “stage” perspective would be a dream come true.

  • John Pyburn

    I think you are on to something in modern mixing “styles” being more centered. I have an upgraded system in my car, and for a while I thought there was something wrong with either 1) my system, or 2) what XM/Sirius was broadcasting. After much comparison, it turned out to be track specific – the front door and dash component speakers can disappear (in a bad way) with some mixes from the last 15 years or so. On other tracks (more often from my iPod, USB stick, or CD, but also from the radio) there is a nice little soundstage that opens up right in front of me. I just don’t get it. Who sits in a studio and says “hey, that sounds great like that”?

    Thanks for all you do. And I appreciate the education and the thought-provoking way your mind works.

    John P

  • Camilo Rodriguez

    Hi Mark,

    As you know, I’m always there to try to conceptually counter your take on what you call a “documentary” approach to recording, when it comes to the merit A/B stereo recordings, and the attempt to capture a soundfield vs trying to put one together from multiple tracks.

    I have a question regarding good stereo recordings, like some of those – unfortunately not all are great – made by Chesky Records and MA Recordings, and if you also experience them as “flat” on your setup? I’m thinking of a couple specific recordings:

    David Chesky – The Body Acoustic (Chesky Records)
    Silvia Perez Cruz & Ravid Goldschmidt – Llama (MA Recordings)
    Nima Ben David – Viola da Gamba (MA Recordings)
    Sera una Noche – La Segunda (MA Recordings)
    Mark Nauseef – With space in Mind (MA Recordings)

    (Also some of Morten Lindberg’s recordings include a stereo version which is from a pair of omnis, and some are remarkably good.)

    There are other important guys in audio who still support stereo and binaural being superior to any 5.1 surround recording, like Siegfried Linkwitz and Edgar Choueiri, and who I believe have make good points.


    • David, Todd, Morten, and I are friends and I do appreciate the quality of their work. Todd has mastered the art and science of capturing a space where music is being performed. The openness of the sound, the direct to reverberated sound, and the blurring of the ensemble into a real life blend is laudable and appreciated by many. It’s just not my preferred sound. As I’ve written repeatedly…I need to be closer to the sound. Using multiple stereo pairs of microphones close to the sound sources produces a sound that I like…and obviously many reviewers and customers agree.

      • Camilo Rodriguez

        My immediate question back to you would be:

        Don’t you think that your choice for what you call a more “aggressive surround mix” plays right into the hands of current industry recording practices and the acquired taste for how recorded music should sound which these recording practices have instituted over time? Recording practices that you otherwise fiercely criticize, and whose wrongs lie precisely in taking a more spectacular and entertainment approach vs what you ironize as “documentary approach”.

        A couple of posts back you sounded far more “agressive” regarding this documentary approach” than pointing to a mere personal preference when defending your privilege of a more “aggressive surround mix”, making the “documentary” crowd sound like a bunch of dusty and outdated old farts that have to jump on the wagon of multitrack and DSP before it’s too late:

        “Some traditionalists cling to the outdated model that a music recording is supposed to be a sonic documentary. They believe that any audio reproduction should strive to recreate the sense of being in a room with the live musicians. That notion was abandoned years ago when multitrack recording equipment and extensive overdubbing became the standard way of producing commercial recordings. Les Paul and Mary Ford laid down multiple layers of harmony guitars and vocals that could only be played from records”. (What’s so natural about stereo?, 3 October 2014)

        I think the gentleman that pointed towards the surround mix of your recordings that feature video of the performance, and the coherence of the soundfield of the venu, with that of the video, made a great point. A point that you again, in my opinion, dismiss to quickly with the entertainment prerogative. I believe that the enjoyment or entertainment, if you wish, also suffers from the incoherence of trying to put back together a soundfield from multiple tracks, rather than capturing it as is, in stereo.

        This is THE point that Edgar Choueiri makes in favor of Stereo – or Pure Stereo (purified from crosstalk, etc.) – and logically in detriment of Surround, and which is a crucial point of his Pure Stereo concept, as it clearly points to the flaws of Surround as 3D audio:

        “Pure Stereo has nothing to do with surround sound. Surround sound, which was originally conceived to make the sound of movies more spectacular, does not (and cannot) attempt to reproduce a 3D soundfield. What 5.1 or 7.1 sur- round sound aims to do is provide some degree of sound envelopment for the listener by surrounding the listener with five or seven loudspeakers. For serious music listening of music recorded in real acoustic spaces, audio played through a surround sound system can at best give a sense of simulated hall ambiance but cannot offer an accurate 3D representation of the soundfield.

        In contrast, Pure Stereo’s primary goal is accurate 3D soundfield reproduc- tion. It gives the listener the same 3D audio perspective as that of the ideal listener in the original recording venue2. Soundstage “depth” and “width”, concepts often used liberally in hi-end audio literature to describe an essentially flat image (relative to that in Pure Stereo), become literal terms in Pure Stereo. If, for instance, in the original soundfield a fly cicrles the head of the ideal listener during the recording, a listener of that recording played back through the two loudspeakers of a Pure Stereo system will hear, simply and naturally, the same fly circling his or her own head. If, in contrast, the same recording is played through standard stereo or surround sound systems the fly will be perceived to be inside the loudspeak- ers or, through the artifice of the phantom image, in the limited vertical plane between the loudspeakers.

