MULTITRACK MASTER, TRACK MASTER
This is the master containing the unmixed tracks from the recording session. They range from 2 to 32 tracks in analog tape formats, up to 48 tracks in digital tape formats, and 128 tracks and beyond on computer-based systems. On modern track masters, each instrument and voice is still on a separate track. On track masters from around 1967/68 and before, you would have two, three or four tracks of combined or compiled (comp'd) recordings. Say if you had the final 4-track master from Sgt. Pepper, on those four tracks you might have all of the Beatle's rhythm section on one track, the London philharmonic on a second, a percussion section on a third, and all of the Beatles vocals on the fourth. Regardless of the number of tracks, these masters have to be mixed to stereo (or mono) before you proceed to mastering and manufacturing. They can be analog or digital reel-to-reel tapes of varying sizes, audio cassettes, VHS or Hi-8 video cartridges, and these days thumb, USB or Firewire drives, data CD-Rs or DVDs.
STEM MASTER
Mixing audio in stems has been commonplace in the film and video industry for decades, and is becoming increasingly popular in music production. Stems are stereo or mono subgroup mixes that are then combined for the complete stereo mix. In music for instance you could mix a stereo vocal stem, a stereo instrumental stem minus bass, and a mono bass stem. This would allow the producer to easily create a vocal up version for radio, edit the vocal for a clean version, pump up the bass for a club version etc. In mastering, stems allow the engineer to process and control the individual stems rather than having to process the entire mix. Stem masters could be any of the same formats as the track masters above.
MIX MASTER, MIXES, MIX FILES, BOUNCES, BOUNCE FILES, SOURCE MASTER (in mastering terminology)
These contain the stereo mixes that have not been edited or mastered. These can be various sizes of analog or digital reel-to-reel, analog cassette tape, VHS, Beta or Hi-8 video tape, DAT tapes, audio CD-Rs, or folders containing audio files on data CD-R, DVD or any form of hard drive.
For people who record and mix 'in the box': Do not be a lazy engineer. Your individual tracks in your session folder should have proper file names, "Kick", "Snare" etc., not "Track 1", "Track 2"... Your mixes should be in one folder labeled as "Mix Masters" etc.
EDIT MASTER, BANDED MASTER, SEQUENCE MASTER, SEQ MASTER
In the analog days of vinyl, this referred to an analog mix master tape that has been sequenced and topped & tailed (noise before and after each song edited out), timed leader tape has been inserted between tracks for proper spacing, and leader tape has been added to the head and tail of the reel. It also implies that any inner-song editing has been done. In the analog days we would say these tapes have been 'prepped', meaning the tape has been prepared for the cutting room. Unless otherwise noted, this master has not had any further processing such as eq, compression or limiting, which was done at the lathe as the lacquer was cut. In today's world, mastering engineers prefer that you do not top or tail your mixes, leave a second or two of noise before and after the audio.
In the digital age, a BANDED MASTER has a new meaning. Many artists want to have some or all songs on their album crossfade between each other, have no space between tracks etc. But of course this can cause problems in the age of downloads since the ending of a song that crossfades into another song will just suddenly chop off if you download the first song only. Or if you download the second song, you hear the end of the first song fading out as the song you wanted starts. So many artists have their mastering engineer create a 'banded master' which has a basic 2 seconds or so of silence between songs. They will use this as the source for online content so the songs have clean in's and out's. This also allows them to suggest purchasing the CD if the listener wants to hear the album the way it was really intended. Unlike the analog version, this type of banded master would be implied to have all mastering processing applied. These banded masters can be on any of the media described in the next category.
