EQ’d Masters

I was in the middle of writing my post this afternoon (I usually write in the mornings but I have university commitments on Mondays and Wednesdays.) when the phone rang. An engineer friend of mine called to chat for a few minutes. Last week, he had heard the sentence that I contributed to the NPR piece on Cookie Marenco of Blue Coast Records.

My friend is a very skilled and experienced mastering engineer at one of the major record labels. He’s been working there for 12 years and was recently put in charge of their mastering studios. As we got talking, he mentioned that he has been doing a lot of work for “one of my main competitors”. It’s his job to process the master tapes that are being licensed for their high-definition digital download site. What he and I talked about was the nature of the masters that are used to generate the high-end digital transfers that customers purchase on the site.

So first I need to provide a little background information.
We did talk about this stuff when I went through the notion of what’s a master and what’s a copy of a master. Well, there’s actually more to it than that. It turns out that there are flat masters, EQ’d masters, vinyl masters, CD masters, cassette masters and archive masters as well. That’s why the engineers that work in the mastering rooms are so busy…they have to keep track of many different versions of the same record. They are all different.

A flat master is the mix as delivered by the artist, producer and mixing engineers. In the past, it was a 1/4″ stereo analog tape at 15 ips (on rare occasions it might a 30 ips master). This is the master that the artist approved. It gets handed over to the mastering house and processed for whatever delivery format is to be included in the project’s release. This might be a vinyl LP, an analog cassette CD or iTunes…or now a high-resolution download website. The processing for each of these formats is different.

The EQ’d master is a transfer of the master tape that has had it’s timbral characteristics changed through the use of equalizers. An equalizer is basically a fancy set of tone controls. There are parametric EQs, 31-band graphic EQs, three-band EQ and a few more types. A mastering engineer also has a variety of filters that they can use to change the “color” of the flat master. There are notch, high-pass, low-pass and bandpass filters.

In preparing a flat master for release on vinyl, the mastering engineer makes alternations to the flat master in order to accommodate the technical limitations of vinyl. He specifically mentioned the regular need to collapse all frequencies below a certain frequency into mono. This is done to prevent the large low frequency undulations from causing the cutting head to move into negative space…above the surface of the lacquer master disc. You don’t have to do this for a CD release…the two channels are complete discrete (not so on vinyl LPs…this is the crosstalk specification).

Another very common adjustment made to vinyl releases is the extreme elevation of all frequencies between 12-15 kHz. According to my friend, “vinyl can’t physically deliver much higher than 15 kHz” so they push the high end to get as much brightness as possible onto a medium that has difficulty in that register. The folks that are all about vinyl LPs being the best representation of a recording are kidding themselves. They get a particular flavor that is unique to that format. It is NOT the same version that you would experience on another format. And it’s not best representation of the album.

But it just might be the version that is transferred to a 192 kHz/24-bit soundfile because it’s convenient, inexpensive to produce and doesn’t require any artist approvals.

Stay tuned…more tomorrow.


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.

5 thoughts on “EQ’d Masters

  • Glen Finn

    I realize this comment is much after the fact. I was trying to research which download sites are forthcoming about what master was used for a Hi Rez release. Your post popped up and was an excellent piece. I’m hoping you get notified when a new comment gets posted. Since the term “remastered” is essentially meaningless and since my experience with HD Tracks has yielded much variability and some disappointment, can you recommend which download sites actually discloses data on the masters and maybe *some* technical data on the conversion process used? Thanks.

    • Admin

      The reality is that most of the albums on most of the sites come from the same source…the labels do the transfers and offer them in digital form to their licensees. The sites that do the real deal are iTrax, 2L, Linn, Pentatone, Channel Classics, Native DSD (if you want DSD), and Blue Coast Records.

  • Musiclover

    “According to my friend, vinyl can’t physically deliver much higher than 15 kHz”

    Thanks for pointing this out! Reading articles by people who talked to the folks cutting records, they
    came to the same conclusion. And it seems the more you play a certain record the worse it gets.

    On the other hand there are experts who say different:

    “Vinyl is superior to CD in many ways. Vinyl playback has a far wider frequency response. It can extend well beyond 40kHz and down to 16Hz where room “sound” and some organ pedals go. CD is 20H-20kHz and brick wall filtered on top. When CDs were introduced the apologists claimed ‘perfection’ but anyone who listened could hear the horrible filters ringing and pre-ringing and the unnatural HF filtering still ruins the experience. While we can’t hear above 20kHz all of the spatial cues that keep the brain engaged (and which we’ve depended upon for our survival) exist beyond 20kHz. The reason people no longer sit and listen to music the way they once did during the LP era is not because today there are “other distractions” or because of the “LP ritual”. It’s because after a few minutes of CD sound the brain says “GET ME OUT OF HERE”. That is why people today listen to music on CD while DOING SOMETHING
    ELSE (reading, cleaning, exercising). Try sitting and listening to a CD while doing nothing else. It’s IMPOSSIBLE.” (Michael Fremer)

    • Vinyl can do a pretty good job with frequency response…nothing like the claims of Mr. Fremer, but certainly as high as 20-30 kHz. And that’s only if the source audio contained those frequencies…and analog tape struggles at those rates. The compromises required to make a vinyl LP are too prevalent for me to bother when PCM digital beats every measurable spec over vinyl and analog tape. Michael may prefer the sound of vinyl but he his “facts” are his personal opinion. He likes the distortions and “warmth” of vinyl, OK fine. Others prefer clean and accurate. I’ve listened to PCM digital at CD rates and high-res rates and it’s glorious. Much better than vinyl or analog tape.

    • @musiclover you said ‘experts’ then you quoted Fremer! LOL, seriously. Anyway, ask him this question (he won’t know the answer but he might know someone who does): What AMPLITUDE can vinyl reproduce 16 Hz and 40 kHz, referenced to the peak amplitude at 1 kHz, without causing severe problems? For PCM the answer is 0 dB across its full bandwidth.


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