        Fortunately (and perhaps to some, unfortunately) flies do not generally buzz around during the recording of great musical events3. However, an acoustically recorded real soundfield is replete with the 3D cues, if not buzzing insects, that give the brain of the listener the proper information it needs to correctly perceive true depth and width of a sound image, locate sound sources in 3D space, and hear the reflections of sound and the reverbation that occur naturally in the space where the recording was made. For instance, recorded applause in
        a concert hall, or laughter or chatter in a jazz club, will be reproduced with uncanny accuracy, and would appear as near to the listener as they were in the original venue during recording.

        Pure Stereo allows the transmission of these recorded cues (which are critical for the perception of a realistic 3D space) by removing an artifice that occurs during playback through loudspeakers (see Q&A 10) and which would otherwise corrupt the natural reception of these important cues by the listener.
        Surround sound does not even attempt to do that. Furthermore, surround sound, like standard stereo, is inherently plagued by so-called comb filtering problems, which are caused by the mixing of the sound waves emanating from the loudspeakers and arriving at the ears of the listener4, even if the listener is sitting in the “sweet spot”. Pure Stereo, in addition to its primary role of reproducing the 3D soundfield, automatically corrects these comb filtering problems and flattens the frequency response at the ears of the listeners, as well as other (spectral and temporal) non-idealities of the loudspeakers, the playback hardware, the listening room (see Q&A 19). It even compensates for the individual features of the listeners outer ears, head shape, and torso (see Q&A 11 on customized Pure Stereo filters), which affect the spatial fidelity of the reproduced sound.”

        I’ll leave it there for now, and give you the floor, but I believe this discussion to be important and relevant to the future of recording practices and also very much relevant for how recording practices will develop the future of HRA. Why not a piece – or series odf post – on Choeuiri’s work and maybe an interview? Would be an interesting topic and in depth discussion worth going for here.


        • Camilo…you might get the award for the longest comment. Perhaps I should dedicate an entire post to the Pure Stereo initiative…I have the pdf paper open in my browser and have been intending to speak to the issue in more detail.

          There are those that seek to use modern recording technology to capture and reproduce the sound of a live concert complete with all of the sonic cues from the hall and environment. And there’s another group that uses the same technology to craft music tracks that have little if any connection to a real life music experience…this group dominates today’s music business. The traditionalist or “give me a live sonic documentary” group includes the Pure Stereo types, Ambisonics fans, binaural practitioners, and Grateful Dead groupies. The rest of the music industry has traveled the road started by Les Paul. Produced records are not recreations of live events…there’s entirely studio productions that please music fans.

          My own preferences tend towards the multichannel group…although I believe that I’ve carved out a unique hybrid approach. I record everyone at once like a live session. I record them playing and singing on the same stage…without overdubs, eq, reverb, dynamic processing, or overdubs. I use stereo microphones close to the sound sources AND mikes in the hall and simply mix for location and level. It’s not the purist approach of 2L or MA Recordings but it does provide me a sound that I much prefer over Pure Stereo, which I find distant and lacking in details. This is personal taste and shouldn’t be taken as a directive for everyone to engineer their records this way. But the feedback that I get from listeners has always been and continues to be very complimentary.

          I’ve heard the Pure Stereo stuff through headphones and speakers and it’s just not interesting to me…in spite of the fact that I did my doctoral dissertation on binaural recording theory and practice. Surround sound recording and mixing is a completely different animal. While it’s true that it was developed for movies, it does wonderful things for music as well. When I play a 5.1 surround music mix through my standard film speaker array, everyone is thoroughly impressed. I don’t agree that 5.1 surround is plagued by comb filtering…if any of the formats suffer from that it’s Pure Stereo…or binaural played back through speakers.

          I’m intrigued by Choeuiri’s work but not really engaged by the results. I would be happy to write about Pure Stereo…stay tuned.

          The goals are different for the these two groups.

    • Craig Allison

      Hi Camilo , Stereo isn’t perfect or capable of recreating a “live” sound-field, and neither can 5.1 or 7.1. But… the stereo illusion, or “Magic Act” as Mr. Linkwitz likes to put it, when properly reproduced, definitely does allow great and time-proven access to the emotion and intent of the artist and music. As Siegfried would put it, it’s about the sound, but it’s also about what happens “after the ears.” Best,Craig

      • Any speaker layout or configuration has advantages and disadvantages…they are used to deliver music in a realistic or creative way. Some people are going to like the Pure Stereo and others the intensity of sitting in a 5.1 surround field. I say let them decide once they’ve hear the two.

