Mastering FAQ


Mastering Engineer
Apr 25, 2009
London UK
Here is a mastering FAQ that may be of use to people, happy new year !

Can I send my tracks one at a time for mastering?

Absolutely, though do bear in mind if the tracks are destined to appear on the same release that it can be of benefit to master them as a single product in one go.Though in many instances this is not the clients preferred way of working.Most ME's will keep the masters so the previous tracks can be referenced as the overall job proceeds.

What are ISRC codes and where do I get them from?

In the U.K. officially from here :

The relevant body differs from country to country but many of my clients have great success (much lowered costs) with CDBaby. You can register your music releases here and request ISRC codes to be sent to you for the tracks. ISRC codes are required to uniquely identify each track and allow automated royalty payments. They can take up 4 weeks from CD Baby so do this well in advance of your release.

I have just paid for a mixing engineer why should I get my music mastered?

Well the mix room may not have had optimized acoustics and very high resolution monitors and so a specialized room and accurate monitoring in a mastering studio will be able to address overall tonal issues missed in mixing.(As an example I use PMC IB1 monitors
Coupled with the ears of a very experienced engineer you get a second opinion if required and a fresh set of ears on your mix away from the pressures of the mix room. During the mix stage overall balances will have been carefully chosen and the dynamics of the track will have been concentrated on. Mixing is often performed under some time pressure and sometimes edits, extraneous studio noises, thumps, pops and other glitches can creep into the mix un-noticed, in mastering these sonic issues are identified, advised on and rectified. And if the music has been produced in a home studio again the acoustics may have been far from perfect.

Why does pricing for mastering vary so much?

Some companies have very high overheads, high rents, loans on equipment and decor and are using top name mastering engineers who demand higher rates. Then at the other end of the market the bottom line is there are chancers operating in the market charging as little as £10.00/track, many recording and mix studios are having a tough time out there and are offering mastering services, it's a mine field , be very careful when someone advertises incredibly cheap rates for mastering, ask yourself..

What is the experience of the engineer?
What equipment are they using?
What monitors are they using?
How well acoustically treated is the mastering room?
Can the correct attention to detail be taken for the rate being asked?
Can the engineer spend time uniquely processing your music for the rate being asked?

I suggest always getting a free preview from a couple of mastering studios so you can hear the differences be it expensive or lower cost.
It puts power in the clients hands.

What is the ultimate point of mastering?

Bring a number of mixes together as one product (especially if mixed on various systems/studios)

Insertion of sub code data to receive your royalties.

Insertion of CD Text and Barcode information.

Add fade ins and fade outs and space the music tracks on disk.

Quality control check on your spectrum through an accurate
room and monitoring system.

Critically listen for vocal pops, glitches, bad edits, thumps, extraneous studio noises, distortion, clicks etc, out of phase mix elements.

To subjectively improve the sound quality of your mixes if necessary.

To correct common problems in frequency response.

To correct/advise on mix problems which may cause playback

To increase perceived punch and if desired loudness with
least amount of artifacts introduced.

If requested, critique of existing mixes.

Increase likelyhood that your CD/DDP master duplicates/replicates at the plant correctly and has a technical contact.

To say your music has been mastered alludes to the fact that you take your musical output seriously.

To maximise compatibility across a variety of playback systems, such as nightclubs, radio broadcasts and online playback.

If requested to subjectively colour the music, warm it up, increase depth,add body, add a sense of fullness or round it out, a skilled mastering engineer should be able to interpret what you mean and what will enhance the music.

What is stem mastering?

Stem mastering is relatively rare and only happens if there are continued issues of balance, it is probably used in less than 5pct of mastering jobs.Stem mastering is a hybrid of mastering and mixing, it takes exported files of grouped instrumentation i.e. drums, bass, guitars, synths, vocals (normally stereo files with the mix effects included in the files) and offers further flexibility in tweaks that the 2 track does not afford. Stem mastering is only required if there are issues with mix balance or if the artist if not 100pct satisfied with the mix balances achieved at mix stage.

What file format is best for sending to a mastering engineer?

24bit resolution .wav or .aiff is preferable at your project/session sample rate.
(check the export/bounce window of your DAW for the "Bit Resolution" 16bit is ok (but not optimal)

It is preferable to do the following when sending your music :

1)Make sure the mix is not peaking above zero (clipping) this is identified by your DAW output meter exceeding zero (0dBFS)
2)Remove any limiters or compressors from the stereo bus (making sure that this does not make point 1 happen), it is ok to leave the compressor if it is deemed an essential part of the overall sound character of the mix.

It is not a good idea to request mastering of an MP3,Ogg Vorbis or WMA file(unless this really is all you have)as these are compressed file formats and have lost some of their sonic quality as the file size has been reduced.The best sounding masters come from 24 bit .wavs or .aiffs.

How do I send my music to be mastered?

Check with your engineer, but I have had great success with (free up to 300MB) and (free up to 100MB), both sites have a desktop upload application which is worth installing as the upload speed is around 30pct faster. And of course you may have your music on CD-R or possibly a DAT tape so postage is also a means of delivery but always "Special Delivery" IMO and preferably with a back up of the medium kept with yourself.

What tools do you use in mastering?

A huge focus is put on the tools of mastering and of course they are important, jobs need to get done and we all like audio equipment !
The most common tool I find myself using and one which I could not live without is the equalizer. Most jobs get EQ'd, tonal balance and
correction of problems is done with EQ. Then we have compression, limiting and occasionally multiband compression to fix specific problems and sometimes character processing to "warm up" audio if requested. Arguably engineer skill/hearing, monitoring and room response are more important.



Mastering Engineer
Apr 25, 2009
London UK
What can mastering do and not do?

Well a big part is quality control, catching glitches, adding fades, spacing and sequencing tracks, rebalancing dynamics with a fader ride. However popular mastering discussion tends to focus on processing the audio. Mastering cannot generally make a bad mix good. If you have serious mix balance issues these are not going to be addressed as successfully as a few mix tweaks, so any M.E. should be able to offer some mix advice if the mix is out of the ballpark for sensible balance. Remember, in mastering when you EQ the vocal you EQ the snare, when you eq the kick you eq the bassline. It is these compromises an M.E. holds in his mind at all times. Good mastering can make a good mix sound great, the level of improvements differ from mix to mix but there is no doubt in my mind that mastering can make a very big difference to the end result.

Shall I leave my bus compression on or off?

For this one personally I would like to hear your mix with and without, I have no desire to stop people using their lovely compressors on the mix bus and sometimes they sound great. Many times they are compressing a little too much for my taste but I do appreciate that sometimes you want your beloved on the overall mix and thats fine. Either way we work out whats best overall, even if 2 master previews have to be made.

Can I deliver Pro Tools .l / .r files ?

It is far from ideal, Pro Tools in all recent version can bounce/export stereo interleaved and this is highly preferable.

How long does mastering an album take?

Well firstly there will be a variation between engineer to engineer/studio to studio.

In general the actual man hours for a typical album mastering job is probably between 7-12 hours inclusive of final quality control (which includes a manual listen back of a CD-R in a CD player/image. However actually scheduling time can vary depending on number of rooms operating, how busy the studio is and how organized and responsive a client is. It is reasonably common to receive at least one tweaked mix for an album so there is often a few part baked jobs going through most studios. So it will vary from time to time, some months are usually notably more busy than others and a fair amount of the scheduling is related to the client themselves. Some studios may be willing to work at weekends to hit an urgent deadline.


Barry Gardner
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