PRODUCTION MASTER, PRE-MASTER, EQ MASTER, EQ AND LIMITED MASTER, PMCD, REFERENCE MASTER, GOLD DISC MASTER, DDP, DDPi
A master that has any of these labels would be assumed to have all mixing, editing, sequencing and masteering applied and is ready for manufacturing as is. Some of these need further explanation:
PRODUCTION MASTER, PRE-MASTER, EQ MASTER, EQ AND LIMITED MASTER - The standard media that manufacturers can or could accept that would have one of these labels would be analog or digital reel-to-reel tape of varying sizes, VHS, Beta, Hi-8, and 3/4" U-Matic video tape, audio cassette tape, DAT tape, red-book standard audio CD-R, and now some manufacturers will accept production master audio files on data CD-R, DVD, any type of hard drive or as uploads to a server. 'EQ Master' and 'EQ and Limited Master' are old-school terms for labeling production master reel-to-reels that were prepped for the cutting room. If your mastering guy uses one of these terms you can be pretty sure he's been around the block.
PMCD, REFERENCE MASTER, GOLD DISC MASTER - These would only apply to a CD-R. The definition of PMCD has changed. Originally, this meant 'Pre-Master CD'. This was a revolution in CD manufacturing that was developed by Sonic Solutions and allowed CD plants to cut glass (explained below) directly from a CD-R, eliminating a very expensive step that will be explained later. The Pre-Master CD was a CD-R that could only be created on Sonic Solutions mastering systems and contained a data burst that fed the TOC (table of contents) timecode information into the glass mastering program independent of the audio. Probably no, or at least very few, CD plants can use Pre-Master CDs any longer, as the CD burners that Sonic needed to create them have been obsolete for about 15 years. And now CD plants can cut glass from ordinary red-book standard audio CD-Rs. These audio CD-R production masters were originally referred to as a Reference Master or a Gold Disc Master (even though the disc may be silver or green). Some still use those terms, but increasingly they are referred to as a PMCD, now meaning 'Production Master CD'. A CD-R with one of these labels would normally be for CD replication, but often production masters for vinyl records or in the days of cassettes would have the same label. If you have a master that is labeled 'PMCD', there is really no way of telling which type it is if you don't have a Sonic Solutions system with the proper CD drive. But never fear, a Pre-Master CD will play on a normal player, and can be used by a CD plant, just like a current Production Master CD.
DDP - The DDP (Disc Description Protocol) is acknowledged as the superior production master for any optical disc medium - CD, DVD or Blu Ray. The DDP is an absolutely error-free master, which creates a superior sounding CD in the case of audio, and also creates CDs that are more reliably played by cheap CD players, boom boxes, car players etc. The DDP breaks the audio, subcodes, TOC and metadata down into separate elements, and is delivered on an 8mm video cassette created by a machine called an Exabyte. The downside is that it is still a mechanical tape cartridge, which can fail, and it requires a specific, costly machine at both the mastering room and the CD plant. So enter the future, and for some, the present:
DDPi - DDPi is a 'Disc Description Protocol image'. and is the new standard in production masters for any optical disc, including audio CDs. It contains all of the elements on a DDP Exabyte tape, but it is written directly to a hard drive in the mastering room and can then be delivered to the CD plant on a data CD-R or DVD or it can be uploaded directly to a CD plant's server. The only downside, if you want to call it that, is that you have to use a cutting edge mastering room that understands and can create a DDPi file set, like DES Mastering (www.desmastering.com) for instance, and you have to use a CD manufacturer that can utilize the technology, which coincidentally DES can steer you to.
The reason Sonic Solutions (now SonicStudio) workstations, as used by DES, have been the mastering industry's standard for 20+ years is not only because of their superior sound quality but because Sonic writes the absolutely lowest error PMCD compared to any other system. However, you would probably be shocked to see how many errors even these comparatively low-error masters have, and these translate directly to your manufactured CDs. The thing is, a CD player has a certain amount of DSP (digital signal processing) allocated for error correction. The amount of DSP being performed will directly affect the sound quality of the playback. So the fewer errors on the CD, the better the sound. That is why real mastering rooms use very specific software and burners. If the person doing your mastering is using standard off-the-shelf CD burners and software, you are losing sound quality. So to emphasize the advantage of DDPi, it is an error-locked system, meaning it is either 100% accurate or 100% fail. If it works, it is absolutely error-free, yielding the best sounding CDs possible. But rest assured that even if you are already using a plant that can only accept Production Master CDs, DES Mastering can provide you with the best quality master possible. OK, enough commercials; onward, through the fog!