  • Could the narrow sound be aimed at the “kids of today” who walk round with only one ear piece in, listening to music while chatting with their mates? Wide sound mixes would lead to them missing half the music.

    • I hadn’t thought of that…but you may have a point.

  • Kit Kimes

    As I mentioned in one of my comments a couple of days ago, it has gotten to the point that I can’t tell on some albums if it is even recorded in stereo, or if it is just mono send to 2 speakers. I hate that narrow stage effect. I don’t want to return to the days of ping-pong stereo, but I do want to be able to close my eyes and visualize approximately where on the stage the various instruments are located.

    • I don’t require that the mixes follow a “live” layout plan…but the instruments and voices should span the space from left to right.

  • Hi, im sat in front of my computer and my near field monitors are 1 meter away and an approximate angle of 40 to 50 degrees between them. If i projected the angle backwards to an imagined stage on which a band etc would be playing where would the performers actually be and where i would hear them to be? This is a clumsy way of asking the question, how do you position the performers in a studio mix to get an accurate stage position when the listeners speakers are so close? Obviously if the engineer / artist / manager etc wants a more artist stereo position these questions are moot. But i know when i have mixed them, and only a few mind, i do position them drums center, bass right, guitar / keyboard left as i tend to see them live. Thanks for your daily thoughts.

    • I mix a stereo pair that contains the primary sound of an individual instrument.

  • I love the way the instruments sound on “time out”. The sound of the room really adds to the sense of realism for me particularly the drums.

  • Joe Whip

    As great as her music is and her performances, the sound of Adele’s CDs is dreadful. Narrow, bright, brittle and compressed. If you want to hear a great pop mix with a jazz flavor, check out Jamie Cullem’s Twentysomething released in 2004. I was listening to it late last night. It is open and wide and fills the room with sound. A tad and I mean just a tad hot on the top end but still very listenable (via a rip onto my computer). I wish all pop CDs sounded this good.

    • I wish I could share the album that I made with Jennifer Warnes…it’s as close to perfect as I’ve every accomplished.

  • Vince Stone

    Given that much popular music is sometimes listened to by young folks sharing earbuds, perhaps the minimal separation is on purpose.

    I am reminded of tracks from the late 60s and early 70s where instruments wander and/or fly from side to side. Discovered this just this morning on Abbey Road. Judy In Disguise (with glasses) effectively shifts between mono and stereo. In other songs from the era you can actually hear poorly conducted instrument movements between parts of a song. I read recently that Don Mclean wanted American Pie to start in mono and end in stereo (but the technology at the time couldn’t support that?).

    • Sharing earbuds…I hadn’t considered that.

  • Camilo Rodriguez

    Sorry for the excessively long post, but I thought it was interesting to post Choueiri’s entire passage.
    I would love to hear your thoughts and in-depth take on Choueiri’s Pure Stereo concept, and didn’t know you had had the chance to audition a rig with his c-BACCH digital filters installed. You mention that you listened to Pure Stereo over headphones, but I understand that Pure Stereo solves the crosstalk problem for speakers, and that according to Choueiri, do a better job than headphones when it comes to reproducing a soundfield in 3D (https://www.princeton.edu/3D3A/Publications/Pure_Stereo.pdf)

    It would be interesting indeed to have a couple of your posts on Choueiri’s work, and even more so if you could get him to install the c-BACCH filters on your rig, or if you could visit his lab and report on your impressions. I’m pretty sure he’d be interested in having someone that really understands what he’s hearing and that can fully appreciate the potential of Pure Stereo have a go at his lab, and even with your own recordings.

    Anyhow, thanks for the your response, I’ll definitely stay tuned for more on this topic. It obviously goes beyong the interesting work of Prof. Choueiri, and touches the topic that you so well explained: the industry has walked down a distintive path when it comes to recording, and following the pioneering work of Les Paul, v/s a classical stereo approach, which could well prove to have more in store for us now after Prof. Choueiri’s research and applications.



  • As a headphone listener, I’m only satisfied with narrow sound image. It sounds more realistic to me.

    • Really? I’d love to get your opinion on the Headphones[xi] mixes that are on the FTP site.

      • Actually it depends how wide soundstage the headphones have. Headphones with not so wide soundstage, like Stax SR-x07 series, which (if I remember correctly) you are using with Smyth Realiser to demoing your records, benefit records with wide soundstage. Phones with wide soundstage by their own (Stax SR-009 and Sennheiser HD-800, for example), those record sounds too wide.

        About headphone samples on your FTP-site: I prefer soundstages of the headphone versions, but tonally I prefer normal stereo mixes. Midrange frequencies of the headphone mixes are too prominent for my ears and my phones. Stereo mixes sounds very good to me, but acoustically little dry, and some samples sounds too wide for phones.

        I know its very difficult (actually impossible) to make mixes for headphones, that sounds natural to every listener: we all have different spatial hearing.

        My rig: Lynx Hilo converter -> Stax SRM-727II amplifier -> Stax SR-009 phones.


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