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[Edit 10 June 2017: Tutorials for demastering your music tracks using the method described in this thread follow: Demastering Part 1 (What and Why).pdf Demastering Part 2 (How To).pdf Part 3 (Advanced Topics) will follow shortly.] Recently I bought a new/old stock (NOS) CD from Amazon, originally recorded on analog tape in 1976, released on vinyl then much later re-released on CD. My particular CD dates from 1990, just before the wide distribution and use in 1991 of multi-band music compressors, and with it the Loudness War on popular music. When this particular CD arrived it was basically unlistenable, i.e., it sounded exceptionally strident and devoid of bass, but retained its music dynamics. At this point, I decided to investigate the reasons why it sounded so bad. My tool of choice: the freeware tool Audacity. What is the Issue? When looking at the frequency spectrum averaged across most of this music track, it's easy to see a few characteristics: The decreasing slope with frequency across its full spectrum (more on the reason for this later) Frequency spikes of narrow width across certain areas of the spectrum A slight "hump" or rounded spectrum from 1000 Hz to about 13 kHz A steep roll-off of low frequencies below about 80 Hz Some immediate questions arise: Is the roll-off toward higher frequencies normal (i.e., is it there in the original master recording before any changes are made to it)? Are the frequency spikes normal? Is the frequency hump from 1-10kHz normal? Is the much steeper roll-off of low frequencies below 80 Hz normal? I found answers to these questions: Roll-off of frequencies from low to high is normal, since the frequencies themselves double in their inherent energy for each increase of an octave - i.e., a -5.5 dB/octave is present in all typical recordings (note: don't confuse this effect with the Fletcher-Munson curves of equal perceived loudness). In fact, any departures in the averaged frequency spectrum from this linearly decreasing amplitude behavior with logarithmic frequency should signal the need for further investigation. The frequency spikes typically correspond to certain types of musical instruments that do not change frequency each time they are played (i.e., piano, percussion, and especially electronic instruments, etc.). These spikes are almost always generated by the musicians themselves, not the recording/mixing/mastering processes. The frequency hump from 1-10 kHz isn't really typical of most live music. There is typically a straight line of deceasing slope tendency for averaged unamplified/unmixed music if the musicians onstage playing together get to adjust their loudness of the various music parts (assuming a multiplicity of instruments including percussion/drums, double bass, and treble instrumentation, like wind and string instruments of the band or orchestra, and voices. (This is probably the most useful observation that I found.) The roll-off in bass below 80 Hz isn't normal or desirable, unless perhaps you don't actually have to listen to the reproduced music, but only to get the music impressed onto phonograph records or CDs without having to decrease its overall loudness/gain to accommodate the very large bass/kick drum transients that are actually there in real, live music. To check the last statement to assure myself that what my ears were telling me was correct, I looked up the frequency range of electric bass guitars. Here is what I found: Note that the "B string" is for 5-string electric basses, and the "C String" for 6-string electric basses. The double bass ("string bass") nowadays has an 31 Hz open "C" string" with fingerboard extension for the lowest frequency string. Most jazz bass players nowadays have begun using 5- and 6-string basses, and therefore will have fundamental frequencies in the 30-40 Hz range. I find that most SACD recordings of jazz bass players, recorded on or after the year 2000 using DSD-only recording will have these frequencies intact on the recording, which is a significant addition to the listening experience. I also checked on the frequency spectrum of kick drums. Here is what I found for the time/frequency graph of a typical kick drum: As you can clearly see, just based on investigation of these two instrument types, the fundamental frequencies of the recorded music to accurately reproduce instrumental performance is more than a octave lower than the 80 Hz roll-off found in the example recording. On What Recordings Is This an Issue? Good questions immediately arise from the information above: why would a mixing or mastering engineer attenuate and thereby remove these frequencies from our recordings, especially in light of the information that 25% of the importance of loudspeaker performance in subjective ratings is due to its bass performance (notably bass performance well below 80 Hz)? (See Floyd Toole's book, pgs. 197 and pgs. 463-464) Is this why many CD releases made before 1991 (and I suspect many phonograph records) sound strident and bass shy when played back on high fidelity sound reproduction systems--like the ones that many forum members own? How many recordings, and of what date released and type are affected by this "mastering feature"? I've found many, many more examples of this type of mastering frequency response profile, especially from pre-1991 recordings. Most of these recordings cut the bass below 100 Hz, not 80 Hz. This is the "missing octave". For pipe organ performance, fundamental frequencies as low as 17 Hz are typical for many large instruments with 32' fundamental stops. Why Are These Recordings Missing The Bottom Octave? Isn't The Bass Originally There During Recordings? Why Would Mastering Engineers Remove Bass Below 100 Hz? This is where the story gets interesting. I've found through my now-many remasterings of different FLAC and WAV files with this characteristic is that the bass frequencies are inherently high in amplitude relative to all other frequencies (remember the decreasing slope of a typical music track, above). This means that any mixing or mastering engineer worried about compressing tracks for the sake of maintaining a "loud" sounding mix, will HAVE TO roll off the amplitude of bass track, either by using equalization filters to cut the output extremely steeply below 100 Hz, or use equalization roll-off and a multi-band compressor that further compresses the bass track disproportionately to the higher frequencies on the compressed recordings... Beginning to get the picture? If you're feeling as though you can't trust a mastering engineer as far as you can throw him/her, you've got the message. Loudness War techniques have been in existence for many years now. Why would someone buy loudspeakers that can reproduce sub-80 Hz music content with great fidelity, but then turn around and find that their music has been intentionally blanked out for 3 of the 5 strings of an electric bass or the most energetic octaves of a kick drum (in fact rendering the drums on the music track for tom-toms and kick