Now things get a little tricky, because we have a difference in terminology between Europe and the U.S. In the U.S., what we do at DES (eq, compression, limiting, song sequencing, spacing etc.) is called 'mastering'. In Europe, this is called 'pre-mastering', and 'mastering' means that you are creating a part that will be used in manufacturing; cutting lacquer for vinyl, cutting glass for CD replication (we'll get to that) etc., and this is also called mastering in the U.S., which causes some confusion.
PCM-1610, PCM-1630
Before Sonic created the Pre-Master CD, anything going to CD replication had to be on either a Sony PCM-1610 or PCM-1630 formatted tape. Simply put, these were like gigantic DAT machines with a couple of extra analog data tracks where timecode and pq subcode info was put. The converter itself was probably 30"wx24"hx30"d and weighed 100 lbs. or so. Rather than a tiny DAT tape the digital audio was recorded onto a professional 3/4" U-Matic video tape, which required an enormous video deck. If I remember correctly, the cost of the converter with the video deck was around $25-$30,000.00. Of course smaller mastering rooms couldn't afford this, so some CD plants would allow Production Master DATs that they would then format to their 1630, for an extra fee of course. If the only master you have is one of these U-Matic tapes, there are still mastering rooms that have a 1630 system and can get your material onto a more usable format, but you would be advised to do this asap. If you need this contact us at george@desmastering.com and we will refer you to the proper people.
GLASS MASTER
Boy, does this cause a lot of confusion. With only the rarest of exceptions, glass mastering is only done at your CD plant. A few of the super high-end (and priced) mastering facilities may cut glass, but they are few. Even a lot of people who consider themselves mastering engineers get it wrong and will call the PMCD (or Reference Master or Gold Disc Master, as you now know) they create a Glass Master. Getting back to the terminology thing; the CD plant uses the European terminology - the processing and assembly done by DES for instance to create a PMCD or DDPi would be 'pre-mastering', cutting the glass at the plant from this would be the 'mastering'. This causes confusion when a plant says that mastering is included in their pricing. What they are talking about is cutting the glass master. Their price does not included pre-mastering.
The glass master is a large glass disc approx. 240mm in diameter that is painted with photo-resist. Then the digital audio from the PMCD, DDP, DDPi or PCM-1610/1630 is photo etched onto this using an LBR (Laser Beam Recorder). Stampers are then created from this and the photo-resist is peeled off the glass which is then highly polished to be used again. So the CD plant will only have a limited number of glass discs that are used over and over. This is the CD equivalent of cutting lacquer for vinyl records.
A note about production masters for download-only releases:
At the very least, this should be a PMCD. Online stores such as iTunes and CD Baby will not allow you to upload your own mp3s or AACs. They want the full resolution, CD-quality audio files. That way, not only can they create the best quality compressed files with their own CODECs, but as technology improves, like when iTunes went to iTunes+, they can create a new set of compressed files from your full-resolution upload. Hopefully, as connection speeds increase and storage gets cheaper, we will be downloading full CD-quality music, or even better.
As we've said before, you should NEVER accept an mp3, AAC or any other data compressed file as a mix master or production master. See our entry "Audio Production in the Age of mp3 and AAC" http://desmastering.blogspot.com/2009/09/audio-production-in-age-of-mp3-and-aac.html.
I intended to include a list here covering a question that we mastering guys hear all of time time; "I've found this (fill in the blank) type of tape/disc from an old session. What could this be?", but this has already gone longer than I expected. I'll do that next entry.