drums indistinguishable)? If you hear bass on these recordings, what you are hearing is actually the second harmonic of the bass player or the upper harmonics of the kick drum - not the fundamental frequencies. It seems insane, doesn't it? Like a huge betrayal of trust. Trust me, you can hear that loss of an octave (or more) and it's not very nice to listen to, IMHE. Can Anything be Done to Recover the Missing Octave(s)? Fortunately, the answer to this question is "yes", if the recording that you have hasn't been compressed using a multi-band compressor, like the Loudness War tracks made from 1991 to the present typically have. So here's the situation: if you have a CD made before 1991 (or certain other CDs made after 1991 but not using compression techniques--which I'm finding are increasingly rare, but they do exist)--excellent results can be had by re-equalizing your CD tracks. How much re-equalization? See the below Audacity filter that I use as the initial starting curve for these bass-deficient tracks (followed immediately with the "Normalize" filter in the Effects menu to re-level the output before saving the new equalized track). Note decreasing gain above 100 Hz, which I find is needed for most (but not all) tracks. I also find that there are favorite EQ curves used by the various artists that seem to run from album to album: And the "after equalization" curve: The "after EQ" track sounds a LOT better now. Highly recommended. Chris
One of the subjects of the thread on "Digital vs. analog" included a discussion of the loudness war (http://en.wikipedia.org/wiki/Loudness_war) and an online database that is systematically measuring the dynamic range of recordings: http://www.dr.loudness-war.info/. Anyone can query this database for their favorite CDs, SACDs, and vinyl rips to disk to see if their particular version of a recording has been subjected to Loudness War compression techniques. In order to do a database query, you put in an artist name and/or album into the search fields. The DR database allows its users to measure their own disks if they happen to not already be in the database using a freeware downloadable application called DR Offline Meter. You can then upload the results of their analysis of their own disks so that other may share with others and expand the database. Observations 1) CDs produced in the 80s and in 1990 uniformly have much more dynamic range than those produced/remastered in the last 20 years, particularly in the last 10 years. I've not been disappointed with most of my 80s-vintage CDs but I've been very disappointed with CDs from the late 1990s/2000s, especially "remasters". 2) Some disks that are recorded at a very quiet level sound "dull" if played back at levels that are typical for most of my other disks. However, when the preamp gain is increased, the recording comes alive. Horn-loaded loudspeakers, such as Klipsch, are fully capable of handling very dynamic recordings without accompanying audible distortion that is typical for direct radiator [cone-type] loudspeakers. 3) Disks that have very high DR ratings but that also sound very good without a great deal of boost typically have a great deal of relatively quiet instrumentation and a lot of dynamic percussion. The "James Newton Howard and Friends" CD is a gold-standard example of this. Other recordings include "Bolero" and "The Planets"--especially "Mars, the Bringer of War", which in both cases build to a very high SPL from very low SPL beginnings. These recordings are notable in that I find myself jumping up to turn the volume down at least twice during the performance when there is anyone else in the room that doesn't prefer to have loud music playing, or they want to hold a conversation. Chris
As I looked this AM at today's menu of news and online forum delights before continuing my intrepid journey remastering my two-channel music collection, something struck me: "Why do I derive such pleasure fixing these recordings over the available news-of-the-day and online dialogue with others having shared interests in music reproduction?" As I first think on the news agencies and specialist news bloggers, it isn't difficult to immediately think on changes in overall world gestalt. That picture--the way that the world looks at itself--isn't really inviting or encouraging. The various audio forums--including this one--really don't make it much of a habit to address a music lover's needs to better enjoy his recorded music over his sound reproduction system. Instead, forums mostly present a close but indirect subject: talking about hardware and individual problems using it in their collections of hardware--"which DAC did you buy today? Oh, that's got worse reviews than the brand that I own...", etc. As I look elsewhere perhaps to critics' articles on music, I don't see that which motivates me to read on. Why this is so is a subject related to my remastering knowledge. It's difficult to keep reading on now that the "cat's out of the bag", so to speak. Besides, music reviews are apparently more rarely read by most "audiophiles" that I know personally, than they might care to admit. The subject of real interest this morning is one of the most famous of W.A. Mozart's piano concertos (...you know...the 3-movement piano pieces with orchestra...). Piano concerto #20, in D minor (K. 466) is said to have been the favorite composition of Joseph Stalin (a dubious distinction at best) and certainly a composition that has drawn in many future music lovers in the past to the other compositions of this--perhaps the most famous music prodigy and composer. Why? I suppose the answer lies in its astonishing beauty and musical invention, its overall and lasting effects on the listener's emotions and subconscious state. But the real reason is that it shows me how great the accomplishments of human effort were 230 years ago. It puts into perspective that the problems we have today are nothing: how insignificant the petty present arguments and "axes to grind" are compared to the real issues of the day back then and in the years following up to the end of world wars, great famine, genocide, pandemics, poverty and malnutrition, and ignorance of effective governance systems and individual freedoms. In this spirit, I decided to stop and share a moment of what I consider to be real inspiration: hearing my recording of this Mozart piano composition essentially for the first time - without it sounding like a "table radio". The spectrum of the third movement before remastering: And the "after" spectrum: The picture of the EQ correction curve for the entire concerto: The recording comes from Decca's Mozart Piano Concertos, Alfred Brendel and the Academy of St. Martin in the Fields, Sir Neville Marriner (Decca 478 2695, disc #9). The XML file for Audacity to correct this recording (all three movements) is enclosed below. I now look at the world with a refreshed set of eyes and ears with anticipation for better things ahead. Try it yourself, for the music that inspires you. Chris Mozart Piano Concerto K466 - Brendel.XML